【作者】 陈伟；

【导师】 谢诞梅；

【作者基本信息】 武汉大学 ， 热能工程， 2021， 硕士

【摘要】 电力、化工、航天航空等领域的发展,对燃气轮机的进口温度和热效率提出更高的要求。常规叶片材料的耐热性,已经不能适应目前的进口温度,对透平叶片采用高效的冷却技术是解决此问题的有效途径之一。静叶前缘是公认的局部难冷区域,较单一冲击冷却,冲击-扰流复合冷却能改善局部冷却效果;泪滴结构具备流线型,能够减小流体流过时的阻力,应用范围广。因此,本文对静叶前缘冲击-泪滴结构的复合冷却性能进行数值模拟研究。在数值模拟研究中,本文重点围绕平板泪滴结构与冲击冷却的作用机理和C3X静叶前缘冲击-泪滴结构的复合冷却性能这2个方面进行。首先,构建了具有1排9列射流孔以及泪滴凸起的平板模型,设置SST k-omega(Low Re)湍流模型,探究了三类影响因素的作用机理,包括射流腔参数、泪滴参数和特殊结构参数。其次,参考平板研究中换热性能优越的泪滴和射流腔参数,构建了三种静叶前缘冲击-泪滴复合冷却叶片-V1叶片无泪滴,V2和V3分别在前缘与射流孔错排布置泪滴凸起和泪滴扰流柱;基于流固耦合传热的数值方法,设置SST k-omega湍流模型和组分输运模型,探究了 8种不同质量流量(MFR)工况下的复合冷却性能。研究结果表明:(1)影响平板冲击-泪滴复合冷却流动与换热特性的三类因素,作用机理不同。当Hfp/Dfp,ih为1时,由于射流强度足够穿透横流,下游处Nu不断加强:Nu提高15.6%,ξp提高72.1%。当Lfp,td/Dfp,ih从1.15增加到3.15时,由于泪滴表面的冷却工质扰动,复合冷却性能不断提高:Lfp,td/Dfp,ih为3.15的Nu提高1.5%,ξp提高2.3%。当ar从0增加到1.6时,由于气膜孔的抽吸作用,复合冷却性能不断提高:ar为1.6的Nu提高14.4%,射流腔ξp提高5.3%。(2)错排布置的复合冷却性能好,Nu提高0.8%,ξp降低0.3%;αfp,td为0°的复合冷却性能好,Nu提高0.8%,ξp提高0.3%。(3)针对C3X叶型布置的泪滴结构能有效改善叶片的复合冷却性能。在MFR较低时,推荐使用V3,η提高可达9.29%;增加MFR可以改善流动与换热特性,当MFR从0.25%增加到1.00%,ξp先增大后减小。(4)随着MFR从0.25%增加到2.00%,泪滴结构的改善效果逐渐降低;当MFR大于等于1.00%,V3的流动与换热特性均优于V2:V2平均恶化效果为 5.2%,V3 为 4.6%。更多还原

【Abstract】 Demand for gas turbine inlet temperature and thermal efficiency is buoyant,with development of power,chemical industry,and aerospace.Thermal resistance of general blade material cannot adapt to inlet temperature nowadays.Using efficient cooling technology in gas turbine blade is an effective way to solve this problem.Leading edge of stationary blade is acknowledged as local areas which is difficult to cool down.Cooling performance is enhanced by impingement-turbulence composite cooling,compared with single impingement cooling.Blade model is less adapted by relative studies.Teardrop has streamline shape.Resistance is reduced when fluid flows past teardrop and teardrop is applied widely.Therefore composite cooling performance of impingement-teardrop structure at the leading edge of stationary blade is numerically investigated by this article.This article divided the numerical investigation into two parts.One part was interaction mechanism between teardrop-structure and impingement cooling of flat plate.The other part was impingement-teardrop-structure composite cooling performance at the leading edge of C3X stationary blade.Firstly,flat plate was constructed,which had 1 row,9 columns of impingement hole and teardrop-protrusion.The SST k-omega(Low Re)turbulence model was set up.Three kinds of influencing factors were investigated,which included impingement chamber parameter,teardrop parameter and special structure parameter.Secondly,three kinds of stationary blade were constructed,which had impingement-teardrop composite cooling structure at the leading edge.Blade V1 had no teardrop.Teardrop-protrusion and teardropcolumn were arranged respectively in the V2 and V3.Teardrop parameter and impingement chamber parameter were selected,which were superior in heat transfer performance of flat plate investigation.Impingement hole and teardrop were in stagger arrangement.The SST komega turbulence model and species transport model were set up.Based on numerical investigation of conjuate heat transfer,composite cooling performance of three stationary blades was investigated,under 8 working conditions with different mass flow rates(MFRs).The results showed that:(1)Mechanisms of three kinds of influencing factors which influenced the flow and heat transfer characteristic of impingement-teardrop structure composite cooling in the flat plat were different.Strength of jet flow was strong enough to penetrate transverse flow when Hfp/Dfp,ih was equal to 1.Nu was enhanced at downstream.Nu was increased by 15.6%and ξp was increased by 72.1%.Disturbance of coolant near teardrop surface was high.Composite cooling performance was improved when Lfp,td/Dfp,ih ranged from 1.15 to 3.15.Nu was increased by 1.5%and ξp was increased by 2.3%when Lfp,td/Dfp,ih was equal to 3.15.Due to suction effect of film hole,composite cooling performance was improved when ar ranged from 0 to 1.6.Nu was increased by 14.4%and ξp was increased by 5.3%when ar was equal to 1.6.(2)Composite cooling performance of stagger arrangement was better.Nu was increased by 0.8%and ξp was decreased by 0.3%.Composite cooling performance was better when afp,td was equal to 0°.Nu was increased by 0.8%and ξp was increased by 0.3%.(3)Teardrop structure investigated in C3X blade profile effectively enhanced composite cooling performance.V3 performed better with η improvement of 9.29%under low MFR.Raising MFR could improve flow and heat transfer characteristic because ξp first increased and then decreased with MFR ranging from 0.25%to 1.00%.(4)The η improvement of teardrop structure decreased gradually with MFR ranging from 0.25%to 2.00%.When MFR was greater than or equal to 1.00%,the flow and heat transfer characteristic of V3 were better than V2.Averaged deterioration of V2 was 5.2%and averaged deterioration of V3 was 4.6%.更多还原