Numerical Simulation of Thermal and Fluid-Dynamic Behaviour of Reciprocating Compressor

2000 ◽  
Author(s):  
Zhilong He ◽  
Xueyuan Peng ◽  
Pengcheng Shu
Keyword(s):  
Numerical Simulation ◽  
Fluid Flow ◽  
Heat Balance ◽  
Dynamic Behaviour ◽  
Fluid Dynamic ◽  
Reciprocating Compressor ◽  
One Dimensional ◽  
Compressor Design ◽  
Suction Line ◽  
Hermetic Compressor

Abstract This paper presents a numerical method for simulating the thermal and fluid-dynamic behavior of hermetic compressors in the whole compressor domain. The model of fluid flow is developed by integrating transient one-dimensional conservation equations of continuity, momentum and energy through all of the elements from suction line to discharge line. The model describing thermal behavior is based on heat balance in the components such as muffler, connecting tubes and orifices. The calculation of the thermodynamic and transport properties for different refrigerants at various conditions has been considered, and some numerical results for a hermetic compressor are presented. The present study has demonstrated that the numerical simulation is a fest and reliable tool for compressor design.

Adaptive FE-Meshfree-Modelling for Impacts of Liquid Filled Vessels on Thin Walled Structures

2003 ◽  
Author(s):  
Stefan Hiermaier ◽  
Martin Sauer
Keyword(s):  
Numerical Simulation ◽  
Fluid Flow ◽  
World Trade ◽  
Fluid Dynamic ◽  
World Trade Center ◽  
Meshfree Methods ◽  
Trade Center ◽  
Thin Walled ◽  
Break Up ◽  
The Impact

A principal approach to simulate the airplane impact and the collapse of World Trade Center North Tower has been shown by Quan and Birnbaum [4]. Using the general purpose hydrocode AUTODYN the impact damage, fire induced strength reduction and progressive collapse were investigated. Both for the fuel propagation after tank break up and the thermodynamic burn processes assumptions have been taken. It is the aim of this paper to focus on the numerical aspects of simulating the fluid propagation after vessel break up. The release of a fluid out of a broken vessel after impact is not easily represented in a numerical simulation as the fluid flow and its interaction with structures can not be modelled using Lagrangian type element formulations. These elements, typically applied for structural analyses, fail under massive deformation and usually need then to be taken out of the simulation. Typical fluid dynamic discretization methods, so called Eulerian grids, would have to cover the whole space potentially being reached by the fluid flow and are therefore inefficient in a large three dimensional simulation. As an alternative method a coupled discretization using Lagrange elements and Lagrange type meshfree methods is proposed here. Meshfree methods have been introduced to structural dynamics more then ten years ago specifically to simulate processes including large deformation [1]. Originally developed as pure meshfree code, the EMI SOPHIA [3] provides now a new form of adaptivity that allows for more efficiency and accuracy. This is achieved by the use of finite elements as long as deformation is capable for the elements. At definable strain or failure thresholds any element can be transformed into one or more meshfree particles. This way, mass and volume of the original elements are conserved. As the particles interact with each other as well as with the remaining elements, all physical processes can be modelled continuously. The purpose of this study was to contribute to numerical simulation of the airplane impacts into the World Trade Center. It includes impact simulations of cylindrical vessels filled with water against thin walled rectangular shaped bars. It shows that coupled discretizations and specifically an adaptive FE-meshfree discretization offer the flexibility needed to gain both accuracy and efficiency in the simulation.

Time-Dependent Solution of Unsteady Fluid Flow Equations for High Speed Oscillating Compressible Flows and Blast Wave Propagations

2020 ◽  
Author(s):  
Ramlala P. Sinha
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Blast Wave ◽  
High Speed ◽  
Fluid Dynamic ◽  
Time Dependent ◽  
Arbitrary Boundary ◽  
One Dimensional ◽  
Unsteady Fluid ◽  
Energy Equations

Abstract A solution of the highly complex unsteady high speed oscillating compressible flow field inside a cylindrical tube has been obtained numerically, assuming one dimensional, viscous, and heat conducting flow, by solving the appropriate fluid dynamic and energy equations. The tube is approximated by a right circular cylinder closed at one end with a piston oscillating at very high resonant frequency at the other end. An iterative implicit finite difference scheme is employed to obtain the solution. The scheme permits arbitrary boundary conditions at the piston and the end wall and allows assumptions for transport properties. The solution would also be valid for tapered tubes if the variations in the cross-sectional area are small. In successfully predicting the time dependent results, an innovative simple but stable solution of unsteady fluid dynamic and energy equations is provided here for wide ranging research, design, development, analysis, and industrial applications in solving a variety of complex fluid flow heat transfer problems. The method is directly applicable to pulsed or pulsating flow and wave motion thermal energy transport, fluid-structure interaction heat transfer enhancement, and fluidic pyrotechnic initiation devices. It can further be easily extended to cover muzzle blasts and nuclear explosion blast wave propagations in one dimensional and/or radial spherical coordinates with or without including energy generation / addition terms.

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