三面压缩高超进气道附面层抽吸研究

针对超燃冲压发动机中,三面压缩进气道激波/附面层干扰诱发的隔离段流向涡现象,探索了不同的附面层抽吸方式对隔离段流向涡的影响.结合附面层油流图谱及数值模拟考察了相应附面层流态,并分析了不同抽吸工况下的抽吸流量及其对出口截面总压恢复与流向涡的影响.发现隔离段流向涡气流主要源于侧壁附面层分离,相比于再附区抽吸,分离区抽吸大幅度抑制了侧壁附面层的分离流动,从源头上控制了隔离段流向涡的形成,大幅削弱了流向涡尺度,提高了进气道总压恢复.同时,抽吸面积越大,流动品质的改善作用就越明显,但是也伴随着流量损失.      

H2O污染对煤油燃料超燃冲压发动机燃烧室性能影响的数值模拟

在超声速燃烧设备上进行了带凹槽的直连式双模态煤油燃料超燃冲压发动机污染与纯空气来流的对比试验.为了研究来流污染对超燃冲压发动机试验性能的影响,在相同的试验气体参数(马赫数为2,总温约为828K和总压约为800kPa)下,对带凹槽煤油燃料燃烧室进行了一系列对比燃烧试验.采用AHL3D软件对3个试验条件的燃烧室反应流场进行了数值模拟.计算和试验得到的压强分布比较接近且趋势一致.通过数值模拟获得反应流场的细节,探究污染影响的机理.      

复合材料质量烧蚀率计算模型实验研究

通过对CF/S- 157PF复合材料进行氧-乙炔烧蚀试验研究,得到了质量烧蚀率,并利用多元线性回归方法,拟合得到了该参数与热流密度和烧蚀时间的数学模型,即M=0.043.q0.128·t-0.191.经检验,该回归模型适用性较好,预测精度较高,为复合材料该项烧蚀性能的评估建立了快速、有效、可靠的试验方法.     

Experimental and Numerical Studies of Vitiated Air Effects on Hydrogen-fueled Supersonic Combustor Performance

This paper deals with the vitiation effects of test air on the scramjet performance in the ground combustion heated facilities. The primary goal is to evaluate the effects of H2O and CO2, the two major vitiated species generated by combustion heater, on hydrogen-fueled supersonic combustor performance with experimental and numerical approaches. The comparative experiments in the clean air and vitiated air are conducted by using the resistance heated direct-connected facility, with the typical Mach 4 flight conditions simulated. The H2O and CO2 species with accurately controlled contents are added to the high enthalpy clean air from resistance heater, to synthesize the vitiated air of a combustion-type heater. Typically, the contents of H2O species can be varied within the range of 3.5%-30% by mole, and 3.0%-10% for CO2 species. The total temperature, total pressure, Mach number and O2 mole fraction at the combustor entrance are well-matched between the clean air and vitiated air. The combustion experiments are completed at the fuel equivalence ratios of 0.53 and 0.42 respectively. Furthermore, three-dimensional (3D) reacting flow simulations of combustor flowpath are performed to provide insight into flow field structures and combustion chemistry details that cannot resolved by experimental instruments available. Finally, the experimental data, combined with computational results, are employed to analyze the effects of H2O and CO2 vitiated air on supersonic combustion characteristics and performance. It is concluded that H2O and CO2 contaminants can significantly inhibit the combustion induced pressure rise measured from combustor wall, and the pressure profile decreases with the increasing H2O and CO2 contents in nonlinear trend; simulation results agree well with experimental data and the overall vitiation effects are captured; direct extrapolation of the results from vitiated air to predict the performance of actual flight conditions could result in over-fueling the combustor, possible inlet un-start and inappropriate combustion mode transition. The detailed analysis and discussion are presented and the research conclusions are summarized.     

电子束固化复合材料固化过程温度分布模型

为了深入理解电子束固化复合材料固化成型过程中的传热行为,在电子束固化阳离子环氧树脂的固化反应动力学研究的基础上,结合传统传热原理,建立并验证了电子束固化复合材料固化过程中的热传递与温度分布模型.研究表明,建立的温度变化模型与复合材料实际辐射固化过程中的温度变化规律基本一致.     

辐射板强化喷管换热与红外抑制效果试验研究

试验研究了在发动机喷管中加装金属辐射板前后,喷管壁面温度、热喷流温度与喷管红外辐射特征的变化.结果表明,加装金属辐射板后,热喷流与喷管壁面之间的热量传递显著增强,热喷流中心温度降低,壁面温度明显升高,在90°方向上,热喷流3 ～ 5μm波段的红外辐射强度降低了38.5％.文中从热喷流、喷管壁面以及金属辐射板等相关部件的温度变化情况对红外辐射强度的变化原因进行了解释.     

双模态超燃冲压发动机流量匹配的临界面积法

建立基于控制体法的0-D守恒方程(流量连续方程、动量守恒方程和能量守恒方程)的热力喉道(Ma=1.0)求解集总参数模型,该模型包括了壁面摩擦模型、燃油喷射模型、燃油雾化掺混模型和化学动力学模型.并针对集总参数模型求解热力喉道的特殊性,提出了基于流量平衡的临界面积法,应用于隔离段和燃烧室的1-D流场计算,实现了双模态超燃冲压发动机具有热力喉道时的各种模态的隔离段和燃烧室的流量平衡计算,精确捕捉到热力学喉道,确定了隔离段流动状态和燃烧室的工作模态及相关的流路沿程参数.计算结果表明:采用了临界面积法的集总参数计算模型能解决热力学喉道求解问题,其计算精度达10-4,单点工况计算时间小于0.1s.      

Research on modeling of heat source for electron beam welding fusion-solidification zone

In this paper, the common heat source model of point and linear heat source in the numerical simulation of electron beam welding (EBW) were summarized and introduced. The combined point-linear heat source model was brought forward and to simulate the welding temperature fields of EBW and predicting the weld shape. The model parameters were put forward and regulated in the combined model, which included the ratio of point heat source to linear heat source Qpr and the distribution of linear heat source Lr. Based on the combined model, the welding temperature fields of EBW were investigated. The results show that the predicted weld shapes are conformable to those of the actual, the temperature fields are reasonable and correct by simulating with combined point-linear heat source model and the typical weld shapes are gained.     

隔离段进口非对称来流对激波串结构的影响

考虑进气道出口流场的影响,设计了针对非对称超声速来流矩形隔离段流场研究的直联式试验风洞,模拟进气道出口流场的各种非对称进口条件进行了吹风试验,并测量了隔离段壁面静压和隔离段进口皮托压力。研究发现,随隔离段进口流动非对称程度的增加,激波串长度增加而隔离段耐受反压的能力下降。考虑了隔离段进口流动非对称的影响,对Billig—Wahrup的激波串长度公式作了改进,故提高了激波串长度预测的精确程度。     

氧换热器在两相流条件下的压力脉动机理分析

氢氧液体火箭发动机氧换热器在研制过程中出现了压力脉动现象，影响了换热器的正常工作。以该型换热器为研究对象，将换热器分为燃气侧、汇总管、圆管等结构，进行了CFD仿真计算，与试验结果对比，修正了传热相关参数，建立了换热器理论计算模型用于参数计算；利用非线性方法分析试验数据，确定了该换热器为混沌系统；利用两相流分析与电路类比两种方法分别针对换热器进行了建模与计算，均捕捉到了相变下换热器内的压力脉动。结果表明：通过CFD仿真及试验修正后的参数用于计算换热器的稳态参数，具有较好的一致性；换热器出现压力脉动时，具有一定非线性特征，且压力脉动越大，非线性程度越高；该换热器出现压力脉动的原因为氧工况接近两相区，相变使得介质密度发生剧变。根据分析结果提出了提高换热器设计压力的改进措施，通过试验得到了有效验证。