Rain/Fog Environment Simulator Design And Experimental Study Of Rain Inhalation Effect On Axial Compressor Performance

Modern aircrafts demand all-weather fly ability, which requires the planes can ensure flight safety even in bad weather conditions. In the rain/fog weather, the engines will swallow a large amount of water from the atmosphere. In addition, if there are water puddles on the airport ground, the water may be sucked into the engines when the airplane is landing and the engines are close to the ground. During descent, the engines are usually operated at reduced power with small air flowrate, the percentage of inhaled water increases dramatically, which may induce compressor surge, deteriorate the engines’performance, and even causes runaway airplanes dropped to the ground. Within the engine, the compressor is the first component that is subject to the impact of inhaled water drops. Nevertheless, the related research for the rain/fog environment influence on the compressor, both numerical simulation and experimental method are rarely found in the literature. This thesis performs a systematic investigation on the rain/fog environment influence on the compressor with experimental approaches.The experiments are carried out in our laboratory compressor which was specially remodeled to cope with wet inlet conditions. The rain/fog environment simulation experiments are carried out in three sets of different casing, examining the effects on the torque/pressure rise/stability of compressor. With the flow field visulization and dynamic pressure sensing and high-frequency data acquisition, the mechanism of rain/fog effects on the compressor performance is also explored.Part I of this thesis introduced the design and construction of the experimental platform for rain/fog environment simulation and the related measurement methods. The system is mainly composed of three parts:a rain/fog generator, an axial compressor and an air/water separator. The rain/fog generator emulates the rain/fog environment by injecting highly atomized water through high-pressure water nozzles, while the air/water separator removes the water from the exhaust air/water mix. The measurement methods are also modified to cope the possible effects of the water on the sensors and/or other measurement devices. The tests prove those measurement modifications are feasible. Part Ⅱ of this thesis is compressor tests under the newly simulated rain/fog environments.......The results show that:1. the effect of water which exists in flow on drive torque is immediately effective right from the smallest quantity of water content, the torque increases linearly with the amount of water content, three sets of compressor casings’ results are consistent with trend.2. In the single rotor experiment, the water content’s influence on the compressor performance is different with different compressor blade tip clearance, but the turning point is almost identical; there is also a turning point in the single stage experiment. When water content is small, the impact on the compressor is basically the same, if the water content over the point, the compressor performance has a significant degradation. The turning point may be related to the water which gathered in the compressor casing. The blade tip clearance will change when the water content to a certain extent, and leading to the change of compressor performance.3. To analysis the power spectral density of compressor casing dynamic pressure signal, the characteristic frequency band’s energy of tip Leakage flow Unsteadiness enhance, and the compressor stall in advance.