英语翻译中文六

Fig.11ashowsthevelocityprofilesoftheplaneparalleltothejetaxis(x–yplane)atz=0betweenstreamwisedistance,xof0.1and1.3mwithanincrementofevery0.1m.图11a示出了在流向距离x为0.1和0.3之间（以每0.1m的增量）z＝0时，平行于射流轴线的平面（x－y平面）的速度剖面。Fig.11ashowstheevolutionofthejetvelocityprofileanditsdevelopmentdownstream.图11a示出了射流速度分布的演变及其向下游的发展。Itbeginsasa‘top-hat’profileclosetothejetnozzle,eventuallyformingafully-developedprofilefurtherdownstream.它以接近喷嘴的“大礼帽”分布开始，最终在进一步的下游形成一个完全展开的剖面。Thisvariationcharacterizesthespreadingofthemomentum-deficitshearlayersthatwereshedfromthetopandbottomnozzleedgesbyentrainmentastheflowprogressesdownstream.这样的变化表征了动量损失剪切层（momentum-deficitshearlayer）的扩展，它们随着气流向下游进展而作为夹带由喷嘴顶部和底部边缘脱离而形成。Theendofthejet’spotentialcoreisclearlyseentobesituatedbetweenx=0.8and0.9m,or3.6–4Dh,whereDh,isthehydraulicdiameterofthenozzle.射流势核的末端可清楚看到是位于x＝0.8和0.9m之间，或3.6－4Dh之间，这里Dh为喷嘴的水力直径。ItisexpectedthatthislengthisrelativelyconstantovertherangeofReynoldsnumbersproposedhere.据预料，这一长度在这里提出的雷诺数范围内是相对恒定不变的。Thedistributionofthevelocityprofilesaveragedacrossthey-axisatdifferentspanwiselocationofthenozzleexitplaneatx=0.05misshowninFig.11b.在x＝0.05m的喷嘴出口平面的不同展向位置，跨y轴平均的速度剖面分布示于图11b。Fromthefigure,apartfromtheleftandrightedgeswheremixinglayersexist,thevelocityprofileacrossthenozzleexitplaneisfoundtobeuniformwithanaveragejetvelocityof21.6m/sinthisexample.从此图可以看出，在这一例子中，除了存在混合层的左右边缘外，跨喷嘴出口平面的速度剖面在21.6m/s的平均射流速度下都是均匀的。Flowuniformitywasdemonstratedbythesmallerrorbarscorrespondingtothemaximumandminimumvelocitydeviationsinsidethepotentialcore.流速的均匀性由势核内最大和最小速度偏差所对应的小误差范围所证实。TheresultsinFig.11aandbprovideaclearindicationoftheextentandprofileofthepotentialcoreinwhichtheairfoilmustbecompletelylocatedtoperformthetrailingedgeself-noisestudytoavoidthenoisecontributionfrominteractionwithextraneousturbulence.图11a和b中的结果清楚的表明了机翼必须完全位于在内，以进行拖尾边缘自噪声研究，从而避免噪声贡献与外来湍流相互作用的势核的范围和剖面。TheturbulenceintensityintheexitjetwasmeasuredusingaTSI1210-T1.5miniaturehotwireprobewith3.8lmdiameter.出口射流中的湍流强度用一台3.8lm直径的TSI1210－T1.5小型热线风速仪进行测量。Thesamecomputer-controlledtraversesystemwasusedtomeasureatseveralpointsfromthenozzleedgetothecentreinasinglerun.采用相同的计算机控制的横移系统在一次行程中测量从喷嘴边缘到中心的若干点。Fig.12showsthedistributionoftheturbulenceintensityalongthez-axisofthefreejetat60m/sfromthenozzleedge(z=0.225m)tothecentre(z=0).图12示出了湍流强度沿着从喷嘴边缘（z＝0.225m）到中心（z＝0）、60m/s速度的自由射流x轴线的分布。Thismeasurementwasperformedatastreamwisedistance,x=0.1mawayfromthenozzleexit.这一测量是在离喷嘴出口的流向距离x＝0.1m处进行的。Apartfromthefirstpointneartheedgethatislocatedwithintheshearlayer,thepotentialcoreofthefreejethasatypicalturbulenceintensityofabout0.1%.除了靠近位于剪切层内的边缘的第一点以外，自由射流的势核具有大约0.1％的典型湍流强度。Thisvalueiswellbelowtheinitialtargetof0.5%.Withsuchlowdisturbancelevelinthefreeflow,extraneousnoisecausedbytheinteractionofthejetturbulencewiththeairfoilleadingedgeislikelytobeinsignificant.此值大大低于0.5％的初始目标。由于在自由流动中这么低的扰动水平，所以由射流湍流与机翼前缘的相互作用所引起的外来噪声很可能是不显著的。