Optimization of the inlet air line of an automotive turbocharger

Abstract

This paper presents different aspects of air inlet behaviour near the inducer of a radial compressor and how the geometry can contribute to its stability and performance. Unfortunately the space reserved for installation of an automotive turbocharger in a vehicle is constantly being reduced, so it is necessary to study the effects that elbows and abrupt changes in flow directions originate on the compressor performance. The work presented in this paper studies the effect that different 90º elbows have on the compressor with respect to its ideal, straight, no-elbow configuration, in order to obtain the best possible elbow configuration.The methodology followed has been to, initially, study different geometries in CFD code in order to obtain the best possible configuration. Then, several 90º elbows were constructed and characterised on a continuous flow test bench in order to validate the CFD results and to obtain optimum results. The elbows were then installed on a radial compressor and tested on a hot, continuous turbocharger test bench, where the compressor was characterised and maps were obtained with each different elbow. The results were compared with respect to the ideal, no-elbow configuration, which was taken as the base performance.After analysing the results obtained, it is possible to observe that in most of the cases the elbows have a negative effect on the compression ratio, which tends to be reduced especially at high rotor velocities and high air mass flow. On the other hand, the effect on the surge limit seems to be positive, as the surge line shifts to lower air mass flows, although the maximum mass flow allowed is reduced. It seems as if the compressor map shifts to the left with a reduction in compression ratio. From theoretical and experimental study it has been concluded that flow uniformity index and pressure loss are the most important factors affecting the performance of the compressor.

Surge Limit Prediction for Automotive Air-Charged Systems

“…The inflow is assumed to be inhomogeneous for both configurations; however, increased map width could be detected. Similar results were investigated by Galindo et al [5][6][7], Hou et al [8], Elkamel [9], Marelli et al [10] and Serrano [11]. In contrast to Kerres' results, Bayomi [12] stated that map width enhancement is gained by assembling flow straighteners upstream of the compressor, providing a more homogeneous inflow.…”

Methodology for experimental validation of a CFD model for predicting noise generation in centrifugal compressors

“…In this kind of map, the leftmost points of each speed line conform the socalled deep surge line. Although this limit is usually regarded as a property of the compressor, previous experience [19,20,21] shows that compressor inlet conditions have a great influence on surge onset.…”

Simulations and measurements of automotive turbocharger compressor whoosh noise

“…Furthermore, the downsizing and downspeeding trends lead the turbomachinery used toward tighter requirements, particularly, in terms of flow range. In order to enlarge the flow range in the compressor from lower surge limit to higher choked flows, several techniques have emerged to reduce the surge limit flow such as ported shroud (Semlitsch et al, 2014) or improved compressor entry designs (Serrano, Margot, Tiseira, & García-Cuevas, 2013). However, the stable working area gained in this process results to be quite noisy (Evans & Ward, 2006).…”