Numerical Simulation And Experimental Study On Impingement Cooling Technology Of Turbine Blades

The improvement of turbine inlet temperature is the main way to improve the power output and thermal efficiency of gas turbine.Meanwhile,the high temperature performance of turbine blade is put forward.At present,the turbine inlet temperature is much higher than the temperature that turbine blade material can bear.Therefore,it is necessary to strengthen the development of turbine blade cooling technology while continuing to develop high tempera-ture resistant materials.The cooling technology of high temperature turbine blades in gas tur-bine mainly includes internal cooling and external cooling.Among all the internal cooling methods,impingement-cooling is the most efficient and the most potential cooling technology.It is mainly used in the region where the heat load is relatively high,such as the turbine rotor blade leading edge,or a middle region of some turbine blades.The research of impinge-ment-cooling plays an important role in the field of turbine blade cooling technology.In this paper,the impingement cooling structure of turbine blade was simplified,and the flow field and heat transfer characteristics of single jet impingement cooling and array jet im-pingement cooling were studied by means of numerical simulation.Finally,the transient liq-uid crystal temperature measurement was used for the further research of array impingement cooling.The experimental data are provided as the base of numerical simulation results.For the single jet impingement cooling structure,it is found that the increase of jet Reynolds number can increase the local Nusselt number of the target surface and enhance the cooling effect;The area-weight average Nusselt number of target surface and the 0.66 power of Reynolds number(Re^0.66)presents a nearly perfect linear relationship.The increase of the jet impingement distance makes the second peak of the local Nusselt number disappear grad-ually,and at the H/D=2,the area-weight average Nusselt number of the target surface reach-es the peak value.For the array jet impingement cooling structure,the results show:a)Increasing the jet Reynolds number of can improve the local Nusselt number and the area-weight average Nusselt number of target surface,but also increase the impinging pressure and reduce the tar-get surface temperature uniformity which may cause some strength problems.b)The greater the impinging distance,the impinging pressure of the target plate is smaller.At the relative spacing H/D=2⁴,with the increase of H/D,the area-weight average Nusselt number of the target surface decreases gradually,but the surface temperature uniformity increases.c)The area-weight average Nusselt number of the staggered structure is not significantly different from that of the sequential structure,but the temperature uniformity of the target surface of the staggered structure is higher than that of the sequential structure.d)With the initial lateral flow velocity increasing,the average Nusselt number of the target surface decreases;the une-venness of the target surface temperature distribution decreases;the initial transverse flow can improve the homogeneity of the target surface temperature distribution and,to a certain extent,the strength problem can be solved caused by the uneven temperature distribution and jet pressure differences.e)The Nusselt number at the same position is about 40%higher than that under air cooling when the vapor jet is used,and the improvement percentage of ar-ea-weight average Nusselt number of the target plate surface is about 50%or more.However,the homogeneity of the target surface temperature distribution is reduced and the thermal stress is easy to be formed on the target plate.In the thermal stress tolerance range of the tar-get plate,the steam jet cooling is still an efficient cooling method and deserves to be adopted.f)The area-weight average Nusselt number of the target surface is higher than that of the uni-directional flow in the bidirectional outflow condition,and the uniformity of the surface tem-perature distribution of the target surface is improved by the bidirectional outflow.In this paper,the influence of five kinds of jet spacing,different jet Reynolds number and outflow direction on the heat transfer performance of array jet impingement cooling based on transient liquid crystal temperature measurement was studied.In the range of H/D=1⁵,for the bidirectional outflow structure,the longitudinal average Nusselt number of target sur-face increases with the increase of jet Reynolds number and decreases with the increase of H/D.There are five average Nusselt number peaks at the target surfaces which are farther away from the outflow boundary reaches the maximum at H/D=3.Other five peak values that near the outflow boundary show a decreasing tendency with the increase of H/D.Under the same or similar experimental conditions,the average Nusselt number of the bidirectional outflow structure target surface was higher than that of the unidirectional,But the difference between them decreases with the increase of H/D and the increase of inlet flow.In this paper,the error of numerical simulation results and experimental results is about 10%to 20%.Ex-perimental study provides a large amount of data base for numerical simulation calculation.