Perspective: Fluid Dynamics and Performance of Automotive Torque Converters: An Assessment

1996 ◽  
Vol 118 (4) ◽  
pp. 665-676 ◽  
Author(s):  
T. W. von Backstro¨m ◽  
B. Lakshminarayana
Keyword(s):  
Measurement Techniques ◽  
Torque Converter ◽  
Fast Response ◽  
Secondary Flows ◽  
Experimental Investigations ◽  
Meridional Plane ◽  
Suction Surface ◽  
Pressure Surface ◽  
Torque Converters ◽  
Pump Inlet

Experimental investigations by various groups over the past decade have uncovered the main features of the flow in hydraulic torque converters. Measurement techniques include laser and hot wire velocimetry, fast response and conventional five-hole probes, and blade and wall static pressure measurement. In both the pump and turbine, the through flow velocity is high near the pressure surface shell corner while the flow in the suction surface core corner is highly turbulent and may be separated and reversed. The position of the stator in a passage curved in the meridional plane leads to secondary flow and low velocities at the core near the pump inlet. Velocity gradients coupled with flow turning and rotor rotation lead to strong secondary flows. By using data from a combination of measurement techniques, torque converter torque, power and efficiency are calculated, and the effect of element efficiency on overall efficiency is demonstrated. It is concluded that design methods should be developed that allow for nonuniform velocity profiles, flow separation, secondary circulation and interaction effects between elements.

scholarly journals Laser Velocimeter Measurements in the Stator of an Automotive Torque Converter

2000 ◽  
Vol 6 (6) ◽  
pp. 417-431 ◽  
Author(s):  
Steven B. Ainley ◽  
Ronald D. Flack
Keyword(s):  
Secondary Flow ◽  
Mass Flow ◽  
Torque Converter ◽  
Speed Ratio ◽  
Pressure Side ◽  
Suction Surface ◽  
General Direction ◽  
Flow Rates ◽  
Pressure Surface ◽  
Mass Flow Rates

The flow field in the stator of a clear torque converter was studied using laser velocimetry. Five planes in the stator were studied at a speed ratio of 0.800 and three planes were studied at a speed ratio of 0.065. Data complements previously available pump and turbine data. Flow in the stator inlet plane is highly non-uniform due to the complicated flow exiting the turbine. At the 0.800 speed ratio, separation regions are located in the 1/4 and mid-planes in the corepressure corner region. In the 3/4 and exit planes, separation regions are located in the shellsuction corner. In the inlet plane a region of high velocities is located along the shell near the pressure side for a speed ratio of 0.800. The high velocity region migrated to the shell-suction corner and suction side in the 1/4 and mid-planes. The overall velocity field for the speed ratio of 0.065 changes significantly from the inlet plane to the mid-plane. The velocity magnitude generally decreases from the suction to the pressure side of the inlet plane and the general direction of the tangential velocity is from pressure-to-suction surface. At the speed ratio of 0.065 a strong secondary flow in the inlet from suction surface to pressure surface was seen. However, at the high speed ratio a moderate secondary flow in the inlet from pressure surface to suction surface was observed. Mass flow rates at the different planes are within the experimental uncertainty and also within the uncertainty of pump and turbine mass flow rates. The flow in the stator inlet plane are significantly influenced by the turbine relative blade position. The turbine influence on the mid-plane data is significantly less than on the inlet plane data. The influence of the pump blade position on the stator exit plane is small.

The Measurement of Boundary Layers on a Compressor Blade in Cascade: Part 4 — Flow Fields for Incidence Angles of −1.5 and −8.5 Degrees

1989 ◽  
Author(s):  
W. C. Zierke ◽  
S. Deutsch
Keyword(s):  
Boundary Layers ◽  
Separation Bubble ◽  
Measurement Techniques ◽  
Leading Edge ◽  
Compressor Blade ◽  
Laser Doppler ◽  
Laser Doppler Velocimeter ◽  
Suction Surface ◽  
Laminar Separation ◽  
Pressure Surface

Measurements, made with laser Doppler velocimetry, about a double-circular-arc compressor blade in cascade are presented for −1.5 and −8.5 degree incidence angles and a chord Reynolds number near 500,000. Comparisons between the results of the current study and those of our earlier work at a 5.0 degree incidence are made. It is found that in spite of the relative sophistication of the measurement techniques, transition on the pressure surface at the −1.5 degree incidence is dominated by a separation “bubble” too small to be detected by the laser Doppler velocimeter. The development of the boundary layers at −1.5 and 5.0 degrees are found to be similar. In contrast to the flow at these two incidence angles, the leading edge separation “bubble” is on the pressure surface for the −8.5 degree incidence. Here, all of the measured boundary layers on the pressure surface are turbulent — but extremely thin — while on the suction surface, a laminar separation/turbulent reattachment “bubble” lies between roughly 35% and 60% chord. This “bubble” is quite thin, and some problems in interpreting backflow data.

Laser Velocimeter Measurements in the Pump of an Automotive Torque Converter: Part I—Average Measurements

1996 ◽  
Vol 118 (3) ◽  
pp. 562-569 ◽  
Author(s):  
J. K. Gruver ◽  
R. D. Flack ◽  
K. Brun
Keyword(s):  
Angular Position ◽  
Torque Converter ◽  
Secondary Flows ◽  
Speed Ratio ◽  
Exit Plane ◽  
Centrifugal Pumps ◽  
Torque Distribution ◽  
Average Flow Velocity ◽  
Pump Shaft ◽  
Pump Inlet

A torque converter was tested for two turbine/pump rotational speed ratios, 0.065 and 0.800, and a laser velocimeter was used to measure three components of velocity within the pump. Shaft encoders were used to record the instantaneous pump angular position, which was correlated with the velocities. Average flow velocity profiles were obtained for the pump inlet, mid-, and exit planes. Large separation regions were seen in the mid- and exit planes of the pump for a speed ratio of 0.800. Strong counterclockwise secondary flows were observed in the midplane and strong clockwise secondary flows were seen in the exit plane of the pump for all conditions; vorticities were evaluated and are reported. Velocity data were also used to find the torque distribution. For both speed ratios the torque was approximately evenly distributed between the inlet and exit. Finally, slip factors were evaluated at the mid-and exit planes. At the midplane they were approximately the same as for conventional centrifugal pumps; however, at the exit plane the slip factors are larger than for centrifugal pumps.

Aerodynamics and Heat Transfer for a Cooled One and One-Half Stage High-Pressure Turbine: Part II—Influence of Inlet Temperature Profile on Blade Row and Shroud

2010 ◽  
Author(s):  
R. M. Mathison ◽  
C. W. Haldeman ◽  
M. G. Dunn
Keyword(s):  
Heat Flux ◽  
Temperature Profile ◽  
Secondary Flows ◽  
Inlet Temperature ◽  
Fluid Temperature ◽  
Suction Surface ◽  
Pressure Surface ◽  
Purge Flow ◽  
Hot Streak ◽  
Gas Segregation

Heat-flux measurements are presented for the un-cooled blades of a one-and-one-half stage turbine operating at design corrected conditions with a fully cooled upstream vane row and with rotor disk cavity purge flow. The paper highlights the differences in blade heat flux and temperature caused by uniform, radial, and hot streak inlet temperature profiles. A general discussion of temperature profile migration is provided in Part I, and Part III presents data for hot streak magnitudes and alignments. The heat-flux and fluid-temperature measurements for the blade airfoil, platform, angel wing (near the root), and tip as well as for the stationary outer shroud are influenced by the vane inlet temperature profile. The inlet temperature profile shape can be clearly observed in the blade Stanton Number measurements, with the radial and hot streak profiles showing a greater redistribution of energy than the uniform case due to secondary flows. Hot gas segregation is observed to increase with the strength of the temperature distortion. Measurements for the hot streak profile show a segregation of higher temperature fluid to the pressure surface when compared to a uniform profile. The introduction of vane and purge cooling is found to further accentuate the flow segregation due to coolant migration to the suction surface.

Investigation of Cooling-Air Injection on the Flow Field Within a Linear Turbine Cascade

1997 ◽  
Author(s):  
Yang Hong ◽  
Chen Fu ◽  
Gong Cunzhong ◽  
Wang Zhongqi
Keyword(s):  
Leading Edge ◽  
Secondary Flows ◽  
Air Injection ◽  
Internal Flows ◽  
Suction Surface ◽  
Flow Angle ◽  
Pressure Surface ◽  
Secondary Air Injection ◽  
Secondary Air ◽  
Cooling Air

In order to make clear how air injection influence the internal flows of turbine guide vanes, flows in a lagre-scale linear cascade were surveyed with secondary air injection from the locations of the blade leading-edge, and the rear of the suction and the pressure surfaces. The experimental results show that the secondary air interacts with the vortices in the cascade, alters the pressure distribution over blade profile and increases the energy loss obviously. It has been found that the air injection from the rear of the suction surface leads to the largest effect on the loss increase while the air injection from the rear of the pressure surface exerts the least influence. All the injections pertaining to the experiment have been found to have little effect on the exit flow angle. Effects on secondary flows, vortex intensity, and some averaged parameters are also discussed in this paper.

Aerodynamics and Heat Transfer for a Cooled One and One-Half Stage High-Pressure Turbine–Part II: Influence of Inlet Temperature Profile on Blade Row and Shroud

2011 ◽  
Vol 134 (1) ◽  
Author(s):  
R. M. Mathison ◽  
C. W. Haldeman ◽  
M. G. Dunn
Keyword(s):  
Heat Flux ◽  
Temperature Profile ◽  
Secondary Flows ◽  
Inlet Temperature ◽  
Fluid Temperature ◽  
Suction Surface ◽  
Pressure Surface ◽  
Purge Flow ◽  
Hot Streak ◽  
Gas Segregation

Heat flux measurements are presented for the uncooled blades of a one and one-half stage turbine operating at design corrected conditions with a fully cooled upstream vane row and with rotor disk cavity purge flow. This paper highlights the differences in blade heat flux and temperature caused by uniform, radial, and hot streak inlet temperature profiles. A general discussion of temperature profile migration is provided in Part I, and Part III presents data for hot streak magnitudes and alignments. The heat flux and fluid temperature measurements for the blade airfoil, platform, angel wing (near the root), and tip as well as for the stationary outer shroud are influenced by the vane inlet temperature profile. The inlet temperature profile shape can be clearly observed in the blade Stanton number measurements, with the radial and hot streak profiles showing a greater redistribution of energy than the uniform case due to secondary flows. Hot-gas segregation is observed to increase with the strength of the temperature distortion. Measurements for the hot streak profile show a segregation of higher temperature fluid to the pressure surface when compared with a uniform profile. The introduction of vane and purge cooling is found to further accentuate the flow segregation due to coolant migration to the suction surface.

Pressure Surface Separations in Low Pressure Turbines: Part 2 of 2 — Interactions With the Secondary Flow

2001 ◽  
Author(s):  
Michael J. Brear ◽  
Howard P. Hodson ◽  
Paloma Gonzalez ◽  
Neil W. Harvey
Keyword(s):  
Secondary Flow ◽  
Turbine Blades ◽  
Low Pressure ◽  
Secondary Flows ◽  
Suction Surface ◽  
Linear Cascade ◽  
Surface Separation ◽  
Pressure Surface ◽  
Low Pressure Turbine ◽  
Turbine Design

This paper describes a study of the interaction between the pressure surface separation and the secondary flow on low pressure turbine blades. It is found that this interaction can significantly affect the strength of the secondary flow and the loss that it creates. Experimental and numerical techniques are used to study the secondary flow in a family of four low pressure turbine blades in linear cascade. These blades are typical of current designs, share the same suction surface and pitch, but have differing pressure surfaces. A mechanism for the interaction between the pressure surface separation and the secondary flow is proposed and is used to explain the variations in the secondary flows of the four blades. This mechanism is based on simple dynamical secondary flow concepts and is similar to the aft-loading argument commonly used in modern turbine design.

Vibration Characteristics due to Cavitation in Stator Element of Automotive Torque Converter at Stall Condition

2012 ◽  
Author(s):  
Satoshi Watanabe ◽  
Ryosuke Otani ◽  
Shun Kunimoto ◽  
Yoshinori Hara ◽  
Akinori Furukawa ◽  
...  
Keyword(s):  
Vibration Spectrum ◽  
Mechanical Vibration ◽  
Leading Edge ◽  
Outer Wall ◽  
Torque Converter ◽  
Suction Surface ◽  
Pump Speed ◽  
Pressure Surface ◽  
Wide Range ◽  
Charge Pressure

Cavitation behaviors in an automotive torque converter at pump speed of 600, 700 and 800 min−1 at the stall condition are investigated by means of the transparent model. At the same time, the influences of cavitation on mechanical vibration are studied. As a result, at the onset of cavitation, the longitudinal corner vortex cavitation is formed at the corner between outer wall and either suction or pressure surface of stator blades. After the further decrease of charge pressure, the cavitation bubbles are observed in the flow separation region formed at the leading edge on the suction surface of stator blades. Vibration spectrum peaks are found in the wide range of frequency, which increase with the development of cavitation but then decrease with its excessive development. Discussions are made for higher and lower frequency ranges separately to understand the relation between mechanical vibrations and cavitation.

Flow Development in Radial Turbine Rotors

1996 ◽  
Author(s):  
Nicholas C. Baines
Keyword(s):  
Incidence Angle ◽  
Leading Edge ◽  
Secondary Flows ◽  
Complex Flow ◽  
Suction Surface ◽  
Blade Loading ◽  
New Approach ◽  
Pressure Surface ◽  
Strong Vortex ◽  
Coherent Picture

This paper surveys the development of the primary and secondary flows in the rotors of radial-inflow turbines. Information previously scattered throughout the literature has been brought together, and it has been possible to create a coherent picture and a good understanding of the complex flow processes which occur. The secondary flow is generated by cross-passage forces due to the turning of the blades, and Coriolis forces. Near the leading edge these give rise to a strong vortex adjacent to the pressure surface, moving low momentum fluid from hub to tip. This feature helps to explain why best efficiency occurs typically at 20°–30° negative incidence. Attempts to correlate the optimum incidence angle using traditional slip factor expressions can give quite misleading results, but a new approach based on the blade loading shows considerable promise. Nearer the exit there is motion of fluid from hub to tip near the suction surface and a vortex in the suction surface-shroud corner, and this is linked to the highly non-uniform flow at exit. The latter effect makes the prediction and correlation of rotor deviation information very difficult, despite the development of a rational exit averaging procedure. The present deviation data are sparse and not easy to correlate.

Understanding of Secondary Flows and Losses in Radial and Mixed Flow Turbines

2020 ◽  
Vol 142 (8) ◽  
Author(s):  
Bijie Yang ◽  
Peter Newton ◽  
Ricardo Martinez-Botas
Keyword(s):  
Secondary Flows ◽  
Limited Attention ◽  
Centrifugal Forces ◽  
Suction Surface ◽  
Flow Topology ◽  
Mixed Flow ◽  
Tip Leakage Vortex ◽  
Tip Leakage ◽  
Surface Separation ◽  
Pressure Surface

Abstract Radial or mixed flow turbines are very common in industrial application, spanning turbochargers, small turbines for power generation, and energy recovery systems. Secondary flows have received a limited attention in the literature, and this papers aims to fill this gap of knowledge. The secondary flow structures in mixed flow turbines are particularly complex due to its geometry, high curvature, and the appearance of Coriolis and centrifugal forces. The focus of the present work is to investigate the evolution of secondary flows and their losses in a mixed flow turbine by using an experimentally validated three-dimensional computational fluid dynamics (CFD). The flow topology is analyzed to explain the formation and evolution of flow separations at the pressure, suction, and hub surfaces. The suction surface separation is caused by centrifugal forces, and it induces the formation of a hub separation. As the inlet velocity decreases, the hub separation increases in strength. A major feature found is the pressure surface separation, located at the leading edge tip, formed due to flow incidence; as the incidence decreases, this separation extends to the hub. Losses caused by those separations as well as the tip leakage vortex are studied by calculating locally entropy generation. Results show that the tip-leakage vortex accounts for the majority of losses (60%) and renders the losses caused by suction surface and induced hub separations to be small. The presence of the more severe hub separation was also found to have a significant detrimental effect on the turbine efficiency, which increases losses on the hub and the suction surface from 40% to 65%. Pressure surface separation, however, does not vary the total amount of losses significantly but rather redistributes the losses in the blade passage.

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