Dalibor Jajcevic

Usage and validation of a fluid structure interaction methodology for the study of different suction valve parameters of a hermetic reciprocating compressor

The dynamics of the flatter valves inside a hermetic reciprocating compressor used in household appliances is the most important factor concerning the gas dynamic behaviour of such a compressor. Hence for a good valve design and for a reliable simulation of the compressor the ability to predict the movement of the valves is indispensable. The present paper describes a methodology which allows the prediction of the valve dynamics. For the validation of the methodology the simulation results of the suction valve dynamics have been compared with experimental data obtained out of measurements with a Laser-Doppler-Vibrometer. Furthermore the method has been used for the variation of some suction valve parameters and their influence onto the overall compressor performance has been shown. The whole methodology has been implemented into a commercial available CFD code (FLUENT) as a user defined function (UDF).

A cyclic boundary condition for time delayed technical problems and its application for IC-engine simulation

The continuous improvement of numerical methods together with the increase of computer power allows the simulation of more and more complex technical problems even for large calculation domains. Growing calculation domains combined with the simulation of physically complex phenomena increase the simulation effort non-linearly and make them impracticable in the daily work of an engineer. A decrease of simulation time can be realised by the reduction of the calculation domain. In this paper, a new cyclic and time delayed boundary condition is introduced together with its application in the simulation of an IC-engine. The boundary conditions are calculated during the simulation and are set on the corresponding faces in the calculated domain. Furthermore, the data for the boundary condition is deducted from the simulation itself and therefore do not need to come from another software or measurements, what additionally reduces the pre-processing effort.