Numerical Simulation and Performance Analysis of a Scramjet Based on Three Dimensional Design

本文以超燃冲压发动机为研究对象，将其中的各部件置于整个发动机的大环境下进行了设计与性能分析。 以流线追踪三维Busemann型面作为进气道，研究了其不启动时的流场特征以及非设计点下的性能。随后将该进气道与隔离段模型相结合进行了数值模拟，结果表明增加隔离段长度可提升极限反压，但长度越长，反压比提升的幅度越小；进气道来流的影响使隔离段在反压作用下的流场呈现不均匀性，反压越高，不均匀性越强，进气道所受的压阻也越大。 在燃烧室设计过程中，以均匀来流为条件分别考察了边界层厚度、狭缝抽吸、凹腔以及喷氢口布置方案对基础燃烧室构型的性能影响，结果表明边界层抽吸可抑制激波串前推；凹腔结构能有助于提升燃烧效率...A scramjet was investigated with all its parts being designed and analyzed in the environment of the whole engine. A streamline traced Busemann inlet was designed, its started and unstarted flowfields as long as off design performance were studied. It was then simulated in combination with the isolator, the results indicated that increasing the length of the isolator could help to raise the maxim...学位：工程硕士院系专业：物理与机电工程学院_工程硕士(电子与通信工程)学号：3312012115265

Performance Analysis of Three Kinds of Aero-Engine with Inter-Stage Turbine Burner

为探究级间燃烧室对各种航空发动机的性能影响,利用热力循环原理分别计算了在有无级间燃烧室的情况下涡喷、涡扇和涡轴发动机的性能结果并与实际型号做出对比。通过计算获得了上述三种发动机在加入级间燃烧室后的单位推力和耗油率随飞行马赫数等参数在一定范围内变化的曲线。结果表明加入级间燃烧室后对各种发动机的动力性能提升都在10%以上,个别涡轴发动机可达30%。同时若能将加入级间燃烧室后增加的质量控制在一定范围内,则对于各型发动机均可提高其推重比。In order to investigate the effects of the inter-stage turbine burner( ITB) on aero-engines,the thermodynamic cycle analysis was performed to demonstrate the performance of three kinds of aero-engines with the inter-stage turbine burners.The performance curves for different flight and operation conditions were obtained by calculation.Results show that specific thrust can be improved by at least 10%,and for one turboshaft engine the specific thrust even can be improved by 30%.Based on comparison between the real aero-engine performance and the calculation results,the errors are acceptable and the thrust-weight ratios show the potential capability of ITB application.国家自然科学基金(11002125;51106131); 中央高校基本科研业务费专项资金(2013121019

Effects of Pre-Diffuser on Performance of Dump Diffuser

研究了突扩扩压器中前置扩压器各参数与总压损失和静压恢复间的关系。采用实验与fluEnT计算结合的方法,通过水槽PIV实验得出扩压器内的流场信息,对照不同的湍流模型,得出最佳的计算方案。根据此计算方案计算不同的扩张角下前置扩压器性能的变化,得出各参数之间的规律。结果表明雷诺应力模型能够较好地预测扩压器内部流场;前置扩压器扩张角存在一个最佳值,大于最佳值前置扩压器会出现流动分离;结合理论分析和计算数据总结出计算前置扩压器总压损失系数和静压恢复系数的公式,利用此公式还可求出最佳的前置扩张角和前置扩压器长度,计算误差在5%左右。Diffuser is one key component of the gas turbine combustor following the compressor.Its primary function is to slow down the air flow delivered by the compressor in order to promote efficient combustion and avoid large total pressure losses.An experimental and computational study of cold flow in the dump diffusers was presented.The main aims were to evaluate the influence of pre-diffuser wall angle and pre-diffuser length on the performance of dump diffusers,and to identify the pressure loss mechanisms.PIV experiments were conducted in a simplified test model to help choose of congruent turbulence model.It was observed that apparent flow separation occurred on pre-diffuser wall when pre-diffuser wall angle amplified to certain degree.The pre-diffuser exit flow was distorted,indicating that the uniform exit conditions typically assumed in the diffuser design were violated.Skew distribution of the pre-diffuser outlet flow can result in strong transverse mixing for liquid,the total pressure loss of pre-diffuser increases significantly.The formula of the total pressure loss coefficient and the pressure recovery coefficient was developed.The optimal pre-diffuser length and pre-diffuser wall angle can be conveniently obtained by this equation,the calculation error was less than 5%.中央高校基本业务费(2013121019); 航空基金(20132268003

JUNO Sensitivity on Proton Decay p→νˉK+p\to \bar\nu K^+ Searches

The Jiangmen Underground Neutrino Observatory (JUNO) is a large liquid scintillator detector designed to explore many topics in fundamental physics. In this paper, the potential on searching for proton decay in $p\to \bar\nu K^+$ mode with JUNO is investigated.The kaon and its decay particles feature a clear three-fold coincidence signature that results in a high efficiency for identification. Moreover, the excellent energy resolution of JUNO permits to suppress the sizable background caused by other delayed signals. Based on these advantages, the detection efficiency for the proton decay via $p\to \bar\nu K^+$ is 36.9% with a background level of 0.2 events after 10 years of data taking. The estimated sensitivity based on 200 kton-years exposure is $9.6 \times 10^{33}$ years, competitive with the current best limits on the proton lifetime in this channel

JUNO sensitivity on proton decay p → ν K + searches*

The Jiangmen Underground Neutrino Observatory (JUNO) is a large liquid scintillator detector designed to explore many topics in fundamental physics. In this study, the potential of searching for proton decay in the $p\to \bar{\nu} K^+$ mode with JUNO is investigated. The kaon and its decay particles feature a clear three-fold coincidence signature that results in a high efficiency for identification. Moreover, the excellent energy resolution of JUNO permits suppression of the sizable background caused by other delayed signals. Based on these advantages, the detection efficiency for the proton decay via $p\to \bar{\nu} K^+$ is 36.9% ± 4.9% with a background level of $0.2\pm 0.05({\rm syst})\pm$$0.2({\rm stat})$ events after 10 years of data collection. The estimated sensitivity based on 200 kton-years of exposure is $9.6 \times 10^{33}$ years, which is competitive with the current best limits on the proton lifetime in this channel and complements the use of different detection technologies