Application of thermodynamic laws on a military helicopter engine

Accepted Manuscript Application of thermodynamic laws on a military helicopter engine

Coban Kahraman, Colpan C. Ozgur, Karakoc T. Hikmet PII:

S0360-5442(17)31373-7

DOI:

10.1016/j.energy.2017.07.179

Reference:

EGY 11367

To appear in:

Energy

Received Date:

28 December 2016

Revised Date:

04 June 2017

Accepted Date:

24 July 2017

Please cite this article as: Coban Kahraman, Colpan C. Ozgur, Karakoc T. Hikmet, Application of thermodynamic laws on a military helicopter engine, Energy (2017), doi: 10.1016/j.energy. 2017.07.179

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ACCEPTED MANUSCRIPT APPLICATION OF THERMODYNAMIC LAWS ON A MILITARY HELICOPTER ENGINE

1

Coban KAHRAMAN1*, Colpan C. OZGUR2, Karakoc T. HIKMET3 Anadolu University, Airframe and Powerplant Maintenance Department, Graduate School of Sciences Iki Eylul Kampusu, Eskisehir, 26470, Turkey 2 Dokuz Eylul University, Faculty of Engineering, Mechanical Engineering Department Tinaztepe Yerleskesi, Izmir, 35397, Turkey 3 Anadolu University, Faculty of Aeronautics and Astronautics Iki Eylul Kampusu, Eskisehir, 26470, Turkey * Corresponding author: [email protected]

ABSTRACT By definition, a turboshaft engine is simply a gas turbine used to deliver shaft power such as to a helicopter rotor. This paper presents the energetic and exergetic analyses of a turboshaft engine which is used for military helicopter at various load values. The main objectives of this study are to assess the performance of the engine and to calculate the amount of exergy destructions in the components of the engine. The calculations were performed at four different load values (284 N∙m for test #1, 436 N∙m for test #2, 547 N∙m for test #3 and 579 N∙m for test #4) and all analyses were performed and presented on the basis of the experimental engine ground test data together with a theoretical thermodynamic performance evaluation. The exergetic performance parameters, such as the relative exergy destruction, the fuel depletion ratio, the productivity lack, the improvement potential were also investigated. The exergy destruction values for the combustion chamber, which has the highest exergy destruction among all the components, were calculated as 1170.30 kW, 1474.50 kW, 1650.12 kW, and 1702.50 kW for tests #1, #2, #3 and #4, respectively. In addition, the ratio of the exergy destruction to the total exergy destruction was obtained to be the highest in the combustion chamber (88.81%) at test #2; whereas this ratio was found to be the lowest in the high-pressure turbine (0.75%) at test #2. Keywords: Exergy, Gas Turbine, Turboshaft, Energy, Helicopter Engine

ACCEPTED MANUSCRIPT

1 . INTRODUCTION Due to the global energy and environmental problems, researchers, scientists, and policy makers have been interested in finding solutions for the improvement of efficiency of energy systems and the reduction of environmental problems (i.e. air pollution, climate change, and thermal pollution) while taking into account the economic issues. Accordingly, more industrial sectors have started implementing sustainable energy technologies in the last decade. The aviation industry is one of these sectors, which invests on sustainable solutions for the propulsion systems aiming at maximizing the energy savings, minimizing the energy consumptions and developing environmentally benign propulsion systems [1]. In this sector, a significant attention is given to the jet engine emissions which cause serious global environmental concerns. Brasseur and Gupta [2] presented that aviation is responsible for 13% of the transportation related fossil fuel consumption and 2% of all anthropogenic carbon dioxide emissions. Greenhouse gases such as carbon dioxide (CO2), water vapor, ozone (O3), nitrous oxide (N2O) and methane (CH4) from jet fuel combustion are estimated to increase between 200% and 500% more than their values estimated in 1995 by the year 2050 [3]. Even under the most optimistic scenario about the effectiveness of technological measures, aviation CO2 emissions in 2036 are still expected to be 2.5 times higher than 2006 emissions according to estimation of a strong increase in demand for aviation [4]. In addition to environmental concerns, fuel cost is another driver for the propulsion innovations due to being responsible for 20% to as high as 50% of the direct operating cost of aircraft. Therefore, airlines and implicitly manufacturers are extremely interested in fuel saving technologies [5]. Consequently, it is obvious that fuel conservation is required for sustainable development of aviation industry. However, it is a critical trade-off for engine designers, to increase the performance of the engine with a better fuel utilization while taking into account the economical and environmental concerns. The performance of an energy conversion system can be analyzed thermodynamically using the energy and exergy concepts. These concepts have been widely utilized in thermodynamic and sustainability analyses in the literature [6,7,8]. While the energy analysis takes into account the quantity of energy, the exergy analysis deals with the quality of the energy. Exergy is defined as the maximum theoretical work accessible during a process when the system is brought into equilibrium with its environment [9]. Since the exergy unveils the degradation of energy, which causes the inefficiency of the system, it can be useful to benefit from exergy analysis in defining the type, location and magnitude of the destructions. This allows the designers to pay attention to components where the greatest exergy is destroyed accordingly, and thus modify the design of the energy system [10]. Therefore, many engineers and scientists suggest that thermodynamic performance is best evaluated using exergy analysis since it provides more insights and is more useful in efficiency improvement efforts than energy analysis [11]. Turboshaft engines are mainly used in applications that require a high power output and a reliable, small size and lightweight power producing system. One of these applications is helicopter lifting and propulsion. This type of engines is similar to turboprops and combines transmission box on the vehicle with an output shaft driven by turbine stage(s). Turboshaft engine in the simplest term is a type of gas turbine that powers a rotating cylindrical shaft. This shaft is generally used for driving a helicopter rotor. Therefore, the engine provides required mechanical power by transforming the energy contained both in the ambient air and in the fuel into mechanical energy. During engine operation, the power turbine speed is kept constant with the help of engine control, which adjusts the fuel amount injected into the engine. Optimizing the efficiency of a turboshaft engine is desired to improve the overall system performance and also to reduce the specific fuel consumption and pollutant emissions. Since working principle of a turboshaft engine is based on the thermodynamic laws, it is necessary to apply exergy and thermodynamic optimization methods in the design of aircraft systems [7]. With the help of these methods, engine efficiency and fuel utilization could be increased and the environmental impact of aviation emissions can be reduced substantially. In the open literature, several studies on exergy-based approach have been performed on aero engines. Tona et al. [12] applied exergetic methods on an aircraft engine. Authors assessed overall engine performance during complete mission and they emphasized that different dead state conditions are critical on the analysis results. Etele and Rosen [13] performed an exergy analysis to examine the effects of using different reference-environment models on a turbojet engine at various flight attitudes ranging from sea level to 15,000 m. It was found that the actual rational efficiency of the engine decreased with increasing altitude, ranging from a value of 16.9% 2

ACCEPTED MANUSCRIPT at sea level to 15.3% at 15,000 m. Balli et al. [14] investigated the energy and exergy performances of J69-T25A turbojet engine and found that exergetic efficiency is 34.84% while the component having the highest exergy destruction was the combustion chamber with a value of 3.7 MW. In another research [15], a small turbojet engine was investigated and found that 43% of fuel exergy is lost to the environment. Turgut et al. [16] made an exergy analysis of a turbofan engine with augmenter at sea level and an altitude of 11,000 m. Their work presents the exergy destructions and the exergy efficiency of each component of the engine. The augmenter unit had the highest exergy destruction with 48.1% of the whole engine at the sea level, followed by the exhaust, the combustion chamber and the turbine, with amounts of 29.7%, 17.2% and 2.5%, respectively. Another turbofan engine was assessed by Sohret et al [17] by applying an advanced exergy analysis. Maximum improvement potential was obtained at the combustion chamber with an avoidable exergy destruction rate of 2.7 MW. Sohret et al. [18] benefited from exergy analysis methodology to evaluate the performance of a turboprop engine. Energy and exergy efficiencies of the engine were calculated to be 27.89% and 26.74%, respectively. Balli and Hepbasli [19] evaluated a T56 turboprop engine in their study. Energetic and exergetic analysis of the overall engine and its components were presented for various power loading operation modes. It was concluded that the maximum destruction rate occurred in the combustion chamber and its value increased considerably with changing operation modes (i.e. load values). Aydın et al. [20] performed a component based exergetic assessment for a CT7 turboprop engine based on experimental measurements and determined performance parameters. They showed that the exergy destruction rates for all components increase as torque value increases and the lowest exergy destruction rate was obtained for the gas turbine at the maximum load value. Finally, a recent study on a turboshaft engine, which is similar to Makila 1A1 engine, was reported [21]. They performed energy and exergy analyses for the engine and its components at the maximum power ratio. According to this work, the exergy efficiency of the engine was found to be 27.5%. The exergetic efficiencies of the components were 83.8% for the compressor, 88.6% for the power turbine, 80.6% for the combustor, and 91.4% for the gas generator turbine. Several other similar studies can be found in the literature and most of these were reviewed by Sohret et. al, [22]. In this paper, energy and exergy analyses for a turboshaft engine are conducted and the performance of this engine at various load conditions is assessed. The engine analyzed is an advanced helicopter engine that is used in different climate conditions worldwide today. The main objective of this study is to assess the exergy efficiencies and destructions of the main components of the engine and also calculate some other exergetic performance assessment parameters. These parameters include the relative exergy destruction ratio, the fuel depletion ratio, the productivity lack, and the improvement potential rates. The difference of this study from the existing studies found in the literature, especially from [21], is that detailed energy and exergy assessment of the turboshaft engine and its components are performed at various load settings that are based on experimental results. In addition, the pressurization air for turbine bearings has been taken into account in this study for the energy and exergy analyses of the components of the engine.

2 . SYSTEM DESCRIPTION The selected turboshaft engine for this study (Makila 1A1 engine) is a derivative of Makila 1A, which was started to be produced in 1984. The engine is mainly used as twin-engine configuration by AS332 Puma and AS532 Cougar helicopters. The engine delivers 1820 shaft horse power (shp) while take-off and 1589 shaft horse power (shp) while cruising [23]. The engine has proved its versatility in different climate conditions and harsh military environments around the world. Although the flame temperature reaches approximately 2500 oC, the high-pressure turbine blades do not have cooling. The main components of the turboshaft engine are axial and centrifugal compressors, combustion chamber, high-pressure turbine, power turbine, and exhaust duct which are presented with their corresponding station numbering in Fig.1. The compressor rotor assembly consists of three axial stages and one centrifugal compressor stage. The three axial stages and one centrifugal stage are used to pressurize the coming air prior to entering the combustion chamber. The energy of the hot and high velocity gases is converted to torque on the transmission shaft by the turbine rotors. The reduction gear converts the high rotational speed and low torque values of the high-pressure turbine shaft to low rotational speed and high torque values in order to drive the accessories. The air first enters into the engine through bellmouth equipment. The engine analyzed in this paper is tested by a water brake dynamometer connected to power turbine 3

ACCEPTED MANUSCRIPT transmission shaft on a test bench. The power turbine speed is measured by engine and dynamometer sensors and these values are compared with each other continuously during the test. In addition, the torque transferred by the power turbine transmission shaft of the turboshaft engine is accurately measured by a torquemeter sensor. Test and some theoretical parameters of the engine and the environmental conditions used in the analyses are presented in Table 1.

3 . THERMODYNAMIC ANALYSIS 3.1

Energy Analysis

For a steady state process in a control volume, the mass balance equation can be expressed in rate form as: ∑𝑚𝑖𝑛 = ∑𝑚𝑜𝑢𝑡

(1)

where m is the mass flow rate, and subscripts in and out represents inlet and outlet, respectively. The general energy balance for a control volume at steady state can be presented as: 𝑄 ‒ 𝑊 + ∑𝑖𝑛𝑚 (ℎ +

𝑉2 2

(

+ 𝑔𝑧) ‒ ∑𝑜𝑢𝑡𝑚 ℎ +

𝑉2 2

)

+ 𝑔𝑧 = 0

(2)

where Q is the net heat transfer rate into the control volume, W denotes the net power output, ℎ is the specific enthalpy, 𝑉 is the velocity, 𝑔 is the gravitational acceleration, and 𝑧 is the elevation. The system and its components were modeled by applying the above mass and energy equations for Makila 1A1 turboshaft engine. Specific equations for the compressor, the combustion chamber, the gas turbine, and other components are given below [24]. The pressure and temperature at the centrifugal compressor outlet are given in Eqs. 3 and 4, respectively. (3)

𝑃3 = 𝑟 𝑃1

(

𝑇3 = 𝑇1 1 +

1

[

𝛾𝑎 ‒ 1

𝜂𝑐 𝑟

𝛾𝑎

])

(4)

‒1

where 𝑃, 𝑟. 𝑇, 𝜂𝑐 and 𝛾𝑎 are the pressure, the compressor pressure ratio, the temperature, the compressor isentropic efficiency, and the specific heat ratio of air, respectively. Compressor power input is determined according to Eq.5. (5)

𝑊𝑐 = 𝑚𝑎 (ℎ3 ‒ ℎ2)

Where 𝑚𝑎 , 𝑊𝑐 and ℎ are the mass flow rate of air, the power input to the compressor, and the specific enthalpy, respectively. The combustion chamber energy balance can be formulated as in Eq. 6. (6)

𝑚3ℎ3 + 𝑚𝑓𝐿𝐻𝑉 = 𝑚𝑔ℎ4 + (1 ‒ 𝜂𝑐𝑐)𝑚𝑓𝐿𝐻𝑉

where 𝑚𝑓, 𝑚𝑔, 𝐿𝐻𝑉 and 𝜂𝑐𝑐, are the mass flow rate of fuel, the mass flow rate of the gas mixture leaving the combustion chamber , the lower heating value of fuel, and the combustion chamber efficiency, respectively. The temperature at the high-pressure turbine outlet is given in Eq.7 as follows.

( [

𝑇5 = 𝑇4 1 ‒

1

𝜂𝑇 1 ‒

1 ‒ 𝛾𝑔

() 𝑃4 𝑃5

])

𝛾𝑔

(7)

4

ACCEPTED MANUSCRIPT where 𝜂𝑇 and 𝛾𝑔 are the turbine isentropic efficiency and the specific heat ratio of the gas mixture leaving the combustion chamber, respectively. The fuel burned in the engine is Kerosene type of Jet A-1 and is formulated as C12H23 [25]. The combustion reaction is given in Eq. 8. On a mole or volume basis, dry air shown in this reaction is assumed to be composed of 77.48% N2, 20.59% O2, 0.03% CO2, and 1.90% H2O. During combustion N2 behaves as an inert gas and does not react with other elements, other than forming a negligible amount of NOx [26].

{

𝐶12𝐻23 + 𝜆1

}

0.7748𝑁2 + 0.2059𝑂2 + 0.0003𝐶𝑂2 →𝜆2𝐶𝑂2 + 𝜆3𝐻2𝑂 + 𝜆4𝑂2 + 𝜆5𝑁2 + 0.019𝐻2𝑂

(8)

The combustion reaction equation constants (i.e. number of moles for one mole of fuel) (λ) for combustion gases were calculated for each load values by applying the conservation of atoms for the carbon, hydrogen, oxygen, and nitrogen, respectively. These constants were used for calculating the enthalpy and entropy values of the gas mixture at streams 4, 5, 6 and 7. The results are summarized in Table 2. Power output of the turbine can be found as follows. (9)

𝑊𝑇 = 𝑚𝑔 (ℎ4 ‒ ℎ5)

The shaft power 𝑊𝑆𝑃 produced by the engine was measured by the dynamometer and is related to power output of the power turbine according to Eq.9. 𝑊𝑃𝑇 =

𝑊𝑆𝑃

(10)

𝜂𝑚

where 𝑊𝑃𝑇, 𝜂𝑚 and 𝑊𝑆𝑃 are the power output of the power turbine, the transmission shaft mechanical efficiency, and the transmission shaft power, respectively. Exhaust duct (ED) energy balance can be written as in Eq.11. 𝜂𝐸𝐷 =

(ℎ6 ‒ ℎ7𝑎𝑐)

(11)

(ℎ6 ‒ ℎ7𝑠)

where 𝜂𝐸𝐷 is the energy efficiency of the ED and was assumed as 99%. Overall efficiency of the turboshaft engine (𝜂𝑇𝐸) is defined as the ratio of the net shaft power generated to the rate of heat input supplied, and is expressed as: 𝑊𝑆𝑃

(12)

𝜂𝑇𝐸 = 𝑚 𝐿𝐻𝑉 𝑓

3.2

Exergy Analysis

Although energy is a conserved quantity, this is not the case for the exergy, which is always destroyed as entropy is produced. Exergy analysis uses the conservation of mass and energy together with the second law of thermodynamics in order to design and improve thermal systems. The rate form of steady state exergy balance for control volumes can be given as [26,27]: 𝐸𝑥ℎ𝑒𝑎𝑡 ‒ 𝐸𝑥𝑤𝑜𝑟𝑘 + 𝐸𝑥𝑚𝑎𝑠𝑠, 𝑖𝑛 ‒ 𝐸𝑥𝑚𝑎𝑠𝑠, 𝑜𝑢𝑡 ‒ 𝐸𝑥𝑑𝑒𝑠𝑡 = 0

( (

))

𝐸𝑥ℎ𝑒𝑎𝑡 = ∑ 1 ‒ 𝑇0 𝑇𝑗 𝑄𝑗

(13) (14)

𝐸𝑥𝑤𝑜𝑟𝑘 = 𝑊

(15)

Ex𝑚𝑎𝑠𝑠 = ∑𝑚𝑒𝑥𝑓

(16)

5

ACCEPTED MANUSCRIPT where, 𝑄𝑗 is the heat transfer rate through the boundary at temperature 𝑇𝑗, 𝑊 is the work rate, 𝐸𝑥 is the exergy rate of inlet and outlet streams, 𝑒𝑥𝑓 is the specific flow exergy and 𝐸𝑥𝑑𝑒𝑠𝑡 is the exergy destruction rate. The specific flow exergy is calculated as follows: 𝑒𝑥𝑓 = (ℎ ‒ ℎ0) ‒ 𝑇0(𝑠 ‒ 𝑠0)

(17)

where s is the entropy and the subscript zero indicates the properties at the restricted dead state of 𝑃0 and 𝑇0. Eq. 17 can be also shown for air as follows applying constant specific heat approach [8]:

[ (

𝑇

)

𝑃

𝑒𝑥𝑓,𝑎𝑖𝑟 = 𝑐𝑝 𝑇 ‒ 𝑇0 ‒ 𝑇0𝑙𝑛𝑇 + 𝑅𝑇0𝑙𝑛𝑃 0

]

(18)

0

The specific chemical exergy of liquid fuels on a unit mass can be determined according to below correlation provided by [8]: 𝑒𝑥𝑐ℎ,𝑓 𝐿𝐻𝑉

ℎ

𝑜

(

𝑠

)

ℎ

= 𝜑 = 1.0401 + 0.1728 𝑐 + 0.0432𝑐 + 0.2169𝑐 1 ‒ 2.0628 𝑐

(19)

where ℎ, 𝑐, 𝑜 and 𝑠 are the mass fractions of hydrogen, carbon, oxygen and sulphur, respectively. In addition, φ denotes the fuel exergy grade function which is calculated to be 1.06789 for kerosene of type JP8 (LHV of 42800 kJ/kg). For the kerosene fuel (C12H23), sulphur is neglected in the calculation due to a nearly zero fraction of it in the fuel composition [28]). Finally the chemical exergy of exhaust gas mixture is determined as [29]: 𝑒𝑥𝑐ℎ,𝑔 = ∑𝑒𝑥𝑐ℎ,𝑖𝑥𝑖 + 𝑅 𝑇0∑𝑥𝑖𝑙𝑛𝑥𝑖

(20)

where 𝑒𝑥𝑐ℎ,𝑖, 𝑥𝑖 , 𝑅, and 𝑇0 are the molar specific chemical exergy, the mole fraction of gas 𝑖, the universal gas constant, and the environmental temperature, respectively. The chemical exergy values of the chemical species of interest are as follows: 639 kJ·kmol–1 for N2, 3951 kJ·kmol–1 for O2, 14176 kJ·kmol–1 for CO2 and 8636 kJ·kmol–1 for H2O [29].

3.3

Performance assessment parameters of the system components

Exergy efficiency, which aims at measuring the degree of thermodynamic perfection of the system, can be defined as the ratio between the useful exergy output to the consumed exergy input. Therefore, exergy balance and exergy efficiency equations for the main components can be written as shown in Table 3. In addition to the exergy efficiency, other thermodynamic measures are useful for the evaluation of a system. These include the relative exergy destruction 𝜒, the fuel depletion ratio 𝛿, the productivity lack 𝜁, and the rate of exergetic improvement potential 𝐼𝑃. A detailed study of these parameters was reported by [30,31]. Descriptions of these measures are as follows [32]. Relative exergy destruction 𝜒 gives the exergy destruction of any unit as a percentage of the total exergy destruction for the entire system. 𝐸𝑥𝐷,𝑘

𝜒𝑘 = 𝐸𝑥

(21)

𝐷,𝑡𝑜𝑡𝑎𝑙

Fuel depletion ratio 𝛿 expresses the exergy destruction for a system unit as a percentage of the total fuel exergy and can be written as 𝐸𝑥𝐷,𝑘

𝛿𝑘 = 𝐸𝑥

(22)

𝑓𝑢𝑒𝑙,𝑡𝑜𝑡𝑎𝑙

Productivity lack, which is similar to the fuel depletion ratio, gives the product loss in the form of exergy destruction or shows how much product exergy potential is lost due to exergy destructions. Productivity lack 𝜁 can be shown as 𝜁𝑘 = 𝐸𝑥

𝐸𝑥𝐷,𝑘

(23)

𝑝𝑟𝑜𝑑𝑢𝑐𝑡,𝑡𝑜𝑡𝑎𝑙

6

ACCEPTED MANUSCRIPT Rate of exergetic improvement potential expresses the rate at which the system could be improved further. The rate of exergetic improvement potential 𝐼𝑃 also allows the component or components available for improvements to be defined, and can be written as (24)

𝐼𝑃𝑘 = (1 ‒ 𝜂𝑒𝑥,𝑘)( 𝐸𝑥𝑖𝑛 ‒ 𝐸𝑥𝑜𝑢𝑡)

4 . RESULTS and DISCUSSION The turboshaft engine was analyzed using the energy and exergy relations presented in Section 3. First, an energy analysis was performed in order to find the thermodynamic properties at each station (e.g. the temperature, pressure, specific enthalpy and specific entropy at the inlet and exit of each component) taking into account the data taken from experimental tests. Calculations were performed using measured data in order to find the unknown thermodynamic properties at the outlet of HPT, PT and ED and the isentropic efficiencies of compressor (AC and CeC) and turbine (HPT and PT) modules. The calculations were repeated for four different test runs in which different load values (247 N∙m, 436 N∙m, 547 N∙m and 579 N∙m) were taken. The measured parameters, which were used for evaluating the unknown values at each station, are listed below and their values are presented in Table 1.         

Ambient pressure and temperature (𝑃0, 𝑇0) Axial compressor inlet pressure (𝑃2) Centrifugal compressor outlet pressure (𝑃3) Axial compressor inlet temperature (𝑇2) Centrifugal compressor outlet temperature (𝑇3) Power turbine inlet temperature (𝑇5) Mass flow rate of fuel (𝑚𝑓) Mass flow rate of air (𝑚𝑎) Shaft power (𝑊𝑆𝑃)

T4 and P4 parameters were calculated through the test system software using other measured parameters. T4 parameter was calculated according to the engine manufacturer’s correlation formula, as similar to the calculation of the P4 parameter. Please note that these calculations and correlations are proprietary information of the engine manufacturer. An exergy analysis was then performed for the complete system including its main components to determine the exergetic efficiency of the components, the location and the quantity of the exergy destructions and other aforementioned quantities (e.g. relative exergy destruction, fuel depletion ratio, productivity lack, and exergetic improvement potential rate). The following assumptions were made during the analyses in this study:       

4.1

Air and exhaust gases in the engine are ideal gases. Specific heats were considered as constant at an average temperature between the initial and final states The engine components were considered as thermally insulated. The changes in the kinetic energy and exergy, and the potential energy and exergy within the engine were assumed to be negligible. The combustion reaction was complete. The velocity of air entering the engine was taken as zero as the test run was performed in a static condition in the test cell. The bleed airflow used to pressurize the turbine bearings section was assumed to be 2% of the total airflow entering the engine.

Results for the energy analysis

In Table 1, the engine parameters obtained from test runs for four different load values are presented. In addition, the fluid type of each stream and the corresponding values of the mass flow rate, the pressure, the temperature, the specific enthalpy, the specific entropy, and the exergy for each station of the turboshaft engine at different four test runs are presented in Tables 4–7 in accordance with their state numbers as specified in Fig. 1. According to the results of the experimental test and energy analysis as presented in Tables 4-7, air pressure get its highest value at the combustion chamber inlet (912.46 kPa at 1405.10 kW for test #4) owing to high

7

ACCEPTED MANUSCRIPT compression of both axial centrifugal compressors as seen in Fig. 2. On the contrary, the lowest air pressure is found to be at the exhaust duct since the final expansion process occurs at this point. In addition, air pressure decreases about 4-5% in the combustion chamber mainly due to turbulence occurring in the combustion reaction. This pressure drop causes higher fuel consumption and lower power output. The air and mixture pressure increases through the engine components as the power load increases. The temperature distribution throughout the engine was also obtained as can be seen in Fig. 3. This figure shows that the maximum temperature is obtained at the inlet of high-pressure turbine. At this point, the value for this temperature is found to be 1327.50 K for the highest load taken (i.e. test #4). As the load decreases, this value also decreases up to 1090 K whilst having lower highpressure inlet pressure values. The turbine inlet temperature is a critical design parameter since the high values of this temperature leads to higher load values for the engine. However, the turbine blades cannot withstand temperatures higher than a certain value due to the material limitations. On the other hand, high temperature levels also cause high NOx levels. This phenomenon is a critical optimization problem that stands in front for the engine manufacturers and researchers.

4.2

Results for the exergy analysis

In this study, the purpose behind the use of exergy analysis is to determine the magnitudes of the exergy destructions and their exact locations within the components of the turboshaft engine. Using the values given in Tables 4–7, the exergy destruction rates, the exergetic efficiency, the fuel depletion ratio, the productivity lack, the relative exergy destruction ratio, and the exergetic improvement potential were calculated for each component of the turboshaft engine; and they are given in Tables 8–11 according to the different test runs. As discussed above, the kinetic exergy was neglected in the calculations as the contribution of this exergy component to the exergy flow rate of a given state is quite small. In addition to this, the elevation difference between the inlet and outlet streams of the engine components is considered to be negligible. Thus, potential exergy was also neglected in the exergy analysis [33]. The results for the exergetic efficiency of the engine components for different test runs are shown in Fig. 4. There are no significant changes of exergy efficiency values for AC and CeC components during four test runs whereas there are some slight variations for HPT, PT and ED components. However, the results are more obvious for CC where the efficiency shows an improvement of 10% from 284 N∙m to 579 N∙m. The reason of this finding is that we have less excess air for the complete reaction at high load values as seen in Table 2 where the combustion reaction is close to the stoichiometric conditions. Finally, the exergetic efficiency of the turboshaft engine was calculated for all load values through measured shaft power and computed fuel exergy rates which were found to be 2,985.7 kW at the test #1, 3,964 kW at the test #2, 4,777.12 kW at the test #3 and 5,098.65 kW at the test #4. The results show that as the load value (i.e. shaft power) increases, the exergetic efficiency also increases for the engine where it is maximum at 547 N∙m. As the load value increases in the test run #4, the exergetic efficiency slightly decreases (by 0.3%) compared to the test run #3. Therefore, it can be concluded that engine design point is close to test run #3 conditions and as more fuel exergy is supplied, the net shaft work cannot be increased relatively. The exergy analysis clearly indicates that, for all test runs, due to the high irreversibilities within the component, the combustion chamber has the highest exergy destruction rates within the components. The exergy destruction rates of the this component were found to be 1,170.30 kW, 1,474.50 kW, 1,650.12 kW and 1,702.50 kW for the test run #1, the test run #2, the test run #3 and the test run #4, respectively..According to the results, it was seen that as the fuel rate increases, the destruction rate also increases for all components. Exergy destruction rate increases from 33.72 kW to 60.65 kW for AC, whereas this rate increases from 37.98 kW 59.27 kW for CeC with increasing load values from 284 N∙m to 579 N∙m. The exergy destruction rate values for HPT and PT show variations during the test runs, where the minimum value is 12.38 kW for HPT and 50.49 kW for PT. Finally, the ED has maximum exergy destruction rate at the test run #4 with a value of 109.27 kW. Using the exergy destruction results, the relative exergy destruction ratio of all components are calculated and the results are presented in Fig. 5 It is seen that the

8

ACCEPTED MANUSCRIPT relative exergy destruction ratio is maximum (88.81% at 436 N∙m engine load) for the combustion chamber as expected.

Fuel depletion ratio and productivity lack for all components of the engine are shown in Fig. 6 and Fig. 7, respectively, for various load values. Figure 6 indicates that the combustion chamber has the highest fuel depletion ratio and productivity lack ratio with decreasing values in accordance with the test runs which shows that a great amount of fuel and product exergy potential is lost in the combustion chamber. This result is as expected since the exergy destruction rate of the combustion chamber is much higher compared to other components. There are no significant changes of fuel depletion ratio and productivity lack values for other components where fuel depletion ratio for AC and CeC changes from 0.42% to 0.51% and 0.47% to 0.54%, respectively. In addition, productivity lack for these components varies between 0.52% - 0.61% and 0.58% 0.67%, respectively. Fuel depletion ratio for HPT decreases in the test #2 and then a slight increase can be seen in other runs. The same behavior is also valid for the productivity lack values. PT component has also low values for the fuel depletion ratio and its value varies between 0.66% and 1.00%. As for the HPT, the same trend is valid for the productivity lack value of PT. Both fuel depletion ratio and productivity lack values for ED change between 0.63% - 0.91% and 0.76% - 1.16%, respectively.

The highest exergetic improvement potential was obtained for the combustion chamber for all test cases. The value of this parameter varied between 458.72 kW and 569.99 kW for four test cases and it was seen that its value is maximum at the load value of 547 N∙m. The component having a significant amount of improvement potential was found to be ED, in which the value of this parameter changes between 3.34 kW and 7.45 kW. The CeC and AC, on the other hand, have a steady increasing trend from 2.28 kW to 3.51 kW and 2.16% to 4.66% of improvement potential, respectively, as the engine load increases. For the turboshaft engine, the lowest exergetic improvement potential is observed to be for the HPT component, in which the value varied between 0.09 kW and 2.12 kW whilst it is between 2.28 kW and 5.01 kW for the PT component. These results show that the combustion chamber is by far the most important component that needs the most improvement according to these results. In order to decrease the exergy destruction and improvement potential, one needs to understand the causes of the irreversibilities in combustion chamber. The main reasons of the irreversibilities can be given as pressure drop (due to friction), mixing of streams, chemical reaction and heat transfer processes.

5 . CONCLUSIONS This study presents the energy and exergy analyses of the Makila 1A1 Turboshaft engine and its main components at four different load values according to component-based analyses. The results of the energy analysis indicate that the isentropic efficiencies of the compressor (AC and CeC) and the turbine (HPT and PT) vary between 82%-84.3% and 89.4%-94.4%, respectively. Maximum isentropic efficiencies for both components occur at the test run #2 (load value of 436 N∙m). The exergy analysis provides more insights than the energy analysis. The results of the component-based exergy analysis performed here on a turboshaft engine indicate that the combustion chamber unit contains the majority of the exergy destruction at all various loads. The combustion chamber has very low values of exergy efficiency and high values of fuel exergy depletion, productivity lack ratio, relative exergy destruction rates and exergetic improvement potential due to high irreversibilities..In addition, the highest value of the exergy efficiency for the turboshaft engine is found to be 27.65% at test run #3 (load value of 547 N∙m). The methodology and the results of this study can be beneficial to guide improvement studies as the locations and the reasons of irreversibilities are clarified. The results can also be useful in the design and development of similar turboshaft/turboprop propulsion systems. In a future study, the current study can be expanded to include exergo-economic, exergo-environmental and exergo-

9

ACCEPTED MANUSCRIPT sustainability analyses to conduct a more detailed study. Acknowledgements The financial support of this research is provided by Anadolu University under the contract number of 1503F106. Nomenclature AFR cp E 𝑒𝑥 ex Ex h 𝐼𝑃 LHV

𝑚 pe P r φ 𝑄 𝑅 SP T 𝑊

𝑥𝑖

Air -Fuel Ratio on a mass basis Constant-Pressure specific heat, (kJ/kg·K) Energy rate (kW) Specific flow exergy (kJ/kg) Specific exergy on a molar basis (kJ/kmol) Exergy rate (kW) Enthalpy (kJ/kg) Improvement potential (kW) Lower heating value (kJ/kg) Mass flow rate (kg/s) Potential energy (kW) Pressure (kPa) Compressor pressure ratio Fuel exergy grade function Heat rate (kW) Gas constant (kJ/kg·K) Shaft Power Temperature (K) Power (kW) Mole fraction of combustion gas i

Greek letters 𝜂 𝜒 𝛿 𝜁 𝜆 𝛾

Efficiency Relative exergy destruction ratio Fuel depletion ratio Productivity lack Combustion equation constant Spesific heat ratio

Superscripts . ¯

Rate Molar

Subscripts

0 a ac AC c cc CeC ch D ED exh f g HPT in k m out

Dead State conditions Air Actual Axial Compressor Compressor Combustion chamber Centrifugal compressor Chemical Destruction Exhaust duct Exhaust Fuel Combustion gases High pressure turbine Inlet Kinetic Mechanical Outlet

10

ACCEPTED MANUSCRIPT p ph PT s SP T TE

Potential Physical Power turbine Isentropic Shaft power Turbine Turboshaft engine

References [1] Atigan,R., Turan, O.,Altuntaş,O.,Aydın,H., Synylo,K. Environmental impact assessment of a turboprop engine with the aid of exergy. Energy 2013; 58,664-671. [2] Brassseur, G.P. and Gupta,M. Impact of Aviation on Climate:Research Priorities.Bull.Amer.Meteor.Soc.2010;91,461-463. [3] Norton, Travis M. Aircraft Greenhouse Gas Emissions during the Landing and Takeoff Cycle at Bay Area Airports. Master's Projects 2014;Paper 15. [4] European Commission.Impact assessment on Proposal From the Commission to the European Parliament and Council for derogating from Directive 2003/87/EC.2013;Retrieved from http://ec.europa.eu/clima/policies/transport/aviation/docs/swd_2013_430_en.pdf [5] Lee, J., Mo, J. Analysis of Technological Innovation and Environmental Performance Improvement in Aviation Sector. Int. J. Environ. Res. Public Health, 2011;8, 3777-3795. [6] Rosen,M.A.,Pedinelli,N. and Dincer,I. Energy and exergy analyses of cold thermal storage systems.Int.J.Energy Res. 1999;23:1029-1038. [7] Bejan A., Siems D.L. The need for exergy analysis and thermodynamic optimization in aircraft development, Exergy, An International Journal 2001;1: 14-24. [8] Kotas, T.J. The Exergy Method of Thermal Plant Analysis, Reprint ed. 1995, Krieger, Malabar, Florida. [9] Moran,M.J.,Shapiro,H.N.,Boettner,D.D.,Bailey,M.B.Fundamentals of EngineeringThermodynamics.Westford. John Wiley & Sons, Inc.,2011. [10] Tai, V.C., Mares, C., See,P.C. Optimisation of energy and exergy of turbofan engines using genetic algorithms.Int.J.Sustainable Aviation 2014;Vol.1,No.1,25-42. [11] Dincer, I., and Rosen, M.A. Thermodynamic aspects of renewables and sustainable development. Renewable and Sustainable Energy Reviews 2005;Vol. 9, 169–189. [12] Tona C., Antonio P., Pellegrini L.F., de Oliveira Jr. S., Exergy and thermoeconomic analysis of a turbofan engine during a typical commercial flight, Energy 2010;35: 952-959. [13] Etele, J. and Rosen, M.A. Sensitivity of exergy efficiencies of aerospace engines to reference environmental selection. International Journal of Exergy 2001; Vol. 1, No. 2, pp.91–99. [14] Balli O, Aras H, Aras N, Hepbasli A. Exergetic and exergoeconomic analysis of an Aircraft Jet Engine (AJE). Int J Exergy 2008;5(5/6):567-81. [15] Ekici,S., Sohret,Y.,Coban,K.,Altuntas,O.,Karakoc,T.H. Performance Evaluation of an Experimental Turbojet Engine. Int J Turbo Jet Eng 2016. ISSN (online):2191-0332, ISSN (Print): 0334–0082. DOI:10.1515/tjj–2016–0016 [16] Turgut E.T, Karakoc T.H, Hepbasli A. Exergetic analysis of an aircraft turbofan engine. Int J Energy Res 2007;31(14):1383–97. [17] Sohret Y, Acikkalp E, Hepbasli A, Karakoc TH. Advanced exergy analysis of an aircraft gas türbine engine: splitting exergy destructions into parts. Energy 2015;90:1219–28. [18] Söhret, Y., Sogut, M.Z., Karakoc, T.H., Turan, O. Customised application of exergy analysis method to PW120A turboprop engine for performance evaluation. International Journal of Exerg 2016; Vol.20,48 – 65. [19] Balli,O.,Hepbasli,A. Energetic and exergetic analyses of T56 turboprop engine.Enegy convergent.and Management 2013;73.106-120. [20] Aydin H., Turan O., Karakoc T.H., Midilli A. Component-based exergetic measures of an experimental turboprop/turboshaft engine for propeller aircrafts and helicopters. International Journal of Exergy 2012; Vol. 11: 322-348. [21] Aydin, H.,Turan, O. Numerical calculation of energy and exergy flows of a turboshaft engine for power generation and helicopter applications.Energy 2016;115.914-923. [22] Söhret Y, Ekici S, Altuntas O, Hepbasli A, Karakoc TH. Exergy as a useful tool for the performance assessment of aircraft gas turbine engines: a key review. Prog Aerosp Sci 2016;83:57–69. [23] www.safran-helicopter-engines.com/helicopter-engines/over-2000-shp/makila/makila-1a1/1a2/1k2 [last access: October 11, 2016]. [24] Mansouri M.T., Ahmadi, P., Kaviri, A.G., Jaafar, M.N.M. Exergetic and economic evaluation of the effect of HRSG configurations on the performance of combined cycle power plants. Energy Convers Management 2012;58: 47–58. [25] Annamalai,K., and Puri,I.K. Combustion Science and engineering. Boca Raton.:CRC Press/Taylor&Francis,2007. 11

ACCEPTED MANUSCRIPT [26] Cengel Y.A., Boles M. Thermodynamics: An Engineering Approach 5th Edition. McGraw-Hill Higher Education,2006. [27] Dincer I., Rosen M.A., (2013).Exergy, Energy, Environment and Sustainable Development. Elsevier Ltd., 2nd Edition. 2013. [28] Aydin H., Turan O., Karakoc T.H., Midilli A. Energetic and exergetic performance assessment of a turboprop engine at various loads. International Journal of Exergy 2013; Vol. 13: 543-563. [29] Bejan A, Tsatsaronis G, Moran M. Thermal design and optimization. New York: John Wiley & Sons Inc.,1996. [30] Gool, V. Energy policy fairy tales and factualities. Innovation and Technology-Strategies and Policies 1997;, Kluwer, Dordrecht. 93–105. [31] Xiang, J.Y., Cali, M. and Santarelli, M. Calculation for physical and chemical exergy of flows in systems elaborating mixed-phase flows and a case study in an IRSOFC plant. International Journal of Energy Research 2004; Vol. 28, No. 2, 101–115. [32] Turgut, E.T., Karakoc, T.H., Hepbasli, A., and Rosen, M.A. Exergy analysis of a turbofan aircraft engine. International Journal of Exergy 2009b; Vol. 6, No. 2, 181–199. [33] Aydin, H, Turan, O., Karakoc, T.H., Midilli, A. Exergo-sustainability indicators of a turboprop aircraft for the phases of a flight. Energy 2013;58:550-60.

Figure Captions List Fig. 1. Schematic of the turboshaft engine Fig. 2. Pressure distribution throughout the engine for different test runs Fig. 3. Temperature distribution throughout the engine for different test runs Fig. 4. Exergetic efficiency of the engine components Fig. 5. Relative exergy destruction ratio of the engine components Fig. 6. Fuel depletion ratio of the engine components Fig. 7. Productivity lack of the engine components

Fig.1. Schematic of the turboshaft engine

12

ACCEPTED MANUSCRIPT

Fig.2. Pressure distribution throughout the engine for different test runs

Fig.3. Temperature distribution throughout the engine for different test runs

Fig.4. Exergetic efficiency of the engine components

13

ACCEPTED MANUSCRIPT

Fig.5. Relative exergy destruction ratio of the engine components

Fig.6. Fuel depletion ratio of the engine components

Fig.7. Productivity lack of the engine components

14

ACCEPTED MANUSCRIPT Table Captions List Table 1. Turboshaft engine parameters at four ground operation test runs Table 2. Constants of combustion reaction at various test runs Table 3. Exergy balance and exergy efficiency equations Table 4. Turboshaft engine thermodynamic values (test run #1) Table 5. Turboshaft engine thermodynamic values (test run #2) Table 6. Turboshaft engine thermodynamic values (test run #4) Table 7. Turboshaft engine thermodynamic values (test run #4) Table 8. Engine components performance parameters (test run #1) Table 9 Engine components performance parameters (test run #2) Table 10 Engine components performance parameters (test run #3) Table 11 Engine components performance parameters (test run #4

Table 1 Turboshaft engine parameters at four ground operation test runs Test run number (Load Value)

Atmospheric pressure (kPa) Atmospheric temperature (K) Power (kW) Power turbine speed (rpm) Gas generator speed (rpm) Mass flow rate of inlet air (kg s-1) Mass flow rate of fuel (kg s-1) Power turbine inlet temperature (K) High pressure turbine inlet temperature (K) Compressor module exit pressure (kPa) Compressor module exit temperature (K) Air-fuel ratio

1

2

3

4

(284 N∙m)

(436 N∙m)

(547 N∙m)

(579 N∙m)

92.00 288.15 683.30 22997.00 29103.00 4.54 0.06 863.15 1090.15 669.85 546.64 68.23

92.00 288.15 1053.00 23072.00 31044.00 5.20 0.09 930.15 1191.15 802.05 573.90 59.08

92.00 288.15 1320.90 23071.00 32634.00 5.55 0.10 1010.55 1283.70 889.64 599.04 52.27

92.00 288.15 1405.10 23158.00 33297.00 5.62 0.11 1054.15 1327.50 912.46 605.70 49.60

Table 2 Constants of combustion reaction at various test runs Constant 𝝀𝟏 𝝀𝟐 𝝀𝟑 𝝀𝟒 𝝀𝟓

1 393.64 12.12 19 63.30 305

Test run number 2 3 340.88 301.58 12.10 12.09 18 17.20 52.43 43.34 264.12 233.66

4 285.70 12.10 16.90 41.10 221.40

Table 3 Exergy balance and exergy efficiency equations Component

Exergy balance

15

Exergy efficiency

ACCEPTED MANUSCRIPT Axial Compressor (AC)

𝐸𝑥1 + 𝑊10 ‒ (𝐸𝑥2 + 𝐸𝑥2.1) = 𝐸𝑥𝐷,𝐴𝐶

Centrifugal Compressor (CeC)

𝐸𝑥2 + 𝑊9 ‒ 𝐸𝑥3 = 𝐸𝑥𝐷,𝐶𝑒𝐶

Combustion chamber (CC)

𝐸𝑥3 + 𝐸𝑥3.𝑓 ‒ 𝐸𝑥4 = 𝐸𝑥𝐷,𝐶𝐶

High-pressure turbine (HPT) Power turbine (PT) Exhaust duct (ED)

(𝐸𝑥4 ‒ 𝐸𝑥5) ‒ 𝑊𝐻𝑃𝑇 = 𝐸𝑥𝐷,𝐻𝑃𝑇

(𝐸𝑥2.1 + 𝐸𝑥5 ‒ 𝐸𝑥6) ‒ 𝑊𝑃𝑇 = 𝐸𝑥𝐷,𝑃𝑇

𝜂𝑒𝑥,𝐴𝐶 =

(𝐸𝑥2 + 𝐸𝑥2.1) ‒ 𝐸𝑥1 𝑊𝐴𝐶 𝜂𝑒𝑥,𝐶𝑒𝐶 =

𝜂𝑒𝑥,𝐶𝐶 =

𝐸𝑥6 ‒ 𝐸𝑥7 = 𝐸𝑥𝐷,𝐸𝐷

𝑊𝐶𝑒𝐶

𝐸𝑥4 𝐸𝑥3.𝑓 + 𝐸𝑥3

𝜂𝑒𝑥,𝐻𝑃𝑇 = 𝜂𝑒𝑥,𝑃𝑇 =

𝐸𝑥3 ‒ 𝐸𝑥2

𝑊𝐻𝑃𝑇 𝐸𝑥4 ‒ 𝐸𝑥5 𝑊𝑃𝑇

(𝐸𝑥2.1 + 𝐸𝑥5) ‒ 𝐸𝑥6

𝜂𝑒𝑥,𝐸𝐷 =

Turboshaft engine (TE) 𝜂𝑒𝑥,𝑇𝐸 =

𝐸𝑥7 𝐸𝑥6 𝑊𝑆𝑃

𝑚𝑓𝑒𝑥𝑐ℎ,𝑓

Table 4 Turboshaft engine thermodynamic values (test run #1) Station No.

Fluid type/work

0 1 2 2.1 3 3.f 4 5 6 7 8

Air Air Air Air Air Fuel Comb. gases Comb. gases Comb. gases Comb. gases Power output from HPT Power input to CeC Power input to AC Power output from PT Engine shaft power

9 10 11 12

Mass flow rate (kg∙s-1) 0.00 4.54 4.44 0.09 4.44 0.06 4.51 4.51 4.60 4.60

Temperature (K)

Pressure (kPa)

288.15 288.15 410.16 410.16 546.64 288.15 1090.15 863.15 722.23 711.69

92.00 92.00 264.28 264.28 669.85 220.00 637.12 215.44 97.44 92.00

Specific Enthalpy (kJ/kg) 293.31 293.31 418.42 418.42 560.86

Specific Entropy (kJ/kg∙K) 6.92 6.92 6.98 6.98 7.00

1189.18 921.52 759.66 747.86

7.85 7.89 7.92 7.92

Exergy (kW) 0.00 0.00 484.07 9.81 1078.51 2985.70 2893.91 1635.12 889.04 834.59 1207.14 632.42 527.61 699.29 683.30

Table 5 Turboshaft engine thermodynamic values (test run #2) Station No.

Fluid type/work

Mass flow rate

Temperature (K) 16

Pressure (kPa)

Specific Enthalpy

Specific Entropy

Exergy (kW)

ACCEPTED MANUSCRIPT (kg∙s-1) 0 1 2 2.1 3 3.f 4 5 6 7 8 9 10 11 12

Air Air Air Air Air Fuel Comb. gases Comb. gases Comb. gases Comb. gases Power output from HPT Power input to CeC Power input to AC Power output from PT Engine shaft power

0.00 5.20 5.10 0.10 5.10 0.08 5.18 5.18 5.29 5.29

288.15 288.15 419.16 419.16 573.89 288.15 1191.15 930.15 745.45 730.72

92.00 92.00 286.39 286.39 802.06 220.00 764.17 255.06 99.52 92.00

(kJ/kg)

(kJ/kg∙K)

293.31 293.31 427.71 427.71 589.76

6.92 6.92 6.97 6.97 7.00

1315.58 1000.77 787.35 770.71

7.93 7.94 7.95 7.96

0.00 0.00 604.79 11.86 1387.26 3964.09 3876.85 2233.78 1125.57 1036.82 1630.69 826.43 656.11 1069.57 1053.00

Table 6 Turboshaft engine thermodynamic values (test run #3) Station No.

Fluid type/work

0 1 2 2.1 3 3.f 4 5 6 7 8

Air Air Air Air Air Fuel Comb. gases Comb. gases Comb. gases Comb. gases Power output from HPT Power input to CeC Power input to AC Power output from PT Engine shaft power

9 10 11 12

Mass flow rate (kg∙s-1) 0.00 5.55 5.44 0.11 5.44 0.10 5.55 5.55 5.66 5.66

Temperature (K)

Pressure (kPa)

288.15 288.15 429.22 429.22 599.04 288.15 1283.70 1010.55 797.81 782.04

92.00 92.00 301.62 301.62 889.64 220.00 848.55 282.67 99.63 92.00

Specific Enthalpy (kJ/kg) 293.31 293.31 438.12 438.12 616.58

Specific Entropy (kJ/kg∙K) 6.92 6.92 6.98 6.98 7.02

1433.7 1098.70 848.67 839.59

7.99 8.01 8.04 8.05

Exergy (kW) 0.00 0.00 686.81 13.89 1601.14 4777.12 4728.14 2827.55 1427.57 1357.03 1859.65 970.82 755.47 1342.51 1320.90

Table 7 Turboshaft engine thermodynamic values (test run #4) Station No.

Fluid type/work

Mass flow rate

Temperature (K) 17

Pressure (kPa)

Specific Enthalpy

Specific Entropy

Exergy (kW)

ACCEPTED MANUSCRIPT (kg∙s-1) 0 1 2 2.1 3 3.f 4 5 6 7 8 9 10 11 12

Air Air Air Air Air Fuel Comb. gases Comb. gases Comb. gases Comb. gases Power output from HPT Power input to CeC Power input to AC Power output from PT Engine shaft power

0.00 5.62 5.51 0.11 5.51 0.11 5.62 5.62 5.73 5.73

288.15 288.15 433.24 433.24 605.67 288.15 1327.50 1054.15 833.17 816.75

92.00 92.00 308.45 308.45 912.46 220.00 870.87 292.54 99.69 92.00

(kJ/kg)

(kJ/kg∙K)

293.31 293.31 442.28 442.28 623.67

6.92 6.92 6.99 6.99 7.02

1490.47 1152.47 890.25 871.25

8.03 8.06 8.09 8.09

0.00 0.00 713.63 14.25 1653.81 5098.65 5049.96 3099.27 1602.13 1492.85 1899.54 999.45 788.52 1424.40 1405.10

Table 8 Engine components performance parameters (test run #1) Component AC CeC CC HPT PT ED

𝑬𝒙𝑫(𝒌𝑾) 33.72 37.98 1170.30 51.65 56.60 54.45

𝜼𝒆𝒙(%) 93.61 94.00 60.80 95.90 92.51 93.88

𝝌(%) 2.44 2.74 84.56 3.73 4.09 3.93

𝜹(%) 0.48 0.54 16.60 0.73 0.80 0.77

𝜻(%) 0.60 0.67 20.73 0.92 1.00 0.96

𝑰𝑷(𝒌𝑾) 2.16 2.28 458.72 2.12 4.24 3.34

Table 9 Engine components performance parameters (test run #2) Component AC CeC CC HPT PT ED

𝑬𝒙𝑫(𝒌𝑾) 39.46 43.96 1474.50 12.38 50.50 88.75

𝜼𝒆𝒙(%) 93.98 94.68 62.80 99.25 95.49 92.11

𝝌(%) 2.38 2.65 88.81 0.75 3.04 5.35

𝜹(%) 0.42 0.47 15.79 0.13 0.54 0.95

𝜻(%) 0.52 0.58 19.34 0.16 0.66 1.16

𝑰𝑷(𝒌𝑾) 2.37 2.34 548.46 0.09 2.28 7.00

Table 10 Engine components performance parameters (test run #3) Component AC CeC CC HPT PT ED

𝑬𝒙𝑫(𝒌𝑾) 54.77 56.49 1650.12 40.94 71.36 70.54

𝜼𝒆𝒙(%) 92.75 94.18 65.46 97.85 94.95 95.06

𝝌(%) 2.84 2.93 85.57 2.12 3.70 3.66

𝜹(%) 0.49 0.50 14.67 0.36 0.63 0.63

Table 11 Engine components performance parameters (test run #4) 18

𝜻(%) 0.59 0.61 17.74 0.44 0.77 0.76

𝑰𝑷(𝒌𝑾) 3.97 3.29 569.99 0.88 3.60 3.49

ACCEPTED MANUSCRIPT Component AC CeC CC HPT PT ED

𝑬𝒙𝑫(𝒌𝑾) 60.64 59.27 1702.50 51.15 86.99 109.28

𝜼𝒆𝒙(%) 92.31 94.07 66.61 97.38 94.24 93.18

𝝌(%) 3.00 2.93 84.23 2.53 4.30 5.41

19

𝜹(%) 0.51 0.50 14.25 0.43 0.73 0.91

𝜻(%) 0.61 0.60 17.23 0.52 0.88 1.11

𝑰𝑷(𝒌𝑾) 4.66 3.51 568.49 1.34 5.01 7.45

ACCEPTED MANUSCRIPT Highlights 

The energy and exergy analyses of a military helicopter turboshaft engine are presented.

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Analyses are performed for the engine main components.

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Exergy indicators of the engine are compared for four load values.