Compressor Housing Design for Small Turbocharger Compressors

Abstract

Compressor housing can greatly impact the behavior of centrifugal compressors used in small turbochargers. This is particularly significant in passenger car applications, where constrains on size and cost of manufacturing pose particular challenges to maintaining aerodynamic efficiency. This paper describes the development of a new compressor housing that overcomes these issues whilst delivering good performance. The concept for the improved design was conceived from an understanding of the loss mechanism inside the housing and the relationship between flow losses and housing geometry. The choice of certain key housing geometric parameters was guided by studies using the Design of Experiment (DOE) method. Computational fluid dynamics (CFD) simulations were also employed in the design of the housing and its use is discussed for several different approaches to the rotor-stator interface. These include a “Mixing Plane”, a “Frozen Rotor” and a “Housing Only” interface model, amongst others. Each differs in its numerical accuracy and computational efficiency and it is important to balance these two factors when choosing a method. Additionally a spreadsheet was built to enable the manipulation of the 3D configuration of the compressor housing. By providing more direct control over the geometry, it reduces the need for extensive and time consuming CAD work. To minimize the fabrication cost for the new housing, die-cast manufacturing was subsequently explored for its smooth surface finish. The final result is a more compact compressor housing that achieves higher efficiency at a lower cost.