共查询到19条相似文献,搜索用时 109 毫秒
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跨音速压气机级的三维周期性非定常流动计算 总被引:1,自引:0,他引:1
对跨音速压气机级动静叶排相干形成的三维非定常流场进行了数值研究,利用时间推进LU-SGS稳式迭代法求解三维非定常欧拉方程,对流项采用高分辨率NND格式离散。对某压气机第一级动静叶排相干非定常流场的计算结果表明,本文方法不仅在收敛速度上明显地优于一般显式方法,而且保持了流场中激波的高分辨率,适于推广到计算量巨大的的多级轴流压气机三维非定常流场的数值分析问题 相似文献
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整理和归纳出合适的流动损失和落后角模型,并将其与逐排基元叶片算法相结合,给出了计算多级轴流压气机特性工程方法;进一步将其与复合形优化方法相结合,对多级轴流压气机多叶排调节扩稳进行了优化模拟,并应用于某8级轴流压气机算例计算.结果表明,在部分转速工况下,采用带性能约束的优化调节在不明显降低性能的同时能够显著减小多级压气机不稳定点流量;在设计工况下,采用适当的变几何优化调节不仅能明显扩大压气机稳定工作范围,还能明显提高压气机绝热效率. 相似文献
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计算多级轴流压气机阻塞系数和减功系数的新方法 总被引:4,自引:0,他引:4
讨论了轴流压气机环壁边界层的流量阻塞效应和减功效应,提出了一种工程上可以简便适用波压气机设计和分析用的新的阻塞系数和减功系数计算方法,并应用于二台导叶可调及淡可调的十多级轴流压气机变工况的性能分析计算,结果与实验值吻合良好。 相似文献
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变几何叶片对压气机特性影响的实验研究及分析 总被引:3,自引:0,他引:3
利用带导叶的单级轴流压气机实验台,详细测量了进口导叶无预旋、全叶高预旋2度和叶顶端部预旋2度对压气机总性能、基元性能及失速边界的影响。在设计及非设计转速下,通过对比三种导叶几何条件下的性能曲线,探讨了导叶预旋在非设计转速下的扩稳效果及设计转速下对 气机性能的影响,分析了利用端弯技术扩大压气机稳定工作范围的机理,该研究进一步说明了端弯技术是推迟轴流压气机不稳定流动发生的有效手段之一,可以很方便的用于实际轴流压气机中。 相似文献
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轴流压气机机匣处理研究进展及评述 总被引:21,自引:0,他引:21
喘振和旋转失速裕度等稳定性问题是压气机设计者所关心的主要问题之一, 不稳定
流动大多数情况下都是从压气机端部区域开始的, 如果能够延迟端部区域的失速,
就能提高压气机的稳定工作范围. 在过去的30多年中,许多种型式的处理机匣结
构被用于改善端部区域流动, 提高压气机的稳定工作范围. 从机匣处理的实验
研究、理论分析和数值模拟3个方面对轴流压气机机匣处理的研究进行了回顾, 讨
论了处理机匣内部流动机理及其对轴流压气机性能和稳定性的影响, 并指出了机匣
处理研究的发展趋势. 相似文献
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轴流压气机叶片堵塞颤振的数值预测 总被引:1,自引:0,他引:1
在多级轴流压气机的实际运行中,中间级和后面级叶片所发生的低负攻角堵塞颤振主要是弯曲振型。但现有文献只研究了扭转振型的叶片堵塞颤振。本文采用前一阶段发展的有限差分方法,预测到在高亚音进口Mach数、低负攻角条件下,跨音振荡叶栅弯曲振型堵塞颤振的发作。此外,还研究了一些几何参数及气动参数对于跨音叶栅弯曲振荡稳定性的影响。初步数值结果表明,激波的存在对跨音叶栅气动弹性稳定性的影响是显著的。 相似文献
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轴流压气机级内三维粘性流动的数值模拟 总被引:1,自引:0,他引:1
考虑轴流压气机中实际气流沿径向和周向都不均匀的特点,采用亚松弛方法改进传统的混合界面模型,发展了轴流式压气机级内全三维粘性流场的数值计算程序,并以某轴流式双排对转压气机的进口导叶/转子为研究对象,将本文发展的程序与商用 NUMECA 软件的结果进行对比,对本文发展的程序进行了验证。对比结果表明:由于混合界面法引入了“人工掺混”,商业软件计算得出的总压在通过交界面时存在一定的总压损失,而自编程序计算结果保证了总压在交界面处的一致性。流场分析结果表明:该转子叶片在设计工况下处于负攻角状态,在导叶出口轮毂处、压力面50%弦长处、吸力面靠近尾缘处均出现了轻微的流动分离现象。 相似文献
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分离涡模拟DES是压气机流动模拟中常用的高保真湍流模式。为了使DES准确解析湍流,数值耗散必须限制在合理范围内。然而,当前的压气机流动DES类研究工作中仍然普遍采用高耗散的迎风格式。本文首先基于DES类方法计算的各向同性衰减湍流结果,定量比较了多种不同数值格式的耗散,证实了高耗散迎风格式严重低估中高波数湍流能量。高阶重构格式可以一定程度上改善该问题,但能量耗散仍然过高。本文在高阶重构的基础上,进一步引入自适应耗散函数修改Riemann求解器,构造了自适应耗散格式。该格式在全波数范围都能准确地预测湍流能谱。将该格式配合DES类方法模拟跨声速离心压气机流动,其预测的压比相比于三阶迎风格式,更加接近实验结果。此外,自适应耗散格式显著提高了中小尺度流动结构的分辨率。分析表明,在使用DES类方法模拟压气机流动时,有必要采用数值耗散较低的离散格式,以准确预测压气机总体性能和流动结构。本文构造的自适应耗散格式是一种良好选择。 相似文献
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高压液体通过喷嘴加速,形成高速射流,与相反方向的另一股射流相互撞击,发生强烈的相互作用,产生强烈的径向和轴向湍流速度分量以及狭窄的高压高速湍流区,在此区域内,相间或液滴间的碰撞互磨产生的挤压力和剪切力使流体被细化。本文从液体连续相撞击流的两个特征:微观混合和压力波动入手,逐一分析了撞击速度与微观混合、压力波动的关系,得出了压力波动与撞击流速度乱U0成正比关系,微观混合与U^3 0成正比的规律。同时,用流体模拟软件Fluent对喷嘴的结构和尺寸进行优化,并得出最合理的喷嘴结构和尺寸。模拟认为:在相同压力下,采用矩形槽,出口孔径为0.2mm,槽的深度为0.27mm的结构时撞击速度达到最大,并通过实验验证了这一结论。 相似文献
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A reduced form of Navier–Stokes equations is developed which does not have the usual minimum axial step size restriction. The equations are able to predict accurately turbulent swirling flow in diffusers. An efficient single sweep implicit scheme is developed in conjunction with a variable grid size domain-conforming co-ordinate system. The present scheme indicates good agreement with experimental results for (1) turbulent pipe flow, (2) turbulent diffuser flow, (3) turbulent swirling diffuser flow. The strong coupling between the swirl and the axial velocity profiles outside of the boundary layer region is demonstrated. 相似文献
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The flow control effects of nanosecond plasma actuation on the boundary layer flow of a typical compressor controlled diffusion airfoil are investigated using large eddy simulation method. Three types of plasma actuation are designed to control the boundary layer flow, and two mechanisms of compressor airfoil boundary layer flow control using nanosecond plasma actuation have been found. The plasma actuations located within the laminar boundary layer flow can induce a small vortex structure through influencing on the density and pressure of the flow field. As the small vortex structure moves downstream along the blade surface with the main flow, it can suppress the turbulent flow mixing and reduce the total pressure loss. The flow control effect of the small vortex structure is summarized as wall jet effect. Differently, the plasma actuation located within the turbulent boundary layer flow can act on the shear layer flow and induce a large vortex structure. While moving downstream, this large vortex structure can suppress the turbulent flow mixing too. 相似文献
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In this paper large-eddy simulation is used to study buoyancy-induced flow in a rotating cavity with an axial throughflow of cooling air. This configuration is relevant in the context of secondary air systems of modern gas turbines, where cooling air is used to extract heat from compressor disks. Although global flow features of these flows are well understood, other aspects such as flow statistics, especially in terms of the disk and shroud boundary layers, have not been studied. Here, previous work for a sealed rotating cavity is extended to investigate the effect of an axial throughflow on flow statistics and heat transfer. Time- and circumferentially-averaged results reveal that the thickness of the boundary layers forming near the upstream and downstream disks is consistent with that of a laminar Ekman layer, although it is shown that the boundary layer thickness distribution along the radial direction presents greater variations than in the sealed cavity case. Instantaneous profiles of the radial and azimuthal velocities near the disks show good qualitative agreement with an Ekman-type analytical solution, especially in terms of the boundary layer thickness. The shroud heat transfer is shown to be governed by the local centrifugal acceleration and by a core temperature, which has a weak dependence on the value of the axial Reynolds number. Spectral analyses of time signals obtained at selected locations indicate that, even though the disk boundary layers behave as unsteady laminar Ekman layers, the flow inside the cavity is turbulent and highly intermittent. In comparison with a sealed cavity, cases with an axial throughflow are characterised by a broader range of frequencies, which arise from the interaction between the laminar jet and the buoyant flow inside the cavity. 相似文献
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Turbulence-intensity measurements were made in a Taylor-Couette flow reactor consisting of two counter-rotating concentric cylinders designed for the purpose of studying turbulent premixed-flame propagation. In the annulus separating the two cylinders, a nearly homogeneous turbulent flow is generated. The intensities of turbulent velocity fluctuations in the annulus in both axial and circumferential directions were measured by using laser-Doppler velocimetry for a wide range of cylinder rotation rates, corresponding to low through high (120 cm/s) intensities relative to typical laminar flame speeds for lean methane-air mixtures. The experimental measurements indicate a linear relation between turbulence intensities and average cylinder surface speed and demonstrate the usefulness of the Taylor-Couette apparatus for studies of premixed-flame propagation in high-intensity turbulent flow. 相似文献
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Measurements of mean velocity components, turbulent intensity, and Reynolds shear stress are presented in a turbulent lifted
H2/N2 jet flame as well as non-reacting air jet issuing into a vitiated co-flow by laser doppler velocimetry (LDV) technique. The
objectives of this paper are to obtain a velocity data base missing in the previous experiment data of the Dibble burner and
so provide initial and flow field data for evaluating the validity of various numerical codes describing the turbulent partially
premixed flames on this burner. It is found that the potential core is shortened due to the high ratio of jet density to co-flow
density in the non-reacting cases. However, the existence of flame suppressed turbulence in the upstream region of the jet
dominates the length of potential core in the reacting cases. At the centreline, the normalized axial velocities in the reacting
cases are higher than the non-reacting cases, and the relative turbulent intensities of the reacting flow are smaller than
in the non-reacting flow, where a self-preserving behaviour for the relative turbulent intensities exists at the downstream
region. The profiles of mean axial velocity in the lifted flame distribute between the non-reacting jet and non-premixed flame
both in the axial and radial distributions. The radial distributions of turbulent kinetic energy in the lifted flames exhibit
a change in distributions indicating the difference of stabilisation mechanisms of the two lifted flame. The experimental
results presented will guide the development of an improved modelling for such flames. 相似文献