【作者】 沈天荣；

【导师】 刘松龄；

【作者基本信息】 西北工业大学 ， 热能工程， 2006， 硕士

【摘要】 随着铸造技术的突破,使得在传统叶片内部铸出更微小的冷却通道成为可能,并且可以在微小通道中使用冲击冷却。由于射流冲击有着较高的换热效率,并且铸造的腔室空间较小,射流在腔内形成较为强烈的旋涡使整个通道内的换热效果得到显著改善。此项技术用于燃气涡轮发动机涡轮叶片的冷却,将能收到显著提高燃气温度、减少冷气消耗的效果。本文以涡轮叶片内部梯形截面的冷气通道为对象,考虑射流,旋流,气膜孔溢流的综合作用,在放大模型上详细研究通道内部及出流孔内流动特性,以深入了解该冷却方案的强化换热机理。 本文主要工作如下: 1,测量通道内的速度场及沿通道的压力分布,获取通道内的流场特性和流动结构,并研究射流和旋流相互作用。 2,测量通道侧壁出流孔和气膜出流孔内的流场和流量系数,了解不同雷诺数及不同射流角度,横流对孔内流场和流量系数的影响。 3,采用七孔压力探针测量大角度射流,进行了七孔压力探针的设计、加工、校准及具体应用,开发数据采集程序和实验数据后处理程序。 4,应用商用软件(FLUENT)对实验模型进行数值模拟,得到的数值结果与实验结果进行比较。 在对冲击/旋流/气膜出流冷却结构进行系统研究后,得出以下主要结论: 1,射流、横流、不同位置出流对通道流场影响很大。在不同射流角度的错排射流的冷却通道中,大射流从射流孔冲击出来后在通道内形成旋涡,并使旋涡变得更强烈。气膜孔出流流量和出流位置对通道内流场的影响很小。不同气膜出流流量对靶面附近流场有影响,但对整个通道内流动变化影响非常小。横流流量大小对旋涡强度几乎没有影响。 2,侧壁出流孔流场受横流影响很大。射流雷诺数,射流角度的变化,气膜出流孔排的位置变化和流量变化对孔内流场的影响很小。横流对通道下游孔内流场影响较大。 3,不同射流角度和横流流量对侧壁出流孔流量系数影响很大。射流雷诺数对侧壁出流孔的流量系数的影响很小。射流雷诺数对离射流较近的气膜出流孔流量系数的影响较大。 4,数值计算结果与实验数据基本相符,可以采用数值模拟方法捕捉实验方更多还原

【Abstract】 Recent developments in soluble core casting technology have allowed very intricate internal passages to be manufactured. This has opened up the possibility of cooling by impingement in turbine blades. Because of impingement jets with high heat transfer and small internal passage, the jets cause swirl flow which provides further heat transfer enhancement. This thesis details the experimental measurement of both channel and outlet hole flow fields which model the intricate passage in turbine blade. And the detailed knowledge of the heat transfer enhancement in this configuration is understood.The major works of this study are following:1)The velocity fields and pressures along channel wall are measured, which find out the characteristic of flow fields in the channel and the interaction between jets and swirl flow.2) The velocity and discharge coefficients of side-wall outlet holes and film holes are measured, which consider the influence of jet angle, jet Reynolds number and cross-flow.3) The velocity of the flow with high angle is measured by a seven-hole-probe. And this probe is systematically investigated, including designing, fabricating, calibrating and data collecting and experiment results post-proceed program developing.4) Numerical results from commercial software (FLUENT) are compared with the experiment results.The major conclusions of this study are following:1) The effects of jets, cross-flow and different position outflow on the flow fields in the channel are strong. In the investigated cooling channel with different angle stagger jets, the big jets cause swirl flow in the middle of channel and make the swirl flow stronger. The mass flow rate and position of film outflow are less effective on the flow field in the channel. Different mass flow rate of film outflow change the flow field near the target surface, but the flow field in the channel isn’t influenced. There are no relation between mass flow rate of cross-flow and swirl flow intensity.2) The flow field in side-wall outflow hole changes with the cross-flow mass rate. The jet angle and Reynolds number, mass flow rate and position of the film hole don’t affect the flow field in the outflow hole as well. The cross-flow influence the flow field of downstream outflow.3) The discharge coefficients of the side-wall outflow hole are affected by the jet angle and cross-flow mass flow rate. The variation of the jet Reynolds number doesn’t change discharge coefficients of the side-wall outflow hole significantly. The jets Reynolds number affects the discharge coefficients of film hole located near the jet.4) The numerical simulation provides more detailed flow fields than the experimental data. The results from numerical simulation agree well with the experiment data. It is possible to get the near-wall flow field by numerical simulation, which is difficult to be hunted.更多还原