Numerical Simulations on Performance of a Hybrid and a Tandem Rotor

In the quest of maximizing the pressure ratio and the efficiency of the gas turbine engine, designing a compressor that can generate the required pressure ratio with a minimum number of stages is one of the challenges. A single blade, if designed with a higher diffusion factor, has an inherent problem of flow separation. Tandem or slotted blades with the help of nozzle-gap phenomenon have shown promising results in terms of higher pressure ratio and efficiency, but it has mechanical complexity and lower stall margin. The hybrid rotor called part-span tandem has been designed to get the benefits of both a single rotor as well as tandem rotor blades. Design methodology as well as parallel comparison of results of a low speed hybrid rotor, tandem rotor, and a single rotor is included in the paper. CFD results such as pressure distribution at different span locations, total pressure rise, static pressure rise, contours of Mach number, entropy, the behavior of the tip leakage flow, and performance curve are included in this paper. Full span tandem rotor has higher pressure rise, and the hybrid rotor has a better stall characteristic.