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Laminar-turbulent transition of thin radial liquid film flow
Experimental Heat Transfer, Fluid Mechanics, and Thermodynamics 149
Transition of Oscillatory Flow in a Symmetric Sinusoidai Wavy-Walled Channel Tatsuo Nishimura
Department of Mechanical Engineering Yamaguchi University Ube, Japan Yuji Kawamura
Department of Chemical Engineering Hiroshima University Higashi-Hiroshima, Japan Oscillatory flow in a two-dimensional sinusoidal wavywalled channel is investigated experimentally. Attention is focused on the transition of two-dimensional to threedimensional flow. The critical value of the Reynolds number at the onset of three-dimensional flow strongly depends on the Strouhal number. The flow is most unstable in the range of Strouhal numbers between 0.02 and 0.03. Two distinct three-dimensional flows are formed and their distinction can be made only by whether the Strouhal number exceeds about 0.02. Steady flow is free from the transition, which is due to a three-dimensional centrifugal instability of the flow.
Laminar-Turbulent Transition Of Thin Radial Liquid Film Flow Tsuneo Azuma Tatsuroh Wakimoto
Department of Mechanical Engineering Osaka City University Sum~yoshi, Osaka, Japan Makoto Nunobe
Technical Research Laboratory Toyo Unpanki Co., Ltd. Ibaraki, Japan A remarkable transition from laminar to turbulent flow of a thin liquid film flow is investigated. The radial liquid film flow was generated by a water discharge to the atmosphere from a clearance between the lower end of a vertical pipe and the horizontal fiat surface of a disk. The transition process was elucidated by high-speed photography. Characteristic properties of the disturbance in the transitional region were made clear by measurement of wall-pressure fluctuation. A linear stability analysis of the flow was carried out. The measured values of the phase velocity, the frequency, and the amplification factor of disturbance were in agreement with the linear stability theory. Thus, it was found that this transition does not occur due to the shearing stress on the liquid surface, but rather to the amplification of disturbance inside the liquid film.
Boundary Layer on A Plate with Directed Injection into the Laminar Stream V. M. Epifanov A. A. Klimov S. A. Trdatyan
Moscow State Technical University Moscow, Russia Results of an experimental investigation of the boundary layer on a perforated plate under conditions of moderate
and severe injection into the laminar boundary layer (both in the direction of the main flow and counter this direction) are presented. Laminar, transitional, and turbulent flow modes are discussed. Data concerning the flow structure, velocity distribution, and turbulence intensity in the boundary layer and also on wall friction for injection angles a = 20° and a = 160° are presented.
Experimental Study of the Flow in the Cavity between Rotating Discs X. P. Gan S. A. MacGregor
School of Mechanical Engineering University of Bath Bath, United Kingdom An experimental investigation using laser Doppler anemometry was conducted in the cavity between rotating discs. Measurements of velocity were taken for Rotorstator and contra-rotating disc flows. Batchelor-type flow was observed for the rotor-stator flow, and Stewartson-type flow exist in the contra-rotating disc system. The core flow of the contra-rotating discs is turbulent for x z Re6 as low as 2.16 × 10 4, but the boundary layer flow remains laminar for x z Re4, < 1.1 × 105. The velocity measurements show good agreement with previously published hot-wire anemometry measurements and theoretical predictions.
Fluid Flow Behavior Inside a Circular Helicoidal Pipe Using a Laser Doppler Anemometry/Velocimetry (LDA/LDV) System I. Muguercia E. Largaespade W. Li M. A. Ebadian
Department of Mechanical Engineering Florida International University Miami, FL An e x p e r i m e n t a l study using laser D o p p l e r anemometry/velocimetry (LDA/LDV) was carried out to investigate the fully developed Newtonian laminar flow inside a helicoidal pipe. In the helicoidal pipe test section, the curvature ratio of the centerline of the coil diameter to the pipe diameter, D j d , and the pitch ratio of the centerline of the coil diameter to the pitch of the coil, De/b, are 13.6 and 4.0, respectively. The uncertainties for velocity, the friction factor, the Reynolds number, and the Dean number were found to be under 1.52%, 3.41%, 2.37%, and 2.60%, respectively. In the present investigation, the friction factor for the helicoidal pipe was measured, and it was found that the flow remains laminar until Re = 8,000, which is much higher than the critical Reynolds number for a straight pipe (RecT = 2,500). In addition, the ratio of friction factor of the current helicoidal pipe (fn) to the friction factor of the straight pipe (f,) has been compared with previous investigations, and good agreement has been obtained. Furthermore, the axial velocity distributions at two different cross-sections of a helicoidal pipe for dif-
Transition of Oscillatory Flow in a Symmetric Sinusoidai Wavy-Walled Channel Tatsuo Nishimura
Department of Mechanical Engineering Yamaguchi University Ube, Japan Yuji Kawamura
Department of Chemical Engineering Hiroshima University Higashi-Hiroshima, Japan Oscillatory flow in a two-dimensional sinusoidal wavywalled channel is investigated experimentally. Attention is focused on the transition of two-dimensional to threedimensional flow. The critical value of the Reynolds number at the onset of three-dimensional flow strongly depends on the Strouhal number. The flow is most unstable in the range of Strouhal numbers between 0.02 and 0.03. Two distinct three-dimensional flows are formed and their distinction can be made only by whether the Strouhal number exceeds about 0.02. Steady flow is free from the transition, which is due to a three-dimensional centrifugal instability of the flow.
Laminar-Turbulent Transition Of Thin Radial Liquid Film Flow Tsuneo Azuma Tatsuroh Wakimoto
Department of Mechanical Engineering Osaka City University Sum~yoshi, Osaka, Japan Makoto Nunobe
Technical Research Laboratory Toyo Unpanki Co., Ltd. Ibaraki, Japan A remarkable transition from laminar to turbulent flow of a thin liquid film flow is investigated. The radial liquid film flow was generated by a water discharge to the atmosphere from a clearance between the lower end of a vertical pipe and the horizontal fiat surface of a disk. The transition process was elucidated by high-speed photography. Characteristic properties of the disturbance in the transitional region were made clear by measurement of wall-pressure fluctuation. A linear stability analysis of the flow was carried out. The measured values of the phase velocity, the frequency, and the amplification factor of disturbance were in agreement with the linear stability theory. Thus, it was found that this transition does not occur due to the shearing stress on the liquid surface, but rather to the amplification of disturbance inside the liquid film.
Boundary Layer on A Plate with Directed Injection into the Laminar Stream V. M. Epifanov A. A. Klimov S. A. Trdatyan
Moscow State Technical University Moscow, Russia Results of an experimental investigation of the boundary layer on a perforated plate under conditions of moderate
and severe injection into the laminar boundary layer (both in the direction of the main flow and counter this direction) are presented. Laminar, transitional, and turbulent flow modes are discussed. Data concerning the flow structure, velocity distribution, and turbulence intensity in the boundary layer and also on wall friction for injection angles a = 20° and a = 160° are presented.
Experimental Study of the Flow in the Cavity between Rotating Discs X. P. Gan S. A. MacGregor
School of Mechanical Engineering University of Bath Bath, United Kingdom An experimental investigation using laser Doppler anemometry was conducted in the cavity between rotating discs. Measurements of velocity were taken for Rotorstator and contra-rotating disc flows. Batchelor-type flow was observed for the rotor-stator flow, and Stewartson-type flow exist in the contra-rotating disc system. The core flow of the contra-rotating discs is turbulent for x z Re6 as low as 2.16 × 10 4, but the boundary layer flow remains laminar for x z Re4, < 1.1 × 105. The velocity measurements show good agreement with previously published hot-wire anemometry measurements and theoretical predictions.
Fluid Flow Behavior Inside a Circular Helicoidal Pipe Using a Laser Doppler Anemometry/Velocimetry (LDA/LDV) System I. Muguercia E. Largaespade W. Li M. A. Ebadian
Department of Mechanical Engineering Florida International University Miami, FL An e x p e r i m e n t a l study using laser D o p p l e r anemometry/velocimetry (LDA/LDV) was carried out to investigate the fully developed Newtonian laminar flow inside a helicoidal pipe. In the helicoidal pipe test section, the curvature ratio of the centerline of the coil diameter to the pipe diameter, D j d , and the pitch ratio of the centerline of the coil diameter to the pitch of the coil, De/b, are 13.6 and 4.0, respectively. The uncertainties for velocity, the friction factor, the Reynolds number, and the Dean number were found to be under 1.52%, 3.41%, 2.37%, and 2.60%, respectively. In the present investigation, the friction factor for the helicoidal pipe was measured, and it was found that the flow remains laminar until Re = 8,000, which is much higher than the critical Reynolds number for a straight pipe (RecT = 2,500). In addition, the ratio of friction factor of the current helicoidal pipe (fn) to the friction factor of the straight pipe (f,) has been compared with previous investigations, and good agreement has been obtained. Furthermore, the axial velocity distributions at two different cross-sections of a helicoidal pipe for dif-