Intermittent gas flow through the suction and discharge ports of a screw compressor generates pressure oscillations in the suction and discharge systems. These have been recognised as the main source of structural vibration and noise within the compressor system. Parameters proposed in earlier studies did not help in finding a means to reduce these gas pulsations. This thesis describes a detailed analytical and experimental study of the screw compressor process, which was therefore carried out to predict the level of gas pulsations thus generated and how they could be reduced. Three different simulation models were used to determine the pressure variations within the discharge chamber. These comprised a thermodynamic model of the screw compressor discharge process, a 3-D CFD model of flow through the compressor, originally used to predict pressure variations, and a coupled model which joins the 3-D model of flow in the discharge chamber with a thermodynamic model of the working chamber and the discharge system. The last model accounts for the complex geometry of the discharge chamber and reduces computational time. It was shown in the simulation results that the shape of the discharge port is an important parameter which influences the level of gas pulsations in the discharge chamber. If selected carefully it can reduce gas pulsations without a substantially adverse effect on the compressor performance. The analytical procedure used was then validated in a test programme, carried out on a standard oil injected air compressor to compare predicted and measured pulsations within it. Test results confirmed the trends shown by the predictions.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:511782 |
| Date | January 2009 |
| Creators | Mujic, Elvedin |
| Publisher | City University London |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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