英语翻译英译汉,不要图片形式,公式不必翻译If there is no viscous separation or induced downwash,the leading-edge suction force exactly balances the rearward component of the normal force and the airfoil experiences zero drag.This is

英语翻译英译汉,不要图片形式,公式不必翻译If there is no viscous separation or induced downwash,the leading-edge suction force exactly balances the rearward component of the normal force and the airfoil experiences zero drag.This is
英语翻译
英译汉,不要图片形式,公式不必翻译
If there is no viscous separation or induced downwash,the leading-edge suction force exactly balances the rearward component of the normal force and the airfoil experiences zero drag.This is the idea 2-D case described by d’Alembert’s paradox,and is called“100% leading-edge suction.”
A 3-D wing is considered to have 100% leading-edge suction when the Oswald efficiency factor (e) exactly equals 1.0.When e equals 1.0,the induced-drag constant K exactly equals the inverse of the aspect ratio times π.
On the right side of Fig.12.35 is a zero-thickness flat-plate airfoil.Even without the leading-edge separation,which will almost certainly occur,this airfoil must have higher drag because there is no forward-facing area for the leading-edge pressure forces to act against.All pressure force for a zero-thickness flat plate must act in a direction perpendicular to the plate,shown as N.There is zero leading-edge suction,and the lift and induced drag are simply .
Thus,in the worst case of zero leading-edge suction,the drag-due-to-lift factor K is simply the inverse of the slope of the life curve (in radians),as previously determined.
All real wings operate somewhere between 100 and 0% leading-edge suction.The percentage of leading-edge suction a wing attains is called S (not to be confused with the force S in Fig.12.35).
During subsonic cruise,a wing with moderate sweep and a large leading-edge radius will have S equal to about 0.85-0.95(85-95% leading-edge suction).The wing of a supersonic fighter in a high-g turn may have an S approaching zero.
The following method for calculating K for high-speed aircraft is based upon an empirical estimate of the actual percent of leading-edge suction attainable by a wing,which is then applied to the calculated K values for 100 and 0% leading-edge suction.The actual is calculated as a weighted average of the 100 and 0% K.as in Eq.(12.58):
K=SK_100+ (1-S)K_0 (12.58)
The 0% K value is the inverse of the slope of the lift curve,as determined before.The 100%K value in subsonic flight is the inverse of the aspect ratio times π.
In transonic flight .staring at Mdd,the shock formation interferes with leading-edge suction .This increases the K value.When the leading-edge becomes supersonic,the suction goes to zero,and so the K value equals the 0% K value.
This occurs at the speed at which the Mach angle (arcsine1/M) equals the leading-edge sweep .Above that speed the wing has zero leading-edge suction so the K values is always the inverse of the slope of the life curve.
For initial analysis,the supersonic behavior of the 100% K line may be approximated by a smooth curve .as shown in Fig.12.36.This shows the typical behavior of the 100 and 0% K values vs Mach number.
必须通顺,想用翻译软件糊弄的就不要来凑数了

英语翻译英译汉,不要图片形式,公式不必翻译If there is no viscous separation or induced downwash,the leading-edge suction force exactly balances the rearward component of the normal force and the airfoil experiences zero drag.This is
如果没有粘性分离或诱导下洗流,前缘吸力正好平衡了外力向后的分量,此时机翼处于零阻力状态.这就是贝朗特相悖论描述的理想二维状态,也叫做“100%前缘吸力”状态.
而对于三维机翼来说,当奥斯瓦德有效因数等于1.0时,可认为有100%的前缘吸力.诱导阻力常数K为π乘以长宽比的倒数.
图12.35的右侧是一个零厚度的平板机翼.即使没有前沿气流的分离,机翼一定具有很强的阻力,因为前缘压力在机翼表面没有向前的着力面.所有加在零厚度平板上的压力一定作用在垂直于板面方向,及图中的N方向.平板机翼没有前缘吸力,并且升力和诱导阻力都比较简单.因此,零前缘吸力的最坏情况是：由升力引起的阻力系数K是前面确定的升力曲线斜率的倒数（弧度制）.
所有实体机翼都处在100%~0%的前缘吸力之间.机翼所获得的前缘吸力的百分比被称为S（不要与图12.35中的力S混淆）
在亚音速巡航中,小后掠角和大前缘半径的机翼的S值大概在0.85-0.95（前缘吸力的85%-95%）.超音速战斗机的机翼在大速度,小半径转弯时的S值接近于0.
接下来计算高速度飞行器K值的方法基于对机翼获得实际前缘吸力百分比的经验估计值, 此经验估计值用于计算100%和0%前缘吸力时K的值.实际计算的是100%和0%K的加权平均数.例如方程（12.58）
K=SK_100+ (1-S)K_0 (12.58)
0%K的值是前面确定的升力曲线的斜率倒数.对于亚音速飞机,100%k的值是π乘以长宽比倒数.
在跨声速飞行中,激波的形成会干扰前缘吸力,这会使K值增加.当前缘速度变为超音速时,吸力下降为0, 此时的K值也等于0% K的值.
当速度为马赫角（arcsin 1/M）等于前缘后掠角时的速度,就按前面的方法计算K值.当速度大于马赫角（arcsin 1/M）等于前缘后掠角时的速度时,机翼的前缘吸力为零,此时的K值一直保持为升力曲线斜率的倒数值.
对于初始分析,100%K值曲线在超音速时的趋势接近于一条平滑曲线.如图12.36所示.图中为100%k和0%K值与马赫数之间的典型关系.