Steady and Unsteady Flow Field at Pump and Turbine Exits of a Torque Converter

The steady and unsteady flow field at the pump and the turbine exit of a 245 mm diameter automotive torque converter was measured by a miniature high-frequency-response five-hole probe and a high-frequency-response total pressure Pitot probe in the stationary reference frame. The data were decomposed into blade periodic, blade aperiodic, and unresolved unsteady components. The periodic flow data shows that the pump exit flow has four major zones; the free-stream flow, the blade wake flow, the core-suction corner separation flow, and the mixing zone. The unsteady flow data shows that the unsteadiness in the free-stream is uniform, and the unsteadiness in the wake mixing flow zone is very high. The turbine exit flow is almost fully developed at the measurement plane, the flow field is uniform in the tangential direction, and only radial gradients in flow properties exist. A region of separated flow with high unsteadiness and high axial component of vorticity was observed at the measurement plane near the core.

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A High-Frequency-Response Pressure Probe for the Measurement of Unsteady Flow Between Two Rotors in a Hydrodynamic Turbomachine

Volume 1: Turbomachinery ◽

10.1115/96-gt-412 ◽

1996 ◽

Author(s):

C. Achtelik ◽

J. Eikelmann

Keyword(s):

Unsteady Flow ◽

Frequency Response ◽

High Frequency ◽

Torque Converter ◽

Pressure Probe ◽

Ensemble Averaging ◽

Probe Diameter ◽

High Frequency Response ◽

Single Sensor ◽

Response Pressure

A new, specially-developed high-frequency-response pressure probe was used to measure the unsteady flow in the interaction region between the pump and the turbine in a hydrodynamic torque converter. In order to reduce the probe diameter, a single-hole, single-sensor cylindrical probe (⌀=1.33mm) was developed, to replace the standard multi-hole probe. The smaller the probe the higher the accuracy in unsteady flow. Therefore this is an improvement over three-hole probe. Three-hole probe measurements were simulated by recording data in three different angular positions. The time variable velocity vectors were determined using the probe’s calibration coefficients and the knowledge of the rotor positions (measured by angle-encoders) for every measurement value. During the data processing, a double ensemble averaging was carried out, taking into account the positions of the pump and the turbine.

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Flow Field in the Turbine Rotor Passage in an Automotive Torque Converter Based on the High Frequency Response Rotating Five-hole Probe Measurement Part II: Flow field at the off-design condition and effects of speed ratio

International Journal of Rotating Machinery ◽

10.1155/s1023621x01000239 ◽

2001 ◽

Vol 7 (4) ◽

pp. 271-284 ◽

Cited By ~ 1

Author(s):

Y. F. Liu ◽

B. Lakshminarayana ◽

J. Burningham

Keyword(s):

Pressure Drop ◽

Flow Field ◽

High Frequency ◽

Flow Measurement ◽

Torque Converter ◽

Turbine Rotor ◽

Speed Ratio ◽

High Frequency Response ◽

Measurement Results ◽

Overall Performance

The flow field at the design condition was presented and interpreted in Part I. The flow field at one off-design condition (Speed Ratio 0.065) is presented and interpreted in this part. In addition, the hydraulic performance is analyzed by using flow measurement results both upstream and downstream of the turbine and inside the turbine rotor passage. It is found that at the off-design conditions, especially the near stall condition (Speed Ratio 0.065), most of the pressure drop occurs in the first half of turbine passage. About 82% of the total torque is extracted between the turbine inlet and the middle plane. In addition, the shell develops torque at nearly five times the rate of core. Furthermore, the higher the speed ratio, the higher the total pressure drop. Loss is maximum at the near stall condition and varies almost linearly with the speed ratios. A compromise has to be made between the design and the off-design performance in order to improve the overall performance and fuel economy of torque converters.

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Experimental Investigation of Steady and Unsteady Flow Field Downstream of an Automotive Torque Converter Turbine and Stator

International Journal of Rotating Machinery ◽

10.1155/s1023621x95000224 ◽

1995 ◽

Vol 2 (2) ◽

pp. 67-84 ◽

Cited By ~ 7

Author(s):

B. V. Marathe ◽

B. Lakshminarayana

Keyword(s):

Experimental Data ◽

Flow Field ◽

Unsteady Flow ◽

Torque Converter ◽

Mean Value ◽

Frame Of Reference ◽

Secondary Flows ◽

Flow Properties ◽

The Core ◽

Stationary Frame

The objective of this investigation is to understand the steady and the unsteady flow field at the exit of an automotive torque converter turbine and stator with a view towards improving it's performance. A high frequency response five-hole probe was designed and built to measure the three-dimensional steady and unsteady flow fields. The measurements were conducted in a stationary frame of reference and the data were processed to derive the flow properties in the relative (turbine) frame of reference. The experimental data were processed in the frequency domain by spectrum analysis and in temporal-spatial domain by ensemble averaging technique. The data show that the flow field is highly unsteady with high unresolved unsteadiness (approx. 17-21% of mean value) and significant blade-to-blade periodic component approx. 6% of mean value). The unresolved unsteadiness and periodic unsteadiness increase with an increase in the radius from the shell to the core whereas the aperiodic unsteadiness does not show any systematic variation with the radius. The experimental data reveal the presence of a low momentum region near the core due to possible flow separation and reattachment inside the turbine passage. Data also show the presence of strong secondary flow near the core and weak secondary flow near the shell at the exit of the turbine. These secondary flows generate high levels of turbulence. A comparison of the flow properties upstream and downstream of the stator in the stationary frame of reference indicate the presence of high losses near the core due to high turbulence levels and large secondary flows, and high losses near the shell due to possible corner separation near the shell suction surface inside the stator blade passage. The unsteadiness in the flow properties upstream of the stator is high. The rms value of the unsteady total velocity is approx. 20% of the steady state value. Periodic and aperiodic unsteadiness were also found significant.

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The Static Pressure Field on the Casing of the Turbine Rotor in an Automotive Torque Converter Based on High Frequency-Response Rotating Probe Measurement

Volume 1: Fora, Parts A and B ◽

10.1115/fedsm2002-31325 ◽

2002 ◽

Author(s):

Y. F. Liu ◽

B. Lakshminarayana

Keyword(s):

Frequency Response ◽

Coriolis Force ◽

High Frequency ◽

Static Pressure ◽

Leading Edge ◽

Torque Converter ◽

Turbine Rotor ◽

High Frequency Response ◽

Pressure Distributions ◽

Turbine Casing

The static pressure on the rotating turbine casing wall of an automotive torque converter was measured using high frequency-response probe at different speed ratios. The static pressure drop on the turbine rotor casing is the highest compared to the data near the casing wall and the mass averaged value at both the design condition (SR = 0.6) and the peak efficiency condition (SR = 0.8) due to higher centrifugal force effect. The static pressure distributions along the camber line indicate that the blade loading is highest near the turbine mid-chord region at all speed ratios, which can be attributed mainly to the strong Coriolis force due to the strong flow turning both in the meridional direction and on the blade-to-blade surface along the camber line. The normalized static pressure contours indicate that the flow does not separate near the turbine casing (shell). A substantial pressure gradient exists across the passage, which indicates that flow turning and Coriolis force have significant influences. The total unsteadiness is relatively high near the turbine leading edge and low near the turbine trailing edge. The low unsteady level may indicate that the highly viscous fluid employed in the torque converter may have a strong influence on damping the unsteadiness caused by rotor/rotor and rotor/stator interactions.

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