Aerodynamic Optimization of a Turbocharger Compressor Impeller using modeFRONTIER

Robert Lotz | BorgWarner

This paper presents a design approach of a turbo charger radial compressor for commercial diesel applications. The primary goal of the design is to maximize total to static efficiency at a specific mass flow rate and pressure ratio, while also providing useful performance at off design conditions (map width). The design of the impeller uses modeFRONTIER as the optimization driver, Concepts NREC AxCent as the geometry engine, and Concepts NREC pbCFD as aerodynamic analysis tool. Several optimizations with setups of increasing complexity are explored, from a simple single objective at one operating condition to multiple objectives at multiple operating conditions. The resulting designs were then evaluated on a gas stand at the BorgWarner Tech Center in Arden, NC. CFD predictions are compared with test data and discrepancies are quantified. The resulting impeller designs show that substantial peak efficiency gains over conventional designs can be achieved, at the cost of a more narrow operating range. Attempts at increasing map width show promising results, despite the low fidelity of CFD predictions at the surge side of the operating range.