【作者】 张惠；

【导师】 徐建中；

【作者基本信息】 中国科学院研究生院（工程热物理研究所） ， 工程热物理， 2008， 博士

【摘要】 对转涡轮技术是提高涡轮叶片负荷、减少叶片排数、减轻重量,从而提高发动机推重比的重要方式。近年来,对转涡轮技术越来越受到重视。目前,在欧美等发达国家中,1+1对转涡轮已经开始应用于某些先进的现役航空发动机中,而1+1/2对转涡轮也已经在一些研制中的发动机上得以应用。国际上普遍的看法是,在不久的将来,1+1/2对转涡轮将广泛地应用于各种先进的航空发动机中。然而,与欧美等发达国家相比,我国在这方面的研究上还相对比较落后。因此,为了大力提高我国航空发动机的研发水平,有必要针对对转涡轮这一关键技术进行研究,尤其对1+1/2对转涡轮的变工况特性进行分析。另外,为了达到更高的推重比、更高的热效率,现代燃气轮机的进口温度已经增至2200K以上,远远超过了金属材料的耐热程度。为了保证叶片的安全性和寿命,迫切需要先进、有效的冷却措施。研究和改善对转涡轮叶片的冷却技术,以降低其工作温度,显得尤为重要。国外对燃气轮机技术的垄断也主要集中在高温部件的设计和制造技术,其中包括透平冷却技术。正是在此背景下,本文利用先进的CFD技术对1+1/2对转涡轮的变工况特性及其气膜冷却流动机理进行了详细的数值研究,并且利用我所国内首座暂冲式短周期对转涡轮实验台对换热实验件的气膜冷却换热特性进行了实验研究。其中所涉及的重要研究内容如下:1.对非设计工况下的1+1/2对转涡轮的流动特性进行了数值研究,并且与实验结果进行了对照。研究得到了该对转涡轮的工作特性,具体表现为,在相同的落压比下,高低压涡轮的出功比和1+1/2对转涡轮的效率随涡轮转速的提高而增大;在非设计工况下,低压涡轮的做功能力随涡轮转速的提高而减弱;1+1/2对转涡轮的有效工作范围随涡轮转速的升高而逐渐变窄。该研究结果表明,借助本文的数值模拟方法能够定性地预测1+1/2对转涡轮的变工况性能。2.对1+1/2对转涡轮高压导叶、高压动叶设计了冷却方案,并且对不同冷却方案下的1+1/2对转涡轮流动特性进行了三维数值模拟。探讨了冷气射流在1+1/2对转涡轮中的运动规律,分析了叶片表面冷却气膜形成的特点以及冷气射流与主流的相互作用;冷气喷射对叶片表面气动参数的影响。为了研究变工况下高压动叶气膜冷却性能,对三种典型的工况进行了详细的数值模拟。研究了变工况下转速、吹风比以及落压比对高压动叶气膜冷却效果的影响;揭示了高压动叶前缘、压力面、吸力面冷气射流的流动特征;给出了冷气喷射对高压动叶叶片表面马赫数及压力分布的影响;分析了高压动叶不同位置处冷气射流对气动参数以及高压动叶通道内复杂波系结构的影响。3.利用国内首座暂冲式对转涡轮实验台对安装于1+1/2对转涡轮高、低压动叶之间的实验件的气膜冷却换热特性进行了初步的实验研究,并且将实验结果与二维非定常计算结果进行了对比。结果表明引入气膜冷却后,实验件各测点的换热量与无冷却时相比均有明显的降低。实验测量的热流率和二维非定常计算结果虽然在定量上存在一定的差别,但是趋势基本一致,表明数值模拟结果与实验结果定性上基本相符。更多还原

【Abstract】 Counter-Rotating turbine technology is the most important way to increase blade loading,to decrease blade rows and weight,so as to gain higher thrust-weight ratio.In the recent few years,Counter-Rotating turbine has been more and more regarded.At present,1+1 stage Counter-Rotating turbine has been used in some advanced active duty aero-engines.And,Vaneless Counter-Rotating Turbine(VCRT, 1+1/2 stage counter-rotating turbine),which is composed of a highly loaded single stage high pressure turbine and a vaneless counter-rotating single stage low pressure turbine,has been also applied in some up-to-date test engines in Euro-America developed countries.It is obvious that the VCRT will be widely adopted in real aero-engines in the future.However,the research level of the Counter-Rotating turbine in China greatly lags behind developed countries.So,it is very necessary to perform some systemic investigations focusing on Counter-Rotating turbine, especially on the off-design performance of VCRT.In addition,to achieve higher thrust power and thermal efficiency,the inlet temperature of modern gas turbine has increased to 2200K above,which is far beyond the allowable metal temperature.Thus, to maintain acceptable life and safety standards,calls for an efficient cooling technology.It is important to research and improve cooling technology in order to reduce the operating temperature of high-temperature components.Foreign monopolies on gas turbine technologies are mainly concentrated on the high-temperature component in the design and manufacturing technology,including turbine cooling technology.Based on the background,off-design flow characteristics and film cooling mechanisms of VCRT were investigated by means of advanced CFD tools in this paper,film cooling heat transfer characteristics were experimental studied by means of blow-down short duration turbine facility.The blow-down short duration turbine facility is the first and unique in China.The main content in this paper is listed as follows:1.Numerical investigations were performed to study the flow characteristics of VCRT at off-design conditions.Numerical results were compared with experimental data.The operating characteristics of the VCRT are obtained depending on these investigations.The results indicate that the ratio of specific work of the high pressure turbine to that of the low pressure turbine and the efficiency are increased in the VCRT as the rotation speed of the rotor increases under the same expansion ratio.And the research results show that when the rotation speed of the rotor increases,the specific work of the low pressure turbine is decreased,and the effective operation range of the VCRT is reduced.The investigation results also indicate that the numerical code in this paper can qualitatively predict the flow characteristics of the VCRT at off-design conditions.2.Film cooling schemes were designed for the high pressure stator and the high pressure rotor of the VCRT and 3D numerical simulation were performed.The flow characteristic of coolant injection in the VCRT,the interaction between coolant injection and mainstream,the influence of coolant injection on the blade pressure distribution and Relative Ma distribution were investigated.In order to study the film cooling performance for high pressure rotor at off-design conditions,three typical conditions were simulated.The affect of speed,blowing ratio and pressure ratio on the film cooling effectiveness were considered.The coolant injection characteristic on the leading edge,pressure side and suction side of the high pressure rotor were studied. The influences of coolant injection on the pressure distribution and relative Ma distribution of the high pressure rotor blade were given.The affect of coolant injection at different location of pressure side and suction side of high pressure rotor on the complex shock systems were investigated.3.Some preliminarily experimental investigations were performed to study the film cooling heat transfer characteristics of the experimental model which was installed between the high pressure rotor and the low pressure rotor of the VCRT.The experimental data were compared with the 2D unsteady simulation results.And the results show that with film cooling,the heat flux ratio of measured points on the heat transfer experimental model decreased much compared with the data of no film cooling.There are some difference in quantity between the experiment results and 2D numerical simulation data,but the trends are consistent.更多还原