A Novel Design Concept for Highly-Loaded Compressor Airfoils

Abstract

Compressor blade design has always faced the challenge of meeting the performance requirements of the compressor while keeping losses to a minimum. Over the past decades, a number of different airfoil types have been developed and grouped into methodologies. The best-known example of such a methodology is the NACA airfoil systematic, which is still the basis for many pre-design procedures. With the introduction of modern optimization methods and artificial intelligence approaches, the airfoil design changed to the development of customized blading. In the present study, a novel concept for highly-loaded compressor airfoils is developed using the DLR optimization method autoopti and the flow solver trace. The aim here is to combine customized airfoil design with a new design methodology. The new approach leads to a load-splitting airfoil (LSA) methodology. The concept behind this airfoil method is fundamentally presented in this study on the basis of the DLR-LSA cascade. The conventional NACA 65 K48 cascade was used to define the boundary conditions and requirements for the new cascade, since it is highly loaded and provides a wide basis of comparison for the evaluation of the new airfoil concept. The inflow Mach number is 0.67 and a working range of 10 deg is to be achieved, resulting in an extremely high aerodynamic load. Based on detailed numerical simulations, the concept of load redistribution by passive boundary layer energization is presented and described. This is followed by an experimental validation of the cascade in DLR’s transonic cascade wind tunnel (TGK). In addition to the details of the boundary layer development, the analysis also includes the evaluation of the classical performance parameters of a compressor cascade. The loss distribution, deflection, and deceleration behavior are determined over the entire operating range. The results of the experimental validation confirm the design and also the function of the load shifting approach. Finally, the performance of the novel compressor airfoil design is evaluated in comparison to the baseline NACA 65.