用CFD研究涡轮静叶栅的二次流损失

利用CFD软件Fluent对大转折角涡轮叶栅三维流场进行了数值模拟。采用静叶栅前移动的圆柱列替代上游动叶,发现圆柱尾迹进入叶栅流道的位置不同,对叶栅总压损失有较大影响。同时,通道内逐渐增大的横向压力梯度对二次涡发展产生了显著的影响,引起沿流向叶栅总压损失的急剧增大,认为叶高的减小会极大提高叶栅的二次流损失。     

Investigation of Internal Flow in Ultra—Highly Loaded Turbine Cascade by PIV Method

IntroductionSeveral investigations for highly loaded turbineblades have been tried in order to increase the turbineloading and the turbine inlet tempefature["']. Thehighly loaded tUrbine blades are able to reduce both thenumber of blades and the stages. Thus, the highly loadedturbine cascades can reduce the weight and theproduction cost of turbojet-engines. However, in order toachieve the high loading of the turbine blade, the highturning angle is necessmp. As the consequence, the strongt…     

Experimental investigation on flow improvement in compressor cascades

There is no general rule in the literature to help choose a correct flow control device for any given case of turbomachinery applications. This suggests individual optimization of flow control devices for each specific case. The objective of this study is to prove experimentally the benefits of passive control methods in improving the compressor performance. This allows to reduce the fuel consumption, leading to energy saving and reduction of atmospheric pollution. Two features have been controlled in this study: flow separation over the blade surfaces and the secondary flow over the cascade endwalls. Vortex generator ribs are tested on the blade suction side for flow reattachment on the blade surfaces, and low‐profile vortex generators are tested on the side walls of the compressor cascade against secondary flow losses. Different vortex generator designs are compared for total pressure recovery, flow turning, boundary layer characteristics, and pressure distributions over the endwalls. Copyright © 2016 John Wiley & Sons, Ltd.     

Profile and secondary flow losses in a high-lift LPT blade cascade at different reynolds numbers under steady and unsteady inflow conditions

The aerodynamic flow field downstream of a Low-Pressure High-Lift(HL)turbine cascade has been experimentally investigated for different Reynolds numbers under both steady and unsteady inflows,in order to analyse the cascade performance under real engine operating conditions.The Reynolds number has been varied in the range 100000相似文献   

An Experimental Study on 3—D Flow in an Annular Cascade of High Turning Angle Turbine Blades

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余速损失对Wells透平性能影响

利用实验方法系统研究了稳态流动中威尔斯透平的速度场、压力场的变化规律，并利用实验数据分析了余速损失对威尔斯透平性能的影响。分析结果指出，当进气迎角较大时，余速损失对透平性能的影响几乎可以忽略；随着进气迎角的减小（wells透平逐渐过渡到正常工作区内），余速损失对透平性能的影响略有增加。针对这一现象，就如何改进透平结构以降低余速损失的方法进行了讨论。     

Numerical investigation on wet steam non-equilibrium condensation flow in turbine cascade

Based on the two-phase wet steam flow with spontaneous condensation,experimental verification and flow analysis on nozzle and 2D cascade are carried out.The 3D Reynolds-Averaged gas-liquid two-phase flow control equation solver is explored with k ε k p turbulence model.Furthermore,3D flow numerical simulation on the last stage stator of the steam turbine is carried out.The results show that a sudden pressure rise on blade suction surface is mainly caused by the droplet growth in condensation flow.The more backward the condensation position is in cascade passage,the less the sudden pressure rise from condensation is,and the larger the nucleation rate is,the maximum under-cooling and the number of droplets per unit volume are.Interaction of condensation wave and shock wave has imposed greater influence on the parameters of the blade cascade outlet.     

大气温度对燃气轮机做功能力损失的影响分析

基于热力学第二定律,针对燃气轮机实际简单循环,推导出燃气轮机各部件做功能力损失的计算公式。通过对某型燃气轮机的定量计算,得出燃气轮机在不同大气温度下的做功能力损失。结果表明,大气温度对燃气轮机的做功能力损失有较大的影响。     

Numerical 3D model of viscous turbulent flow in one stage gas turbine and its experimental validation

The paper describes 3D numerical Reynolds Averaged Navier-Stokes (RANS) model and approximate sector approach for viscous turbulent flow through flow path of one stage axial supercharge gas turbine of marine diesel engine. Computational data are tested by comparison with experimental data. The back step flow path opening and tip clearance jet are taken into account. This approach could be applied for variety of turbine theory and design tasks: for offer optimal design in order to minimize kinetic energy stage losses; for solution of partial supply problem; for analysis of flow pattern in near extraction stages; for estimation of rotational frequency variable forces on blades; for sector vane adjustment (with thin leading edges mainly), for direct flow modeling in the turbine etc. The development of this work could be seen in the direction of unsteady stage model application.     

燃气初温对燃气轮机[火用]损失的影响分析

基于热力学第二定律,对燃气轮机实际简单循环推导出了燃气轮机各部件[火用]损失的计算公式。通过对某型燃气轮机的定量计算,得出了燃气轮机在不同燃气初温下的[火用]损失。结果表明,燃气初温对燃气轮机的[火用]损失有较大的影响。     

Trailing edge noise reduction of wind turbine blades by active flow control

In the current study, we investigate a route to reduction of the turbulent boundary layer–trailing edge interaction noise. The trailing edge noise is generated by surface pressure fluctuations beneath a turbulent boundary and scattered at the trailing edge of wind turbine blades. Trailing edge noise is considered to be the dominant noise source of modern wind turbines. Therefore, efforts are constantly made to attenuate the noise. Today, noise emission can be reduced by proper airfoil design or passive devices, such as trailing edge serrations. A further improved candidate technology for trailing edge noise attenuation is active flow control in the form of wall‐normal suction. With active flow control, the boundary layer features responsible for trailing edge noise generation can be manipulated, and correspondingly the trailing edge noise can be reduced. Detailed experimental investigations were performed at the Universities of Tel‐Aviv and Stuttgart. The tests showed that steady wall‐normal suction has a positive effect on the trailing edge noise by reducing the boundary layer thickness, and with it the integral length scales of the eddies within the boundary layer. Copyright © 2014 John Wiley & Sons, Ltd.     

Experimental investigation of the root flow in a horizontal axis wind turbine

This research investigates the flow behavior and its features in the blade's root region of a horizontal axis wind turbine by using stereoscopic particle image velocimetry (PIV) technique. Wind tunnel tests are conducted to measure the velocity field, phase‐locked with the blade motion, at different azimuth angles and at different spanwise positions. The pressure distribution is obtained from PIV velocity field by solving the Navier–Stokes momentum equations. In this paper, we aim to answer two questions: (i) How is the flow behavior in the root region? (ii) How is the evolution of the root vortex? The analysis of the velocity fields shows an outboard radial flow motion in the root region and a vorticity driven inboard motion at the blade?s maximum chord position. As a result of this vorticity driven flow, an increase in the axial velocity close to nacelle is measured. Wake sheets are observed and further discussed in the measured velocity and vorticity distributions. The formation and evolution of the root vortices conveyed downstream by the axial velocity are analyzed through vorticity and pressure distributions. Although the azimuthal vorticity in 3D representation is showing the trailing vorticity, the tilting of the root vortex tube is observed in the axial vorticity distribution. Moreover, the radial vorticity and azimuthal velocity from chordwise measurements show separation on the suction surface of the blade. This research concluded that the flow in the blade wake is driven by the root vortex; hence, the local effects of the root vortex cannot be ignored. Copyright © 2013 John Wiley & Sons, Ltd.     

Experimental Studies on Heat Transfer in the Tip Gap of a Sectorial Turbine Cascade

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Influence of Blade Chordwise Lean on Development of Cascade Losses

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Effect of streamwise fences on secondary flows and losses in a two-dimensional turbine rotor cascade

To control secondary flows,streamwise fences were attached to end wall of a linear turbine rotor cascade.Thecascade had 8 blades of 400 mm long and 175 mm chord.The blades deflected the flow by 120°.The fences weremade out of 0.7 nun thick brass sheet and the heights of the fences were 14 mm,18 mm respectively.The curva-ture of the fences was the same as that of the blade camber line.The fences were fixed normal to the end wall andat half pitch away from the blades.The experimental program consists of total pressure,static pressure measure-ments at the inlet and outlet of the cascade,by using five-hole probe.In addition,static pressure on the blade suc-tion surface and pressure surface was also obtained. Fences are effective in preventing the movement of the pres-sure side leg of the horseshoe vortex.Consequently the accumulation of low energy fluid on the suction surface isminimised.End wall losses are reduced by the fences due to weakening of the end wall cross flow.     

船用增压锅炉烟气涡轮级叶栅三维湍流流动的数值模拟

以某船用增压锅炉涡轮增压机组烟气涡轮级为研究对象,采用三维数值模拟技术和“混合平面”方法传递级间参数,利用标准κ-ε双方程湍流模型和耦合隐式求解器,通过求解三维雷诺平均守恒Navier—Stokes方程,来模拟烟气涡轮级叶栅三维湍流流动。文中给出了烟气涡轮级叶栅出口静压、总压、速度以及总温和静温等各参数的变化规律,对于烟气涡轮叶栅气动优化设计具有一定的参考价值。     

Influence of microcylinders with different vibration laws on the flow control effect of a horizontal axis wind turbine

Due to the flow separation on the blade of the NREL Phase VI wind turbine, a new flow control technique involving installation of an off‐surface vibrating small structure is proposed. By considering the actual flow condition, fluid‐solid coupling is applied in which two kinds of microcylinder vibration modes are set up, and the aerodynamic performance is numerically studied. The influence of the vibration modes, amplitude, and frequency of the off‐surface vibrating small structure on the aerodynamic performance is explored. For various stall conditions, the flow separation can be well suppressed by utilizing a suitable vibrating microcylinder rather than a static microcylinder. In addition, the vibrating microcylinder shows a noticeable suppression effect on large flow separation. Both the vibration direction and vibration amplitude play leading roles in the improvement of the aerodynamic performance, and a microcylinder with a high vibration frequency can more quickly suppress surface flow separation to achieve an optimum aerodynamic performance than a microcylinder with a low vibration frequency. By setting microcylinders with suitable vibration rules close to the blade surface, the wind energy coefficient can be obviously increased compared with those obtained when adding a static microcylinder or without microcylinder addition.     

Investigations of Interaction of the Main Flow with Root and Tip Leakage Flows in an Axial Turbine Stage by Means of a Source／Sink Approach for a 3D Navier—Stokes Solver

IntroductionFundamental stUdies of losses in tUrbomachinery in-dicate that, besides giving rise to losses of work, leakageflows contribute to the overall creation of entropy andkinetic encrgy losses. Some entropy is created in thelabyrinth seals and in passages between the fixed androtating pats of turbomachinery. CFD computations inlabyrinth seal geometries enable the evaluation of theentropy ereation PrOCesses there. CFD-based analysis canm1nindze the mass fiow rates of the tip leakage a…     

Wind turbine aerodynamics and loads control in wind shear flow

Wind turbine is subjected to some asymmetrical effects like wind shear, which will lead to unsteady blade airloads and performance. Fatigue loads can lead to damage of turbine components and eventually to failures. It is evident that the variation of the velocity over the rotor disc has an influence on the blade and introduces both flap-wise and edge-wise fatigue damage on the blade as a result of moment fluctuations in the two directions. The flap-wise moments on the blade are the origin of the rotor yaw and tilt moments which transmit to the turbine structure through the drive train to the yaw system and the tower. A lifting surface method with time marching free wake model is used to investigate the periodic unsteady nature in the wind shear. Individual pitch control (IPC) that is applied nowadays is the most advanced active control to reduce the fatigue. The blade airloads and performance of the turbine are also predicted under IPC control. It is found that IPC of the fluctuating blade root flap-wise moment can reduce the flap-wise fatigue damage remarkably while the blade root edge-wise moments are less sensitive to the varying blade pitch than the blade root flap-wise moments.     

透平端壁湍流分离_再附边界层计算

本文根据Veldman的边界层与势流相互作用模型,提出了一种带有湍流分离气泡的端壁边界层的计算方法。本文给出的计算方法适用于由凸台、凹槽、后台阶、壁面扩张角较大及根部反动度为负等因素引起的带有湍流分离气泡的边界层的计算,并且具有计算时间短,节省计算机内存等特点。