scholarly journals Учет влияния перекоса в зазоре между плунжером и втулкой на величину утечек в авиационном аксиально-плунжерном насосе

2021 ◽  
pp. 24-31
Author(s):  
Владимир Николаевич Доценко ◽  
Иван Григорьевич Лихошерст
Keyword(s):  
Thermal State ◽  
Relative Length ◽  
Theoretical Research ◽  
Cylinder Block ◽  
Working Fluid ◽  
Geometrical Parameters ◽  
Plunger Pump ◽  
Finite Element Software ◽  
First Time ◽  
Axial Piston

The subject of study in the article is the amount of leaks of the working fluid in the gap between the plunger and the bushing of an aircraft axial-plunger pump, depending on the position of the plunger relative to the bushing. The level of fluid leaks in the gap between the plunger and the cylinder block bushing is a component of volumetric losses, affects the thermal state, wear, the state of the plunger-bushing pair, as well as the level of pressure pulsations of the working fluid and, ultimately, the change in the efficiency of the axial-plunger pump. Researches deal with the influence of piston defects in a bushing on losses through a gap between them that is not discovered in existent literature. The aim of this work is theoretical research of the influence of piston defect on the leakage of working liquid through a gap between the piston and cylindrical bushing in aviation axial-piston pump under workloads. The tasks are: it is necessary to define the losses quantity for the three cases: the axes of piston and bushing coincide; piston is displaced (axes are parallel) with a maximal eccentricity ε = 0.99; piston is twisted in a bushing so that the edges of piston touch a bushing. For the problem-solving methods as follows were used. The task of thin film laminar flow in a gap between piston and bushing was solved by a numeral method in finite-element software. Losses on a piston are considered as a sum of the losses, related to the motion of the piston at a speed W and losses due to the pressure gradient dp/dz. The results are: to obtain the laws of geometrical parameters influence on the losses amount investigation for one piston was undertaken in the first part of the study. It is marked that most losses take place for piston displaced in parallel, and the least - for twisted. Total losses for the real pump on different operational behaviors are considered and volume loss-of-flows are obtained in the second part of the article. Conclusions. Dependences of losses through a gap at the different gap sizes and relative length of bushing for twisted piston are first time obtained. The results allow estimating the losses quantity in a pump on the efficiency of his work at planning and exploitation.

scholarly journals Virtual Prototyping of Axial Piston Machines: Numerical Method and Experimental Validation

Energies ◽  
2019 ◽  
Vol 12 (9) ◽  
pp. 1674 ◽  
Author(s):  
Rene Chacon ◽  
Monika Ivantysynova
Keyword(s):  
Numerical Models ◽  
Optimization Procedure ◽  
Cylinder Block ◽  
Plate Interface ◽  
Piston Cylinder ◽  
Swash Plate ◽  
Physical Prototype ◽  
First Time ◽  
Axial Piston ◽  
Plate Type

This article presents a novel methodology to design swash plate type axial piston machines based on computationally based approach. The methodology focuses on the design of the main lubricating interfaces present in a swash plate type unit: the cylinder block/valve plate, the piston/cylinder, and the slipper/swash plate interface. These interfaces determine the behavior of the machine in term of energy efficiency and durability. The proposed method couples for the first time the numerical models developed at the authors’ research center for each separated tribological interface in a single optimization framework. The paper details the optimization procedure, the geometry, and material considered for each part. A physical prototype was also built and tested from the optimal results found from the numerical model. Tests were performed at the authors’ lab, confirming the validity of the proposed method.

Effects of Varying Geometrical Parameters on Boiling From Microfabricated Enhanced Structures

2003 ◽  
Vol 125 (1) ◽  
pp. 103-109 ◽  
Author(s):  
C. Ramaswamy ◽  
Y. Joshi ◽  
W. Nakayama ◽  
W. B. Johnson
Keyword(s):  
Heat Dissipation ◽  
Layer Structure ◽  
Single Layer ◽  
Nucleate Boiling ◽  
Heat Fluxes ◽  
Working Fluid ◽  
Geometrical Parameters ◽  
Small Range ◽  
Two Phase ◽  
Wall Superheat

The current study involves two-phase cooling from enhanced structures whose dimensions have been changed systematically using microfabrication techniques. The aim is to optimize the dimensions to maximize the heat transfer. The enhanced structure used in this study consists of a stacked network of interconnecting channels making it highly porous. The effect of varying the pore size, pitch and height on the boiling performance was studied, with fluorocarbon FC-72 as the working fluid. While most of the previous studies on the mechanism of enhanced nucleate boiling have focused on a small range of wall superheats (0–4 K), the present study covers a wider range (as high as 30 K). A larger pore and smaller pitch resulted in higher heat dissipation at all heat fluxes. The effect of stacking multiple layers showed a proportional increase in heat dissipation (with additional layers) in a certain range of wall superheat values only. In the wall superheat range 8–13 K, no appreciable difference was observed between a single layer structure and a three layer structure. A fin effect combined with change in the boiling phenomenon within the sub-surface layers is proposed to explain this effect.

scholarly journals Novel design of hydrodynamic–magnetic compound support for cylinder block–valve plate in axial piston pump

AIP Advances ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 115221
Author(s):  
Jihai Jiang ◽  
Boran Du ◽  
Jian Zhang ◽  
Geqiang Li
Keyword(s):  
Valve Plate ◽  
Piston Pump ◽  
Cylinder Block ◽  
Axial Piston Pump ◽  
Axial Piston ◽  
Novel Design

scholarly journals Constraints on quasinormal modes and bounds for critical points from pole-skipping

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
Navid Abbasi ◽  
Matthias Kaminski
Keyword(s):  
Critical Points ◽  
Thermal State ◽  
Quasinormal Modes ◽  
Scalar Perturbation ◽  
Black Brane ◽  
Massive Scalar ◽  
Dual Operator ◽  
Conformal Dimension ◽  
Scalar Operator ◽  
First Time

Abstract We consider a holographic thermal state and perturb it by a scalar operator whose associated real-time Green’s function has only gapped poles. These gapped poles correspond to the non-hydrodynamic quasinormal modes of a massive scalar perturbation around a Schwarzschild black brane. Relations between pole-skipping points, critical points and quasinormal modes in general emerge when the mass of the scalar and hence the dual operator dimension is varied. First, this novel analysis reveals a relation between the location of a mode in the infinite tower of quasinormal modes and the number of pole-skipping points constraining its dispersion relation at imaginary momenta. Second, for the first time, we consider the radii of convergence of the derivative expansions about the gapped quasinormal modes. These convergence radii turn out to be bounded from above by the set of all pole-skipping points. Furthermore, a transition between two distinct classes of critical points occurs at a particular value for the conformal dimension, implying close relations between critical points and pole-skipping points in one of those two classes. We show numerically that all of our results are also true for gapped modes of vector and tensor operators.

Improving the Volumetric Efficiency of the Axial Piston Pump

2012 ◽  
Vol 134 (11) ◽  
Author(s):  
Shu Wang
Keyword(s):  
Operating Conditions ◽  
Volumetric Efficiency ◽  
Valve Plate ◽  
Piston Pump ◽  
Efficient Design ◽  
Axial Piston Pumps ◽  
Definition Of ◽  
Engineering Practices ◽  
First Time ◽  
Axial Piston

The volumetric efficiency is one of the most important aspects of system performance in the design of axial piston pumps. From the standpoint of engineering practices, the geometric complexities of the valve plate (VP) and its multiple interactions with pump dynamics pose difficult obstacles for optimization of the design. This research uses the significant concept of pressure carryover to develop the mathematical relationship between the geometry of the valve plate and the volumetric efficiency of the piston pump. For the first time, the resulting expression presents the theoretical considerations of the fluid operating conditions, the efficiency of axial piston pumps, and the valve plate designs. New terminology, such as discrepancy of pressure carryover (DPC) and carryover cross-porting (CoCp), is introduced to explain the fundamental principles. The important results derived from this study can provide clear recommendations for the definition of the geometries required to achieve an efficient design, especially for the valve plate timings. The theoretical results are validated by simulations and experiments conducted by testing multiple valve plates under various operating conditions.

Advanced Virtual Prototyping of Axial Piston Machines

2016 ◽  
Author(s):  
Rene Chacon ◽  
Monika Ivantysynova
Keyword(s):  
Numerical Models ◽  
Virtual Prototyping ◽  
Valve Plate ◽  
Cylinder Block ◽  
Plate Interface ◽  
Design And Optimization ◽  
Swash Plate ◽  
Axial Piston Machine ◽  
Axial Piston ◽  
Plate Type

This paper explains how a combination of advanced multidomain numerical models can be employed to design an axial piston machine of swash plate type within a virtual prototyping environment. Examples for the design and optimization of the cylinder block/valve plate interface are presented.

scholarly journals Load of the slipper-swash plate kinematic pair of an axial piston pump

2018 ◽  
Vol 157 ◽  
pp. 08013 ◽  
Author(s):  
Tadeusz Złoto ◽  
Konrad Kowalski
Keyword(s):  
Piston Pump ◽  
Geometrical Parameters ◽  
Kinematic Pair ◽  
Axial Piston Pump ◽  
Swash Plate ◽  
Axial Piston

The paper presents problems related to the twisting moment of the slipper. The load of the slipper and the piston has been presented and the complex formula of twisting moment of the slipper has been established. Achieved results has been presented graphically. The conducted research has indicated that the value of the twisting moment relays on both the exploitation and geometrical parameters.

scholarly journals MULTIPARAMETRIC OPTIMIZATION OF THE SHAPE AND THICKNESS OF INSULATED ENERGY EFFICIENT CONSTRUCTED BUILDING WITH A SPECIFIC NUMBER OF FACES

2021 ◽  
pp. 196-204
Author(s):  
Viacheslav Martynov
Keyword(s):  
Energy Efficiency ◽  
Energy Efficient ◽  
Heat Losses ◽  
Geometrical Parameters ◽  
Energy Efficient Buildings ◽  
Multiparametric Optimization ◽  
Heat Influx ◽  
Number Of Faces ◽  
The Given ◽  
First Time

To calculate the optimal parameters of outbuildings, a mathematical model and method for optimizing the shape and resistance of heat transfer for opaque and transparent structures with a certain constant number of faces, building volume and amount of insulation to minimize the thermal balance of enclosing structures with the environment during the heating period In the course of calculations the geometrical parameters of translucent, opaque structures in the heat-insulating shell of buildings are determined taking into account heat losses, heat influx from solar radiation by the criterion of ensuring minimum heat losses through enclosing structures, rational parameters (buildings) The given technique and mathematical models should be used in the future in the design of energy efficient buildings in the reconstruction and thermal modernization of buildings. This will increase their energy efficiency and, accordingly, the energy efficiency class of buildings. For the research faceted attached building in the form of a triangular pyramid, the reduction in heat loss was 14.82 percent only due to the optimization of the shape and redistribution of the insulation. Similar results were obtained for other initial forms. For the first time, a computerized method was proposed, an algorithm and application package Optimparam for multiparameter shape optimization and insulation of translucent and opaque structures for outbuildings with a given number of arbitrarily arranged faces were developed.

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