An Optimization-Based Design Strategy for Centrifugal Compressors of Automotive Turbochargers and the Comparison of Five Particular Optimization Methods

Abstract

It is possible to optimize a turbocharger's performance for a broad range of engine operating points. However, most of the turbochargers have distinctive performance characteristics independent of engine operation. Therefore, the correct way to obtain the maximum performance from an engine is to design its turbocharger with the specific engine performance map in mind. This paper deals with the effective use of computational methods to create optimal turbocharger compressors for realistic engine operating conditions. The present process has four steps: preliminary analysis, throughflow analysis, optimization, and computational fluid dynamics (CFD) analysis. In the preliminary analysis, gas dynamics and Euler turbomachinery equations are used to calculate the basic dimensions. In the throughflow analysis, calculated dimensions are used to create a parametric three-dimensional (3D) geometry. A throughflow analysis generates the two-dimensional flow results using the meridional geometry of this 3D geometry. The main contribution of this research is the five different optimization methods that are employed and compared. The efficiency of the rotor is defined as the objective function to be maximized. A comparison of the five optimization schemes showed that the genetic algorithm (GA) is the most suitable method for the current design optimization problem. In the final step, a CFD solver is used to assess the created design's final performance. The CFD results' validity is checked against a reference compressor's test results. This study also indicates that preliminary sizing followed by a well-built throughflow analysis eliminates the need for a fully parametric 3D CFD-based design.