scholarly journals Lumped parameter model and experimental tests on a pressure limiter for variable displacement pumps

2020 ◽  
Vol 197 ◽  
pp. 07005
Author(s):  
Paola Fresia ◽  
Massimo Rundo
Keyword(s):  
Experimental Tests ◽  
Control Flow ◽  
Lumped Parameter Model ◽  
Load Sensing ◽  
Axial Piston Pumps ◽  
Discharge Coefficients ◽  
Lumped Parameter ◽  
Variable Displacement ◽  
Flow Through ◽  
And Control

The paper presents the lumped parameter model of a pressure limiter for axial piston pumps developed in the Simcenter Amesim® environment. The control includes both the absolute and differential (load sensing) pressure limiter in a single body. The continuous position valve was tested experimentally alone on a test rig in order to estimate the discharge coefficients required for tuning the model. The tests were performed at imposed positions of the spool and the corresponding modulated pressure and control flow through the valve were measured. A contactless transducer was used for measuring with a very high accuracy the spool position. The influence of the bleed orifice on the pressure gain was also measured experimentally. It was found that the discharge coefficients have a significant influence on the hydraulic characteristic of the valve with also a consequence on the dynamic behavior of the entire displacement control.

Review of Early Work on Digital Displacement® Hydrostatic Transmission Systems

2018 ◽  
Author(s):  
Niall Caldwell
Keyword(s):  
Time Domain ◽  
Lumped Parameter Model ◽  
Primary Control ◽  
Hydrostatic Transmission ◽  
Load Sensing ◽  
Lumped Parameter ◽  
Good Comparison ◽  
Displacement Pump ◽  
Variable Displacement ◽  
Work Done

The paper describes the work done by the author (1) from 1999 to 2006 to develop the Digital Displacement Pump (DDP) and Pump/Motor (DDPM) and demonstrate the feasibility of off-highway vehicle applications. The link between DDPM capacity and the solenoid valve performance was identified. Magnetic geometry was improved by parametric FEA, then time-domain behavior was improved with a hybrid FEA/lumped-parameter model. Software improvements allowed variable speed and bidirectional operation, enabling the demonstration of the first Digital Displacement Transmission (DDT) systems on a vehicle, one featuring a load-sensing DDP and secondary control by DDPM displacement, and one featuring primary control by DDP displacement and a conventional axial motor. A time-domain simulation was created of the primary-controlled vehicle, which yielded good comparison to experimental results. The deterministic nature of the DDP lends itself to model-based system design methods, which have since been used to develop larger commercial systems. The first detailed analysis of DDP efficiency characteristics revealed profound differences to conventional variable displacement pumps, including exceptional part-load efficiency and the dominant effect of fluid compressibility. A peak overall efficiency of 97% was recorded for a DDP after analysis of loss sources prompted design improvement.

Method for Lumped Parameter Simulation of Digital Displacement Pumps/Motors Based on CFD

2013 ◽  
Vol 397-400 ◽  
pp. 615-620 ◽  
Author(s):  
Daniel Beck Roemer ◽  
Per Johansen ◽  
Henrik C. Pedersen ◽  
Torben O. Andersen
Keyword(s):  
Computational Cost ◽  
Simulation Models ◽  
Lumped Parameter Model ◽  
Model Parameters ◽  
Lumped Parameter ◽  
Displacement Pump ◽  
Variable Displacement ◽  
And Performance ◽  
And Control ◽  
Low Computational Cost

Digital displacement fluid power pumps/motors offers improved efficiency and performance compared to traditional variable displacement pump/motors. These improvements are made possible by using efficient electronically controlled seat valves and careful design of the flow geometry. To optimize the design and control of digital displacement machines, there is a need for simulation models, preferably models with low computational cost. Therefore, a low computational cost generic lumped parameter model of digital displacement machine is presented, including a method for determining the needed model parameters based on steady CFD results, in order to take detailed geometry information into account. The response of the lumped parameter model is compared to a computational expensive transient CFD model for an example geometry.

scholarly journals Sensitivity Analysis of the Transmission Chain of a Horizontal Machining Tool Axis to Design and Control Parameters

2014 ◽  
Vol 6 ◽  
pp. 169064 ◽  
Author(s):  
Stefano Mauro ◽  
Stefano Pastorelli ◽  
Tharek Mohtar
Keyword(s):  
Sensitivity Analysis ◽  
Lumped Parameter Model ◽  
Control Parameters ◽  
Damping Coefficients ◽  
Transmission Chain ◽  
Lumped Parameter ◽  
Tool Axis ◽  
Optimal Value ◽  
Structural Parts ◽  
And Control

This paper reports how a numerical controlled machine axis was studied through a lumped parameter model. Firstly, a linear model was derived in order to apply a modal analysis, which estimated the first mechanical frequency of the system as well as its damping coefficients. Subsequently, a nonlinear system was developed by adding friction through experimentation. Results were validated through the comparison with a commercial servoaxis equipped with a Siemens controller. The model was then used to evaluate the effect of the stiffness of the structural parts of the axis on its first natural frequency. It was further used to analyse precision, energy consumption, and axis promptness. Finally a cost function was generated in order to find an optimal value for the main proportional gain of the position loop.

Modeling and Control of a High Pressure Combined Air/Fuel Injection System

2009 ◽  
Author(s):  
Chao Yong ◽  
Eric J. Barth
Keyword(s):  
High Pressure ◽  
Fuel Injection ◽  
Lumped Parameter Model ◽  
Injection System ◽  
Fuel Injection System ◽  
Modeling And Control ◽  
Lumped Parameter ◽  
Mass Flow Rates ◽  
And Control ◽  
Liquid Piston

A high pressure combined air-fuel injection system is designed and tested for an experimental free liquid-piston engine compressor. The application discussed utilizes available high pressure air from the compressor’s reservoir, and high pressure fuel to mix and then inject into a combustion chamber. This paper addresses the modeling, design and control for this particular high-pressure air-fuel injection system, which features an electronically controlled air/fuel ratio control scheme. This system consists of a fuel line and an air line, whose mass flow rates are restricted by metering valves. These two lines are connected to a common downstream tube where air and fuel are mixed. By controlling the upstream pressures and the orifice areas of the metering valves, desired A/F ratios can be achieved. The effectiveness of the proposed system is demonstrated by a lumped-parameter model in simulation and validated by experiments.

A Note on the Reattachment of Two-Dimensional Compressible Jets to Planes

1967 ◽  
Vol 71 (681) ◽  
pp. 655-657 ◽  
Author(s):  
R. D. Begg
Keyword(s):  
Reynolds Number ◽  
Fluid Velocity ◽  
Experimental Tests ◽  
Two Dimensional ◽  
Inclined Plane ◽  
Air Jets ◽  
Bubble Length ◽  
Flow Through ◽  
Basic Characteristics ◽  
And Control

The rapid growth of interest in fluid logic and control elements has refocused attention on the reattachment of two-dimensional jets to plane surfaces. Of particular interest is the size of the low-pressure bubble enclosed between the jet and the adjacent inclined plane, and the effect on this of fluid velocity and compressibility. Several full studies have been made of such flows, notably by Bourque and Newman, Sawyer and Olson, and the basic characteristics have been well established. Agreement has been reached that bubble length is independent of jet Reynolds number (above 104), but doubts remain as to the best method of measuring the bubble length and also as to the effect of compressibility on this measurement. In order to clear up some of these points for an investigation of compressible flow through control valves, some experimental tests have been carried out on the reattachment of air jets to a plane.

Passive control of microclimate in museum display cases: A lumped parameter model and experimental tests

2015 ◽  
Vol 16 (4) ◽  
pp. 413-418 ◽  
Author(s):  
Francesco Romano ◽  
Luigi P.M. Colombo ◽  
Mirco Gaudenzi ◽  
Cesare M. Joppolo ◽  
Luigi P. Romano
Keyword(s):  
Passive Control ◽  
Experimental Tests ◽  
Lumped Parameter Model ◽  
Lumped Parameter ◽  
Museum Display

Design, Analysis, Experimentation, and Control of a Partially Compliant Bistable Mechanism

2019 ◽  
Vol 142 (1) ◽  
Author(s):  
Ayse Tekes ◽  
Hongkuan Lin ◽  
Kevin McFall
Keyword(s):  
Dynamic Response ◽  
Elliptic Integral ◽  
Three Dimensional ◽  
Design Analysis ◽  
Lumped Parameter Model ◽  
Lumped Parameter ◽  
Rigid Body Model ◽  
3D Printed ◽  
Bistable Mechanism ◽  
And Control

Abstract This study presents the design analysis and development of a novel partially compliant bistable mechanism. Motion behavior dependence on links and relative angles are analyzed, lumped parameter model is derived, mechanism parts including the compliant members are three-dimensional (3D) printed and a state feedback controller is implemented so that the slider follows a well-defined trajectory if designed as an actuator. The proposed mechanism consists of initially straight, large deflecting fixed-pinned compliant links, rigid links, and a sliding mass. Dynamic response of the mechanism is studied using elliptic integral solutions, pseudo rigid body model (PRBM), vector closure loop equations and Elliptic integrals. Nonlinear model is simulated in matlab simulink using fourth‐order Runge‐Kutta algorithms. The research emphasizes on the realization and dynamic response of the mechanism and the trajectory control of the slider so that the slider can be kept constant at specified distances resulting a dwell motion if designed as a linear actuator.

Three Formulations of Sling Load Dynamics for UAV Motion Planning and Control

2018 ◽  
Author(s):  
Alexander Cicchino ◽  
Inna Sharf
Keyword(s):  
Elastic Properties ◽  
Computational Cost ◽  
Solution Space ◽  
Linear Complementarity ◽  
Lumped Parameter Model ◽  
Complementarity Conditions ◽  
Planning And Control ◽  
Lumped Parameter ◽  
Aerial Vehicle ◽  
And Control

In this paper, the sling load dynamics of an aerial vehicle carrying a payload are investigated by employing three formulations of the governing equations. They are the hybrid formulation where the system exists in either a taut cable or slack cable configuration, with appropriate treatment of the transition between the two; the linear complementarity problem (LCP) formulation where the cable constraints are imposed as linear complementarity conditions and finally, the lumped parameter formulation where the cable is modelled with a series of spring-mass elements. The hybrid and LCP formulations neglect the elasticity of the cable while the lumped parameter model explicitly accounts for the elastic properties of the cable, albeit in a discrete way. The importance of the incorporation of elastic properties of the cable on the system is investigated for the variation in solution space of the payload. The three formulations are compared numerically, for information on the computational cost, motion of the payload, and tension profile, for several aerial maneuvers, including an aggressive obstacle avoidance with a window clearance flight.

the functionally univentricular circulation in the norwood procedure: from analysis of fluid dynamics to surgical procedures

2004 ◽  
Vol 14 (S3) ◽  
pp. 81-84
Author(s):  
carlo pace napoleone ◽  
gaetano gargiulo
Keyword(s):  
Fluid Dynamics ◽  
Surgical Procedures ◽  
Lumped Parameter Model ◽  
Norwood Procedure ◽  
Critical Element ◽  
Residual Pressure ◽  
List Type ◽  
Lumped Parameter ◽  
Flow Through ◽  
Left Heart Syndrome

the norwood procedure and its modifications have become the most commonly used surgical procedures for patients with hypoplastic left heart syndrome. many efforts have been made to understand the fluid dynamics of the norwood circulation, with the major impetus coming from the lumped-parameter model described by migliavacca et al. in this model, a large number of variables have been analysed to understand their effect on the norwood circulation. in the clinical setting, some of these parameters can be influenced by the surgeon during the operation. the shunt has been demonstrated to be the critical element in regulating the pulmonary and systemic flows, with the goal of the surgeon being to obtain balanced flows. in order to do this, it is possible to influence the flow through the shunt in three ways:by augmenting the pressure of perfusion of the shunt, with a suboptimal aortic reconstruction that can leave some residual pressure gradient. this can work like an increment of systemic vascular resistance;by varying the size of the shunt;by varying the type of architecture of the shunt, since flow through the shunt is dependent on the site of anastomosis, the angle with the vessels, and so on.in order to validate or verify the results obtained from the lumped-parameter model, we have reviewed our experience with the norwood procedure since 1992.

scholarly journals Engineering Procedure for Positive Displacement Pump Performance Analysis Based on 1D and 3D CFD Commercial Codes

2017 ◽  
Author(s):  
Aleksandar Josifovic ◽  
Matthew Stickland ◽  
Aldo Iannetti ◽  
Jonathan Corney
Keyword(s):  
Cfd Simulation ◽  
Numerical Data ◽  
Experimental Tests ◽  
Input Function ◽  
Lumped Parameter Model ◽  
Cfd Analysis ◽  
Positive Displacement ◽  
Lumped Parameter ◽  
Time Required ◽  
Parameter Approach

A numerical analysis methodology, which demonstrates how a 1D pipework simulation can be enhanced with the results of a 3D CFD simulation of key components, is used to estimate the performance of multi-cylinder Positive Displacement pumps. The procedure uses of a 1-D lumped fluid dynamics model whose accuracy was improved by incorporating CFD analysis of the PD pump valves. The application describes how valve loss co-efficient resulting from CFD analysis was utilised by the lumped parameter model as an input function. The results suggest that the combination of the CFD and lumped parameter approach exceeds the limitations found by Iannetti [1] in modelling the interaction between the pump chambers of a multi-cylinder pump as the simplified lumped parameter approach makes the entire multi-cylinder model affordable in terms of computational power and time required. The results obtained are validated by means of experimental tests the results of which are presented together with the numerical data. An example of the capability of the procedure developed and the support it is able to provide to designers is also presented.

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