Passive Control of Steady Condensation Shock Wave

IntroductionA rapid expansion of moist air or steam in asupersonic nozzle gives rise to nonequilibriumcondensation phenomena. Thereby, the nozzle flow isaffected by the latent heat released by condensation ofwater vapouf, and if the heat released exceeds a certainquantity, a condensation shock wave will occur[1-4].Many works for the passive contfol of shockboundary layer interaction using the porous wall with aplenum underneath have been repofted on the applicationof the technique tO tfansonic…     

Passive control of unsteady condensation shock wave

IntroductionIn the case of moist air or steam rapidly expanding ina supersonic nozzle, nollequilibrium condensation occursin the flow field and the flow will be affected by thelatent heat leleased by condensationll-4]. Thereby, if theheat exceeds a certain quantity, the flow will becomeunstable and oscillations of a periodic flow occurs[5-91. Forthe unsteady condensation shock wave, it is blown thatthere are three types of oscillationslg]. These types aredescribed below:1. Mode l: A condensat…     

Effect of nonequilibrium condensation of moist air on transonic flow fields

luttoductionMany studies on condensation occwhng in the caseof the rapid expansion of moist air mr steam in asupersonic nozzle have been performed experimentallyand numerically, and the characteristics of condensationhave been nearly clchfiedll4]. Schnerr et al.[5] and lriya atal.le] investigated the effect of condensation on thestrength of shock wave on suiface of wing, drag and liftnumerically. However, the. effect of condensation on theshock wave on s~e of wing and talulences behindshock wa…     

Passive Control of Condensation Shock Wave in Prandtl—Meyer Expansion Flow

In this paper, the effects of the passive technique by using the slotted wall on the characteristics of a condensation shock wave generated in a Prandtl-Meyer flow were investigated experimentally. Furthermore, in order to clarify the variation of condensation properties in the flow field, Navier-Stokes equations were solved numerically using a 3rd-order MUSCL type TVD finite-difference scheme with a second-order fractional-step for time integration. Baldwin-Lomax model was used as a turbulence model in the computations. From experimental results, it was found that the shock strength on the slotted wall became weak in comparison with no passive case (solid wall), and the present passive technique was the most effective when a foot of the condensation shock wave was located at the middle of slotted wall. Furthermore, it was confirmed numerically that the passive technique was also effective for the unsteady condensation shock wave.     

Effect of non-equilibrium condensation of moist air on unsteady behaviour of shock waves around a circular arc blade

The unsteady phenomena in the transonic flow around airfoils are observed in the flow field of fan,compressorblades and butterfly valves,and this often causes serious problems such as the aeroacoustic noise,the vibration.In the transonic or supersonic flow where vapour is contained in the main flow,the rapid expansion of the flowmay give rise to a non-equilibrium condensation.However,the effect of non-equilibrium condensation on thetransonic internal flows around the airfoil has not yet been clarified satisfactorily.In the present study,the effectof non-equilibrium condensation of moist air on the self-excited shock wave oscillation on a circular arc bladewas investigated numerically.The results showed that in the case with non-equilibrium condensation,frequenciesof the flow oscillation became smaller than those without the non-equilibrium condensation.     

Study of the Unsteady Condensation of Moist Air in Shock Tube

The major flow physics of the unsteady condensation in the subsonic flows induced by the unsteady expansion waves in shock tube was studied in this paper. The unsteady condensation phenomenon was analyzed by using the two-dimensional, unsteady, Navier-Stokes equations, which were fully coupled with a droplet growth equation. The third-order TVD MUSCL scheme was applied to solve the governing equation systems. The computational results were compared with the previous experimental data. The time-dependent behavior of unsteady condensation of moist air in shock tube was investigated in details. The results show that the major characteristics of the unsteady condensation phenomenon in shock tube are very different from those in the supersonic wind tunnels.     

气汽混合流体凝结液膜传热特性研究

液膜厚度对凝结传热具有较大影响,且传热管管型影响着凝结液膜形成及排除。为了通过改变管型降低液膜厚度达到强化传热的目的,对圆管、椭圆管及滴形管等三种管型凝结液膜建立了相应的物理及数学模型,并计算了液膜沿管壁的厚度分布及传热系数;分析了三种管型对液膜传热的影响。结果表明:在气汽混合流体凝结传热过程中,不同管型其凝结液膜厚度差别较大;壁面温度和混合流体速度对液膜传热均有影响;相同条件下滴形管管壁上所形成的液膜,其平均厚度较薄,传热系数较高,因此滴形管传热性能优于其他管型。     

Control of transonic flow fields using local occurrence of non-equilibrium condensation

Control of supersonic flow fields with shock wave is important for some industrial fields. There are many studies for control of the supersonic flow fields using active or passive control. When non-equilibrium condensation occurs in a supersonic flow field, the flow is affected by latent heat released. Many studies for the condensation have been conducted and the characteristics have been almost clarified. Further, it was found that non-equilibrium condensation can control the flow field. In these studies, the condensation occurs across the passage of the flow field and it causes the total pressure loss in the flow field. However, local occurrence of non-equilibrium condensation in the flow field may change the characteristics of total pressure loss compared with that by the condensation across the passage of the nozzle and there are few for researches of locally occurred non-equilibrium condensation in supersonic flow field. The purpose in the present study is to clarify the effect of local occurrence of non-equilibrium condensation on the transonic flow field in a nozzle with a circular bump. As a result, local occurrence of non-equilibrium condensation reduced the shock strength and total pressure loss in the transonic flow field by flowing the moist air from trailing edge of the circular bump to the mainstream.     

Effect of Nonequilibrium Homogenous Condensation on Flow Fields in a Supersonic Nozzle

INTRODUCTIONManystudies[1-131onthecondensationshockwaveoccurringinthecaseoftheraPidexPansionofmoistairorsteaminasupersonicnozzlehavebeenper-formed,andthecharacteristicsofcondensationshock'wavehavenearlybeenclarilied.Acondensationshockwavealsooccursinthebladepassageinasteamturbinel14,15]andsuchacondensationshockwavinteractswiththeboundarylayeronthesurfaceoftheblade.Thus,thefiowinthebladepassageofthesteamturbinewiththecondensationshockwavehasnotyetbeenclariliedl16'17].InthepreseDtstudythee…     

凝结蒸汽中加入添加剂对凝结换热影响研究

研究当凝结蒸气中含有表面添加剂时单根管外的凝结换热。在对圆管外Marangon i凝结换热过程进行了理论分析的基础上,建立了含有凝结液膜的物理模型和基于边界层方程组的数学模型,应用相似理论进行了无量纲变换。计算结果表明,添加添加剂可以诱发界面流动,从而导致了气液界面处的液膜的不稳定,在气体凝结过程中产生了自发的扰动,加强了凝结换热。     

超音速分离管中水蒸气凝结相变的数值研究

基于超音速分离管中混合气体流动属于伴随凝结相变的可压缩、跨音速的特点,建立了考虑传质效应与非平衡凝结过程的数学模型,并采用数值方法对伴随水蒸气凝结的超音速分离管中的流动进行分析研究。以空气、水蒸气及液态水为流动介质,采用两相流动中的VOF模型结合凝结相变模型以及组分传输模型,研究不同进出口参数及不同水蒸气含量对凝结流场的影响。研究结果表明,所建立的分离管内部非平衡凝结相变模型可以较好的再现超音速流中的凝结成核及液滴生长过程;数值计算结果表明,入口压力、温度及水蒸气含量对分离管内流动凝结过程有直接且重要的影响。因此在进行超音速分离管设计时,考虑温度压力参数的同时,考虑水蒸气含量对分离管性能的影响也是非常重要的。     

Study on Characteristics of Steady Flow Condensation Heat Transfer in a Fube Under Zero—Gravitation

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Film condensation on a vertical microchannel

In this paper, a two dimensional laminar liquid film which condenses on a vertical microchannel is investigated analytically. A liquid film thickness, condensation mass flux flow and the variation of the velocity through the liquid thickness were determined by modified Navier–Stockes and energy equations. The effect of some parameters on the liquid film thickness, condensation mass flow rate and velocity are investigated. These parameters include slipping in temperature, β, and velocity, α, due to microscale interaction. It was found that, the liquid film thickness, δ, decreases as the slipping factors increases, and diminishes as a value of slipping factors (α and β) become more than or equal to 0.1. Increasing the slip in temperature due to microscale interaction causes the condensation mass flow rate to increase as the value of slip in velocity increases. Additionally, the slip value in the channel was found to increase as the slip value in velocity, α, increases.     

An investigation of liquid film thickness during solutal Marangoni condensation using a laser absorption method: Absorption property and examination of measuring method

The objective of the study is to establish a method for measuring the thickness of thin condensates of liquid mixtures using a laser light absorption method during the process of water–ethanol Marangoni dropwise condensation. First, the extinction property of the test material, with unknown properties related to infrared laser light having a wavelength of 3.39µm, was measured. Next, measurements were made of the variations in condensate film thickness after the sweeping of the heat transfer surface by departing drops in the Marangoni dropwise condensation cycle. The precision of this method was investigated on the basis of the extinction coefficient of the test material and the thickness of the liquid film. Results showed that this method provides good precision and is applicable to the measurement of other similar materials. © 2003 Wiley Periodicals, Inc. Heat Trans Asian Res, 32(8): 700–711, 2003; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.10124     

Theoretical research of convective condensation heat transfer for mixture gas on a horizontal tube

The mechanism of convective condensation heat transfer of moist mixed gas across a horizontal tube was studied in this paper. The models referring to how the liquid film flows and the heat transfers on the tube are set up by combining modified film model and Nusselt condensation theory. The effects of Re number, wall temperature, and water vapor concentration on condensation heat transfer are discussed. Results predict that the film thickness profile on the tube is influenced greatly by vapor shear force on liquid film. Local Nusselt number depends remarkably on gas phase heat resistance, which is different from pure vapor and very similar to single‐phase gas. © 2007 Wiley Periodicals, Inc. Heat Trans Asian Res, 36(6): 324–333, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.20169     

Experimental and Numerical Investigation of Condensation Shock in Shock Tube

INTRODUCTIONThehomogeneousnucleationwithsubsequentspon-taneouscondensationofwater,pentanol,andethanolVaPorsinacarriergasareinvestigatedexperimen-tallyandtheoreticallyintheexpansionpartofashocktube.AswasshownbySislianandGlass(l976)forsupercriticalconditionsthecondensationshockwave(Cw)occurs.Thehomogeneousnucleationofwatervaporinacarriergaswasfirststudiedexperimentallyintheex-pansionpartofashocktubeusinglightscatteringbyBarschdorff(1975)andthenumericalsolutionwasaddedbySislianandGlaJss(1…     

The effect of non-equilibrium condensation on the drag coefficient in a transonic airfoil flow

In this study,a transonic flow past NACA0012 profile at angle of attack α=00 whose aspect ratio AR is 1.0 with non-equilibrium condensation is analyzed by numerical analysis using a TVD scheme and is investigated using an intermittent indraft type supersonic wind tunnel.Transonic flows of 0.78-0.90 in free stream Mach number with the variations of the stagnation relative humidity(Φ0)are tested.For the same free stream Mach number,the increase in Φ0 causes decrease in the drag coefficient of profile which is composed of the drag components of form,viscous and wave.In the case of the same M∞ and T0,for more than Φ0=30%,despite the irreversibility of process in non-equilibrium condensation,the drag by shock wave decreases considerably with the increase of Φ0.On the other hand,it shows that the effect of condensation on the drag coefficients of form and viscous is negligible.As an example,the decreasing rate in the drag coefficient of profile caused by the influence of non-equilibrium condensation for the case of M∞=0.9 and Φ0=50% amounts to 34%.Also,it were turned out that the size of supersonic bubble(that is,the maximum height of supersonic zone)and the deviation of pressure coefficient from the value for M=1 decrease with the increase of Φ0 for the same M∞.     

Research on convective condensation heat transfer for a gas mixture in a vertical tube

This paper discusses the convective condensation of a gas mixture in a vertical tube. A mathematical model was derived by combining a modified film model and Nusselt's condensation theory. The effect of wall temperature on film thickness and interfacial temperature was predicted and film thickness was calculated. When compared with the gas phase resistance method, the film model is better. The phenomenon of SO₂ absorption into condensate is illustrated and discussed. © 2004 Wiley Periodicals, Inc. Heat Trans Asian Res, 33(4): 219–228, 2004; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.20011     

Mechanism research of convective condensation heat transfer for a gas mixture flowing over a horizontal tube

The modified film model combined with Nusselt's condensation theory are used for the study of convective condensation heat transfer on a horizontal tube with moist mixed horizontal gas flows at a given speed. A theoretical model considering gas boundary layer separation was set up. The liquid film flows and the heat transfer on the tube are presented. The effects of the flow direction on condensation heat transfer are discussed. The results predict that the condensate film is so thin that the liquid phase heat resistance can be ignored. © 2008 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.20238     

Effects of Heterogeneous Condensation on the Transonic Flow Fields on a Bump Model

In the present study, effect of the heterogeneous condensation on the characteristics of shock wave generated on the bump model in the transonic flow field was investigated numerically. As a result, it was found that, for the flow field with steady adiabatic shock wave on the bump model, the condensation with heterogeneous nucleation has a strong effect on the whole flow field, and it reduced the strength of the shock. Furthermore, the total pressure loss was dependent on the concentration of the solid particles per unit volume.