Development of Advanced Compressor Airfoils for Heavy-Duty Gas Turbines: Part II — Experimental and Theoretical Analysis

Abstract

In Part I of this paper a family of numerically optimized subsonic compressor airfoils for heavy-duty gas turbines, covering a wide range of flow properties, is presented. The objective of the optimization was 10 create profiles with a wide low loss incidence range. Therefore, design point and off-design performance had to be considered in an objective function. The special flow conditions in large scale gas turbines have been taken into account by performing the numerical optimization procedure at high Reynolds numbers and high turbulence levels. The objective of Part II is to examine some of the characteristics describing the new airfoils, as well as to prove the reliability of the design process and the flow solver applied. Therefore, some characteristic members of the new airfoil series have been extensively investigated in the cascade windtunnel of DLR Cologne. Experimental and numerical results show profile Mach number distributions, total pressure losses, flow turning and static pressure rise for the entire incidence range. The design goal with low losses and especially a wide operating range could be confirmed, as well as a mild stall behavior. Boundary layer development, particularly near stall condition, is discussed using surface flow visualization and the results of boundary layer calculations. An additional experimental study, using liquid crystal coating, provides necessary information on suction surface boundary-layer transition at high Reynolds numbers. Finally, results of Navier-Stokes simulations are presented which enlighten the total pressure loss development and flow turning behavior especially at high incidence in relation to the results of the design tool.

Automated Design Optimization of Compressor Blades for Stationary, Large-Scale Turbomachinery

“…In contrary, it is better to have a strong acceleration and deceleration close to the leading edge where the turbulent boundary layer is thin and to reduce the deceleration towards the trailing edge where the boundary layer is thicker. Airfoil shapes which are similar to the obtained designs were investigated numerically and experimentally by and Küsters et al (2000). The profiles were also highly front-loaded and showed an early transition.…”

Advanced Endwall Contouring for Loss Reduction and Outflow Homogenization for an Optimized Compressor Cascade

“…On the right hand side, the loss-incidence characteristics show The profile section isentropic Mach number distribution is shown in Figure 7, left. It can be seen that the DLR airfoil shows a more frontloaded design, often seen in new airfoil development projects, such as Siemens HPA-Airfoils (see Köller et al [25] and Küsters et al [26]). It is still subsonic in OP0.…”

Advances in Aerodynamic Design of Gas Turbines Compressors

“…Pierret, 1999 used an artificial neural network coupled with a Navier-Stokes solver to maximize the efficiency and/or operating range of two-dimensional compressor cascades and then staggered them in radial direction to obtain the three dimensional blade. Köller et al, 2000 andKüsters et al, 2000 developed a new family of compressor airfoils, characterized by low total pressure losses and larger operating range with respect to standard Controlled Diffusion Airfoils (CDA), using a gradient optimization method and an inviscid/viscous code. Until today, the use of evolutionary techniques in combination with CFD codes for solving multi-objective optimization problems in compressor aerodynamics has been limited by the tremendous computational effort required.…”