涡轮机匣内部冷却结构换热特性的实验研究

In order to obtain the heat transfer characteristics of the internal cooling structure of turbine casing, transient thermochromic liquid crystal test technology was used to measure the heat transfer coefficient on the inner surface of the annual cavity and rear cavity. The combined effect of Reynolds number and outflow ratio on the detailed distribution of Nusselt number were studied for 3×10⁴≤Re≤9.5×10⁴ and 0.5≤M≤2.0. The results indicate that in the range of Re number studied in present paper, the Nusselt number on the surface of turbine casing increases as the Reynolds number increases. The development of the jet-flow in the circumferential and axial directions make the surface near the entrance of the annular cavity appear triangular and circular high heat exchange zones. After the jet impacts the inclined target surface, the adjoining jet forms a secondary impact on the up surface of the back cavity, which strengthens the local heat transfer coefficient. As the increasing of the outflow ratio, the average Nusselt number on the upstream region of the stagnation area gets higher accordingly and the maximum increases are 8.5% and 12.3% for each, while the average Nusselt number on the downstream region becomes down relatively and the maximum decreases are 18.5%, 26.3% and 34.6% for each. The change of outflow ratio has little effect on average Nusselt number of the up surface.