英语翻译As mentioned above,when the velocity on the duct induced

英语翻译
As mentioned above,when the velocity on the duct induced by propeller is computed,two different treatments are applied.Fig.4 gives the comparison of results obtained by two treatments,in which“CAV”and“NAV”denote circumferentially averaged and not averaged treatments respectively.It is seen from Fig.4 that the thrust of duct at lowadvance coefficient can be improved when the induced velocity of propeller to duct is not circumferentially averaged,namely the wake behind the duct exists.This conclusion is coincident with that from Ref.[7].
In Figs.5 and 6,parameter BTKI is a coefficient determining the hydrodynamic pitch angle in the transition region of the wake of propeller.Usually BTKI=0.5 is adopted by panel method for the single propeller.It can be seen from Figs.5 and 6 that BTKI=0.43 gives better results for the case of JD7704 duct+KA propeller series and BTKI=0.48 for the case of JD7704 duct + JDC propeller series.
In the numerical calculations of panel method,the trialing wake sheet of the propellerand duct are truncated at certain distance behind the propeller or duct.Fig.7 shows that reasonable results can be obtained when transition wake range of the propeller is 1080 degrees.It is found from the Fig.8 that the numerical result becomes converged gradually with the increment of region of trailing vortex wake of duct,and there will be no effect on the thrust of duct if the wake length of the duct is over four times of the length of the duct,which will be used in the following calculations.Fig.9 shows that the contraction coefficient of the transition wake of the propeller,RW0,makes no influence on the calculated results,even RW0=0.83,0.98 or 1.0 (“No Contra”in the figure).RW0=0.83 is adopted in the present paper.

如上述提到的,当计算出由螺旋桨在导管上引起的周转率时,可应用两种措施.图4给出了两种措施的结果比较,分别在“恒定角速率”及“NAV 环绕地表示平均处理与不平均处理时的情况.从图4看出当螺旋桨的诱导速度对导管环绕不平均时,低推进系数上的导管推力可以得到改善,也就是说导管后面的尾迹是存在的.这个结论与文献[7]是一致的.
在图5和图6,BTKI参数决定了螺旋桨尾迹的转变区水动力螺距角的系数.通常BTKI=0.5时单一螺旋桨采用板块法.从图5和图6可看出,当BTKI=0.43时,对JD7704 导管+KA螺旋桨系列与BTKI=0.48时,对JD7704导管+JDC螺旋桨系列可以给出更好的结果.
再问： 求大神再帮我翻译下补充的内容，追加30分，拜托了，万分感谢。
再答： 在板块法的数值计算中，在螺旋桨或导管后面的螺旋管尾部尾迹薄板与导管被缩短到一定的距离。图7显示出当螺旋桨的转变区尾迹范围值为1080度时可以获得合理的结果。从图8可以发现当导管的尾部涡流尾迹的范围增量时数值结果会逐渐变得聚合起来，并且如果导管尾迹的长度超过导管长度的4倍时将会对导管推力没有影响，这将会被使用到下面计算。图9显示了螺旋桨转变区尾迹的收缩系数: RW0，这对计算结果没有影响，即使RW0=0.83, 0.98 或 1.0 （图表“没有对立面”）时对计算结果还是没有影响的。本论文采取了RW0=0.83的值 。 第二部分手工翻译如上，希望帮到你。