Experimental Investigation on Cavitation Performance of Torque Converter Using Transparent Model

2019 ◽  
Author(s):  
Yusuke Katayama ◽  
Yuki Hosoi ◽  
Yuta Fukuda ◽  
Satoshi Watanabe ◽  
Shin-ichi Tsuda ◽  
...  
Keyword(s):  
High Speed ◽  
Turbine Blades ◽  
Suction Side ◽  
Torque Converter ◽  
Working Fluid ◽  
Speed Ratio ◽  
Cavitation Phenomenon ◽  
Cavitation Bubbles ◽  
Charge Pressure ◽  
Dissolved Air

Abstract In this study, we experimentally investigated the influence of the amount of dissolved air in working fluid and the rotation speed ratio of turbine to pump elements on cavitation phenomenon in automotive torque converter. In order to directly observe the cavitation phenomenon, transparent model was used. The applied charge pressure was varied to change the significance of cavitation. The pump and turbine torques were simultaneously measured to clarify the relation between torque performance and cavitation phenomenon. As a result, the cavitation region was found to depend on the speed ratio; cavitation occurred on the suction side of turbine blades at low speed ratios while in the pump region at high speed ratios. The effect of the amount of dissolved air was significant, which enhanced the growth of cavitation bubbles through the deposition of dissolved air. In such cases, with the further decrease of charge pressure, a large number of gaseous cavitation bubbles appeared in the whole flow passage. The torque performance was deteriorated at this stage.

Laser Velocimeter Measurements in the Turbine of an Automotive Torque Converter: Part II—Unsteady Measurements

1997 ◽  
Vol 119 (3) ◽  
pp. 655-662 ◽  
Author(s):  
K. Brun ◽  
R. D. Flack
Keyword(s):  
Velocity Field ◽  
Turbine Blades ◽  
Angular Position ◽  
Torque Converter ◽  
Speed Ratio ◽  
Velocity Data ◽  
Velocity Fluctuations ◽  
Blade Passage ◽  
Turbine Pump ◽  
Output Torque

The unsteady velocity field found in the turbine of an automotive torque converter was measured using laser velocimetry. Velocities in the inlet, quarter, mild, and exit planes of the turbine were investigated at two significantly different turbine/pump rotational speed ratios: 0.065 and 0.800. A data organization method was developed to visualize the three-dimensional, periodic unsteady velocity field in the rotating frame. For this method, the acquired data are assumed to be periodic at synchronous and blade interaction frequencies. Two shaft encoders were employed to obtain the instantaneous angular position of the torque converter pump and turbine at the instant of laser velocimeter data acquisition. By proper “registration” of the velocity data, visualizing the transient interaction effects between the turbine, pump, and stator was possible. Results showed strong cyclic velocity fluctuations in the turbine inlet plane as a function of the relative turbine-pump position. These fluctuations are due to the passing of upstream pump blades by the slower rotating turbine blades. Typical fluctuations in the through flow velocity were 3.6 m/s. Quarter and midplane velocity fluctuations were seen to be lower; typical values were 1.5 m/s and 0.8 m/s, respectively. The flow field in the turbine exit plane was seen to be relatively steady with negligible fluctuations of less than 0.03 m/s. From the velocity data, the fluctuations of turbine performance parameters such as flow inlet angles, root-mean-square unsteadiness, and output torque per blade passage were calculated. Incidence angles were seen to vary by 3 and 6 deg for the 0.800 and 0.065 speed ratios, respectively, while the exit angles remained steady. The turbine output torque per blade passage fluctuated by 0.05 Nm for the 0.800 speed ratio and 0.13 Nm for the 0.065 speed ratio.

Cooling of Turbine Blades With Expanded Exit Holes: Computational Analyses of Leading Edge and Pressure-Side of a Turbine Blade

2017 ◽  
Vol 139 (4) ◽  
Author(s):  
Fariborz Forghan ◽  
Omid Askari ◽  
Uichiro Narusawa ◽  
Hameed Metghalchi
Keyword(s):  
High Speed ◽  
Turbine Blades ◽  
Leading Edge ◽  
Weak Shock ◽  
Suction Side ◽  
Pressure Side ◽  
Blade Surface ◽  
Cooling Effectiveness ◽  
Hot Gas ◽  
Computational Analyses

Turbine blades are cooled by a jet flow from expanded exit holes (EEH) forming a low-temperature film over the blade surface. Subsequent to our report on the suction-side (low-pressure, high-speed region), computational analyses are performed to examine the cooling effectiveness of the flow from EEH located at the leading edge as well as at the pressure-side (high-pressure, low-speed region). Unlike the case of the suction-side, the flow through EEH on the pressure-side is either subsonic or transonic with a weak shock front. The cooling effectiveness, η (defined as the temperature difference between the hot gas and the blade surface as a fraction of that between the hot gas and the cooling jet), is higher than the suction-side along the surface near the exit of EEH. However, its magnitude declines sharply with an increase in the distance from EEH. Significant effects on the magnitude of η are observed and discussed in detail of (1) the coolant mass flow rate (0.001, 0.002, and 0.004 (kg/s)), (2) EEH configurations at the leading edge (vertical EEH at the stagnation point, 50 deg into the leading-edge suction-side, and 50 deg into the leading-edge pressure-side), (3) EEH configurations in the midregion of the pressure-side (90 deg (perpendicular to the mainstream flow), 30 deg EEH tilt toward upstream, and 30 deg tilt toward downstream), and (4) the inclination angle of EEH.

scholarly journals Measurements of Strain on 310 mm Torque Converter Turbine Blades

2004 ◽  
Vol 10 (1) ◽  
pp. 55-63
Author(s):  
P. O. Sweger ◽  
C. L. Anderson ◽  
J. R. Blough
Keyword(s):  
Turbine Blade ◽  
Turbine Blades ◽  
Torque Converter ◽  
Operating Conditions ◽  
Surface Strain ◽  
Speed Ratio ◽  
Constant Input ◽  
Wide Range ◽  
Blade Tip ◽  
Input Torque

An automotive torque converter was tested in order to determine the effect of converter operating condition and turbine blade design on turbine blade strain in the region of the inlet core tab restraint. The converter was operated over a wide range of speed ratios (0 to 0.95) at constant input torque and a stall condition for two input torques. Foil-type strain gages in combination with wireless microwave telemetry were used to measure surface strain on the turbine blade. Strain measurements were made on two turbine blade designs.The steady component of strain over the range of speed ratios suggests the effect of both torque loading and centrifugal loading on the turbine blade tip. The unsteady strain was greatest at stall condition and diminished as speed ratio increased. Greater input torque at stall condition resulted in both greater steady strain and greater unsteady strain. The spectral distribution of strain over the range of tested speed ratios displayed an increase in low-frequency broadband fluctuations near stall condition. A blade-periodic event is observed which correlates to the pump-blade passing frequency relative to the turbine rotating frame. Reducing the blade-tip surface area and increasing the inlet-tab root radius reduced the range of steady strain and magnitude of unsteady strain imposed near the inlet core tab restraint over the range of operating conditions.

scholarly journals Laser Velocimeter Measurements in the Pump of an Automotive Torque Converter Part II – Effect of Pump Speed and Oil Viscosity

2000 ◽  
Vol 6 (3) ◽  
pp. 181-190 ◽  
Author(s):  
Ronald D. Flack ◽  
Steven B. Ainley ◽  
Klaus Brun ◽  
Leonard Whitehead
Keyword(s):  
Rotational Speed ◽  
Three Dimensional ◽  
Torque Converter ◽  
Secondary Flows ◽  
Working Fluid ◽  
Speed Ratio ◽  
Oil Viscosity ◽  
Low Velocity ◽  
Pump Speed ◽  
Mass Flows

The velocity field inside a torque converter pump was studied for two separate effects: variable pump rotational speed and variable oil viscosity. Three-dimensional velocity measurements were taken using a laser velocimeter for both the pump mid- and exit planes. The effect ofvariable pump rotational speed was studied by running the pump at two different speeds and holding speed ratio (pump rotational speed]turbine rotational speed) constant. Similarly, the effect of viscosity on the pump flow field was studied by varying the temperature and]or using two different viscosity oils as the working fluid in the pump. Threedimensional velocity vector plots, through-flow contour plots, and secondary flow profiles were obtained for both pump planes and all test conditions. Results showed that torque converter mass flows increased approximately linearly with increasing pump rotational speed (and fixed speed ratio) but that the flow was not directly proportional to pump rotational speed. However, mass flows were seen to decrease as the oil viscosity was decreased with a resulting increased Reynolds number; for these conditions the high velocity regions were seen to decrease in size and low velocity regions were seen to increase in size. In the pump mid-plane strong counter-clockwise secondary flows and in the exit plane strong clockwise secondary flows were observed. The vorticities and slip factors were calculated from the experimental results and are presented. The torque core-to-shell and blade-to-blade torque distributions were calculated for both planes. Finally, the flow fields were seen to demonstrate similitude when Reynolds numbers were matched.

Effects of Number of Stator Blades on the Performance of a Torque Converter

2011 ◽  
Author(s):  
Shoab Ahmed Talukder ◽  
B. Phuoc Huynh
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Software Package ◽  
Torque Converter ◽  
Working Fluid ◽  
Speed Ratio ◽  
Industrial Oil ◽  
Transmission Shaft ◽  
Computational Fluid Dynamics Cfd ◽  
Speed Change

Torque converter (TC) is a totally enclosed hydrodynamic turbomachine, used most often in automobiles for the smooth transfer of power and speed change from the engine to the transmission, and torque magnification. A typical TC has 3 major components: a pump that is attached directly to the TC cover and connected to the engine shaft, a turbine connected to the transmission shaft, and a stator connected to the transmission housing via a one-way clutch and providing guidance for the fluid flow. In this work, effects of the number of stator blades on the performance of a TC are investigated numerically, using a commercial Computational Fluid Dynamics (CFD) software package. The standard k-epsilon turbulence model was used. A Newtonian fluid whose properties correspond to industrial oil was used for the working fluid. The range of speed ratio (between turbine’s speed and pump’s) of 0.2–0.8 was considered. It was found that as the stator blades’ number increases (here from 13 to 19), the TC’s efficiency and torque ratio vary significantly, passing through minimum and generally also reaching a maximum.

Influence of Stator Blade Geometry on Torque Converter Cavitation

2017 ◽  
Vol 140 (4) ◽  
Author(s):  
Cheng Liu ◽  
Wei Wei ◽  
Qingdong Yan ◽  
Brian K. Weaver ◽  
Houston G. Wood
Keyword(s):  
High Speed ◽  
Torque Converter ◽  
Operating Conditions ◽  
Hydrodynamic Performance ◽  
Speed Ratio ◽  
Capacity Loss ◽  
Wide Range ◽  
Stator Blade ◽  
Torque Converters ◽  
Blade Geometry

Cavitation in torque converters may cause degradation in hydrodynamic performance, severe noise, or even blade damage. Researches have highlighted that the stator is most susceptible to the occurrence of cavitation due to the combination of high flow velocities and high incidence angles. The objective of this study is to therefore investigate the effects of cavitation on hydrodynamic performance as well as the influence of stator blade geometry on cavitation. A steady-state homogeneous computational fluid dynamics (CFD) model was developed and validated against test data. It was found that cavitation brought severe capacity constant degradation under low-speed ratio (SR) operating conditions and vanished in high-speed ratio operating conditions. A design of experiments (DOE) study was performed to investigate the influence of stator design variables on cavitation over various operating conditions, and it was found that stator blade geometry had a significant effect on cavitation behavior. The results show that stator blade count and leaning angle are important variables in terms of capacity constant loss, torque ratio (TR) variance, and duration of cavitation. Large leaning angles are recommended due to their ability to increase the cavitation number in torque converters over a wide range of SRs, leading to less stall capacity loss as well as a shorter duration of cavitation. A reduced stator blade count is also suggested due to a reduced TR loss and capacity loss at stall.

Paper 38: Water Drainage from a Cascade of Hollow Slotted Low-Pressure Turbine Blades

1967 ◽  
Vol 182 (8) ◽  
pp. 357-365 ◽  
Author(s):  
D. H. McAllister ◽  
C. T. Moore
Keyword(s):  
High Speed ◽  
Turbine Blades ◽  
Rotor Blades ◽  
Working Fluid ◽  
Steam Turbines ◽  
Water Drainage ◽  
Low Pressure Turbine ◽  
Wide Range ◽  
Trailing Edges ◽  
Hollow Cavity

To prevent or minimize the erosion of the last row rotor blades in large high-speed steam turbines it has been proposed to remove the film of water on the surfaces of the last row stator blades before it reaches the trailing edges and is swept off by the steam drag into the path of the rotor blades. The paper describes experiments with a cascade of hollow stator blades with various dispositions of slots providing communication from the blade surfaces to the hollow cavity. The same cascade was used in turn with three different wet air tunnels, the experiments thus covering a wide range of Mach number and Reynolds number. With suitably disposed slots, and bleeding a very small proportion of the working fluid, about 90 per cent of the deleterious water can be removed, thus preventing it from striking the moving blades.

Effects of Periodic Unsteady Inflow on Film Cooling and Heat Transfer on Highly Loaded High Pressure Turbine Blades With Flow Separation

2012 ◽  
Author(s):  
Reinaldo A. Gomes ◽  
Reinhard Niehuis
Keyword(s):  
Heat Transfer ◽  
Flow Separation ◽  
Film Cooling ◽  
High Speed ◽  
Turbine Blades ◽  
Suction Side ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Unsteady Inflow ◽  
Highly Loaded

Film cooling experiments were run at the High-Speed Cascade Wind Tunnel of the University of the Federal Armed Forces Munich. The investigations were carried out on a linear cascade of highly loaded turbine blades. The main targets of the tests were to assess the film cooling effectiveness and the heat transfer in zones with main flow separation. The previous cascade was designed to have a large zone with flow separation on the pressure side starting at the leading edge and reaching up to approximately half of the axial chord. This cascade was changed for a new design with a larger pitch to chord ratio in order to set the focus on flow separation on the suction side. This increased pitch forces a massive separation on the suction side due to strong shocks. The flow separation is controlled with aid of vortex generating jets in order to reduce the total pressure loss caused by it. Film cooling is provided on the suction side upstream of the vortex generating jets. The measurements comprise of blade loading, profile loss, adiabatic film cooling effectiveness and heat transfer coefficient under two Mach numbers at a Reynolds number of 390,000. In a previous publication detailed results with homogeneous inflow where shown. Now, the focus is set on the effects of periodic unsteady wakes resulting from bars moving upstream of the cascade. These moving bars create a periodic unsteady inflow similar to the interaction between stator and rotor in the machine. It is shown how these wakes have significant influence on the heat transfer in the acceleration region of the suction side and affect the adiabatic film cooling effectiveness upstream of the shock.

Effects of Periodic Unsteady Inflow on Film Cooling and Heat Transfer on Highly Loaded High Pressure Turbine Blades With Flow Separation

2013 ◽  
Vol 136 (2) ◽  
Author(s):  
Reinaldo A. Gomes ◽  
Reinhard Niehuis
Keyword(s):  
Heat Transfer ◽  
Flow Separation ◽  
Film Cooling ◽  
High Speed ◽  
Turbine Blades ◽  
Suction Side ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Unsteady Inflow ◽  
Highly Loaded

Film cooling experiments were run at the high-speed cascade wind tunnel of the University of the Federal Armed Forces Munich. The investigations were carried out on a linear cascade of highly loaded turbine blades. The main targets of the tests were to assess the film cooling effectiveness and the heat transfer in zones with main flow separation. The previous cascade was designed to have a large zone with flow separation on the pressure side starting at the leading edge and reaching up to approximately half of the axial chord. This cascade was changed for a new design with a larger pitch to chord ratio in order to set the focus on flow separation on the suction side. This increased pitch forces a massive separation on the suction side due to strong shocks. The flow separation is controlled with aid of vortex generating jets in order to reduce the total pressure loss caused by it. Film cooling is provided on the suction side upstream of the vortex generating jets. The measurements comprise of blade loading, profile loss, adiabatic film cooling effectiveness, and heat transfer coefficient under two Mach numbers at a Reynolds number of 390,000. In a previous publication detailed results with homogeneous inflow where shown. Now, the focus is set on the effects of periodic unsteady wakes resulting from bars moving upstream of the cascade. These moving bars create a periodic unsteady inflow similar to the interaction between stator and rotor in the machine. It is shown how these wakes have significant influence on the heat transfer in the acceleration region of the suction side and affect the adiabatic film cooling effectiveness upstream of the shock.

scholarly journals Flow Field in the Turbine Rotor Passage in an Automotive Torque Converter Based on the High Frequency Response Rotating Five-hole Probe Measurement Part I: Flow Field at the Design Condition (Speed Ratio 0.6)

2001 ◽  
Vol 7 (4) ◽  
pp. 253-269 ◽  
Author(s):  
Y. F. Liu ◽  
B. Lakshminarayana ◽  
J. Burningham
Keyword(s):  
Pressure Drop ◽  
Flow Field ◽  
Flow Separation ◽  
Suction Side ◽  
Torque Converter ◽  
Turbine Rotor ◽  
Stagnation Pressure ◽  
Wake Flow ◽  
Speed Ratio ◽  
The Core

The relative flow field in an automotive torque converter turbine was measured at three locations inside the passage (turbine 1/4 chord, mid-chord, and 4/4 chord) using a highfrequency response rotating five-hole-probe. “Jet-Wake” flow structure was found in the turbine passage. Possible flow separation region was observed at the core/suction side at the turbine1/4chord and near the suction side at the turbine mid-chord. The mass averaged stagnation pressure drop is almost evenly distributed along the turbine flow path at the design condition(SR=0.6). The pressure drop due to centrifugal and Coriolis forces is found to be appreciable. The rotary stagnation pressure distribution indicates that there are higher losses at the first half of the turbine passage than at the second half. The major reasons for these higher losses and inefficiency are possible flow separation and a mismatch between the pump exit and the turbine inlet flow field. The fuel economy of a torque converter can be improved through redesign of the core region and by properly matching the pump and the turbine. The Part I of the paper deals with the design speed ratio(SR=0.6), and Part II deals with the off-design condition(SR=0.065)and the effects of speed ratio.

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