New Approach to Turbocharger Optimization Using 1-D Simulation Tools

New Approach to Turbocharger Optimization Using 1-D Simulation Tools

ABSTRACT

The paper deals with the investigation of turbocharger op-timization procedures using amended 1-D simulation tools. The proposed method uses scaled flow rate/effficiency maps for different sizes of a radial turbine together with a fictitious compressor map. The compressor pressure ra-tio/efficiency map depends on compressor circumference velocity only and predicts the both compressor specific power and achievable efficiency. At the first stage of opti- mization, it avoids the problems of reaching choking/surge limits. It enables the designer to find a suitable turbine type under realistic unsteady conditions (pressure pulses in exhaust manifold) concerning turbine flow area. Once the optimization of turbine/compressor impeller diameters is finished, the specific compressor map is selected.

The proposed method provides the fast way to the best solution even for the case of a VGT turbine. Additional fea-tures have been developed for the representation of scaled turbine and compressor maps. They are based on appli-cation of versatile regression functions. No recalculation of normalized curves is needed.

The method is presented for the model of a one-loop hot gas stand (steady performance compressor/turbine opti- mization) and for a modelled engine with different com- pressors. The potential of optimized turbocharger is evalu- ated at simulated typical operation points for a passenger car equipped with a 4-cylinder 2 dm3 engine.

INTRODUCTION

The current development of downsized, turbocharged en-gines calls for mastering more effective approach in find-ing an optimal turbocharger or two-stage system of tur-bocharging. The widely used trial-and-error method using a collection of turbocharger maps is not an ideal one be- cause of non-transparent results. It does not provide hints for turbocharger amendment.

The presented procedure of finding optimal turbocharger for an engine is based on authors’ experience with turbo-matching (e.g., 0-D code [4]). An application of the pro-cedure is relatively fast and allows for finding suitable tur-bocharger without a need to calculate all feasible combi-nations of turbine and compressor maps provided by tur-bocharger manufacturers. The paper deals with one of the possible ways, using a 1-D model of turbine [6], amended by a compressor map extrapolation and combined with a 1-D engine simulation package [1]. The main problems are listed in the following section, the newly developed tools are described and finally some results of turbocharger op-timization are commented on.

Download full seminar papers At
http://www.enjineer.com/forum