Research project in application basis by the gas turbine laboratory are as follows:
1. Research on boundary layer behaviors and flow controls of ultra-high-lift turbine profile under unsteady wakes
In order to obtain high thrust to weight ratio in aero engine, the design of low pressure turbine blades trends to the direction of ultra high lift (Zweiful number more than 1.4). However, with the increase of inverse pressure gradient on suction surface of the blade, coupled with low Reynolds number of the low pressure turbine under high-altitude cruise state, flow separation and sharply increasing loss is still inevitably for ultra-high-lift and low-pressure turbine even after the introduction of wake sweeping. Sponsored by the National Natural Science Fund, research team from gas turbine laboratory has completed the design, process, installation and debugging of two sets of ultra-high-lift and low-pressure turbine blade, whose testing system based on the surface hot film, hotline, seven hole probes. Under the steady flow, developing process of the boundary layer of the suction surface with different Reynolds number and turbulence were studied. After the upstream upgraded, behaviors of unsteady boundary layer on the suction surface under periodically unsteady wake were investigated. The boundary layer separation and transition characteristics under different upstream and wake frequency was analyzed, based on which flow control of boundary layer characteristic roughness were obtained Through optimizing the roughness size and rough position, flow control near the separation point under periodic wake sweep were realized.
2. Research on mixing mechanism of forced flow in lobed mixer
The lobed nozzle is widely used in turbofan engine with small and medium bypass ratio for its significant effects in increasing thrust, reducing acoustic emissions and suppressing the infrared radiation. Sponsored by the National Natural Science Foundation, taking a real engine lobed mixer as the research object and a low speed wind tunnel with different swirl (different pre whirl angle and radial distribution) as experimental platform, research team explored the evolution process including generation, development, attenuation of the internal stream-wise vortex and orthogonal vortex under different inlet swirl. With the help of seven probes, 3D hotline probes and oil flow probes, mixing mechanism of forced flow in lobed mixer was further investigated. Based on the quantitative analysis of the impact of main parameters on mixed performance, the relationship among the mixing efficiency, mixing loss and an inlet swirl along with the best radial inlet swirl distribution were obtained. The work provided a basic support for the design of high performance of aero-engine lobe mixer.
