- Email: [email protected]
Turbulence simulation
<7
Turbulence simulation In 1976 when Atkins were asked to study the dispersion of unburnt flammable gas from a proposed flare stack on an oil rig platform, they carried out the tests required in a wind tunnel using a 1:125
scale model of the deck and modules. But in 1978, when Total Marine of Paris wanted a similar study performed on the temperature distribution around a platform caused by the exhaust efflux from
Flare stack
Hot exhaust 4--- ,,f27 f
._ ~ . -_:~__:~_'c.,u~i~_"~../ ¢'"-~--~,_ - - ~ ~ ' t ~ i ~ , ' ~ - - - . =,,~I.I ,~I~I
/
/ - -
---
~ _ / 4 ~I/I ~
..--.,,.--
Helideck
Turbine compressor stack
Predictions by CA FE of flow velocities and temperature contours of the hot turbine-compressor exhaust gasesas they are dispersed over the FRIGG Field platform MCP-OI by the oncoming wind.
Engineering analysis system
the large power-generation turbines, Atkins chose to use a recently-developed computer program called CAFE instead of a physical model. CAFE (computational Atkins flow evaluation), developed by Atkins, uses the finite-difference method to solve equations of motion and turbulence in the flow. Problems concerning combustion, chemical reaction, radiation, conduction, particle transport and the mixing of gasesor liquids, can be solved in 2D or 3D with constant or time-varying conditions. The recent study for Total was an example of a hot gas mixing in a cold flow. CAFE was employed to calculate wind velocities and temperatures in and around the complex geometry of the platform modules and structures. The results enabled a clear relationship to be established between the temperature over the helideck and the ratio of wind speed to exhaust gas speed and stack height. This information is required to determine a suitable diameter and height for the turbine exhaust stack. As well as being faster and more economical than physical models for many types of problems, a computational method such as CAFE is also easily repeatable; thus input properties connected with a specific problem can be changed or updated and the 'test' re-run without the need to replace the model in the wind tunnel. Although the scale effects that afflict all model tests may not be entirely solved in a computer simulation, it is easy to study the sensitivity of the final result to errors in scale. (W5 Atkins Group,
Woodcote Grove, Ashley Road, Epsom, Surrey KT18 5BW, UK. Tel: Epsom 26140. Telex: 23497)
solves the fundamental partial differential equations of continuum mechanics in two dimensions, with both plane and axial symmetry. It can accommodate complex structure geometries, time-dependent boundary conditions, nonlinear material modelling and the coupling of Euler, Lagrange or thin shell grids with great accuracy and efficiency. (S/A
PISCES 2DELK, a greatly extended versThe new release extends the range of ion of the PISCES engineering analysis finite difference problem types which system is available on SlA's computer the program can solve. The system can analyse many problems concerning transnetwork. The package was developed and is supported by Physics Internationient fluid flow, coupled fluid-solid inter- Limited, Ebury Gate, 23 Lower Be/grave al Company, a subsidiary of Rocket actions and large-displacement largeStreet, London SW1W ONW. Tel: 01-730 Research Corporation. strain structural analysis. PISCES 2DELK 4544. Telex: 916635)
volume 11 number 2 march 1979
109
Turbulence simulation In 1976 when Atkins were asked to study the dispersion of unburnt flammable gas from a proposed flare stack on an oil rig platform, they carried out the tests required in a wind tunnel using a 1:125
scale model of the deck and modules. But in 1978, when Total Marine of Paris wanted a similar study performed on the temperature distribution around a platform caused by the exhaust efflux from
Flare stack
Hot exhaust 4--- ,,f27 f
._ ~ . -_:~__:~_'c.,u~i~_"~../ ¢'"-~--~,_ - - ~ ~ ' t ~ i ~ , ' ~ - - - . =,,~I.I ,~I~I
/
/ - -
---
~ _ / 4 ~I/I ~
..--.,,.--
Helideck
Turbine compressor stack
Predictions by CA FE of flow velocities and temperature contours of the hot turbine-compressor exhaust gasesas they are dispersed over the FRIGG Field platform MCP-OI by the oncoming wind.
Engineering analysis system
the large power-generation turbines, Atkins chose to use a recently-developed computer program called CAFE instead of a physical model. CAFE (computational Atkins flow evaluation), developed by Atkins, uses the finite-difference method to solve equations of motion and turbulence in the flow. Problems concerning combustion, chemical reaction, radiation, conduction, particle transport and the mixing of gasesor liquids, can be solved in 2D or 3D with constant or time-varying conditions. The recent study for Total was an example of a hot gas mixing in a cold flow. CAFE was employed to calculate wind velocities and temperatures in and around the complex geometry of the platform modules and structures. The results enabled a clear relationship to be established between the temperature over the helideck and the ratio of wind speed to exhaust gas speed and stack height. This information is required to determine a suitable diameter and height for the turbine exhaust stack. As well as being faster and more economical than physical models for many types of problems, a computational method such as CAFE is also easily repeatable; thus input properties connected with a specific problem can be changed or updated and the 'test' re-run without the need to replace the model in the wind tunnel. Although the scale effects that afflict all model tests may not be entirely solved in a computer simulation, it is easy to study the sensitivity of the final result to errors in scale. (W5 Atkins Group,
Woodcote Grove, Ashley Road, Epsom, Surrey KT18 5BW, UK. Tel: Epsom 26140. Telex: 23497)
solves the fundamental partial differential equations of continuum mechanics in two dimensions, with both plane and axial symmetry. It can accommodate complex structure geometries, time-dependent boundary conditions, nonlinear material modelling and the coupling of Euler, Lagrange or thin shell grids with great accuracy and efficiency. (S/A
PISCES 2DELK, a greatly extended versThe new release extends the range of ion of the PISCES engineering analysis finite difference problem types which system is available on SlA's computer the program can solve. The system can analyse many problems concerning transnetwork. The package was developed and is supported by Physics Internationient fluid flow, coupled fluid-solid inter- Limited, Ebury Gate, 23 Lower Be/grave al Company, a subsidiary of Rocket actions and large-displacement largeStreet, London SW1W ONW. Tel: 01-730 Research Corporation. strain structural analysis. PISCES 2DELK 4544. Telex: 916635)
volume 11 number 2 march 1979
109