带有加强肋的涡轮机匣排孔冲击连腔结构内部换热特性研究

Internal Heat Transfer Characteristics of Turbine Casing with High Rib in Rows of Holes Impinging Continuous Cavities Structure

关键词:  冲击冷却  涡轮机匣  瞬态液晶  排孔冲击连腔结构  实验研究

Key words:  Impingement cooling  Turbine casing  Transient liquid crystal  Rows of holes impinging continuous cavities  Experimental investigation

摘要:

为获得涡轮机匣内部表面换热系数分布数据，以带有加强肋的排孔冲击连腔结构为对象进行了瞬态液晶实验。研究了不同射流雷诺数（Re=5.1×10³~1.1×10⁴）、冲击间距比（2.5，5.0，7.5）及轴向间距比（4.0，9.0，14.0）对靶面努塞尔数的影响规律。实验结果表明：增大射流雷诺数对靶面平均努塞尔数的提升最显著。随着冲击间距比的增大，靶面平均努塞尔数逐渐减小，但这种换热削弱效果局限在距冲击驻点2D~3D（D为冲击孔直径）范围内，其它区域的变化很小。在靠近前后端壁的局部区域，表面努塞尔数随冲击间距比的增大而增大。轴向间距比的改变不会影响无出流孔靶面的换热情况，对于有出流孔靶面而言，轴向间距比为9.0的结构换热效果最好。Re=5.1×10³条件下，轴向间距比为9.0结构在有出流孔靶面上的平均努塞尔数相比4.0和14.0结构分别增大了5.7%和8.1%，并且随雷诺数增大，增幅越大。

Abstract:

In order to obtain the heat transfer coefficient distribution data on the internal surface of the turbine casing， transient liquid crystal（TLC） experiments were conducted on the structure of rows of holes impinging continuous cavities with high rib. The effects of jet Reynolds number （Re=5.1×10³~1.1×10⁴）， impingement spacing ratio （2.5， 5.0， 7.5） and axial spacing ratio （4.0， 9.0， 14.0） on the Nusselt number of the target surface were investigated. The results show that increasing the jet Reynolds number has the most significant improvement on the area-averaged Nu of the target surface. With the increase of the impingement spacing ratio， the averaged heat transfer coefficient decreases monotonically， but this weakening effect is limited to the range of 2D~3D （D represents the diameter of impingement holes） from the stagnation point， and the changes in other regions are not significant. In the local area near the front and rear end walls， the surface Nu increases with the increase of the impingement spacing ratio. The variation of axial spacing ratio has no significant influence on the Nu of the target surface without outlet holes， for the target surface with outlet holes， the heat transfer coefficient will be the best if the axial spacing ratio is 9.0. Comparing with the axial spacing ratio of 4.0 and 14.0 structures， under the condition of Re=5.1×10³， the area-averaged Nu of the structure with an axial spacing ratio of 9.0 on the target surface with outflow holes increases by 5.7% and 8.1% respectively， and the increase is greater with increasing Reynolds number.