摘要
采用数值方法研究了燃气透平第1级动叶带3种双凹槽的叶顶传热与冷却性能,双凹槽叶顶的隔板位于凹槽25%、50%和75%弦长位置且垂直于弦长方向(叶顶结构分别称为rib25,rib50和rib75),并与常规凹槽叶顶的透平级内效率、叶顶传热系数、叶顶气膜冷却有效度进行了对比。结果表明,在无气膜冷却时,不论是常规凹槽叶顶还是双凹槽叶顶,在凹槽底部前缘均存在高传热系数区域;相比于常规凹槽叶顶,双凹槽叶顶可以提高透平级的总等熵效率,其中rib50的气动性能最好,总等熵效率可以提高0.43%,但叶顶平均传热系数增大13.7%;叶顶中弧线位置布置气膜冷却孔后,由于叶片的旋转作用和凹槽隔板的限制,使冷气在凹槽内积累,对凹槽底部形成良好的气膜冷却效果;相对于传统凹槽叶顶,3种双凹槽叶顶的气膜冷却效率显著提高,其中rib50的气膜冷却有效度最大并且气动性能最好,带rib50叶顶的透平级内等熵效率可以提高0.36%,叶顶平均传热系数减小14.4%,叶顶平均气膜冷却有效度提高31.8%。
Numerical methods are adopted to investigate the heat transfer and film cooling characteristics at three squealer tips with double cavities in a gas turbine first stage rotor blade.At the squealer tips,the ribs are located at 25%,50%and 75% of axial chord,respectively,and perpendicular to the chord direction,so they are denoted rib25,rib50 and rib75,respectively.The total-to-total isentropic efficiency in the turbine stage,the heat transfer coefficient and the film cooling effectiveness at the blade tip were calculated and also compared with the conventional squealer tip.The results show that,without film cooling,there exists high heat transfer area on the cavity floor near the leading edge for both conventional squealer tip and double-cavity squealer tip.Compared with the conventional squealer tip,the double-cavity squealer tip can improve the total-to-total isentropic efficiency of the turbine stage.Among four squealer tips（conventional squealer tip,rib25,rib50 and rib75）,the aerodynamic performance in rib50 turbine stage is the best,the total-to-total isentropic efficiency can be improved by 0.43%.However,the areaaveraged heat transfer coefficient at the rotor blade tip is increased by 13.7% compared with theconventional squealer tip.When the film cooling holes are arranged at the rotor tip camber line,the film cooling effect on the tip cavities is significantly improved because more coolant is accumulated in the cavities,which can be attributed to the blade rotation and the limitation of the rib to coolant.Compared with the conventional squealer tip,the three kinds of double-cavity squealer tips perform superior film cooling effect at the tips.Among the four squealer tips,rib50 performs the best film cooling effect at the rotor tip and also has the highest aerodynamic performance in the turbine stage.With film cooling,the total-to-total isentropic efficiency in the turbine stage equipped with rib50 tip can be increased by 0.36%,the area-averaged heat transfer coefficient at the tip is reduced by 14.4% and the area-averaged film cooling effectiveness can be improved by 31.8%in contrast to the conventional squealer tip.
作者
叶明亮
晏鑫
何坤
YE Mingliang;YAN Xin;HE Kun(School of Energy and Power Engineering, Xi＇an Jiaotong University, Xi＇an 710049, China)
出处
《西安交通大学学报》
EI
CAS
CSCD
北大核心
2018年第5期116-124,共9页
Journal of Xi'an Jiaotong University
基金
国家自然科学基金资助项目(51306138)
