Flow Model for Large Radius-Ratio Magnetic Annular Shock-Tube Operation

The unsteady flow field due to blade passing at the pump/turbine interface of a torque converter was studied. The current geometry is wide and has a large outer to inner radius ratio. A laser velocimeter was used to measure the periodic velocity components at four operating conditions determined by the speed ratios between the turbine and pump of 0.065 (near stall), 0.600, 0.800, and 0.875 (coupling point). The flow fields at the pump exit and turbine inlet planes were visualized and are presented. Using instantaneous pump and turbine blade positions with the velocity data, animations (“slow-motion movies”) are generated to effectively visualize and understand the unsteady behavior. The turbine inlet flow was markedly periodic due to the exiting jet/wake from the upstream pump passage; however, the pump exit flow field showed little dependence on the turbine blade positions. The highest unsteadiness was seen for the highest speed ratios. Four “shots” from the sequences of one cycle for all speed ratios and each plane are presented herein. The results are also compared to unsteady results for a previously examined torque converter with a small radius ratio to determine the effect of parametric geometric changes on the flow field. Generally, the unsteady velocity fields show no significant difference for the two geometries — the trends are the same.

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Taylor vortices in short fluid columns with large radius ratio

Physics of Fluids A Fluid Dynamics ◽

10.1063/1.857562 ◽

1990 ◽

Vol 2 (9) ◽

pp. 1557-1563 ◽

Cited By ~ 8

Author(s):

C. A. Bielek ◽

E. L. Koschmieder

Keyword(s):

Radius Ratio ◽

Large Radius ◽

Taylor Vortices

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Numerical Investigation of Shock Wave Diffraction over a Sphere Placed in a Shock Tube

International Journal of Aerospace Engineering ◽

10.1155/2016/5740435 ◽

2016 ◽

Vol 2016 ◽

pp. 1-5

Author(s):

Sergey Martyushov ◽

Ozer Igra ◽

Tov Elperin

Keyword(s):

Shock Tube ◽

Drag Coefficient ◽

Flow Model ◽

The Body ◽

Shock Wave Diffraction ◽

Present Scheme ◽

The Past ◽

Steady Flow Condition ◽

Experimental Findings ◽

Good Agreement

For evaluating the motion of a solid body in a gaseous medium, one has to know the drag constant of the body. It is therefore not surprising that this subject was extensively investigated in the past. While accurate knowledge is available for the drag coefficient of a sphere in a steady flow condition, the case where the flow is time dependent is still under investigation. In the present work the drag coefficient of a sphere placed in a shock tube is evaluated numerically. For checking the validity of the used flow model and its numerical solution, the present numerical results are compared with available experimental findings. The good agreement between present simulations and experimental findings allows usage of the present scheme in nonstationary flows.

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Turbulent Taylor-Couette vortex flow between large radius ratio concentric cylinders

Experiments in Fluids ◽

10.1007/s00348-003-0739-1 ◽

2004 ◽

Vol 36 (3) ◽

pp. 419-421 ◽

Cited By ~ 5

Author(s):

W. M. J. Batten ◽

S. R. Turnock ◽

N. W. Bressloff ◽

S. M. Abu-Sharkh

Keyword(s):

Vortex Flow ◽

Radius Ratio ◽

Large Radius ◽

Concentric Cylinders ◽

Taylor Couette

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A 3D Compressible Flow Model for Weak Rotating Waves in Vaneless Diffusers—Part II: Detailed Results

Journal of Turbomachinery ◽

10.1115/1.4003654 ◽

2011 ◽

Vol 134 (4) ◽

Cited By ~ 1

Author(s):

Feng Sheng ◽

Hua Chen ◽

Xiao-cheng Zhu ◽

Zhao-hui Du

Keyword(s):

Mach Number ◽

Radial Velocity ◽

Compressible Flow ◽

Wave Speed ◽

Flow Model ◽

Radius Ratio ◽

Wave Number ◽

Rotating Waves ◽

Inlet Distortion ◽

Vaneless Diffusers

A 3D compressible flow model was presented in Part I of the paper to study the occurrence of weak rotating waves in vaneless diffusers of centrifugal compressors. In this paper, detailed results on the influences of flow and diffuser geometry parameters, including inlet Mach number, inlet distortion, wave number, diffuser outlet-to-inlet radius ratio, diffuser width to inlet radius ratio, and impeller backswept angle, on the rotating waves are presented. It was found that inlet spanwise distortion of radial velocity has little effects on diffuser stability, but rotating wave speed increases with the distortion. The speed also increases with inlet Mach number, so does diffuser instability. Impeller backswept improves diffuser stability and this effect increases with diffuser radius ratio. Multiple resonances were found when impeller backswept is coupled to inlet distortion of radial velocity. These resonances may have similar stabilities but with different wave speeds, suggesting that two rotating waves with different rotating speeds may occur at the same time. Diffuser width was found to have little effects on stability and on wave speed if the same maximum and same minimum values of inlet distortion of radial velocity are kept, but have some effects if the values are not kept. A comparison was also made between the present model predictions and results in open literatures, and good agreement with the experimental results than previous 2D models was achieved.

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Rotating Stall in Vaneless Diffuser of Large Radius Ratio.

TRANSACTIONS OF THE JAPAN SOCIETY OF MECHANICAL ENGINEERS Series B ◽

10.1299/kikaib.61.3842 ◽

1995 ◽

Vol 61 (591) ◽

pp. 3842-3847

Author(s):

Jun Matsui ◽

Junichi Kurokawa ◽

Michiharu Mino ◽

Eiji Hiroki ◽

Takaya Kitahora

Keyword(s):

Rotating Stall ◽

Radius Ratio ◽

Large Radius ◽

Vaneless Diffuser

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A 3D Compressible Flow Model for Weak Rotating Waves in Vaneless Diffusers—Part I: The Model and Mach Number Effects

Journal of Turbomachinery ◽

10.1115/1.4003655 ◽

2011 ◽

Vol 134 (4) ◽

Cited By ~ 7

Author(s):

Hua Chen ◽

Feng Shen ◽

Xiao-Cheng Zhu ◽

Zhao-Hui Du

Keyword(s):

Mach Number ◽

Compressible Flow ◽

Wave Speed ◽

Flow Model ◽

Radius Ratio ◽

Rotating Waves ◽

Flow Angle ◽

Rotating Wave ◽

Vaneless Diffusers ◽

Undisturbed Flow

A three-dimensional compressible flow model is presented to study the occurrence of weak rotating waves in vaneless diffusers of centrifugal compressors. The diffuser considered has two parallel walls, and the undisturbed flow is assumed to be circumferentially uniform, isentropic, and to have no axial velocity. Linearized 3D compressible Euler equations were casted on a rotating coordinate system traveling at the same angular speed as the wave cells. A uniform static pressure at the outlet of the diffuser was imposed. Complex functions of the solutions to the equations were obtained by a second-order finite difference method and the singular value decomposition technique. The influences of the inlet Mach number of undisturbed flow, inlet spanwise distribution of undisturbed radial velocity, and diffuser radius ratio on the rotating waves were studied and results show that (1) the critical flow angle and rotating wave speed are both affected by the Mach number. However, the angle only increases slightly with the Mach number while the wave speed increases rapidly with the Mach number; (2) inlet distribution has minor influences on diffuser instability but the wave speed increases with the inlet distortion; (3) diffuser instability increases rapidly and the wave speed decreases quickly with the diffuser radius ratio; and (4) backward traveling rotating wave may occur if diffuser is sufficiently long and the inlet Mach number is sufficiently small.

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The Effects of Curvature Radius on Cutting Force and Stability during End Milling

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.314-316.1721 ◽

2011 ◽

Vol 314-316 ◽

pp. 1721-1726

Author(s):

Wan Zhu Liu ◽

Qiang Liu ◽

Ge Gao ◽

Xue Yan

Keyword(s):

Cutting Force ◽

End Milling ◽

Milling Process ◽

Radius Ratio ◽

Curvature Radius ◽

Stable Range ◽

Large Radius ◽

Optimal Parameters ◽

Cutting Point ◽

End Milling Process

The influence of radius ratio of cutting point and cutter on cutting force and stability during end milling process is presented in this paper. To derive motion equations, a 2 DOF mechanical model of end milling considering both regenerative and self-excited effects was established. Different ratio values during three milling conditions were analyzed. Cutting forces as well as stability under different radius ratios by changing curvature radius and cutter radius were elaborated respectively. The results show that when other parameters are set fixed, cutter with relative large radius has smaller cutting force and larger stable range. Cutters with same radius will overlap on cutting force when radius ratio is large enough even under different milling conditions. The proposed analysis on cutting force and stability can be used to determine the optimal parameters, such as cutter radius and spindle speed etc. to improve the accuracy and productivity.

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Periodic Velocity Measurements in a Wide and Large Radius Ratio Automotive Torque Converter at the Pump∕Turbine Interface

Journal of Fluids Engineering ◽

10.1115/1.1891150 ◽

2004 ◽

Vol 127 (2) ◽

pp. 308-316 ◽

Cited By ~ 7

Author(s):

S. O. Kraus ◽

R. Flack ◽

A. Habsieger ◽

G. T. Gillies ◽

K. Dullenkopf

Keyword(s):

Flow Field ◽

Turbine Blade ◽

Torque Converter ◽

Operating Conditions ◽

Radius Ratio ◽

Small Radius ◽

Large Radius ◽

Pump Turbine ◽

Turbine Inlet ◽

Significant Difference

The unsteady flow field due to blade passing at the pump∕turbine interface of a torque converter was studied. The current geometry is wide and has a large outer to inner radius ratio. A laser velocimeter was used to measure the periodic velocity components at four operating conditions determined by the speed ratios between the turbine and pump of 0.065 (near stall), 0.600, 0.800, and 0.875 (coupling point). The flow fields at the pump exit and turbine inlet planes were visualized and are presented. Using instantaneous pump and turbine blade positions with the velocity data, animations (“slow-motion movies”) are generated to effectively visualize and understand the unsteady behavior. The turbine inlet flow was markedly periodic due to the exiting jet∕wake from the upstream pump passage; however, the pump exit flow field showed little dependence on the turbine blade positions. The highest unsteadiness was seen for the highest speed ratios. Four “shots” from the sequences of one cycle for all speed ratios and each plane are presented herein. The results are also compared to unsteady results for a previously examined torque converter with a small radius ratio to determine the effect of parametric geometric changes on the flow field. Generally, the unsteady velocity fields show no significant difference for the two geometries—the trends are the same.

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