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Experimental results of a study of pressure recovery in a planar diffuser under imposed pulsations of the air flowrate are presented. The data is obtained in a wide range of imposed pulsation frequencies. Features of distributions of the mean pressure and the pressure drop in the diffuser are described. 相似文献
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In this paper, a technique for simulation of the space-time flow parameters in branched channels under transient boundary conditions is presented. The technique is based on the solution of one-dimensional nonstationary equations of gas dynamics. We suggest the conditions of channel junction with regard for distinctive features of a fluid flow in the adjacent region and compare the data on the flow simulation in the channel with a lateral branch by using one-dimensional and three-dimensional models. Comparing the data obtained with the experimental results, we show that the technique being suggested adequately simulates the real processes in the branched channels. 相似文献
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J.S. Shang S.T. Surzhikov R. Kimmel D. Gaitonde J. Menart J. Hayes 《Progress in Aerospace Sciences》2005,41(8):642-668
A summary of recent research progress in hypersonic plasma actuators for flow control is attempted. It is found that the most effective plasma actuator is derived from an electromagnetic perturbation and amplifies by a subsequent viscous–inviscid interaction. Computational efforts using drift-diffusion theory and a simple phenomenological plasma model, as well as experiments in a hypersonic plasma channel, have shown the effectiveness of using electro–aerodynamic interaction as a hypersonic flow control mechanism. In principle, the plasma actuator based on magneto–aerodynamic interaction should have an added mechanism in the Lorentz force, making it even more effective as a flow control mechanism. However, this approach also incurs additional challenges and complications due to the Hall effect.
Magneto–aerodynamic interactions have also been demonstrated for separated flow control, albeit in a very limited scope. Numerical simulations based on a simple phenomenological plasma model have shown the feasibility of separated flow suppression in shock-boundary-layer interaction over a compression ramp at a hypersonic flow of Mach 14.1. The control mechanism relies on the Lorentz force to energize the retarded shear layer in the viscous interacting region, but the effectiveness of momentum transfer via inelastic collision requires further validation. 相似文献
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Structure of a two-phase flow of boiling water at low-head adiabatic efflux through the laval nozzle
The critical flow conditions and structural forms of a two-phase flow that is formed during water efflux from the region of moderate and low pressures into a rarefied medium are analyzed. The difference in the structural forms of a flow realized at the low-head efflux from the structure of a flow occurring in the fluid flow with moderate and high initial pressures is established. The critical pressure differential characterizing the establishment of the maximum flowrate is determined and the decisive influence of turbulence on the vapor phase generation and flow conditions of a two-phase medium is shown. 相似文献
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基于钇稳定二氧化锆(Yttria-stabilized Zirconia,YSZ)的阻温特性,设计了以YSZ热敏电阻为感受元件的火焰传感器,以传感器热敏电流信号表征火焰状态。采用伏安法,测量了YSZ热敏电阻在673K~1523K温度下的阻值,验证了YSZ阻值与温度的倒数呈指数关系。在Tirril喷灯点火、熄火试验中,研究了激励电压(3V~15V)、火焰温度(720K~1480K)和燃气流量(60L/h~150L/h)对传感器阶跃响应特性的影响。结果表明:热敏电流与激励电压呈正比,随火焰温度的升高而增大;点火响应时间随火焰温度、燃气流量的升高而减小;熄火响应时间基本不受火焰温度与燃气流量的影响。YSZ传感器能够对火焰产生正确响应,并且信号稳定、幅值强烈。 相似文献
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Electrochemical drilling(ECD) provides an alternative technique for drilling multiple small holes in difficult-to-machine materials in numerous industrial applications such as for aeroengines. The value and fluctuation of electrolyte flowrate can seriously affect the machining stability and hole quality in ECD. In particular, when drilling multiple holes, the distribution and fluctuations of the electrolyte flowrate in each channel could influence the uniformity of the electrolyte flowrate among... 相似文献
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V. M. Kraev 《Russian Aeronautics (Iz VUZ)》2007,50(4):380-384
The influence of nonisothermality and hydrodynamic nonstationarity on turbulence generation and development is analyzed. A physical model of a hydrodynamically nonstationary turbulent flow is proposed, the model is created on the basis of previous experimental investigations on the structure of a nonstationary turbulent gas flow in the channel. 相似文献
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基于燃气发生器的概念分析了分开排气涡扇发动机的效率划分。在此基础上,通过理论推导证明了分开排气涡扇发动机的最佳外涵风扇增压比的存在判据,及其单位推力、效率和耗油率极值的等价性。给出的判据可以作为实际分排涡扇发动机设计中的最佳外涵风扇增压比的选择依据。针对两型大涵道比分开排气涡扇发动机热力循环分析的结果表明:当外内涵排气速度的比值与风扇、低压涡轮效率的乘积相等时,发动机的总效率和单位推力最大,耗油率最低,从而证明了本文给出的效率划分和最佳外涵风扇增压比判据是合理的。 相似文献
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为探究高速稀薄流流域凹腔槽道的气动特性,采用直接模拟蒙特卡罗(DSMC)方法,建立了凹腔深宽比为1,槽道高度分别为0、10、20、30、40 mm以及基准高度为20 mm的唇口钝化半径为2~20 mm的凹腔槽道构型,获得了不同算例的气动热系数和气动力系数的变化情况,分析了不同槽道高度以及不同唇口钝化半径的凹腔槽道构型对... 相似文献
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通道参数对再生冷却通道流动换热的影响 总被引:1,自引:0,他引:1
应用RSM模型对冷却通道的流动与换热进行了三维数值模拟,冷却剂为气氢,考虑其物性随温度和压力的变化.所得结果表明:增加壁面粗糙度使冷却剂换热强化,但会增加流阻损失;在突扩突缩区域会出现旋涡,旋涡使局部流阻损失加大且使湍流加强,壁温在旋涡出现处降低;冷却通道内的流动发展不受入口湍流强度的影响;冷却剂离心力引发径向平面内的二次流动,二次流引起的冷却剂质量重新分布使传热在凹曲率段强化,凸曲率段恶化. 相似文献
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We present a technique and results of calculating the cooling air pressure and flowrate in the turbine nozzle deflector vane
duct, coefficients of heat transfer through air and from gas taking into account the influence of an air film heated in the
perforation holes as well as temperature and thermal stresses in the vane elements and its thermal barrier coating in the
GTE takeoff operational conditions. The effect of oval grooves in the coating behind the holes in the gas flow downstream
direction and possible cracking of material on the thermal stress distribution in metal is considered. 相似文献
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采用数值方法研究了冷气掺混对高压涡轮气动性能和叶栅通道内部二次流动结构的影响,计算结果表明:冷气流量增加,冷却高压涡轮导叶和转子型面总载荷降低,导叶进、出口马赫数均减小,转子出口相对马赫数在径向0~0.55区域增大而在径向0.55~1.0区域减小.导叶进、出口气流角受冷气流量的变化影响较小.冷气流量由压气机进口流量的4.83%增加至14.49%,转子进口相对气流角在径向0.05~0.95区域增大而出口相对气流角在径向0.6~1.0区域减小,导叶绝热壁面冷却效率先升高后降低而转子绝热壁面冷却效率提高了19.33%.轮毂和机匣封严气呈束状进入转子叶栅通道且腔内封严气流动受旋转轮盘抽吸效应影响较大. 相似文献
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E. N. Bogomolov S. M. Piotukh I. A. Simonov V. A. Uglov 《Russian Aeronautics (Iz VUZ)》2010,53(4):416-420
A method for calculating the flowrate of the gas flowing through the cellular insert cells over the labyrinth seal strip is
proposed. The gas density is taken to be average with respect to the decisive section. It is assumed that jets flowing out
of cells disrupt the direct flow of the labyrinth seal. A practical implementation of the method is confirmed by the known
experimental data. 相似文献
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黏性对高压空气弹射装置内弹道性能的影响 总被引:1,自引:0,他引:1
针对高压空气弹射装置中,气体黏性流动造成的内耗散和沿程损失对内弹道性能的影响,结合高压下空气黏度公式,重点考虑低压室内的黏性流动,得到了未充分发展黏性流体在非定常状态下的能量损失计算方法。基于高压空气真实气体效应分析,建立了考虑气体摩擦的高压空气弹射内弹道数学模型,进行了数值求解。对比结果表明:气体摩擦效应对快速、瞬时过程造成的干扰量较小,对象宏观特性变化不大,低精度系统中可忽略不计。通过对结果的规律性进行探究,发现摩擦效应降低了有用功的转化率,减缓了气体膨胀速率,造成低压室压力的非均匀分布、高压室到低压室的质量流量波动和弹体初始时刻的碰撞。 相似文献