• <tr id="yyy80"></tr>
  • <sup id="yyy80"></sup>
  • <tfoot id="yyy80"><noscript id="yyy80"></noscript></tfoot>
  • 99热精品在线国产_美女午夜性视频免费_国产精品国产高清国产av_av欧美777_自拍偷自拍亚洲精品老妇_亚洲熟女精品中文字幕_www日本黄色视频网_国产精品野战在线观看 ?

    Experimental study of curvature effects on jet impingement heat transfer on concave surfaces

    2017-11-20 12:06:57ZhouYingLinGuipingBuXueqinBiLizhnWenDongsheng
    CHINESE JOURNAL OF AERONAUTICS 2017年2期

    Zhou Ying,Lin Guiping,Bu Xueqin,*,Bi Lizhn,b,Wen Dongsheng,b

    aSchool of Aeronautic Science and Engineering,Beihang University,Beijing 100191,ChinabSchool of Chemical and Process Engineering,University of Leeds,Leeds LS2 9JT,UK

    Experimental study of curvature effects on jet impingement heat transfer on concave surfaces

    Zhou Yinga,Lin Guipinga,Bu Xueqina,*,Bai Lizhana,b,Wen Dongshenga,b

    aSchool of Aeronautic Science and Engineering,Beihang University,Beijing 100191,ChinabSchool of Chemical and Process Engineering,University of Leeds,Leeds LS2 9JT,UK

    Anti-icing system;Concave surface;Curvature effect;Heat transfer;Jet impingement

    Experimental study of the local and average heat transfer characteristics of a single round jet impinging on the concave surfaces was conducted in this work to gain in-depth knowledge of the curvature effects.The experiments were conducted by employing a piccolo tube with one single jet hole over a wide range of parameters:jet Reynolds number from 27000 to 130000,relative nozzle to surface distance from 3.3 to 30,and relative surface curvature from 0.005 to 0.030.Experimental results indicate that the surface curvature has opposite effects on heat transfer characteristics.On one hand,an increase of relative nozzle to surface distance(increasing jet diameter in fact)enhances the average heat transfer around the surface for the same curved surface.On the other hand,the average Nusselt number decreases as relative nozzle to surface distance increases for a fixed jet diameter.Finally,experimental data-based correlations of the average Nusselt number over the curved surface were obtained with consideration of surface curvature effect.This work contributes to a better understanding of the curvature effects on heat transfer of a round jet impingement on concave surfaces,which is of high importance to the design of the aircraft anti-icing system.

    1.Introduction

    Heat transfer associated with jet impingement on a flat or curved surface has been the subject of extensive investigation for decades because of its enhanced local heat exchange performance in a wide variety of applications such as glass tempering,metalannealing,and engine and turbine blades cooling.1,2Impinging jets are also used in the hot-air antiicing system of commercial aircraft where high-pressure hot air,bleeding from the engine,is ducted forward to a pipe with several small holes on it and impinges on the inner surface of the anti-icing cavity to heat the leading edge of wing.Since the anti-icing cavity is a curved surface,the effect of surface curvature should be taken into account when the jet impingement heat transfer performance is considered.

    Many experiments were designed to study the heat transfer of impingement jets,with a focus on flat plates.The very early experimental work for the flat plate case were represented by Gardon3,Goldstein4,Hrycak5and Beltaos et al.6with varying impingement distance,Reynolds number and oblique angle.Many measurement techniques based on naphthalene sublimation technique7,temperature-sensitive liquid crystal8,9and thermal infrared camera10,11were adopted to measure and analyze the flow and heat transfer characteristics.

    Metzger et al.12were probably the first to experimentally investigate the heat transfer characteristics of jets impinging on a concave cylindrical surface.The average heat transfer coefficient of single lines of circular jets was obtained with varied ratios of nozzle to surface distanceHand nozzle diameterdat the Reynolds range from 1150 to 5500.Results indicated that the maximum heat transfer could be obtained at the optimum relative nozzle to surfaceH/d=3–5,whose value decreased with increasing Reynolds number.Compared with the heat transfer performance on a flat plate,the stagnation point Nusselt number was higher on the concave cylindrical surface as reported by Hrycak.13Mayle et al.14also presented that the heat transferred to the boundary layer on the concave plate was greater than that on a flat plate.

    Flow visualization facilities with smoke generation wire were applied by Gau and Chung15and Cornaro et al.16to visualize the flow structure of slot and round jet impinging on concave surfaces.The former result showed that the Nusselt number increased with increasing surface curvature for slot jet impingement on a concave surface,which was caused by the initiation of Taylor-Go¨rtler vortices along the surface.Similar observation was also obtained by Cornaro et al.16,who also found that the heat transfer rate on and around the stagnation point increased with increasing surface curvature.Lee et al.17experimentally investigated the local heat transfer from a long round jet impinging on a smaller relative curvature surface(d/D=0.034,0.056,0.089)with jet Reynolds number from 11000 to 50000.Similarly Yang et al.18investigated the concave effect but using a slot jet in the range 5920≤Rej-≤25500,with a fixed slot-width to diameter ratio of 0.033.Their conclusions were consistent and indicated that the surface curvature and generation of Taylor-Go¨rtler vortices were able to thin the boundary layer and enhance the heat transfer rates further in the downstream region apart from the stagnation point.

    Since last decade,impinging jets have been applied to hotair anti-icing system of aircraft and much progress has been achieved.Brown et al.19experimentally investigated the heat transfer in an aircraft nacelle anti-icing system and a correlation of average Nusselt number on the impingement area was presented with consideration of the distance between the jet holes and the jet Reynolds number.Papadakis et al.20,21conducted experiments in the NASA Glenn Icing Research Tunnel for a range of external conditions representative of inflight icing.The effects of hot air mass flow and temperature,angle of attack,tunnel airspeed and piccolo jet circumferential placement were investigated.Imbriale et al.22used IR thermography to measure 3D surface heat transfer coefficients by a row of jets impinging on a concave surface,representing an airfoil leading edge,and the influences of jet inclination,jet pitch and Reynolds number were analyzed.A more recent study by Bu et al.23investigated the heat transfer characteristics of jet impingement on a variable-curvature concave surface of a wing’s leading edge experimentally.Parameters including jet Reynolds number,relative nozzle-to-surface distance and jet circumferential placement were considered for the effects on local Nusselt number distributions.

    All of above researches indicated an enhanced heat transfer performance of jet impingement on concave surfaces.However the confinement effect of concave surface,which could decrease the heat transfer effect,was seldom studied.When studying 3D temperature distribution of a concave semicylindrical surface impinged by round jets,Fenot24noticed that the confinement effect actually reduced heat transfer as the average Nusselt number for the flat plate was higher than that for the curved plate.It was believed that the confinement prevented ambient air from mixing with the jet air,and thereby increased the flow temperature.The range of Reynolds number was from 10000 to 23000,and the relative surface curvatured/D=0.10,0.15,0.20 andH/d=2–5.

    O¨ztekin et al.25investigated the heat transfer characteristics of slot jet impingement on concave surface for jet Reynolds number from 3423 to 9485 and the dimensionless surface curvatureR/L=0.50,0.75 and 1.30,whereRwas the surface radius andLthe surface trace length.Results indicated that,compared with the flat plate,the average Nusselt number along the concave surface was larger whenR/L=0.75 and 1.30.The average Nusselt number increased with increasing dimensionless surface curvatureR/L,in other words,with decreasing relative surface curvatured/D.A slight increase in Nusslet number with decreasingd/Dwas also observed in Martin and wright’s experiment26with single row of round jets impingement on a cylindrical surface.This trend was more prevalent for larger nozzle to surface distances in the range of jet Reynolds number from 5000 to 20000,relative nozzle to nozzle spacing from 2 to 8,nozzle to surface distance from 2 to 8,andd/D=0.18,0.28.

    As briefly reviewed above,although different studies have shown that surface curvature enhanced the heat transfer,detailed mechanism of heat transfer decay on a concave surface is still not well understood.This work conducted an extensive experimental study focusing on the curvature effect along the curved surface.By analyzing the stagnation point Nusselt number,and the average and local Nusselt number distributions in chordwise and spanwise directions,both the enhancement and confinement effects of the surface curvature were investigated.In addition,experimental data-based correlations of the average Nusselt number over the curved surface with consideration of the surface curvature effect were presented and experimentally verified.

    2.Experimental apparatus

    Fig.1 schematically shows the jet impinging system used in this investigation.The main elements of the experimental apparatus were a steel pipe with a round nozzle on it and an impingement surface.Both were mounted on independent brackets to keep the surface horizontal and the pipe vertically removable for different nozzle to surface distances.As indicated in Fig.1,the high pressure air from the air compressor became much cleaner and more stable after passing through the filter and air tank,and then went through the electronic pressure regulator where its pressure was adjusted to the desired value.The adjusted air flowed into the pipe from one side and injected into the center of the surface normally through the nozzle.The other side of the pipe was sealed and the pressure inside the pipe was measured by a pressure sensor.The mass flow through the nozzle was measured by a mass flowmeter.The steel pipe had an outer diameter of 20 mm with an inner diameter of 16 mm.Nozzles with diametersd=1,2,3 mm were used with the nozzle to surface distanceH=10,20,30 mm,respectively.

    Fig.1 Schematic of experimental apparatus.

    The impingement surfaces with different diameters ofD=100 mm,D=200 mm and a flat surface(regarded asD=1)manufactured from aluminum plates with a thickness of 2 mm were used in the experiments(Fig.2).All of these surfaces are kept square with a constant length ofL=150 mm.The relative curvatures can be calculated in Fenot’s way24:Cr=d/D=0.005–0.030,or in O¨ztekin’s way25:D/L=0.67,1.33.

    A thin film(0.02 mm thickness)electrical heater made of constantan provided a uniform heat flux on the opposite side of the jet impingement side of the plate.The high pressure jet impinges on the impingement surface as the coolant.This film was engraved as an electronic circuit with equidistant(2 mm width)constantan wires(Fig.3).Both ends of the film were connected to a DC power supply.In order to reduce the heat loss through the constantan film heater to the ambience,the rubber sponge which has high thermal resistance was employed to cover the film heater so that most of the heat would be conducted to the impingement surface,and the small heat loss was corrected in the preliminary test,as described subsequently.

    57 type T thermocouples placement was indicated in Fig.2.The distance between two adjacent thermocouples was constant in both chordwise and spanwise directions.All thermocouple junctions were located in the blind holes on the aluminum plate with a distance of 0.5 mm away from the jet impingement surface and glued by the adhesives of good heat conduction and electrical insulation.The inlet temperature of the pipe and the environment temperature were also measured in the experiment.All the temperature data were acquired by three Agilent 34970A modules and stored in the computer.All the thermocouples were calibrated in the range of 20℃ to 80℃ before the experiment.

    Fig.2 Test section and impingement plates.

    Fig.3 Constantan film heater.

    3.Data processing

    The general definition of Reynolds number is

    where m is the kinematic viscosity of air,uthe air velocity which is proportional to the jet flow rate and inverse to the sectional area.

    Thus,the jet Reynolds number can be defined as

    whereGmis the jet flow rate,q the air density and l the dynamic viscosity of air.

    The heater powerQof the constantan film is accurately determined by measuring both the voltage dropUacross and currentIthrough the film.

    The heat fluxqin the heated areaAis calculated as

    The local heat transfer coefficienthis defined in terms of the real convective heat flux and the difference between the surface temperatureTsand an appropriate reference temperatureTref.The jet inlet total temperature is employed as the reference temperature in the present experiment.

    whereqlossis the total heat loss caused by radiation and conduction.

    The average heat transfer coefficient is calculated from local heat transfer coefficient by area-weighted integral along lines of chordwise(s)and spanwise(y)directions respectively:

    The local and average Nusselt numbers can be obtained as follows:

    where k is the thermal conductivity of air.

    Table 1 presents the measurement uncertainties of the directly measured parameters,such as the temperature,pressure,voltage and flow rate.Based on the data in Table 1,the uncertainties ofhandNuwere all smaller than 4.3%.

    Table 1 Uncertainties of measuring equipment.

    4.Experimental results and discussions

    4.1.Preliminary test

    Preliminary tests were conducted to calibrate the heat loss and to minimize the experimental error.In the preliminary work,the plate was heated without cold jet impinging on the surface and the temperature data were recorded when the plate came to thermal equilibrium at a certain power applied to the heater.The total heat input is believed equal to the total heat loss caused by radiation and conduction.The total heat loss as a function of temperature difference DTbetween the surface and environment is shown in Fig.4.

    It is indicated from Fig.4 that the linear correlativity between total heat loss and temperature difference is prominent.The dashed lines are linearly fit for the present experimentalresultsofdifferentplatesasdescribed in the following equations:

    For flat plate:

    ForD=200 mm plate:

    ForD=100 mm plate:

    whereR2is the coefficient of determination.

    Thus,the corrected heat flux of the impingement surface can be deduced by subtracting the heat loss from the input total heat flux.All the results in this paper are corrected in the same way.

    4.2.Effect of jet Reynolds number on Nusselt number

    Fig.4 Total heat loss vs temperature difference between surface and environment.

    Fig.5 shows the influence of the jet Reynolds number on the Nusselt number at the stagnation pointNustagfor two concave surfaces at a fixed relative nozzle to surface distanceH/d=10.As shown in Fig.5,the stagnation point Nusselt numberNustagincreases with jet Reynolds numberRejfor both surfaces.It is mainly because the jet with larger Reynolds number brings more momentum and energy impinging on the stagnation point.Similar results were also shown by other researchers such as Yang et al.18and Lee et al.17However,in the wall jet region,high Reynolds number offers high velocity and turbulence intensity as a contribution of the generation of Taylor-Go¨rtler vortices,and thus enhances the heat transfer along the streamwise direction,which extends over the entire surface.Therefore,the average Nusselt numberNuavgover the whole surface also increases with increasing Reynolds number(Fig.6).In brief,the Reynolds number has a significant influence on heat transfer performance at both stagnation point and the entire impingement surface.

    Fig.5 Influence of jet Reynolds number on Nustagfor H/d=10.

    4.3.Effect of relative nozzle to surface distance on Nus

    Fig.7 shows the distributions of local Nusselt numberNusfor flat and curved plates with different jet Reynolds numbers in the chordwise direction.Fig.8 shows the Nusselt number at the stagnation pointNustagfor varying relative nozzle to surface distanceH/d.As shown in Fig.7,the local Nusselt distributions of concave and flat plate indicate the same variation.The effect ofH/don heat transfer is mainly presented near the stagnation region ofs/d<12.5,whereas ats/d>12.5,little difference in Nusslet number can be observed.The maximum value in heat transfer distribution occurs at the stagnation point,and the stagnation point Nusselt number declines with increasingH/d(Fig.8).It is believed that the surrounding air entrained by the high speed jet before impinging on the surface would slow the arrival velocity at the stagnation point.ThusNustagdecreases with increasingH/d.In addition,this attenuation of the jet velocity is completed within a small range near the stagnation point,so the heat transfer is less affected byH/dfor a farther distance.

    Fig.6 Influence of jet Reynolds number on Nuavg.

    Fig.7 Local Nusselt number distributions for flat and curved plates in chordwise direction.

    Fig.8 Nusselt number at stagnation point for varying H/d(d=2 mm).

    4.4.Curvature effects

    Heat transfer distributions affected by curvature along both chordwise and spanwise directions are investigated in this section for jet Reynolds numberRej=27000–130000,relative nozzle to surface distanceH/d=3.3–30,and relative surface curvatured/D=0.005–0.030.The relative surface curvatureCrwas calculated by the ratio of jet diameterdto the surface diameterD,and thus differentCrvalues could be obtained by varying surface diameterD,as well as the jet diameterd.

    4.4.1.Curvature effects on a fixed surface

    The average heat transfer performance varying with the change of relative surface curvature at different Reynolds numbers is shown in Fig.9 for a constant surface diameter ofD=200 mm.Because Reynolds number changes remarkably with the diameter of jet under the same inlet pressure condition,to figure out the effect ofCrat similar Reynolds number,more tests for jet diameters ofd=1.5 mm andd=2.5 mm were conducted.It can be inferred from the figure thatNuavgincreases with the increase ofCrat a given Reynolds number.

    It is consistent with the results of many other studies that relativecurvatureenhancesaverageheattransfer18and increases local Nusselt number15as a consequence of the growing Taylor-Go¨rtler vortices along the streamwise direction.However,the authors believe that,for the same Reynolds number,the higherCrcaused by a larger jet diameter would lead to a larger flow rate according to Eq.(2).As it is proved by Bu et al.23that average heat transfer performance mainly depends on the flow rate,higherCrbrings better average heat transfer in this section.This point can also explain the results of Lee et al.27on the influence of jet diameters,in which they found the local Nusselt number increased with the increasing nozzle diameter near the stagnation point region when Reynolds number was constant.

    4.4.2.Curvature effects with changed surface diameters

    Fig.10 presents average Nusselt number of curved and flat surfaces at differentH/dford=2 mm andRej=64000,85000.The relative curvatureCr=0.01 forD=200 mm surface andCr=0.02 forD=100 mm.The result shows that the average heat transfer performance is weaker for the curved plate than for the flat plate,andNuavgbecomes lower with increasingCr.The data are interesting since it is against the previous results obtained by Gau and Chung15and Yang et al.18As a new attempt,there is no similar investigation that can be a reference to explain this phenomenon.Unlike most researches in which differentCris obtained by altering the jet diameterd,the variedCrin this section is gained by different surface diametersDinstead,which is of high importance in the real aircraft wing anti-icing system as the surface curvature of airfoil changes constantly.

    An appropriate explanation might be the experiment conducted by O¨ztekin et al.25using dimensionless surface curvatureD/Las defined in Section 2 to discuss the curvature effect of a slot jet flow.They found that the average heat transfer performance on the curved plate was stronger than that of theflatplateat1?D/L=2.6.Furthermore,theD/Lincreased both the local and average Nusselt numbers and the best heat transfer performance was obtained atD/L=2.6.In order to compare the present round jet impingement results with theirs,the average Nusselt numbers are recalculated on the equivalent impinging area(Fig.11).As the dimensionless surface curvaturesD/Lin the present work are 0.67 and 1.33,it appears plausible that the different heat transfer performance of the curved plates may be due to the nonreaching of the optimal dimensionless surface curvatureD/Lto get the best performance.

    Fig.9 Average Nusselt numbers for varying Cr on a fixed surface of D=200 mm.

    Fig.10 Average Nusselt number of flat and curved plate for d=2 mm.

    Fig.11 Effect of D/L on average Nusselt number.

    For a better understanding of the effects on different surfaces,the distributions of local Nusselt number in chordwisesand spanwiseydirection near the stagnation region are presented in Fig.12 forD/L=0.67,1.33 and flat surface.As shown in Fig.12,the increase ofD/Lenhances heat transfer at stagnation point asNustagofD/L=1.33 is larger than that of flat surface,whileNustagofD/L=0.67 is smaller.Another evidence ofD/L’s effect can be seen from the Nusselt distribution characteristics betweensandydirection.WhenD/L=1.33,the local Nusselt number insdirection is slightly higher than that inydirection at the same distance.However,whenD/L=0.67,the local Nusselt numbers are approximately equal in both directions.It is indicated that the curvature effect contributes to thinning the boundary layer and raising turbulent intensity insdirection for a largerD/L,while for a smallD/L,the curvature resists the jet flowing alongsdirection and reduces the heat transfer in this direction,where the local Nusselt number is supposed to be larger than that inydirection due to the thinner boundary layer caused by the curvature.

    Fig.12 Nusselt number in s and y direction for Re=86000,d=2 mm.

    Fig.13 Streamlines in velocity profile of y=0 mm.

    Fig.14 Velocity distributions along s and y direction.

    A numerical simulation method is used to provide the important flow features along different directions.Fig.13 shows the streamlines in the velocity profile ofy=0,which indicate that the surrounding air is entrained by the jet.The flow velocity of the jet impinging onD=200 mm surface in the wall jet region is presented in Fig.14.The air velocity alongydirection is higher than that insdirection within a relatively large range near the stagnation point.It is indicated that the curvature confines the flow along chordwise direction,forcing part of the air to flow along the spanwise direction,and therefore reduces the heat transfer.

    5.Experimental data-based correlation equations

    5.1.Correlation equation for fixed surfaces

    To compare with the previous results of other researchers,the correlation equations ofNuavgare given for each concave surface in terms ofRej,H/dand relative surface curvatured/D:

    ForD=100 mm plate,

    ForD=200 mm plate,

    Nuavgvaries according to(Rej)0.689forD=100 mm and(Rej)0.633forD=200 mm,which approximately agrees with Gau and Chung’s15result of(Rej)0.68and Fenot’s24result of(Rej)0.72.The exponential values ofd/Dare much larger than those ofH/d,suggesting that changingH/dwould have much fewer influence onNuavgthan changingd/D.

    The calculated resultsNuavg,cof Eqs.(9)and(10)compared with the experimental dataNuavg,eare presented in Fig.15,which show a very good fitting with the experimental data.

    5.2.Correlation equation for fixed jet diameter

    Fig.15 Comparison between calculated results and experimental data for fixed surfaces.

    Based on the experimental results,the correlation equation of the average Nusselt numberNuavgin terms of jet Reynolds numberRej,relative nozzle to surface distanceH/d,and dimensionless surface curvatureD/Lfor a fixed diameterd=2 mm is obtained as follow:

    Fig.16 Comparison between calculated results and experimental data for d=2 mm.

    The average Nusselt number increases with growing Reynolds number and increasing dimensionless surface curvatureD/L(i.e.,with decreasingd/D),which agrees with the results of O¨ztekin et al.25The calculated results of Eq.(11)compared with the experimental data are presented in Fig.16,which are in good agreement with the experimental data.

    6.Conclusions

    Extensive experimental study of the heat transfer performance of a round jet impingement on concave surfaces under constant heat fluxes were conducted in this work,where the effects of jet Reynolds numberRej,the relative nozzle to surface distanceH/dand the relative surface curvatured/Don local and average Nusselt number were investigated,and experimental data-based correlationNuavgequations were obtained.The major conclusions of the present study have been summarized as follows:

    (1)Both stagnation point and average Nusselt numbers increased significantly with increasing jet Reynolds number,suggesting that increasing the inlet jet pressure or

    flow rate is an effective way to enhance the heat transfer of an anti-icing system.

    (3)Two opposite effectsof surfacecurvature on jet impingement heat transfer performance were observed.For a fixed surface diameter,the relative surface curvatured/Dincreased both stagnation point and average Nusselt numbers with increasing jet diameterd.In contrast,for a fixedd,the average Nusselt number declined with increasingd/D.TheNuavgincreased as the dimensionless surface curvatureD/Lincreased before reaching the maximum value for an optimalD/L.

    (4)Under the same jet impingement condition(jet diameter and inlet pressure),the average Nusselt number over the entire surface was influenced more by the confinement effect than by the enhancement effect within the range of the present experiment,leading to a smallerNuavgfor the concave surfaces.

    Further experiments of jet impingement on large surface diameters are planned to identify the optimumd/Dfor a givend,and to examine the practical anti-icing effect under different curvatures.

    Acknowledgements

    This work was supported by the National Natural Science Foundation of China(No.51206008)and the EU Marie Curie Actions-InternationalIncoming Fellowships (No.FP7-PEOPLE-2013-IIF-626576).

    1.Zhang JZ,Xie H,Yang CF.Numerical study of flow and heat transfer characteristics of impingement/effusion cooling.Chin J Aeronaut2009;22(4):343–8.

    2.Liu HY,Liu CL,Wu WM.Numerical investigation on the flow structures in a narrow confined channel with staggered jet array arrangement.Chin J Aeronaut2015;28(6):1616–28.

    3.Gardon R,Cobonpue J.Heat transfer between a flat plate and jets of air impinging on it.International heat transfer conference;1961.p.454–60.

    4.Goldstein RJ,Behbahani AI,Heppelmann K.Streamwise distribution of the recovery factor and the local heat transfer coefficient to an impinging circular air jet.Int J Heat Mass Transf1986;29(8):1227–35.

    5.Hrycak P.Heat transfer from round impinging jets to a flat plate.Int J Heat Transf1983;26(12):1857–65.

    6.Beltaos S.Oblique impingement of circular turbulent jets.J Hydraulic Res1976;14(1):17–36.

    7.Sparrow EM,Lovell BJ.Heat transfer characteristics of an obliquely impinging circular.J Heat Transf ASME1980;102(2):202–9.

    8.Goldstein RJ,Timmers JF.Visualization of heat transfer from arrays of impinging jets.Int J Heat Mass Transf1982;25(12):1857–68.

    9.Goldstein RJ,Franchett ME.Heat transfer from a flat surface to an oblique impinging jet.J Heat Transf ASME1988;110(1):84–90.

    10.Lytle D,Webb BW.Air jet impingement heat transfer at low nozzle-plate spacings.IntJHeatMassTransf1994;37(12):1687–97.

    11.Attalla M,Salem M.Experimental investigation of heat transfer for a jet impinging obliquely on a flat surface.Exp Heat Transf2015;28(4):378–91.

    12.Metzger DE,Yamashita T,Jenkins CW.Impingement cooling of concave surfaces with lines of circular air jets.J Eng Power1969;91(3):149–55.

    13.Hrycak P.Heat transfer from a row of impinging jets to concave cylindrical surfaces.Int J Heat Mass Transf1981;24(3):407–19.

    14.Mayle RE,Blair MF,Kopper FC.Turbulent boundary layer heat transfer on curved surfaces.J Heat Transf ASME1979;101(3):521–5.

    15.Gau C,Chung CM.Surface curvature effect on slot-air-jet impingement cooling flow and heat transfer process.J Heat Transf ASME1991;113(4):858–64.

    16.Cornaro C,Fleischer AS,Goldstein RJ.Flow visualization of a round jet impinging on cylindrical surfaces.Exp Therm Fluid Sci1999;20(2):66–78.

    17.Lee DH,Chung YS,Won SY.The effect of concave surface curvature on heat transfer from a fully developed round impinging jet.Int J Heat Mass Transf1999;42(13):2489–97.

    18.Yang G,Choi M,Lee JS.An experimental study of slot jet impingement cooling on concave surface:effects of nozzle configuration and curvature.IntJHeatMassTransf1999;42(12):2199–209.

    19.Brown JM,Raghunathan S,Watterson JK,Linton AJ,Riordon D.Heat transfer correlation for anti-icing systems.J Aircraft2002;39(1):65–70.

    20.Papadakis M,Wong SJ,Yeong HW,Wong SC.Icing tunnel experiments with a hot air anti-icing system.Reston:AIAA;2008.Report No.:AIAA-2008-0444.

    21.Papadakis M,Wong SJ,Yeong HW,Wong SC.Icing tests of a wing model with a hot-air ice protection system.Reston:AIAA;2010.Report No.:AIAA-2010-7833.

    22.Imbriale M,Ianiro A,Meola C,Cardone G.Convective heat transfer by a row of jets impinging on a concave surface.Int J Therm Sci2014;75(1):153–63.

    23.Bu XQ,Peng L,Lin GP,Bai LZ.Experimental study of jet impingement heat transfer on a variable-curvature concave surface in a wing leading edge.Int J Heat Mass Transf2015;90(1):92–101.

    24.Fenot M,Dorignac E,Vullierme JJ.An experimental study on hot round jets impinging a concave surface.Int J Heat Fluid Flow2008;29(4):945–56.

    26.Martin EL,Wright LM,Crites DC.Impingement heat transfer enhancement on a cylindrical,leading edge model with varying jet temperatures.J Turbomach2012;135(3):323–34.

    27.Lee DH,Song J,Jo MC.The effects of nozzle diameter on impinging jet heat transfer and fluid flow.J Heat Transf2004;126(4):554–7.

    27 June 2016;revised 20 October 2016;accepted 21 December 2016

    Available online 21 February 2017

    *Corresponding author.

    E-mail address:buxueqin@buaa.edu.cn(X.Bu).

    Peer review under responsibility of Editorial Committee of CJA.

    svipshipincom国产片| 日本免费一区二区三区高清不卡| avwww免费| 久久久国产精品麻豆| 亚洲成av人片免费观看| 亚洲第一电影网av| 一级黄色大片毛片| 国产真人三级小视频在线观看| 成人免费观看视频高清| 久久久精品国产亚洲av高清涩受| 精品卡一卡二卡四卡免费| 在线观看66精品国产| 久久人人精品亚洲av| 亚洲精品国产精品久久久不卡| 俺也久久电影网| 欧美另类亚洲清纯唯美| 男女那种视频在线观看| 亚洲中文日韩欧美视频| 久久久久免费精品人妻一区二区 | 欧美最黄视频在线播放免费| 免费在线观看日本一区| 看免费av毛片| 中文字幕久久专区| 人妻丰满熟妇av一区二区三区| xxx96com| 免费观看精品视频网站| 精品久久久久久久人妻蜜臀av| 色播在线永久视频| 精品久久久久久久人妻蜜臀av| 又黄又粗又硬又大视频| 欧美不卡视频在线免费观看 | 日韩免费av在线播放| 午夜福利欧美成人| 免费看十八禁软件| 高潮久久久久久久久久久不卡| 夜夜看夜夜爽夜夜摸| 欧美午夜高清在线| 国产欧美日韩一区二区精品| 免费在线观看日本一区| 久久久久久九九精品二区国产 | 久久久久久国产a免费观看| 青草久久国产| 久久草成人影院| 精品国产乱子伦一区二区三区| 精品一区二区三区视频在线观看免费| 久久久水蜜桃国产精品网| 午夜精品在线福利| 热re99久久国产66热| 18禁观看日本| 香蕉丝袜av| 久久久久久亚洲精品国产蜜桃av| 女性被躁到高潮视频| 美女免费视频网站| av视频在线观看入口| 国产成人欧美在线观看| 又黄又粗又硬又大视频| 他把我摸到了高潮在线观看| 久久午夜亚洲精品久久| 国产精品电影一区二区三区| 亚洲av成人不卡在线观看播放网| 搡老妇女老女人老熟妇| 黄色丝袜av网址大全| 国产精品1区2区在线观看.| 男女下面进入的视频免费午夜 | 亚洲午夜理论影院| 99re在线观看精品视频| 国产成人影院久久av| 观看免费一级毛片| 亚洲午夜理论影院| 精品国产亚洲在线| 亚洲精品美女久久av网站| 国产精品久久久久久人妻精品电影| 午夜福利成人在线免费观看| 一级a爱视频在线免费观看| 一区二区日韩欧美中文字幕| 国产亚洲av嫩草精品影院| 久久久久久久久免费视频了| 久久精品人妻少妇| 日本a在线网址| 特大巨黑吊av在线直播 | 久久午夜亚洲精品久久| 看黄色毛片网站| 久久久久亚洲av毛片大全| 免费高清在线观看日韩| 欧美成人免费av一区二区三区| 日韩精品中文字幕看吧| 岛国视频午夜一区免费看| 成人手机av| 看免费av毛片| 在线视频色国产色| 视频在线观看一区二区三区| 日日摸夜夜添夜夜添小说| ponron亚洲| 成人亚洲精品一区在线观看| 久久久久国产一级毛片高清牌| 婷婷亚洲欧美| 亚洲国产欧洲综合997久久, | 一级a爱片免费观看的视频| 日本免费a在线| 亚洲欧美精品综合久久99| 日韩精品中文字幕看吧| 亚洲久久久国产精品| 久久久国产成人免费| 免费一级毛片在线播放高清视频| 亚洲美女黄片视频| 亚洲一码二码三码区别大吗| 久久伊人香网站| 国产视频一区二区在线看| 亚洲男人天堂网一区| 亚洲色图 男人天堂 中文字幕| 成人欧美大片| 搡老岳熟女国产| 久久亚洲真实| 窝窝影院91人妻| 亚洲av成人不卡在线观看播放网| 欧美zozozo另类| 久久伊人香网站| 精品一区二区三区视频在线观看免费| 国产精品精品国产色婷婷| 中出人妻视频一区二区| 久久精品91蜜桃| 亚洲精品粉嫩美女一区| xxxwww97欧美| 亚洲五月色婷婷综合| 亚洲国产欧洲综合997久久, | 亚洲片人在线观看| 禁无遮挡网站| 欧美日本视频| 日韩欧美一区二区三区在线观看| 别揉我奶头~嗯~啊~动态视频| 久久精品国产综合久久久| 国产真人三级小视频在线观看| 久久天躁狠狠躁夜夜2o2o| 国产精品一区二区免费欧美| 国产av在哪里看| 中文字幕另类日韩欧美亚洲嫩草| 成人18禁高潮啪啪吃奶动态图| 亚洲熟女毛片儿| 国产在线观看jvid| 国产一区在线观看成人免费| 欧美黄色片欧美黄色片| 国产精品av久久久久免费| 大香蕉久久成人网| 在线看三级毛片| 级片在线观看| 久久精品亚洲精品国产色婷小说| 麻豆久久精品国产亚洲av| 18禁黄网站禁片免费观看直播| 久久久久久久久久黄片| 久久久久久久精品吃奶| 97超级碰碰碰精品色视频在线观看| 我的亚洲天堂| 又紧又爽又黄一区二区| 国产高清激情床上av| 欧美激情高清一区二区三区| 国产av又大| 精品卡一卡二卡四卡免费| 亚洲国产看品久久| 麻豆成人午夜福利视频| 手机成人av网站| 黄片小视频在线播放| 人人妻人人澡人人看| 超碰成人久久| 变态另类丝袜制服| 亚洲欧美精品综合久久99| 中文亚洲av片在线观看爽| 国产精品九九99| 狂野欧美激情性xxxx| 又紧又爽又黄一区二区| 黄色视频,在线免费观看| 日本三级黄在线观看| 老司机靠b影院| 极品教师在线免费播放| 午夜久久久久精精品| 一进一出抽搐gif免费好疼| 久久中文字幕一级| 午夜免费鲁丝| 国产精品香港三级国产av潘金莲| 后天国语完整版免费观看| 久久久久免费精品人妻一区二区 | 日韩一卡2卡3卡4卡2021年| 国产精品国产高清国产av| 亚洲成av片中文字幕在线观看| 99热6这里只有精品| 老熟妇乱子伦视频在线观看| 久久香蕉国产精品| 国内久久婷婷六月综合欲色啪| 久久久久久人人人人人| 又大又爽又粗| 亚洲va日本ⅴa欧美va伊人久久| 免费电影在线观看免费观看| 欧美中文日本在线观看视频| 成人av一区二区三区在线看| 一级片免费观看大全| 亚洲 欧美一区二区三区| 波多野结衣av一区二区av| 久久久久九九精品影院| 一本综合久久免费| 深夜精品福利| 亚洲国产精品久久男人天堂| 此物有八面人人有两片| 制服诱惑二区| 婷婷精品国产亚洲av| 19禁男女啪啪无遮挡网站| 精品午夜福利视频在线观看一区| www.自偷自拍.com| 国产色视频综合| 人人妻人人看人人澡| 日韩欧美一区视频在线观看| 日本一区二区免费在线视频| 久久精品91蜜桃| 欧美另类亚洲清纯唯美| 97碰自拍视频| 亚洲精华国产精华精| 99精品在免费线老司机午夜| 丁香欧美五月| 久久久精品国产亚洲av高清涩受| 亚洲欧美精品综合一区二区三区| 成人亚洲精品一区在线观看| 欧美一级a爱片免费观看看 | 中亚洲国语对白在线视频| 国产1区2区3区精品| 久久亚洲精品不卡| 国产成人一区二区三区免费视频网站| 精品一区二区三区视频在线观看免费| 亚洲七黄色美女视频| 中文字幕久久专区| 国产欧美日韩一区二区三| bbb黄色大片| 婷婷精品国产亚洲av| 一个人免费在线观看的高清视频| 久久青草综合色| 国产又色又爽无遮挡免费看| 97超级碰碰碰精品色视频在线观看| 亚洲中文字幕日韩| 欧美在线一区亚洲| 久久精品亚洲精品国产色婷小说| 国产午夜精品久久久久久| 午夜久久久在线观看| 久久欧美精品欧美久久欧美| 真人一进一出gif抽搐免费| 欧美精品啪啪一区二区三区| 成在线人永久免费视频| 中文字幕av电影在线播放| 久久婷婷人人爽人人干人人爱| 很黄的视频免费| 日韩中文字幕欧美一区二区| 老鸭窝网址在线观看| 9191精品国产免费久久| 亚洲av美国av| 国产精品 欧美亚洲| 女人高潮潮喷娇喘18禁视频| 午夜免费激情av| 国产精品乱码一区二三区的特点| 久久久国产精品麻豆| 最近最新中文字幕大全电影3 | 精品一区二区三区四区五区乱码| 亚洲国产欧美日韩在线播放| 男女视频在线观看网站免费 | 2021天堂中文幕一二区在线观 | 美女大奶头视频| 久99久视频精品免费| 在线观看66精品国产| 国产伦人伦偷精品视频| 黑人操中国人逼视频| 国产成年人精品一区二区| 亚洲avbb在线观看| 亚洲国产精品sss在线观看| 可以在线观看的亚洲视频| 久久国产精品影院| 欧美在线一区亚洲| 日本熟妇午夜| 日韩欧美免费精品| 9191精品国产免费久久| 欧美日韩中文字幕国产精品一区二区三区| 久久久久久久久免费视频了| 国产91精品成人一区二区三区| 亚洲成国产人片在线观看| 午夜视频精品福利| 免费看美女性在线毛片视频| 久久久久国产一级毛片高清牌| 亚洲欧洲精品一区二区精品久久久| 日本撒尿小便嘘嘘汇集6| 中文资源天堂在线| av在线播放免费不卡| 在线观看日韩欧美| 国产精品亚洲美女久久久| 国产真人三级小视频在线观看| 亚洲aⅴ乱码一区二区在线播放 | 亚洲欧美激情综合另类| 欧美成人午夜精品| 国产精品精品国产色婷婷| xxx96com| 国产精品久久久av美女十八| 精品欧美国产一区二区三| 两性午夜刺激爽爽歪歪视频在线观看 | 中文字幕高清在线视频| 亚洲真实伦在线观看| 国产亚洲av嫩草精品影院| 在线观看舔阴道视频| 午夜a级毛片| 久久性视频一级片| 91九色精品人成在线观看| 精品国产一区二区三区四区第35| www.www免费av| 可以在线观看毛片的网站| 此物有八面人人有两片| 亚洲欧美一区二区三区黑人| 国产人伦9x9x在线观看| 免费在线观看影片大全网站| 亚洲九九香蕉| 国内久久婷婷六月综合欲色啪| 免费在线观看影片大全网站| 国产精品av久久久久免费| 91麻豆av在线| 动漫黄色视频在线观看| 亚洲无线在线观看| 国产精品久久电影中文字幕| 色哟哟哟哟哟哟| 久久久精品欧美日韩精品| 久久伊人香网站| 999久久久国产精品视频| 日韩欧美免费精品| 淫妇啪啪啪对白视频| 欧美日本亚洲视频在线播放| 一夜夜www| 亚洲欧美日韩高清在线视频| 美女高潮喷水抽搐中文字幕| 最新美女视频免费是黄的| 午夜福利一区二区在线看| 老司机福利观看| 美女大奶头视频| 国产区一区二久久| 精品久久久久久,| 老司机午夜十八禁免费视频| 婷婷精品国产亚洲av在线| 免费在线观看黄色视频的| 12—13女人毛片做爰片一| 制服诱惑二区| 国产精品综合久久久久久久免费| 国产极品粉嫩免费观看在线| 999久久久国产精品视频| 一级作爱视频免费观看| 久久久久久九九精品二区国产 | 国产成人av激情在线播放| 国产一卡二卡三卡精品| 亚洲人成网站高清观看| 国产一卡二卡三卡精品| 久久久久久久久免费视频了| 亚洲精品美女久久久久99蜜臀| 精品第一国产精品| 一二三四社区在线视频社区8| 精品一区二区三区av网在线观看| 长腿黑丝高跟| 国产1区2区3区精品| 国产一区二区在线av高清观看| 人妻丰满熟妇av一区二区三区| 亚洲av美国av| 亚洲 欧美一区二区三区| 免费高清视频大片| 可以在线观看毛片的网站| 亚洲精品美女久久av网站| 久久青草综合色| 亚洲精品美女久久av网站| 看免费av毛片| 亚洲无线在线观看| 免费在线观看日本一区| 色综合亚洲欧美另类图片| 欧美中文综合在线视频| 97人妻精品一区二区三区麻豆 | 日本免费一区二区三区高清不卡| 亚洲成人久久爱视频| 国产精品99久久99久久久不卡| 欧美zozozo另类| 曰老女人黄片| 免费看十八禁软件| 成人特级黄色片久久久久久久| 99riav亚洲国产免费| 久久香蕉精品热| 大香蕉久久成人网| 少妇粗大呻吟视频| 亚洲欧美激情综合另类| 国产精品久久久av美女十八| 精品午夜福利视频在线观看一区| 久热这里只有精品99| 欧美国产日韩亚洲一区| 亚洲男人天堂网一区| 精品久久久久久久久久免费视频| 天堂动漫精品| 亚洲中文日韩欧美视频| 国产亚洲精品久久久久5区| 久久久久免费精品人妻一区二区 | 啦啦啦韩国在线观看视频| 免费高清视频大片| 人人妻人人看人人澡| 成在线人永久免费视频| 欧美日韩瑟瑟在线播放| 最近最新免费中文字幕在线| 久久久久久免费高清国产稀缺| 给我免费播放毛片高清在线观看| 日本免费一区二区三区高清不卡| 国产亚洲欧美98| 欧美av亚洲av综合av国产av| 色综合欧美亚洲国产小说| 一级a爱片免费观看的视频| 欧美日韩亚洲国产一区二区在线观看| www日本黄色视频网| 成熟少妇高潮喷水视频| 1024香蕉在线观看| 中文字幕av电影在线播放| 亚洲av电影在线进入| 亚洲国产日韩欧美精品在线观看 | 国产精品免费视频内射| 黄片大片在线免费观看| 久久久久久人人人人人| av片东京热男人的天堂| 中文字幕人成人乱码亚洲影| 国产激情久久老熟女| 国产成人系列免费观看| 久久久久国产一级毛片高清牌| 男女下面进入的视频免费午夜 | 亚洲成人久久性| 丝袜人妻中文字幕| 亚洲精品在线美女| 久久香蕉激情| 老汉色∧v一级毛片| 国产精华一区二区三区| 欧美一区二区精品小视频在线| 操出白浆在线播放| 久久久国产欧美日韩av| 亚洲国产中文字幕在线视频| avwww免费| 一本精品99久久精品77| 国产三级黄色录像| 亚洲专区字幕在线| 老鸭窝网址在线观看| 精品少妇一区二区三区视频日本电影| 欧美乱妇无乱码| www日本黄色视频网| 亚洲avbb在线观看| 亚洲精品色激情综合| 国产99久久九九免费精品| 免费高清在线观看日韩| 老熟妇乱子伦视频在线观看| 久久九九热精品免费| 亚洲 国产 在线| 国产亚洲欧美98| av欧美777| 色尼玛亚洲综合影院| 亚洲国产欧洲综合997久久, | 久久久久久久精品吃奶| 动漫黄色视频在线观看| 亚洲欧美激情综合另类| av欧美777| 精品久久久久久久久久免费视频| 亚洲狠狠婷婷综合久久图片| 岛国在线观看网站| 男人的好看免费观看在线视频 | 老汉色av国产亚洲站长工具| 精品久久久久久久久久久久久 | 国产亚洲精品一区二区www| 亚洲第一青青草原| 免费在线观看亚洲国产| 亚洲精品国产区一区二| 国产精品 国内视频| 日韩国内少妇激情av| 黄色视频,在线免费观看| 精品高清国产在线一区| 久久久水蜜桃国产精品网| 两个人看的免费小视频| 国产欧美日韩一区二区三| 欧洲精品卡2卡3卡4卡5卡区| 中文字幕人成人乱码亚洲影| 十分钟在线观看高清视频www| 好男人电影高清在线观看| 久久久久九九精品影院| 亚洲欧美精品综合一区二区三区| 亚洲一码二码三码区别大吗| 一本大道久久a久久精品| av在线天堂中文字幕| 精品高清国产在线一区| 美女高潮到喷水免费观看| 精品国内亚洲2022精品成人| 亚洲av成人av| 免费在线观看日本一区| 一二三四社区在线视频社区8| 我的亚洲天堂| 91av网站免费观看| 夜夜看夜夜爽夜夜摸| 99热6这里只有精品| avwww免费| 中文字幕久久专区| 一夜夜www| 一区二区三区激情视频| 亚洲欧美激情综合另类| 在线永久观看黄色视频| 一级毛片高清免费大全| 亚洲一码二码三码区别大吗| 老司机靠b影院| 少妇的丰满在线观看| 免费av毛片视频| 波多野结衣巨乳人妻| 久久久久久久精品吃奶| 国产高清视频在线播放一区| 老司机福利观看| 亚洲熟妇中文字幕五十中出| 欧美 亚洲 国产 日韩一| 在线观看免费日韩欧美大片| 国产三级在线视频| 正在播放国产对白刺激| or卡值多少钱| av免费在线观看网站| 麻豆成人午夜福利视频| 99re在线观看精品视频| 亚洲 欧美一区二区三区| 亚洲精品中文字幕一二三四区| 亚洲精品在线美女| 可以免费在线观看a视频的电影网站| 黄片小视频在线播放| 久久久久免费精品人妻一区二区 | 超碰成人久久| 午夜精品在线福利| 成人三级黄色视频| 淫妇啪啪啪对白视频| 免费女性裸体啪啪无遮挡网站| 国产亚洲精品久久久久久毛片| 久久这里只有精品19| 黄色女人牲交| 精品卡一卡二卡四卡免费| 久久精品成人免费网站| 亚洲真实伦在线观看| 中文在线观看免费www的网站 | 亚洲第一欧美日韩一区二区三区| 99热只有精品国产| 老司机深夜福利视频在线观看| 亚洲成av人片免费观看| 亚洲第一av免费看| 啦啦啦观看免费观看视频高清| 久久精品国产亚洲av高清一级| 老司机靠b影院| 午夜福利成人在线免费观看| 国产三级黄色录像| 一二三四在线观看免费中文在| 国产精品美女特级片免费视频播放器 | 两性午夜刺激爽爽歪歪视频在线观看 | x7x7x7水蜜桃| 1024香蕉在线观看| 又黄又粗又硬又大视频| 国产欧美日韩一区二区精品| 亚洲国产看品久久| 亚洲中文日韩欧美视频| 十八禁人妻一区二区| av天堂在线播放| 天堂影院成人在线观看| 国产精品精品国产色婷婷| 亚洲国产高清在线一区二区三 | 日韩精品青青久久久久久| 黄色丝袜av网址大全| 久久中文字幕人妻熟女| 亚洲一区二区三区色噜噜| 欧美成人免费av一区二区三区| 亚洲精品粉嫩美女一区| 一二三四在线观看免费中文在| 99久久精品国产亚洲精品| 久久久久久久久久黄片| 天天一区二区日本电影三级| 操出白浆在线播放| 极品教师在线免费播放| 日本黄色视频三级网站网址| 成年女人毛片免费观看观看9| АⅤ资源中文在线天堂| 搞女人的毛片| 亚洲人成电影免费在线| 在线永久观看黄色视频| 国产精品亚洲美女久久久| 1024手机看黄色片| 国产主播在线观看一区二区| 一区二区三区国产精品乱码| 高清毛片免费观看视频网站| 国产又爽黄色视频| 一区二区三区国产精品乱码| 一本久久中文字幕| 天天躁狠狠躁夜夜躁狠狠躁| 国产激情欧美一区二区| 视频在线观看一区二区三区| 亚洲欧美日韩无卡精品| 窝窝影院91人妻| 久久久久国内视频| 丁香欧美五月| 一级毛片高清免费大全| 男人的好看免费观看在线视频 | 日韩av在线大香蕉| 国产精品影院久久| 国产成人av激情在线播放| 少妇裸体淫交视频免费看高清 | 久久婷婷成人综合色麻豆| 法律面前人人平等表现在哪些方面| 国产一区二区三区在线臀色熟女| 老司机在亚洲福利影院| 亚洲免费av在线视频| 99在线人妻在线中文字幕| av免费在线观看网站| 首页视频小说图片口味搜索| 日韩三级视频一区二区三区| 亚洲专区国产一区二区| 成年女人毛片免费观看观看9| 久久香蕉国产精品| 亚洲熟女毛片儿| 欧美另类亚洲清纯唯美| 99国产综合亚洲精品| 日韩欧美 国产精品| 一本精品99久久精品77| 亚洲av熟女| 亚洲精品一区av在线观看| 亚洲 欧美一区二区三区|