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变循环核心压气机可调特性的数值研究 总被引:1,自引:0,他引:1
《工程热物理学报》2016,(9)
利用三维数值工具对某变循环核心压机在设计转速下内、外涵节流特性进行了模拟,分析了核心机驱动风扇级、高压压气机以及二级涵道的工作特点和匹配关系,分析了变循环核心压气机的可调极限。研究结果表明,外涵道节流可以实现涵道比的大范围调节(0.243~0.062),内涵道节流可以实现总增压比的大范围调节(0.81~1.13倍设计压比)。二级涵道出口导向叶片的失速和核心机驱动风扇级的堵塞决定了外涵道节流的可调极限,高压压气机的失速和堵塞决定了内涵道节流的可调极限。 相似文献
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一、前言 在风扇发动机中,内外涵分流环的形状与位置会对风扇发动机的性能有明显的影响.因而,了解分流环表面的速度、压力等的分布以及其对流场的影响,对于提高风扇发动机的性能具有重要的实际意义. 本文所介绍的这个计算程序采用任意非正交曲线坐标与相应的非正交速度分量的叶 相似文献
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1、前言 本文讨论的混合型问题,仍属叶轮机械中的“正问题”。但其中某些边界条件是未知的,须依赖适当的物理假定。这些假定在被实验证实之前,至少必须在计算求解时是可行的。 典型的例子是具有长短叶栅的离心压气机叶轮的S_1流面流动和有内外涵道的风扇压气机转子内的S_2流面流动。本文将以前者为例,讨论这种“混合型”问题的解法。 2、基本方程 相似文献
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高速、高负荷跨音速单级风扇设计与试验 总被引:7,自引:0,他引:7
本文介绍-高性能单级跨音速风扇的设计与试验结果。该风扇设计压比2.3,设计效率0.88,具有高切线速度510 m/s(相对马赫数达 1.72)和低展弦比。 在气动设计过程中,为了改善级效率,使用了前缘掠型和任意空间积迭曲线新技术。为了提高气动设计的可靠性,对风扇进行了三维有粘流动计算分析和气动的优化。 试验结果表明:这台风扇性能达到了它的设计目标。设计点压比(2.3)效率为89.5%,峰值效率达90.8%,最高压比达2.491,喘振裕度超过11.5%。 这台风扇显示了当今国际上先进风扇水平。高水平性能的取得归功于在高速和高负荷风扇气动设计中准三维和三维粘性设计系统的应用。 相似文献
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I. V. Kumpanenko A. V. Roshchin V. V. Usin E. G. Raevskaya A. V. Bloshenko N. A. Sakharova 《Russian Journal of Physical Chemistry B, Focus on Physics》2012,6(5):671-676
A system for automatic control of a three-step process of water purification is developed. The system includes the online monitoring of the concentrations of pollutants in water at points of the flow diagram corresponding to the primary, fine, and final treatment steps, and consists of a UV-fluorimeter for determining the concentrations of pollutants, solenoid valves for controlling the flow of water in the treatment installation and a computerized central control unit operating according to a preset algorithm of water treatment control. 相似文献
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Particle image velocimetry (PIV) is applied for the first time to study Eckart streaming induced by a medical ultrasonic transducer operating at a frequency of 3.3 MHz and effective acoustic intensities of 0.25 and 3 Wcm(-2). A temporal series of velocities in a two-dimensional plane were recorded resulting in an experimental set comprising over half a million velocity data points. These enabled average and fluctuating properties to be determined and clearly indicated the quasi-steady nature of the flow. The average large scale velocity fluctuations along the axis caused by this quasi-steady property were calculated to be 2 and 20 m ms(-1) at effective intensities of 0.25 and 3 Wcm(-2) respectively corresponding to approximately 25% of the peak flow velocity in both cases. Furthermore averaged shear rates were calculated with peak values of 1 and 8 s(-1) for the low and high intensities respectively. The present investigation indicates the usefulness of PIV for such studies and serves as a prelude to investigations of streaming in biological type fluids. 相似文献
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Cascading failures in large-scale electric power transmission systems are an important cause of blackouts. Analysis of North American blackout data has revealed power law (algebraic) tails in the blackout size probability distribution which suggests a dynamical origin. With this observation as motivation, we examine cascading failure in a simplified transmission system model as load power demand is increased. The model represents generators, loads, the transmission line network, and the operating limits on these components. Two types of critical points are identified and are characterized by transmission line flow limits and generator capability limits, respectively. Results are obtained for tree networks of a regular form and a more realistic 118-node network. It is found that operation near critical points can produce power law tails in the blackout size probability distribution similar to those observed. The complex nature of the solution space due to the interaction of the two critical points is examined.(c) 2002 American Institute of Physics. 相似文献
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合成气压缩机循环段由于高压和流动空间限制,难以测量内部流动参数,导致无法从工程上判断循环段流动性能。为此本文建立了高压缸出口段、混合腔和循环段叶轮流道模型,采用合成气物性,在约14.4 MPa(A)的高压进口条件下,使用CFD的方法研究了循环段内部流动混合发展规律。选取常用的七种损失模型评估了叶轮内损失,并研究了混合腔对下游叶轮性能的影响。结果表明混合腔内呈现出明显的二次流动,随着流动向下游发展,流场变得越来越均匀。混合腔损失、叶片负载损失和尾迹损失是主要的损失源。由于上游混合腔的影响,带有混合腔的叶轮的压比和效率低均低于单独均匀进口叶轮情况,且其工况范围更窄。本文的结果可为新型合成气压缩机产品的设计提供参考。 相似文献
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本文针对配备三通道蛇形阳极流场的液态进料直接甲醇燃料电池阳极两相流及电池性能开展了实验研究.液态进料的直接甲醇燃料电池阳极流床内会形成二氧化碳气泡与甲醇溶液构成的两相流系统,其两相流特性受到电池流道设计、运行工况和工作角度的影响,并同时影响燃料电池的性能.本文设计了三通道蛇形流场,通过可视化实验得到直接甲醇燃料电池三通道蛇形阳极流场内的两相流特性随电流密度变化的规律,并研究了燃料电池在不同旋转角度下的两相流特性和电池性能.实验结果表明:在不同的旋转角度下,电池都体现出较好的工作性能. 相似文献
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D. V. Chirkov P. K. Shcherbakov S. G. Cherny V. A. Skorospelov P. A. Turuk 《Thermophysics and Aeromechanics》2017,24(5):691-703
At full and over load operating points, some Francis turbines experience strong self-excited pressure and power oscillations. These oscillations are occuring due to the hydrodynamic instability of the cavitating fluid flow. In many cases, the amplitude of such pulsations may be reduced substantially during the turbine operation by the air injection/ admission below the runner. Such an effect is investigated numerically in the present work. To this end, the hybrid one-three-dimensional model of the flow of the mixture “liquid?vapor” in the duct of a hydroelectric power station, which was proposed previously by the present authors, is augmented by the second gaseous component — the noncondensable air. The boundary conditions and the numerical method for solving the equations of the model are described. To check the accuracy of computing the interface “liquid?gas”, the numerical method was applied at first for solving the dam break problem. The algorithm was then used for modeling the flow in a hydraulic turbine with air injection below the runner. It is shown that with increasing flow rate of the injected air, the amplitude of pressure pulsations decreases. The mechanism of the flow structure alteration in the draft tube cone has been elucidated, which leads to flow stabilization at air injection. 相似文献
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为深入分析层流状态下对称槽道内涡波流场的流动特性及其变化规律,对流场进行了二维粒子图像测速(2DPIV)测量获取瞬态速度矢量数据,利用本征正交分解(POD)技术进行模态分解以及涡波流场的重构,然后根据重构的流场对对称槽道内涡波流场进行了平均速度剖面、流场脉动强度以及特征点的速度和频谱分布等方面的分析。结果表明:POD的前15阶模态能够表征涡波流场的主导结构,第1,3阶模态主要表现为一对旋向相反的涡对特征,第2阶模态具有涡旋和波状主流的特征;提取了5个涡旋涡核的位置作为流场流动特性的特征点;根据POD重构流场分析发现流向平均速度呈抛物线形状分布,法向平均速度呈对称分布特征;流向脉动强度受壁面的影响较大,法向脉动强度呈现抛物线形状分布;距离中心主流较近的1#,4#,5#特征点的速度脉动程度受主流的脉动强度影响较大,速度的脉动主频0.15 Hz与次频、流场的自然频率0.35 Hz共同影响特征点的速度分布;2#,3#特征点的流向速度呈衰减趋势,法向速度在初期幅度变化较大。 相似文献
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《Heat Recovery Systems and CHP》1988,8(1):33-41
The free choice of operating temperatures in absorption systems is limited by the Gibbs phase rule and the thermodynamic properties of the working pair. For a given combination of temperatures, the concentrations in the absorber and the generator are fixed automatically. This determines the flow ratio. Therefore for any particular working pair, the coefficient of performance is related to the flow ratio.Tables of possible combinations of operating temperatures and concentrations, including flow ratios, Carnot coefficients of performance and enthalphy based coefficients of performance have been presented for a water-lithium chloride absorption system for cooling. The interaction of operating temperatures has been illustrated graphically. The data obtained are also compared with published data for the water-lithium bromide absorption system under identical conditions. 相似文献
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本文借助可视化手段,针对平行流场和蛇形流场,实验研究不同放电电流密度、甲醇浓度、进料温度和入口流量对液相进料直接甲醇燃料电池阳极流场流动阻力特性的影响.结果表明:放电电流密度增加,流场压降随之增加,小电流放电,蛇型流场较平行流场压降增加慢,当超过某一值时,蛇型流场的压降增加较平行流场快;随甲醇浓度的提高,进出口压降均略有减小,且两种流场压降变化趋势一致;随进料温度升高,平行流场压降逐渐增大,蛇彤流场压降变化较小;随着甲醇溶液流量增大,平行流场和蛇行流场压降均逐渐增人,平行流场增加缓慢,蛇形流场压降增加速度远大于平行流场. 相似文献