A two-dimensional numerical analysis of a circular-arc gear pump operating at high pressures and high speeds

2015 ◽  
Vol 231 (3) ◽  
pp. 432-443 ◽  
Author(s):  
Yang Zhou ◽  
Shuanghui Hao ◽  
Minghui Hao
Keyword(s):  
Critical Points ◽  
High Pressures ◽  
Pressure Fluctuations ◽  
Gear Pump ◽  
Circular Arc ◽  
Outlet Pressure ◽  
High Speeds ◽  
Outlet Flow ◽  
The Mathematical Model ◽  
Variation Tendency

This paper examines the flow field of a circular-arc gear pump operating at high pressures and high speeds by the commercial finite-volume-based code Fluent. The performance of circular-arc gear pump operating at high pressures and high speeds have been discussed. The mathematical model of the tooth profile is established. The pressures including gears mesh, outlet pressures, and outlet flow rate are studied under different rated outlet pressures and rotational speeds. There are dynamic pressures at clearance between chamber and tip circle of gear. Moreover, parts of radial leakages are prevented by dynamic pressures. The outlet pressures almost remain constant. However, there are strong pressure fluctuations in gears mesh under the high pressures and high speeds. The pressures are several times higher than the rated outlet pressure when the circular-arc gear pump operates at 10,000 r/min and 12,000 r/min. Gear meshing pressure fluctuations increase with the increase in rotational speeds. However, gear meshing pressure fluctuations decrease with the increase of outlet rate pressures. There are rotational speeds and outlet rate pressure critical points for gear meshing pressures, and the variation tendency of gear meshing pressures changes dramatically when it exceeds the critical points. Hence, the research results provide base model for circular-arc gear pump operating at high pressures and high speeds.

OSCILLATION DAMPER CALCULATION BASED ON THE ELECTRO HYDRAULIC ANALOGY

2020 ◽  
pp. 17-24
Author(s):  
S. V. Britsyn ◽  
M. V. Ryabinin ◽  
S. E. Semenov
Keyword(s):  
Mathematical Model ◽  
Pressure Fluctuations ◽  
Pressure Pulsations ◽  
Plunger Pump ◽  
Outlet Pressure ◽  
Unsteady Fluid Flow ◽  
Flow Through ◽  
Unsteady Fluid ◽  
Hydraulic Analogy ◽  
The Mathematical Model

The method of the synthesis and the pressure fluctuations damping calculation based on the electro-hydraulic analogy is proposed. The mathematical model describing the processes of unsteady fluid flow through the device is developed. Using the composed transfer function and its approximation, the oscillation damper parameters identification to reduce the outlet pressure pulsations in the triplex plunger pump is carried out.

The Tooth Profile Design and Examination of Circular-Arc Gear Pump

2014 ◽  
Vol 672-674 ◽  
pp. 1604-1607
Author(s):  
Yang Zhou ◽  
Shuang Hui Hao ◽  
Ming Hui Hao
Keyword(s):  
Tooth Profile ◽  
Gear Pump ◽  
Helical Surface ◽  
Circular Arc ◽  
Engagement Theory ◽  
Flow Fluctuations ◽  
Profile Design ◽  
The Mathematical Model ◽  
Gear Engagement ◽  
Examination Process

This paper presents the circular-arc tooth profile that has no trapped-oil feature and flow fluctuations. The mathematical model of tooth profile and helical surface is obtained by gear engagement theory. The examination of helical surface is by coordinate measuring machining (CMM). The sections that perpendicular to the axis direction of gear are selected to obtain the trajectory of measuring ball by the starting points and end points of measuring ball. The examination process of CMM is simulated by Matlab in this paper.

Design and performance analysis of a circular-arc gear pump operating at high pressure and high speed

2015 ◽  
Vol 230 (2) ◽  
pp. 189-205 ◽  
Author(s):  
Yang Zhou ◽  
Shuanghui Hao ◽  
Minghui Hao
Keyword(s):  
High Pressure ◽  
High Speed ◽  
Tooth Profile ◽  
Numerical Control ◽  
Gear Pump ◽  
Performance Parameters ◽  
Circular Arc ◽  
Cad System ◽  
Outlet Pressure ◽  
And Performance

This paper presents a high-pressure and high-speed gear pump for aerospace application and introduces a circular-arc tooth profile that has no trapping feature and whose gears are in continuous one-point contact in the plane of rotation. Basic dimensions are determined and performance parameters of the gear pump are obtained by structural design of the gear pump. The performance parameters are discussed for different tooth profiles. A disc tool and hob are designed to generate the circular-arc tooth profile. A computer-aided design (CAD) system for the design of the circular-arc gear pump is developed with features of tooth profile design, tool design, and numerical control. The test gears were processed to verify the correctness of CAD system. A study of the outlet pressure of the circular-arc gear pump reveals that the developed high-pressure and high-speed gear pump has low outlet pressure fluctuations.

Influence of Imperfections in the Working Media on Diesel Engine Indicator Process: Part 2 — Results

1998 ◽  
Author(s):  
Stanislav N. Danov ◽  
Ashwani K. Gupta
Keyword(s):  
Mathematical Model ◽  
Diesel Engine ◽  
High Pressures ◽  
Combustion Process ◽  
Ideal Gas ◽  
Working Medium ◽  
High Pressures And Temperatures ◽  
Specific Heat Capacities ◽  
Working Media ◽  
The Mathematical Model

Abstract In the companion Part 1 of this two-part series paper several improvements to the mathematical model of the energy conversion processes, taking place in a diesel engine cylinder, have been proposed. Analytical mathematical dependencies between thermal parameters (pressure, temperature, volume) and caloric parameters (internal energy, enthalpy, specific heat capacities) have been obtained. These equations have been used to provide an improved mathematical model of diesel engine indicator process. The model is based on the first law of thermodynamics, by taking into account imperfections in the working media which appear when working under high pressures and temperatures. The numerical solution of the simultaneous differential equations is obtained by Runge-Kutta type method. The results show that there are significant differences between the values calculated by equations for ideal gas and real gas under conditions of high pressures and temperatures. These equations are then used to solve the desired practical problem in two different two-stroke turbo-charged engines (8DKRN 74/160 and Sulzer-RLB66). The numerical experiments show that if the pressure is above 8 to 9 MPa, the working medium imperfections must be taken into consideration. The mathematical model presented here can also be used to model combustion process of other thermal engines, such as advanced gas turbine engines and rockets.

The Reduction of Gear Pump Pressure Ripple

1987 ◽  
Vol 201 (2) ◽  
pp. 99-106 ◽  
Author(s):  
K A Edge ◽  
B R Lipscombe
Keyword(s):  
Hydraulic System ◽  
Pressure Fluctuations ◽  
Gear Pump ◽  
Noise Levels ◽  
Flow Ripple ◽  
Flow Fluctuation ◽  
Accurate Knowledge ◽  
Airborne Noise ◽  
Pressure Ripple ◽  
Pump Pressure

Pressure fluctuations in a hydraulic system may be substantially reduced by cancelling the flow ripple produced by the pump. This paper describes a secondary flow ripple generating mechanism which introduces an equal and opposite flow fluctuation to that generated by the pump. Tests have shown that the mechanism can virtually cancel four harmonics of pressure ripple but success is dependent on an accurate knowledge of the pump flow fluctuation characteristic. This is best determined experimentally. Similar improvements can be achieved using a mechanism in a motor. This has the additional benefit of reducing torque fluctuations. The reduction in gear pump pressure ripple achieved with the mechanism has been shown to reduce overall airborne noise levels from a hydraulic system by as much as 10 dB, although the airborne noise radiated from the pump casing was not affected.

On the instability of ventilated cavities

1966 ◽  
Vol 26 (3) ◽  
pp. 437-457 ◽  
Author(s):  
L. C. Woods
Keyword(s):  
Pressure Fluctuations ◽  
Unsteady Motion ◽  
Cavitation Number ◽  
The Body ◽  
Supply Rate ◽  
Velocity Fluctuations ◽  
Air Supply ◽  
Resonance Frequencies ◽  
Axis Of Symmetry ◽  
The Mathematical Model

It has been found that ventilated cavities extending behind hydrofoils, plates, and other two-dimensional bodies, oscillate when the air supply rate is sufficient to reduce the cavitation number to about one-fifth of its natural value. As the rate increases further, higher modes of oscillation occur in which the cavity–water interface supports several waves that are convected downstream towards the wake, which, owing to a pinching-off action replacing the usual entrainment sink, consists of a sequence of large bubbles drifting downstream. A theory of such flows that allows both for the convected velocity fluctuations in the cavity, and for the transport of bubble volume down the wake, is given in this paper. Coupled with a rather simple phenomenological relation between the pressure fluctuations within the cavity and the departure of the pinched-off rear portion of the cavity—explained in terms of the action of the re-entrant jet—this theory successfully predicts the resonance frequencies obtained in experiments by Silberman & Song.The theory also provides a solution of the more general problem of determining the fluctuations in the pressure distribution over the whole surface of the body, when it is in a prescribed unsteady motion along its axis of symmetry (the theory is confined to symmetrical bodies and flows). Thus the growth in drag due to a sudden increment in the upstream velocity can be predicted, and also the damping forces acting on the body when it is forced to oscillate at a given frequency. It is shown that in all cases the body is unstable.One important feature of the mathematical model chosen is that it completely avoids the presence of a time-dependent sink at infinity—with its associated infinite pressures—by conserving total volume of wake and cavity in just the same way as vorticity is conserved in unsteady aerofoil theory.

A Model for the Estimation of Pressure Ripple in Tandem Gear Pumps

2015 ◽  
Author(s):  
Mattia Battarra ◽  
Emiliano Mucchi ◽  
Giorgio Dalpiaz
Keyword(s):  
High Pressure ◽  
Dynamic Behavior ◽  
Low Pressure ◽  
Variable Pressure ◽  
Geometrical Parameters ◽  
Gear Pump ◽  
Helical Gears ◽  
Pressure Stage ◽  
Outlet Pressure ◽  
Pressure Ripple

The present paper addresses the development of a lumped parameters model used to analyze the dynamic behavior of a so-called tandem gear pump. The pump is composed of two coaxial stages, both with external gears: a high pressure stage with spur gears and a low pressure one with helical gears. In particular, the paper deals with the modelling and the analysis of the phenomena bound to the pressure distribution around the gears, since they have the most important effect in the dynamic behavior of the pump. The pressure variation in the inlet and outlet chambers, the variable pressure in the trapped volume as well as the pressure evolution from the low to the high pressure chamber is estimated based on the Euler’s approach. The model is developed in Matlab environment. Attention is particularly focused on the description of the methodology adopted for modelling the low-pressure stage, constituted by helical gears, and its influence on the calculation of the pump geometrical parameters. The results provided by the numerical model are compared with experimental measurements in terms of outlet pressure ripple and volumetric efficiency under different working conditions. The results of the validation can be considered satisfactory. Predicted pressure ripple is shown and the effects of interconnections between stages are analyzed studying the outlet pressure ripple in the frequency domain as well.

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