Development of a Thermodynamic Model to Study the Behaviour of Reciprocating Air Compressor With Disc Valve Used in Automotive Braking System

2006 ◽  
Author(s):  
J. Venkatesan ◽  
S. Kumar ◽  
V. Anandram ◽  
S. Saikishan ◽  
J. Vijaymanikandan
Keyword(s):  
Mathematical Modeling ◽  
Valve Lift ◽  
Physical Parameters ◽  
Connecting Rod ◽  
Computing Technique ◽  
Braking System ◽  
Free Air ◽  
Simplifying Assumptions ◽  
Compressor Performance ◽  
Discharge Pressure

Mathematical modeling is the process of designing a model of a real system and conducting experiments with it for the purpose of understanding the behaviour of the system. Mathematical simulation is widely used for investigating and designing the compressors. Investigations of the processes of reciprocating compressors using mathematical models is an effective tool by high development of computing technique, which enables complicated problems to be solved with a minimal number of simplifying assumptions. A considerable number of previous works has been done on the mathematical modeling and simulation. The aims of the present work are to construct a model which is easy to understand, easy to detect errors in the process of building a model and easy to compute a solution. This project presents a simplified and effective mathematical model for the estimation of reciprocating compressor performance using personal computers that can be easily handled. The effect of various physical parameters, like, clearance volume, cylinder diameter, connecting rod length, crank radius, valve lift and other dimensions, etc., and operating parameters, like, discharge pressure, compressor speed, etc., on thermodynamic behaviour of compressor in working condition has been analysed. The model has been developed for obtaining cylinder pressure, cylinder volume, cylinder temperature, valve lift and resultant torque at different crank angles and free air delivered and indicated power of the compressor.

scholarly journals Mathematical modeling and simulation of a reed valve reciprocating air compressor

2009 ◽  
Vol 13 (3) ◽  
pp. 47-58 ◽  
Author(s):  
Nagarajan Govindan ◽  
Venkatesan Jayaraman ◽  
Retteripatti Venkatasamy ◽  
Murugan Ramasamy
Keyword(s):  
Mathematical Modeling ◽  
Modeling And Simulation ◽  
Valve Lift ◽  
Computing Technique ◽  
Free Air ◽  
Pressure Cylinder ◽  
Simplifying Assumptions ◽  
Compressor Performance ◽  
Reed Valve ◽  
Discharge Pressure

Mathematical modeling is the process of designing a model of a real system and conducting experiments with it for the purpose of understanding the behavior of the system. Mathematical simulation is widely used for investigating and designing the compressors. Investigations of the processes of reciprocating compressors using mathematical models is an effective tool by high development of computing technique, which enables complicated problems to be solved with a minimal number of simplifying assumptions. A considerable number of previous works has been done on the mathematical modeling and simulation. The aim of the present work is to construct a model which is easy to understand, easy to detect errors in the process of building a model, and easy to compute a solution. This paper presents a simplified and effective mathematical model for the estimation of reciprocating compressor performance using personal computers that can be easily handled. The effect of operating parameters, speed and discharge pressure on thermodynamic behavior of compressor in working condition has been analyzed. The model has been developed for obtaining cylinder pressure, cylinder volume, cylinder temperature, valve lift and resultant torque at different crank angles and free air delivered and indicated power of the compressor. The model has been validated using experimental results.

scholarly journals Crossbreed impact of double-diffusivity convection on peristaltic pumping of magneto Sisko nanofluids in non-uniform inclined channel: A bio-nanoengineering model

2021 ◽  
Vol 104 (3) ◽  
pp. 003685042110336
Author(s):  
Safia Akram ◽  
Maria Athar ◽  
Khalid Saeed ◽  
Alia Razia
Keyword(s):  
Mathematical Modeling ◽  
Magnetic Field ◽  
Physical Parameters ◽  
Induced Magnetic Field ◽  
Long Wavelength ◽  
Inclined Channel ◽  
Graphical Data ◽  
Peristaltic Pumping ◽  
Highly Nonlinear ◽  
Linear Pdes

The consequences of double-diffusivity convection on the peristaltic transport of Sisko nanofluids in the non-uniform inclined channel and induced magnetic field are discussed in this article. The mathematical modeling of Sisko nanofluids with induced magnetic field and double-diffusivity convection is given. To simplify PDEs that are highly nonlinear in nature, the low but finite Reynolds number, and long wavelength estimation are used. The Numerical solution is calculated for the non-linear PDEs. The exact solution of concentration, temperature and nanoparticle are obtained. The effect of various physical parameters of flow quantities is shown in numerical and graphical data. The outcomes show that as the thermophoresis and Dufour parameters are raised, the profiles of temperature, concentration, and nanoparticle fraction all significantly increase.

DIMENSIONLESS PHYSICAL-MATHEMATICAL MODELING OF TURBULENT NATURAL CONVECTION

2021 ◽  
Vol 20 (3) ◽  
pp. 37
Author(s):  
S. A. Verdério Júnior ◽  
V. L. Scalon ◽  
S. R. Oliveira ◽  
P. C. Mioralli ◽  
E. Avellone
Keyword(s):  
Mathematical Modeling ◽  
Natural Convection ◽  
Turbulent Flows ◽  
Convection Heat Transfer ◽  
Thermal Engineering ◽  
Physical Parameters ◽  
Problem Situation ◽  
Dimensionless Numbers ◽  
Turbulent Natural Convection ◽  
Cooling Coils

Natural convection heat transfer is present in the most diverse applications of Thermal Engineering, such as in electronic equipment, transmission lines, cooling coils, biological systems, etc. The correct physical-mathematical modeling of this phenomenon is crucial in the applied understanding of its fundamentals and the design of thermal systems and related technologies. Dimensionless analyses can be applied in the study of flows to reduce geometric and experimental dependence and facilitate the modeling process and understanding of the main influence physical parameters; besides being used in creating models and prototypes. This work presents a methodology for dimensionless physical-mathematical modeling of natural convection turbulent flows over isothermal plates, located in an “infinite” open environment. A consolidated dimensionless physical-mathematical model was defined for the studied problem situation. The physical influence of the dimensionless numbers of Grashof, Prandtl, and Turbulent Prandtl was demonstrated. The use of the Theory of Dimensional Analysis and Similarity and its application as a tool and numerical device in the process of building and simplifying CFD simulations were discussed.

Entropy Production as a Predictive Performance Measure: I — Turbomachinery

1999 ◽  
Author(s):  
David M. Paulus ◽  
Richard A. Gaggioli ◽  
William R. Dunbar
Keyword(s):  
Mathematical Modeling ◽  
Energy Conversion ◽  
Entropy Production ◽  
Predictive Performance ◽  
Performance Measure ◽  
Governing Equations ◽  
Compressor Performance

Abstract It is proposed that consideration be given to an alternative, streamlined manner for mathematical modeling of the performance of energy conversion and transfer equipment. We make the case, here, by application to compressors. It is advocated that, instead of using an expression for efficiency as one of the governing equations, performance can be accounted for directly, with entropy production. It is shown that (1) the modeling is more straightforward, using fewer relations, and (2) that compressor performance (e.g. maps) can be represented equally well.

High-Pressure Steam-Driven Jet Pump—Part II: Parametric Analysis

2000 ◽  
Vol 123 (3) ◽  
pp. 701-706 ◽  
Author(s):  
N. Beithou ◽  
H. S. Aybar
Keyword(s):  
Mathematical Modeling ◽  
Parametric Analysis ◽  
Cold Water ◽  
Water Pressure ◽  
Steam Pressure ◽  
Relative Difference ◽  
Inlet Pressure ◽  
Experimental Result ◽  
Jet Pump ◽  
Discharge Pressure

The steam-driven jet pump (SDJP) is a device without moving parts, in which steam is used as an energy source to pump cold water from a pressure much lower than the steam pressure to a pressure higher than the steam pressure. In the previous part of this study, the mathematical modeling of the SDJP has been done, and reported. The results of the mathematical modeling of the SDJP have been compared with Cattadori’s experimental results. The comparisons show that the experimental and calculated pressure distributions are in good qualitative agreement. For the same steam inlet pressure of 8.7 MPa, the discharge pressures in the experiment and in the simulation are 9.8 MPa and 9.54 MPa, respectively. The relative difference is two percent. It can be said that the computed discharge pressure is in good agreement with the experimental result. In the current study, a parametric analysis of the SDJP has been done in terms of four independent parameters: steam inlet pressure and temperature, supply water pressure, and temperature. The output parameters are: discharge pressure, temperature, and mass flow rate. As a result of this parametric study, the operation characteristics of the SDJP have been obtained.

Experiences With Simulation of Reciprocating Compressor Valve Dynamics

1996 ◽  
Author(s):  
Brian Howes ◽  
Leonard Lin ◽  
Val Zacharias
Keyword(s):  
Gas Flow ◽  
Economic Effect ◽  
Operating Conditions ◽  
Valve Lift ◽  
Reciprocating Compressor ◽  
Compression Process ◽  
Flow Area ◽  
Valve Dynamics ◽  
Compressor Performance ◽  
Cylinder Flow

Experience with compressor valve modelling has shown that reciprocating compressor performance can sometimes be improved by subtle changes in valve design. Modelling has led to a better understanding of the physical behaviour of valves and of the compression process. Three compressor valve studies presented here demonstrate the benefits of valve modelling. Case 1 challenges the commonly held assumption that reducing the lift of a compressor valve will reduce the efficiency of the compressor. The capacity of this compressor is increased by reducing the valve lift. A plot of BHP/MMSCFD versus valve lift shows an inflection point that assists the analyst in optimizing the design. Case 1 also presents a method of calculating the economic effect of improvements in valve performance. Case 2 demonstrates the effect of inadequate flow area through the valve. Pressure in the clearance volume cannot decrease fast enough if flow areas are inadequate; the result is late valve closure, and therefore decreased valve life. Case 3 shows the importance of considering the design of the cylinder casting in addition to that of the valves. Here, insufficient cylinder flow area constricted gas flow. Since these cases were simulated, the analyst had the opportunity to evaluate the proposed solution over the entire range of operating conditions. He was able to select a valve which solved the immediate problem and be confident that it would perform adequately throughout the specified range of conditions.

scholarly journals CLIFFORD ALGEBRAS IN FINITE QUANTUM FIELD THEORIES I.

1998 ◽  
Vol 13 (13) ◽  
pp. 2047-2073
Author(s):  
WOLFGANG LUCHA ◽  
MICHAEL MOSER
Keyword(s):  
Gauge Coupling ◽  
Field Theories ◽  
Physical Parameters ◽  
Quantum Field Theories ◽  
Quantum Field ◽  
Gauge Groups ◽  
Yukawa Couplings ◽  
Simplifying Assumptions ◽  
Gauge Anomalies ◽  
Promising Type

Finite quantum field theories may be constructed from the most general renormalizable quantum field theory by forbidding, order by order in the perturbative loop expansion, all ultraviolet-divergent renormalizations of the physical parameters of the theory. The relevant finiteness conditions resulting from this requirement relate all dimensionless couplings in the theory. At first sight, Yukawa couplings which are equivalent to the generators of some Clifford algebra with identity element represent a very promising type of solutions of the condition for one-loop finiteness of the Yukawa couplings. However, under a few reasonable and simplifying assumptions about their particular structure, these Clifford-like Yukawa couplings prove to be in conflict with the requirements of one- and two-loop finiteness of the gauge coupling and of the absence of gauge anomalies, at least for all simple gauge groups up to and including rank 8.

Axial Compressor Aerodynamics Under Sub-Idle Conditions

2013 ◽  
Author(s):  
Enric Illana ◽  
Nicholas Grech ◽  
Pavlos K. Zachos ◽  
Vassilios Pachidis
Keyword(s):  
Mach Number ◽  
Axial Compressor ◽  
Engine Performance ◽  
Separated Flow ◽  
Physical Parameters ◽  
Aerodynamic Coefficients ◽  
Low Speed ◽  
Multi Stage ◽  
Flow Phenomena ◽  
Compressor Performance

With stricter regulations on engine altitude relight capability, the understanding of low-speed axial compressor performance is becoming increasingly important. At such far off-design conditions, compressors behave differently from design point, with large changes in the flow phenomena and reduced reliability on the established empirical equations and assumptions. This work focuses on the aerodynamics of a locked-rotor axial compressor at high inlet Mach number conditions, using a validated numerical simulation approach. In a locked-rotor compressor there is very little compression of the inflow. The air is forced to accelerate, with the rear stages seeing the highest velocities. Depending on the inlet Mach number, the velocity at the rear stages can be close to sonic, until choking conditions are reached. To predict accurately the zero-speed compressor performance close to the choking point, the corresponding blade aerodynamic coefficients are evaluated as a function of the blade’s physical parameters and the inlet Mach number. In addition, the blockage due to the separated flow as a result of the high negative incidences is investigated as a function of inlet Mach number, incidence, solidity and stagger angle. Models that predict the characteristics and choking mass flow of the compressor, require such data. This work offers a better insight into the low-speed and locked rotor characteristics of the compressor. The zero-speed line can be calculated through a stage-stacking technique using the aerodynamic coefficients and flow blockage derived from the numerical simulations. Low-speed lines between the zero and idle-speed line can subsequently be created through interpolation. Using this methodology, it is possible to generate a complete sub-idle map for a multi-stage axial compressor, enhancing the predictive capability of whole engine performance solvers.

Experimental study on a two-stage rolling piston CO2 compressor based on p–V indicator diagrams

2011 ◽  
Vol 226 (4) ◽  
pp. 995-1003 ◽  
Author(s):  
J Yang ◽  
Z Qi ◽  
J Chen ◽  
Z Chen
Keyword(s):  
Experimental Study ◽  
Operating Conditions ◽  
Test Rig ◽  
Two Stage ◽  
Second Stage ◽  
Compressor Inlet ◽  
Compressor Performance ◽  
Overall Efficiency ◽  
Rolling Piston ◽  
Discharge Pressure

In this article, a new two-stage rolling piston CO2 compressor was developed. A test rig was designed to measure the performance of this compressor. Based on the measured p–V indicator diagram, the distributions of indicated power and compressor performance under various operating conditions have been analysed in detail. It is shown that the discharge passage loss of the first stage and the suction passage loss of the second stage are much higher than other losses for the tested compressor. The overall efficiency of the tested compressor decreases by 1.2 per cent with the decrease of the discharge pressure at the same suction conditions. It is also found that the superheating at the compressor inlet has very small (0.3 per cent) effect on the compressor performance.

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