Cavitation in a high-speed aviation axial piston pump over a wide range of fluid temperatures

2021 ◽  
pp. 095765092110469
Author(s):  
Qun Chao ◽  
Zi Xu ◽  
Jianfeng Tao ◽  
Chengliang Liu ◽  
Jiang Zhai
Keyword(s):  
Temperature Effects ◽  
Pressure Pulsation ◽  
Piston Pump ◽  
Limiting Factors ◽  
Fluid Temperature ◽  
Cfd Model ◽  
Axial Piston Pump ◽  
Wide Range ◽  
Fluid Properties ◽  
Axial Piston

The axial piston pump in aerospace applications needs to operate over a wide range of fluid temperatures from −54°C to 135 °C. The fluid properties at such extreme temperatures will significantly affect the cavitation that is one of the major limiting factors for the efficiency and reliability of aviation axial piston pumps. However, it appears that very little of the existing literature studies the effects of extreme fluid temperatures on the pump cavitation. This paper aims to examine the temperature effects on the cavitation in an aviation axial piston pump. First, we develop a three-dimensional (3D) transient computational fluid dynamics (CFD) model to investigate the pump cavitation and validate it experimentally. Second, we use the validated CFD model to investigate the temperature effects on the pump cavitation by changing the fluid properties including viscosity, density, and bulk modulus. The numerical results show that low fluid temperature makes the aviation axial piston pump suffer serious cavitation due to high viscosity, leading to delivery flow breakdown, unacceptable pressure pulsation, and delayed pressure built up. In contrast, high fluid temperatures have minor effects on the cavitation although they increase the pressure pulsation and built-up time slightly.

scholarly journals An Empirical Model for the Churning Losses Prediction of Fluid Flow Analysis in Axial Piston Pumps

Micromachines ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 398
Author(s):  
Ying Li ◽  
Xing Chen ◽  
Hao Luo ◽  
Jin Zhang
Keyword(s):  
Power Density ◽  
High Speed ◽  
Flow Analysis ◽  
Piston Pump ◽  
Cylinder Block ◽  
Axial Piston Pump ◽  
Axial Piston Pumps ◽  
Wide Range ◽  
Fluid Flow Analysis ◽  
Axial Piston

The manufacturing development of axial piston pumps usually takes the trend of high speed and miniaturization, and increases power density. Axial piston pumps are usually characterized as high speed to improve the power density; thus, high-speed churning losses caused by the internal rotating components stirring the oil can increase significantly. In order to improve the efficiency, more attention should be given to the churning losses in axial piston pumps, especially in high-speed conditions. Using the method of least-squares curve fitting, this paper establishes a series of formulas based on the churning losses test rig over a wide range of speeds, which enable accurate predictions of churning losses on the cylinder block and pistons. The reduction coefficient of flow resistance of multi-pistons as calculated. The new churning losses formula devoted to the cylinder block and rotating pistons was validated by comparison with experimental evidence in different geometries of axial piston pumps. According to the prediction model of churning losses, some valuable guidance methods are proposed to reduce the energy losses of the axial piston pump, which are the theoretical support for the miniaturization of axial piston pump manufacturing.

Mathematical Modeling of a Variable Displacement Axial Piston Pump

1999 ◽  
Author(s):  
Jeff W. Dobchuk ◽  
Richard T. Burton ◽  
Peter N. Nikiforuk ◽  
Paul R. Ukrainetz
Keyword(s):  
Mathematical Model ◽  
Operating Conditions ◽  
Piston Pump ◽  
Axial Piston Pump ◽  
Specific Effects ◽  
Lumped Parameter ◽  
Lumped Parameter Models ◽  
Wide Range ◽  
Variable Displacement ◽  
Axial Piston

Abstract The variable displacement axial piston pump has been the subject of much research, having been studied from the controls, noise reduction, and design perspectives. The resulting body of research is large and very diverse in content. A review of the available publications was conducted for this paper in order to identify those works that would be most helpful in developing a complete and accurate mathematical model of an axial piston pump. Most of the available publications can be classified into one of two general groups; those describing a small group of components to understand specific phenomena or those describing the entire pump for control or design purposes. The significant mathematical developments in various publications regarding specific phenomena, particularly those works involving nonlinear friction or pressure transients, were identified by the authors in this paper. When the mathematical developments of the phenomena specific effects are combined with the widely accepted kinematics equations for the pump, an accurate numerical model can be developed. Works on linearized lumped parameter models and parameter sensitivity were examined for this paper and the limitations of these types of models were addressed. While linearized models offer mathematical simplicity, they suffer from poor accuracy over a wide range of operating conditions and do not reflect instantaneous swashplate dynamics. This paper offers insight into the required complexity of a mathematical model that is necessary to achieve a desired accuracy as well as providing the appropriate references to develop that model.

Simulation Model of an Axial Piston Pump Inclusive of Cavitation

2002 ◽  
Author(s):  
G. L. Berta ◽  
P. Casoli ◽  
A. Vacca ◽  
M. Guidetti
Keyword(s):  
Experimental Data ◽  
Pressure Transducer ◽  
Fluid Pressure ◽  
Piston Pump ◽  
Pressure Pulsations ◽  
Axial Piston Pump ◽  
One Dimensional ◽  
Fluid Properties ◽  
Relief Groove ◽  
Axial Piston

A mathematical model of an axial piston pump is presented. The numerical model is based on a finite volume concept. The pump has been divided in different volumes where fluid properties are assumed homogeneous. Since the reduction of the pressure pulsations is one of the most important aims of pump builders, the effects of the port plate relief groove design have been carefully modelled. The gaseous cavitation has been considered in a simplified manner. The pump has been modified in order to measure the fluid pressure inside one of the cylinders; therefore a conduit has been realized to connect the cylinder chamber to a pressure transducer that is placed in a non-rotating position. The fluid pressure inside the conduit has been modelled with a one dimensional scheme for unsteady flow. The code has been tested and calibrated by comparing its numerical results with a set of experimental data. The potentials of the code are presented, spanning over different geometries.

Investigation Into the Effects of Index Angle on Fluidborne Noise and Structureborne Noise of a Tandem Axial Piston Pump

2014 ◽  
Author(s):  
Shaogan Ye ◽  
Bing Xu ◽  
Junhui Zhang
Keyword(s):  
Experimental Tests ◽  
Piston Pump ◽  
Secondary Source ◽  
Fe Model ◽  
Axial Piston Pump ◽  
Revolution Speed ◽  
Noise Characteristics ◽  
Wide Range ◽  
Lp Model ◽  
Axial Piston

High noise level is one of the dominant drawbacks of axial piston pumps which are widely applied in industry, mobile and aircraft applications. Lots of early studies focused on the noise reduction of a single pump, while this study focuses on investigating the noise characteristics of a tandem axial piston pump. We develop a lumped parameters/finite element (LP/FE) model of an axial piston pump for fully capturing its fluidborne noise and structureborne noise characteristics. We consider fluid compressibility and main leakages in the LP model which is verified by a comparison of discharge flow rate with experimental tests built based on the secondary source method. The FE model was developed on the basis of actual pump with excitation forces obtained from the LP model. The effects of index angle in a tandem pump to the fluidborne noise and structureborne noise are analyzed with the LP/FE model, respectively. A sensitivity analysis is carried out in a wide range of discharge pressures and displacements at a fixed revolution speed, further. Results indicate that fluidborne noise is reduced by 52.1%, whilst structureborne noise is increased by 2 dB(A) with an index angle of 20° to zero, respectively.

Influence of power fluid temperature in hydraulics on operating efficiency of hydraulic mining excavators

2020 ◽  
pp. 78-81
Author(s):  
A. E. Krivenko ◽  
◽  
Zhang Kuok Khanh ◽  
Keyword(s):  
Operating Conditions ◽  
Piston Pump ◽  
Open Pit ◽  
Fluid Temperature ◽  
Axial Piston Pump ◽  
Pump Flow ◽  
Hydraulic Mining ◽  
Hydraulic Excavators ◽  
The Republic ◽  
Axial Piston

The Republic of Vietnam has great mineral resources. Open pit mines use hydraulic excavators. In hot climate, the excavators lose capacity, and the number of the hydraulics failures grows. To identify the causes of unstable operation of the hydraulics, the authors analyze the capacity reduction factors, namely, hydraulic pump leaks. The test subject is pump HPV95 for Komatsu hydraulic excavators. The axial-piston pump leaks take place in clearances of control and injection gears, and only have mutable and cyclic behavior in the piston and cylinder clearances. This has an adverse effect on uniformity of the pump flow and on stability of the injection pressure. Generally, leaks can be evaluated from the Reynolds equation of fluid flow rate in the ring clearance. The input data are the design variables of axial-piston pump HPV95 and power fluid temperature range of Komatsu hydraulic mining excavators operated in open pit mining in the south in the Republic of Vietnam. Matlab-based Simulink modeling shows that with increasing temperature of power fluid, leaks in the injection gear grow nonlinearly in the absolute value and so does the surging amplitude in the pump flow. As a consequence, the pressure fluctuations and vibrations in the hydraulic gear elevate. The modeling also exhibits higher surge and reduced net capacity of the hydraulics with rising temperature of power fluid. These changes are caused by reduction in the flow friction in the ring channel between the piston and block of cylinders. Thus, the power fluid cooling system engineering subject to hydraulics capacity, operating conditions and cooling methods is highly critical for the efficient operation of hydraulic mining excavators.

Model and Simulation on Flow and Pressure Characteristics of Axial Piston Pump for Seawater Desalination

2012 ◽  
Vol 157-158 ◽  
pp. 1549-1552
Author(s):  
Jiang Zhai ◽  
Hua Zhou
Keyword(s):  
Lumped Parameter Model ◽  
Piston Pump ◽  
Cfd Model ◽  
Seawater Desalination ◽  
Axial Piston Pump ◽  
Model And Simulation ◽  
Lumped Parameter ◽  
Rough Calculation ◽  
Axial Piston ◽  
Pressure Characteristics

With cavitation model being considered, a LP (Lumped Parameter) model and a CFD (Computational Fluid Dynamics) model on the flow and pressure characteristics of the axial piston pump for seawater desalination were created. Based on the geometry structure and operating condition of the pump, these two models were numerically calculated and corresponding results were compared and discussed. Both the two models can describe the dynamic flow and pressure characteristics of the pump. The CFD model is accurate and many details such as cavitation position can be predicted. LP model is a simplified model compared with CFD model. Because the damping effect of the inlet of the pump is neglected, this model is only suitable for rough calculation in engineering.

scholarly journals Aircraft hydraulic axial piston pump fundamental pulsation and simulation

2021 ◽  
Vol 1208 (1) ◽  
pp. 012008
Author(s):  
Želimir Husnić ◽  
Remzo Dedić ◽  
Faris Ustamujić ◽  
Zlata Jelačić
Keyword(s):  
Fundamental Frequency ◽  
Health Monitoring ◽  
Hydraulic System ◽  
Pressure Pulsation ◽  
Piston Pump ◽  
Axial Piston Pump ◽  
System Health Monitoring ◽  
Predictive Approach ◽  
Hydraulic Axial Piston Pump ◽  
Axial Piston

Abstract The axial piston pump for aircraft hydraulics systems and other high pressure hydraulic system applications is presented. This paper discusses the pump’s pressure pulsation and the fundamental frequency. Pressure pulsation associated with single piston failure is explained in relation to its fundamental frequency. A predictive approach in maintenance and pump sub system health monitoring is proposed, using numerical modelling and applicable software.

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