【作者】 庞黎刚；

【导师】 吉洪湖；

【作者基本信息】 南京航空航天大学 ， 热能工程， 2010， 硕士

【摘要】 航空发动机的进口部件,如支板、整流帽罩等在一定的气象和飞行条件下会出现结冰现象,一旦冰层迅速增厚,将会减小流通面积,改变流道的形状,以及使发动机性能恶化,结冰严重时会使发动机不能正常工作并危及飞行器的安全。进入发动机进口的气流一般要经过一段进气道,对于战斗机为了隐身要求,进气道形状一般都是非圆截面的异形进气道。这时发动机进口的结冰参数与外界大气的结冰参数就有很大的差别。本文主要研究结冰参数沿进气道的变化规律及发动机进口部件结冰的影响。本文以S型、Y型和蛇形这三种进气道为模型,采用欧拉—欧拉法,对飞机零攻角、低来流Ma和均匀来流条件下(液态水含量、温度、速度)的进气道沿程的空气—过冷水滴两相流场与温度场进行了数值计算,得到了进气道沿程、出口截面上和发动机进口部件表面结冰参数的分布和变化特性。研究结果表明:一、二元S型进气道随来流Ma的增加,进气道出口截面上的温度畸变指数逐渐增大,液态水含量畸变指数先增大后减小,当Ma=0.2时液态水含量畸变最大;进气道内迎风壁面附近的液态水含量较大;当Ma=0.5时进气道入口的气动降温可达17K左右。二、二元Y型进气道在Ma=0.3时,在进气道来流迎风壁面处,液态水含量较大,而在沿程方向总压较低的两个区域内水滴浓度较低,且此区域内存在一组速度对涡。进气道进口的气动温降达到6K到7K左右,而在出口区域静温较进口静温高2K到3K左右。三、二元蛇形进气道在Ma=0.3时,在进气道来流迎风壁面处,液态水含量较大;在靠近进气道内上表面的近壁区速度较小,液态水滴浓度较低,且进气道扩张段内的上半部存在速度几乎滞止的区域。四、空气—过冷水滴两相流在经过二元S型进气道到达发动机进口部件处,空气相静温在帽罩滞止区较高,沿流向逐渐降低并在支板根部达到最低值,当Ma=0.4时进口部件上最低静温比来流低11K左右;随着Ma的增大,水滴浓度较大的区域由出口截面的左半区域逐渐向中间移动,帽罩上的水滴浓度较高区域的面积逐渐增大。更多还原

【Abstract】 Ice accretion may occur on the entry components of an aero-engine, such as the struts and the centre conical body under some meteoric and flight conditions. Once the ice becomes thicker and thicker, the mass flow rate of airflow would reduce, that would lead to engine performance deterioration. If the ice accretes severely, the engine couldn’t work normally and even endanger the aircraft. In generally, the airflow entering into the engine may pass through an intake, whose cross section is generally non-circular shaped because of the requirement of stealth. Then the icing parameters at the engine entry will be very different from that in the outside atmosphere. In order to understand the variation characteristics of the icing parameters along the intake and their effects on ice accretion on entry parts of aero-engine, a numerical study is conducted in this thesis.With the Euler-Euler method, the two-phase flow and heat transfer of air and super-cooled water droplets along the S-intake, Y-intake and Serpentine-intake at low Mach number under atmospheric icing conditions were numerically simulated. The distribution and variation characteristics of the icing parameters along the intakes and on the outlet were studied.The results are as following:(1) With the increase of Ma, the distortion index of temperature on the outlet of the two dimensional S-intake increases, while the distortion index of liquid water content increases at first and then decreases with a maximum distortion at Ma = 0.2; the liquid water content near the windward wall of the intake channel is relatively larger than that of other regions; the air temperature drop relative to incoming flow at near the entrance of the intake is up to about 17K at Ma = 0.5.(2) The liquid water content is relatively larger in windward wall of the two-dimensional Y-Intake at Ma = 0.3, while that of region where the total pressure is low along the intake is lower. And there is a group of vortex in this region. The air temperature drop at the intake inlet is about 6K to 7K, while the air temperature incensement at the outlet is about 2K to 3K.(3) The liquid water content is relatively larger in windward wall of the two-dimensional Serpentine-intake at Ma = 0.3, while that of near wall region of the upper surface is lower. And there are local regions where the flow is almost stagnant in the upper part of expansion section of the intake.(4) The air temperature in the stagnation region of the centre conical body is relatively higher, which decreases in the downstream and reaches a minimum at the struts root. When Ma = 0.4 the lowest air temperature is 11K lower than that of incoming flow. With the increase of Ma, the area where the concentration of water droplets is relatively higher moves gradually from the left region to the middle region on the outlet and the corresponding area on the centre conical body increases.更多还原