| Tip clearance flow has profound effects on the performance and stability of the compressor. To improve the performance and reliability of aero-engine and other gas turbines, it is of great importance that the mechanism of the compressor tip clearance flow is well understood, and realized control of it. In the past years, numerous studies were mainly focused on the mechanism of steady tip clearance flow and its impacts on the compressor performance. Recently, the unsteady characteristic of tip clearance flow, which appears in some flow conditions, was discovered and its influence to the compressor performance was recognized. However, the detailed transient flow field,the originating mechanism and the potential application of unsteady tip clearance flow are unclear or not enough understood to date. Therefore, this dissertation, making use of the numerical simulation, is aimed towards providing a revelation of the transient flow field, a new understanding of the originating mechanism of unsteady tip clearance flow, and a possible approach to improve compressor performance through utilizing the unsteadiness of tip clearance flow.ROTOR37 which supplied by NASA was numerically simulated with threedimensional CFD under three different tip clearance size. The results of numerical analysis show that with the increase of tip clearance size, the performance of three stage compressor change obviously, the performance parameters such as efficiency,pressure ratio tended to decrease obviously; Meanwhile, the distribution of static pressure on surface of the compressor casing and the blade surface near the tip has a big influence because of the existence of leakage vortex. Based on the steady flow results, the simulation of unsteady flow of a single stage axial compressor rotor is also made, the results of the study show that the unsteady tip clearance flow characteristics exhibited periodic changes, and it has the certain regularity, and studies and analyzes the mechanism of its formation. |
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