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

1995 ◽  
Vol 2 (2) ◽  
pp. 67-84 ◽  
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.

Experimental Investigation of Steady and Unsteady Flow Field Downstream of an Automotive Torque Converter Turbine and Inside the Stator: Part I—Flow at Exit of Turbine

1997 ◽  
Vol 119 (3) ◽  
pp. 624-633 ◽  
Author(s):  
B. V. Marathe ◽  
B. Lakshminarayana ◽  
D. G. Maddock
Keyword(s):  
Flow Field ◽  
Unsteady Flow ◽  
Separation Zone ◽  
Torque Converter ◽  
Frame Of Reference ◽  
Flow Properties ◽  
Ensemble Averaging ◽  
Suction Surface ◽  
Flow Angle ◽  
Periodic Components

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 inside the stator with a view toward improving its performance. The measurements were conducted in a stationary frame of reference using a high-frequency response five-hole probe, 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 the temporal-spatial domain by ensemble averaging technique. The flow properties (e.g., pressure and velocity) were resolved into mean, periodic, aperiodic, and unresolved components. A velocity profile similar to that of a fully developed flow was observed at all radii. The periodic data in relative reference frame revealed a small separation zone near the suction surface in the core region. The rms values of the unresolved component were found to be significantly higher in this region. The secondary flow vectors show underturning, radially inward flow in the entire passage with a small region of overturning near the separation zone. The overall flow at the turbine exit was nearly two dimensional in nature except in the zone of flow separation. The unsteady flow data show that unresolved and aperiodic components dominate the unsteadiness in the pressure, whereas the periodic components dominate the unsteadiness in velocities and flow angles. Pressure and velocity fluctuations were moderate, whereas the flow angle fluctuations were found to be high. The overall flow at the exit of turbine was found to be highly unsteady.

scholarly journals Experimental Investigation of Steady and Unsteady Flow Field Downstream of an Automotive Torque Converter Turbine and Inside the Stator: Part I — Flow at the Exit of Turbine

1995 ◽  
Author(s):  
B. V. Marathe ◽  
B. Lakshminarayana ◽  
Donald G. Maddock
Keyword(s):  
Flow Field ◽  
Unsteady Flow ◽  
Separation Zone ◽  
Torque Converter ◽  
Frame Of Reference ◽  
Flow Properties ◽  
Ensemble Averaging ◽  
Suction Surface ◽  
Flow Angle ◽  
Periodic Components

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 inside the stator with a view towards improving its performance. The measurements were conducted in a stationary frame of reference using a high frequency response five-hole probe 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 flow properties (e.g. pressure and velocity) were resolved into mean, periodic, aperiodic and unresolved components. A velocity profile similar to that of a fully developed flow was observed at all radii. The periodic data in relative reference frame revealed a small separation zone near the suction surface in the core region. The rms values of the unresolved component were found to be significantly higher in this region. The secondary flow vectors show underturning, radially inward flow in the entire passage with a small region of overturning near the separation zone. The overall flow at the turbine exit was nearly two dimensional in nature except in the zone of flow separation. The unsteady flow data shows that unresolved and aperiodic components dominate the unsteadiness in the pressure whereas the periodic components dominate the unsteadiness in velocities and flow angles. Pressure and velocity fluctuations were moderate whereas the flow angle fluctuations were found to be high. The overall flow at the exit of turbine was found to be highly unsteady.

scholarly journals Experimental Investigation of Steady and Unsteady Flow Field Upstream and Downstream of an Automotive Torque Converter Pump

1999 ◽  
Vol 5 (2) ◽  
pp. 99-116 ◽  
Author(s):  
B. V. Marathe ◽  
B. Lakshminarayana
Keyword(s):  
Flow Field ◽  
Unsteady Flow ◽  
Torque Converter ◽  
Frame Of Reference ◽  
Operating Conditions ◽  
Maximum Efficiency ◽  
Speed Ratio ◽  
Secondary Vortex ◽  
Flow Properties ◽  
Periodic Components

The objective of this investigation is to understand the steady and the unsteady flow field at the exit of an automotive torque converter pump with a view towards improving its performance. The measurements were conducted in a stationary frame of reference using a high frequency response five-hole probe and the data were processed to derive the flow properties in the relative (pump) frame of reference. The experimental data were processed at three different operating conditions: maximum efficiency point, design point and near-stall point. The unsteady values of flow properties (pressure, velocity and flow angles) were divided into five components: mean, periodic, blade aperiodic, revolution aperiodic and unresolved components.The velocity profiles indicate zones of separation near the core region at speed ratio (SR) 0.8. This zone is transported to the shell region at SR 0.065 due to the presence of a strong secondary vortex. The secondary vortex (weak) for the SR 0.8 rotates anti-clockwise, and is located only near core-wake region. The secondary vortex (strong) at SR 0.065 rotates clockwise, and encompasses the entire passage. The unsteady flow data show that unresolved and periodic components dominate the unsteadiness at the pump exit. The overall aperiodicity is negligible and is dominated by the blade aperiodic component.

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

1998 ◽  
Vol 120 (3) ◽  
pp. 538-548 ◽  
Author(s):  
Y. Dong ◽  
B. Lakshminarayana ◽  
D. Maddock
Keyword(s):  
Flow Field ◽  
Unsteady Flow ◽  
Frequency Response ◽  
High Frequency ◽  
Free Stream ◽  
Torque Converter ◽  
Flow Data ◽  
High Frequency Response ◽  
The Core ◽  
Measurement Plane

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.

Investigation of the Flow Field in a HP Turbine Stage for Two Stator-Rotor Axial Gaps: Part II — Unsteady Flow Field

2006 ◽  
Author(s):  
P. Gaetani ◽  
G. Persico ◽  
V. Dossena ◽  
C. Osnaghi
Keyword(s):  
Flow Field ◽  
Unsteady Flow ◽  
Dominant Role ◽  
Outer Part ◽  
Secondary Flows ◽  
Pressure Probe ◽  
Turbine Stage ◽  
Mean Flow ◽  
Tip Leakage Flow ◽  
Flow Measurements

An extensive experimental analysis was carried out at Politecnico di Milano on the subject of unsteady flow in high pressure (HP) turbine stages. In this paper the unsteady flow measured downstream of a modern HP turbine stage is discussed. Traverses in two planes downstream of the rotor are considered and, in one of them, the effects of two very different axial gaps are investigated: the maximum axial gap, equal to one stator axial chord, is chosen to “switch off” the rotor inlet unsteadiness, while the nominal gap, equal to 1/3 of the stator axial chord, is representative of actual engines. The experiments were performed by means of a fast-response pressure probe, allowing for two-dimensional phase-resolved flow measurements in a bandwidth of 80 kHz. The main properties of the probe and the data processing are described. The core of the paper is the analysis of the unsteady rotor aerodynamics; for this purpose, instantaneous snapshots of the rotor flow in the relative frame are used. The rotor mean flow and its interaction with the stator wakes and vortices are also described. In the outer part of the channel only the rotor cascade effects can be observed, with a dominant role played by the tip-leakage flow and by the rotor tip passage vortex. In the hub region, where the secondary flows downstream of the stator are stronger, the persistence of stator vortices is slightly visible in the maximum stator-rotor axial gap configuration, while in the minimum stator-rotor axial gap configuration the interaction with the rotor vortices dominates the flow field. A fair agreement with the wakes and vortices transport models has been achieved. A discussion of the interaction process is reported giving particular emphasis to the effects of the different cascade axial gaps. Some final considerations on the effects of the different axial gap over the stage performances are reported.

Investigation of the Flow Field in a High-Pressure Turbine Stage for Two Stator-Rotor Axial Gaps—Part II: Unsteady Flow Field

2006 ◽  
Vol 129 (3) ◽  
pp. 580-590 ◽  
Author(s):  
P. Gaetani ◽  
G. Persico ◽  
V. Dossena ◽  
C. Osnaghi
Keyword(s):  
High Pressure ◽  
Flow Field ◽  
Unsteady Flow ◽  
Outer Part ◽  
Secondary Flows ◽  
Pressure Probe ◽  
Turbine Stage ◽  
Mean Flow ◽  
Tip Leakage Flow ◽  
Flow Measurements

An extensive experimental analysis was carried out at Politecnico di Milano on the subject of unsteady flow in high pressure (HP) turbine stages. In this paper, the unsteady flow measured downstream of a modern HP turbine stage is discussed. Traverses in two planes downstream of the rotor are considered, and, in one of them, the effects of two very different axial gaps are investigated: the maximum axial gap, equal to one stator axial chord, is chosen to “switch off” the rotor inlet unsteadiness, while the nominal gap, equal to 1/3 of the stator axial chord, is representative of actual engines. The experiments were performed by means of a fast-response pressure probe, allowing for two-dimensional phase-resolved flow measurements in a bandwidth of 80kHz. The main properties of the probe and the data processing are described. The core of the paper is the analysis of the unsteady rotor aerodynamics; for this purpose, instantaneous snapshots of the rotor flow in the relative frame are used. The rotor mean flow and its interaction with the stator wakes and vortices are also described. In the outer part of the channel, only the rotor cascade effects can be observed, with a dominant role played by the tip leakage flow and by the rotor tip passage vortex. In the hub region, where the secondary flows downstream of the stator are stronger, the persistence of stator vortices is slightly visible in the maximum stator-rotor axial gap configuration, whereas in the minimum stator-rotor axial gap configuration their interaction with the rotor vortices dominates the flow field. A good agreement with the wakes and vortices transport models has been achieved. A discussion of the interaction process is reported giving particular emphasis to the effects of the different cascade axial gaps. Some final considerations on the effects of the different axial gap over the stage performances are reported.

scholarly journals Flow Characteristics at the Pump-Turbine Interface of a Torque Converter at Extreme Speed Ratios

2003 ◽  
Vol 9 (6) ◽  
pp. 419-426 ◽  
Author(s):  
A. Habsieger ◽  
R. D. Flack
Keyword(s):  
Flow Field ◽  
Mass Flow Rate ◽  
Flow Rate ◽  
High Velocity ◽  
Torque Converter ◽  
Speed Ratio ◽  
Shell Side ◽  
The Core ◽  
Velocity Gradients ◽  
Coupling Point

The average velocity field at the pump–turbine interface in a scaled version of a truck torque converter was studied. Seven different turbine-to-pump rotational-speed ratios were examined, ranging from near stall (0.065) to overspeed (1.050) so as to determine the effect of the speed ratio on the flow field and on the mass flow rate. Laser velocimetry was used to measure the flow velocity through the pump's exit and the turbine's inlet plane. At the pump's exit, as the speed ratio increases, the high velocities move to the pressure-shell corner and then to both the core-suction and the pressureshell corners. Concentrated velocity gradients are largest at the lowest speed ratio, but areas of velocity gradients are largest near the coupling point. Near the coupling point, the flow field is most nonuniform, which yields a highly periodic flow into the turbine inlet. Above the coupling point, the high velocity remains in the pressure-shell corner but separation is seen to develop at the highest speed ratio. At the turbine's inlet, reverse flow is seen at low speed ratios and is an indicator of flow leakage through the core. Velocity gradients are very large at low speed ratios. As the speed ratio increases to the coupling point, the high velocities remain on the shell side. Above the coupling point, the high-velocity flow migrates from the shell side to the core side. The mass flow rate decreases significantly and nonlinearly with the increase of the speed ratio, but for speed ratios greater than 1.000, the negative slope decreases.

Unsteady Flow and Aeroelasticity Behaviour of Aero-Engine Core Compressors During Rotating Stall and Surge

2006 ◽  
Author(s):  
M. Vahdati ◽  
G. Simpson ◽  
M. Imregun
Keyword(s):  
Experimental Data ◽  
Unsteady Flow ◽  
Mass Flow ◽  
Rotor Blade ◽  
Rotating Stall ◽  
Flow Reversal ◽  
The Core ◽  
Single Passage ◽  
Aero Engine ◽  
Operating Points

The paper will focus on two core-compressor instabilities, namely rotating stall and surge. Using a 3D viscous time-accurate flow representation, the front bladerows of a core-compressor were modelled in a whole-annulus fashion whereas the rest of bladerows were represented in single passage fashion. The rotating stall behaviour at two different compressor operating points was studied by considering two different variable-vane scheduling conditions for which experimental data were available. Using a model with 9 whole bladerows, the unsteady flow calculations were conducted on 32-CPUs of a parallel cluster, typical run times being around 3–4 weeks for a grid with about 60 million points. The simulations were conducted over several engine rotations. As observed on the actual development engine, there was no rotating stall for the first scheduling condition while mal-scheduling of the stator vanes created a 12 band rotating stall which excited the rotor blade 1st flap mode. In a separate set of calculations, the surge behaviour was modelled using a time-accurate single-passage representation of the core compressor. It was possible to predict not only flow reversal into the low pressure compression domain, but also the expected hysteresis pattern of the surge loop in terms of its mass flow vs pressure characteristic.

Fundamental Analysis of the Secondary Flows and Jet-Wake in a Torque Converter Pump—Part I: Model and Flow in a Rotating Passage

2005 ◽  
Vol 127 (1) ◽  
pp. 66-74 ◽  
Author(s):  
R. Flack ◽  
K. Brun
Keyword(s):  
Suction Side ◽  
Torque Converter ◽  
Secondary Flows ◽  
Operating Conditions ◽  
Experimental Results ◽  
Wake Flow ◽  
Rossby Number ◽  
Geometrical Parameters ◽  
Shell Side ◽  
The Core

Previously, experimental results for the velocity field in a torque converter pump showed strong jet/wake characteristics including backflows and circulatory secondary flows. To understand the fundamental flow behavior simplified analytical/numerical Navier-Stokes flow models were developed herein to independently analyze the pump pressure-to-suction side jet/wake flow, the core-to-shell side jet/wake flow, and the secondary flows. Parametric studies were undertaken to evaluate the effect that operating conditions and geometry had on the characteristics. Two relatively simple models were employed: (i) a rotating two-dimensional straight-walled duct to model the pressure-to-suction side jet/wake flow due to rotational Coriolis forces and (ii) a 180 deg flow bend to model the core-to-shell side jet/wake flow due to rapid radial/axial flow turning. The formation and development of the pump jet/wake flow was studied in detail. Results showed that the suction side wake, which was due to the counter-rotational tangential Coriolis force, was almost only a function of the modified Rossby number and independent of the Reynolds number. Increasing the modified Rossby number increased the pressure-to-suction side jet/wake flow. A geometric parameter that was seen to affect the pump flow was the backsweeping angle for the pressure-to-suction side jet/wake. Results showed that using backswept blades can completely eliminate the pressure-to-suction side jet/wake flow effect. Other geometrical parameters were tested but only a small to moderate influence on the jet/wake flow phenomena was found. Predicted trends compared favorably with experimental results.

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