不同雷诺数条件下粗糙度对高亚声速压气机叶型边界层调控机制研究

The Control Mechanism for the Boundary Layer of a High Subsonic Compressor Airfoil by Surface Roughness Under Different Reynolds Numbers

粗糙度(R_(a))对压气机叶型性能的影响与雷诺数(Re)密切相关。以某一高亚声速压气机叶型为研究对象,在R_(e)=1.2×10^(6)和R_(e)=1.5×10^(5)条件下,采用数值模拟方法研究了不同R_(a)大小对边界层分离、转捩及叶型损失的调控机制。研究表明,R_(e)=1.2×10^(6)时,较小粗糙度(R_(a) ≤13μm)不会对叶型性能有明显影响,当R_(a)超过某个临界值(R_(a)=26 μm),叶型性能随粗糙度增加不断恶化。当Re降低至1.5×10^(5)时,叶型损失随着R_(a)增加大幅降低,R_(a)=157 μm时叶型损失最大降低16.4%,之后叶型损失才有所增加。合适大小的粗糙度能够有效抑制分离泡位移效应对叶型性能的不利影响,而粗糙度过大会导致强烈湍流耗散作用恶化叶型性能。针对该高亚声速压气机叶型,提出了最佳粗糙度参数随Re变化的经验关系式。

The effect of surface roughness(Ra)on the aerodynamic performance of a compressor airfoil is closely associated with the Reynolds number(Re)level.Numerical simulations were conducted to compare the boundary layer separation,transition,and aerodynamic performance of a high subsonic compressor airfoil covered with different roughness magnitudes on the suction surface at Re=1.2×10^(6) and Re=1.5×10^(5).Results showed that the effect of small roughness magnitudes(Ra≤13μm)on the aerodynamic performance was almost negligible at Re=1.2×10^(6),while the aerodynamic performance was seriously deteriorated as the roughness magnitude exceeded a critical level(Ra=26μm).As the Reynolds number decreased to 1.5×10^(5),the profile loss was reduced distinctly with the increase of roughness magnitudes,and the maximum decline in the profile loss was 16.4%,which was achieved at Ra=157μm,then the profile loss began to increase at a larger roughness magnitude.It should be noted that the appropriate roughness magnitude has the potential to sufficiently suppress the negative displacement effect of the laminar separation bubble(LSB)on the aerodynamic performance.However,the overlarge roughness magnitudes are prone to induce the strong turbulent dissipation and degrade the aerodynamic performance of compressor airfoil instead.Additionally,the empirical optimal roughness magnitudes varied with Re have been proposed.