Centrifugal compressor modeling development and validation for a turbocharger component matching system

Abstract

This thesis outlines the development of a centrifugal compressor model for the Turbocharger Component Matching System (TuCMS) software package that can be used to inexpensively analyze turbocharger performance. The TuCMS can also be used to match turbocharger components to integrate and optimize turbocharger-engine performance. The software system is being developed with the intent to reduce the time taken to experimentally match a turbocharger with an engine, a task that is key to engine emission reductions. The TuCMS uses one-dimensional thermo-fluid equations to analyze the compressor side of a turbocharger. For each compressor component, the program calculates the velocities, pressures, temperatures, pressure losses, work consumption, and efficiencies for a specified set of turbocharger geometry, atmospheric conditions, rotational speed, and fluid mass flow rate. The compressor includes established loss models found in the open literature. The TuCMS utilizes a component-based architecture to simplify model enhancements. The TuCMS can be used as a cost effective engineering tool for preliminary turbocharger testing during engine upgrades and modifications. In this thesis, the TuCMS compressor model was used as an analysis tool to further understand the Variable Geometry Turbocharger (VGT) experimental results. The VGT is a unique turbocharger that can change the diffuser vane angle over a wide range of positions. The change in diffuser vane angle results in optimal turbocharger performance at various operating conditions, and potentially increases the operating range. The purpose for the use of the TuCMS compressor model analysis is to identify the change in performance as the diffuser vane angles are adjusted. The TuCMS can ideally be used as a control program for the VGT to adjust the diffuser vane angles as the compressor load changes and insure the compressor is operating at the highest efficiency.