Study Of Hub Leakage Flow Characteristics In A Compressor Stator

On the basis of a labyrinth seal test facility with high rotational speed and NAPA software, this paper has studied the stator leakage flow characteristics of a 3-stage compressor and its influence on the performance of compressor using both experimental and CFD mathods. Main research items were listed as follows:Firstly, in order to avoid simulating complicated labyrinth seal flow directly in following CFD research of compressor stator hub leakage flow, experimental study was involved in this paper to create a algebraic modeling of labyrinth seal leakage flow instead of direct simulation. Consequently, test facility of labyrinth seal leakage flow characteristics was established which has a highest tip line speed of 200m/s and a highest pressure ratio between inlet and outlet of 2.5, labyrinth seal blades of different structures and size were replaceable as well. Leakage flow mass and cavity pressure of labyrinth seal under different operating condations were obtained through experimental study from which we also got a clear understanding of how pressure ratio and totational speed affect the leakage characteristics of labyrinth seals.Secondly, both algebraic and computional modeling of labyrinth seal leakage flow were created according to experimental data which reflect the effect of pressure ratio and rotational speed, then, computional modeling was added into NAPA as a specific boundary condation to treat leakage flow equivalently. For verifying whether modeling mentioned above has enough accuracy, BUMP flow was used and found that the modeling we used has an error below 5% only, that is to say, NAPA software cloud simulate leakage flow exactly when using labyrinth seal leakage flow modeling.Finally, CFD study of a 3-stage axial compressor in consideration of stator hub leakage flow was carried on using NAPA code which has already taken leakage flow modeling into consideration, in contrast with no leakage situation, a clear understanding of how leakage flow affect the flow field and overall performance of compressor was obtained and correspond with foreign studys very well related to main flow features when leakage happen; on this basis, this paper has tried several optimizations into practice so as to weaken the negative influence of leakage flow, round corner optimization of cavity outlet has increased performance deterioration on the contrary, however, the rest two optimizations have both improved the performance of compressor which were adding guide vanes and decreasing outlet width.