scholarly journals Experimental Investigation of Cavitation Signatures in an Automotive Torque Converter Using a Microwave Telemetry Technique

2003 ◽  
Vol 9 (6) ◽  
pp. 403-410 ◽  
Author(s):  
C. L. Anderson ◽  
L. Zeng ◽  
P. O. Sweger ◽  
A. Narain ◽  
J. R. Blough
Keyword(s):  
Experimental Investigation ◽  
Automatic Transmission ◽  
Pressure Fluctuations ◽  
Torque Converter ◽  
Differential Pressure ◽  
Operating Conditions ◽  
Pump Speed ◽  
Pressure Transducers ◽  
Charge Pressure ◽  
Transmission Fluid

A unique experimental investigation of cavitation signatures in an automotive torque converter under stall conditions is reported. A quantitative criterion is proposed for predicting early and advanced cavitation in terms of suitable nondimensional pump speeds. The dimensionless pump speed that marks early cavitation is obtained by relating this parameter to the appearance of charge-pressure–dependent pressure fluctuations in the differential pressure transducer readings. The differential pressure transducers were mounted at well-defined locations in the pump passage of a torque converter. The data were transmitted by a wireless telemetry system mounted on the pump housing. Data were received and processed by a ground-based data acquisition system. Automatic transmission fluid exhibited cavitation for charge pressures of 70–130 psi and pump speeds of 1000– 2250 rpm. Advanced cavitation was marked by operating conditions that exhibited a 2% or more torque degradation from the converter's noncavitating performance.For a given family of torque-converter designs and a given transmission fluid, the proposed nondimensional pumpspeed criteria are capable of marking early and advanced stages of cavitation for a range of torque-converter sizes and a range of charge pressures in the torque converter.

Experimental Investigation of a 10 MW Prototype Axial Turbine Runner: Vortex Rope Formation and Mitigation

2020 ◽  
Vol 142 (10) ◽  
Author(s):  
Arash Soltani Dehkharqani ◽  
Fredrik Engström ◽  
Jan-Olov Aidanpää ◽  
Michel J. Cervantes
Keyword(s):  
Experimental Investigation ◽  
Pressure Fluctuations ◽  
Suction Side ◽  
Clear Understanding ◽  
Pressure Side ◽  
Vortex Rope ◽  
Load Variations ◽  
Pressure Transducers ◽  
Load Variation ◽  
Runner Blade

Abstract The transient load fluctuations on the runner blades of prototype hydraulic turbines during load variations are one of the main causes of fatigue and eventual structural failure. A clear understanding of the dynamic loads on the runner blades is required to detect the source of the fluctuations. In this paper, an experimental investigation of vortex rope formation and mitigation in a prototype Kaplan turbine, namely, Porjus U9, is carried out. Synchronized unsteady pressure and strain measurements were performed on a runner blade during steady-state and load variation under off-cam condition. The normalized pressure fluctuation during load variations remained approximately within ±0.2Pref for all the pressure transducers installed on the blade pressure side and is even slightly lower during the transient cycle. Higher pressure fluctuations were found on the blade suction side, approximately four times higher than that of on the pressure side. The synchronous and asynchronous components of the vortex rope were clearly observed at the low discharge operating point and transient cycles. The spectral analysis of the pressure signals showed that the synchronous component appears before the asynchronous component during the load reduction, and it lasts longer during the load increase. These frequencies slightly change during the load variation. In addition, the results proved that the strain fluctuation component on the runner blade arises from the synchronous component of the vortex rope at low discharge while the asynchronous component influence is negligible.

Robust and Simplified Design of Slip Control System for Torque Converter Lock-Up Clutch

2008 ◽  
Vol 131 (1) ◽  
Author(s):  
R. Hibino ◽  
M. Osawa ◽  
K. Kono ◽  
K. Yoshizawa
Keyword(s):  
Control System ◽  
Design Process ◽  
Automatic Transmission ◽  
Torque Converter ◽  
Operating Conditions ◽  
Slip Control ◽  
Design Time ◽  
Actual Design ◽  
High Level ◽  
Relationship Of

A torque converter lock-up clutch slip control system, which is designed to improve fuel economy, must be able to precisely regulate slip speed. Also the system must have a high level of robustness for coping with changes in the operating conditions and any deterioration in the automatic transmission fluid and the clutch. Moreover, to reduce the design time, the design process must be as simple as possible. In this paper, we first propose a loop shaping that aims to optimize complementary sensitivity function of the control system, while satisfying the abovementioned requirements of performance and robustness. Next, a method for simplifying the design process is proposed, that is, a model and a controller are expressed by interpolation. A controller set, which has a relationship of duality to the interpolation parameters of the model, is created in advance so that the construction of a new control system can be realized by identifying the characteristic parameters only. From application to the actual design process for a vehicle, we verified that the design time was reduced to less than 1∕3 of that required for the conventional method. This new method has already been adopted for the design and fitting of new products.

Experimental Determination of Mechanical Stress Induced by Rotating Stall in Unshrouded Impellers of Centrifugal Compressors

2016 ◽  
Author(s):  
Philipp Jenny ◽  
Yves Bidaut
Keyword(s):  
High Cycle Fatigue ◽  
Dynamic Pressure ◽  
Pressure Fluctuations ◽  
Rotating Stall ◽  
Operating Conditions ◽  
Design Phase ◽  
Cycle Fatigue ◽  
Centrifugal Compressors ◽  
Impeller Blade ◽  
Pressure Transducers

Unshrouded centrifugal compressor impellers typically operate at high rotational speeds and volume flow rates. The resulting high mean stress levels leave little margin for dynamic excitations that can cause high cycle fatigue. In addition to the well-established high frequency impeller blade excitations of centrifugal compressors caused by the stationary parts, such as vaned diffusers or inlet guide vanes, the presented study addresses an unsteady rotating flow feature (rotating stall) which should be taken into account when addressing high cycle fatigue during the design phase. The unsteady fluid-structure interaction between rotating stall and unshrouded impellers was experimentally described and quantified during two different measurement campaigns with two full-size compression units operating under real conditions. In both campaigns dynamic strain gauges and pressure transducers were mounted at various locations on the impeller of the first compression stage. The casing was also equipped with a set of dynamic pressure transducers to complement the study. Rotating pressure fluctuations were found to form an additional impeller excitation at a frequency that is not a multiple of the shaft speed. The measurements show that the excitation amplitude and frequency caused by the rotating pressure fluctuations depend on the operating conditions and are therefore challenging to predict and consider during the design phase. Furthermore, the excitation mechanism presented was found to cause resonant impeller blade response under specific operating conditions. For the experimentally investigated impeller geometries a rotating pressure fluctuation caused approximately 1.5 MPa of additional dynamic stress in the structure per 1 mbar of dynamic pressure amplitude when exciting the first bending mode of the impeller. The induced dynamic mechanical stresses due to rotating stall are in the order of 10% of the endurance limit of the material for the tested impeller geometries, therefore they are not critical and confirm a robust and reliable design.

Structural Assessment of Torque Converter at Operating Conditions: A Numerical Study

2014 ◽  
Author(s):  
Subbaramu Shivaramaiah ◽  
Vinod K. Banthia ◽  
S. M. Vijay Kumar
Keyword(s):  
Fluid Pressure ◽  
Torque Converter ◽  
Operating Conditions ◽  
Single Stage ◽  
Reduction Gear ◽  
Speed Ratio ◽  
Pressure Load ◽  
Centrifugal Load ◽  
Transmission Fluid ◽  
Maximum Stresses

A single stage torque converter consists of three elements — pump, stator and turbine. Pump and turbine are coupled by transmission fluid. Unlike a fluid coupling, however, a torque converter is able to multiply torque when there is a substantial difference between input and output rotational speed, thus providing the equivalent of a reduction gear. During its operation all these elements are subjected to centrifugal load, fluid pressure load and heat generated in transmission fluid. Overloading a converter can result in several failure modes, some of them potentially dangerous in nature: ballooning, blade deformation and defragmentation, overheating. In the current work a single stage torque converter, was modelled and analysed numerically for evaluating stress distribution and deformation. The engine operating speed at 2000 rpm was considered for analysis. For static analysis of torque converter components centrifugal load and fluid pressure load were considered. Analysis was carried out for six different speed ratios varying from zero to one. Variation of principal stresses (hoop stress and radial stress) and von-Mises stress has been discussed. Maximum stresses are found to be in pump at speed ratio of one and in turbine at speed ratio of zero. Maximum stresses are at shell core that is near to hub. Blade deformation in pump is maximum at coupling phase and in turbine it is maximum at stall condition. From these results it helps to predict the failure of torque converter components under different operating conditions.

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.

Experimental Determination of Mechanical Stress Induced by Rotating Stall in Unshrouded Impellers of Centrifugal Compressors

2016 ◽  
Vol 139 (3) ◽  
Author(s):  
Philipp Jenny ◽  
Yves Bidaut
Keyword(s):  
High Cycle Fatigue ◽  
Dynamic Pressure ◽  
Pressure Fluctuations ◽  
Rotating Stall ◽  
Operating Conditions ◽  
Design Phase ◽  
Cycle Fatigue ◽  
Centrifugal Compressors ◽  
Impeller Blade ◽  
Pressure Transducers

Unshrouded centrifugal compressor impellers typically operate at high rotational speeds and volume flow rates. The resulting high mean stress levels leave little margin for dynamic excitations that can cause high-cycle fatigue. In addition to the well-established high-frequency impeller blade excitations of centrifugal compressors caused by the stationary parts, such as vaned diffusers or inlet guide vanes (IGVs), the presented study addresses an unsteady rotating flow feature (rotating stall) which should be taken into account when addressing the high-cycle fatigue during the design phase. The unsteady fluid–structure interaction between rotating stall and unshrouded impellers was experimentally described and quantified during two different measurement campaigns with two full-size compression units operating under real conditions. In both campaigns, dynamic strain gauges and pressure transducers were mounted at various locations on the impeller of the first compression stage. The casing was also equipped with a set of dynamic pressure transducers to complement the study. Rotating pressure fluctuations were found to form an additional impeller excitation at a frequency that is not a multiple of the shaft speed. The measurements show that the excitation amplitude and frequency caused by the rotating pressure fluctuations depend on the operating conditions and are therefore challenging to predict and consider during the design phase. Furthermore, the excitation mechanism presented was found to cause resonant impeller blade response under specific operating conditions. For the experimentally investigated impeller geometries, a rotating pressure fluctuation caused approximately 1.5 MPa of additional dynamic stress in the structure per 1 mbar of dynamic pressure amplitude when exciting the first bending mode of the impeller. The induced dynamic mechanical stresses due to rotating stall are in the order of 10% of the endurance limit of the material for the tested impeller geometries; therefore, they are not critical and confirm a robust and reliable design.

Model for Predicting Drag Torque in Open Multi-Disks Wet Clutches

2013 ◽  
Vol 136 (2) ◽  
Author(s):  
Shoaib Iqbal ◽  
Farid Al-Bender ◽  
Bert Pluymers ◽  
Wim Desmet
Keyword(s):  
Stokes Equations ◽  
Volume Fraction ◽  
Automatic Transmission ◽  
Operating Conditions ◽  
Navier Stokes ◽  
Drag Torque ◽  
Navier Stokes Equations ◽  
Transmission Fluid ◽  
Flow Pressure ◽  
Air Film

A mathematical model based on continuity and Navier-Stokes equations, considering laminar flow in the gap between the disks, is presented to estimate the drag torque in open multidisks wet clutches. By taking into account the effects of Poiseuille and centrifugal forces, the flow pressure and velocity fields are investigated. The model quantifies the volume fraction of fluids and predicts the evolution of film shape. The drag torque estimated by the model is the sum of drag torque due to shearing of automatic transmission fluid (ATF) and the mist (suspension of ATF in air) film. In order to validate the model, experiments are performed on SAE# 2 test-setup under actual operating conditions of clutches. The model is capable of predicting the drag torque under conditions of variable flow rate and different disks rotational state for higher clutch speed range.

scholarly journals Laser Velocimeter Measurements in the Turbine of an Automotive Torque Converter: Part I — Average Measurements

1995 ◽  
Author(s):  
Klaus Bran ◽  
Ronald D. Flack
Keyword(s):  
Velocity Vector ◽  
Average Velocity ◽  
Incidence Angle ◽  
Torque Converter ◽  
Operating Conditions ◽  
Speed Ratio ◽  
Flow Angle ◽  
Pump Speed ◽  
Turbine Pump ◽  
Mass Flows

The three-dimensional average velocity field in an automotive torque converter turbine was examined. Two significantly different operating conditions of the torque converter were tested: the 0.065 and 0.800 turbine/pump speed ratio. Velocities were measured using a one-directional, frequency shifted laser velocimeter. The instantaneous angular positions of the torque converter turbine and pump were recorded using digital shaft encoders. Shaft encoder information and velocities were correlated to generate average velocity blade-to-blade profiles and velocity vector plots. Measurements were taken in the inlet, quarter, mid, and exit planes of the turbine. From the experimental velocity measurements, mass flows, turbine output torque, average vorticities, viscous dissipation, inlet incidence flow angles, and exit flow angles were calculated. Average mass flows were 23.4 kg/s and 14.7 kg/s for the 0.065 and 0.800 speed ratios, respectively. Velocity vector plots for both turbine/pump speed ratios showed the flow field in the turbine quarter and mid planes to be highly non-uniform with separation regions and reversed flows at the core-suction corner. For the conditions tested, the turbine inlet flow was seen to have a high relative incidence angle, while the relative turbine exit flow angle was close to the blade angle.

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

1997 ◽  
Vol 119 (3) ◽  
pp. 646-654 ◽  
Author(s):  
K. Brun ◽  
R. D. Flack
Keyword(s):  
Velocity Vector ◽  
Average Velocity ◽  
Incidence Angle ◽  
Torque Converter ◽  
Operating Conditions ◽  
Speed Ratio ◽  
Flow Angle ◽  
Pump Speed ◽  
Turbine Pump ◽  
Mass Flows

The three-dimensional average velocity field in an automotive torque converter turbine was examined. Two significantly different operating conditions of the torque converter were tested: the 0.065 and 0.800 turbine/pump speed ratio. Velocities were measured using a one-directional, frequency-shifted laser velocimeter. The instantaneous angular positions of the torque converter turbine and pump were recorded using digital shaft encoders. Shaft encoder information and velocities were correlated to generate average velocity blade-to-blade profiles and velocity vector plots. Measurements were taken in the inlet, quarter, mid, and exit planes of the turbine. From the experimental velocity measurements, mass flows, turbine output torque, average vorticities, viscous dissipation, inlet incidence flow angles, and exit flow angles were calculated. Average mass flows were 23.4 kg/s and 14.7 kg/s for the 0.065 and 0.800 speed ratios, respectively. Velocity vector plots for both turbine/pump speed ratios showed the flow field in the turbine quarter and midplanes to be highly nonuniform with separation regions and reversed flows at the core-suction corner. For the conditions tested, the turbine inlet flow was seen to have a high relative incidence angle, while the relative turbine exit flow angle was close to the blade angle.

Oil temperature influence on friction torque characteristics in hydraulic pumps

2011 ◽  
Vol 226 (9) ◽  
pp. 2267-2280 ◽  
Author(s):  
Yoshiharu Inaguma
Keyword(s):  
Mathematical Model ◽  
Temperature Region ◽  
Automatic Transmission ◽  
Mechanical Efficiency ◽  
Friction Torque ◽  
Operating Conditions ◽  
Vane Pump ◽  
Pump Speed ◽  
High Pump ◽  
Internal Gear

This article presents a practical approach to the investigation of the influence of oil temperature on the friction torque in various types of hydraulic pumps using a mathematical model. Currently, an external gear, an internal gear or a vane pump is commonly used for an automatic transmission. These pumps have their own friction torque characteristics, which depend not only on pump-operating conditions such as operating pressures, pump speeds and oil temperature but also on structures and dimensions of the pumps. For various pumps, however, the friction torque characteristics can be represented by an identical mathematical model. In the pump-operating conditions, the oil temperature significantly and complicatedly affects them. The pump should be operated under conditions to obtain a higher mechanical efficiency, and the mathematical model is helpful to analyse how the oil temperature influences the friction torque. It is found that with an increase in oil temperature, the friction torque at a high pump speed decreases in a low oil temperature region, but it would not decrease in a high oil temperature region for all the tested pumps. This fact suggests that the pump overall efficiency would not improve at a high oil temperature, even if the volumetric efficiency does not go down.

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