Distribution of Time-Averaged Pressure Fluctuations Along the Boundary of a Round Subsonic Jet
Distribution of Time-Averaged Pressure Fluctuations Along the Boundary of a Round Subsonic Jet
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沿圆形亚音速射流边界的时均压力脉动分布
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发表时间：
1960
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通讯作者：
W. L. Howes
中科院分区：
文献类型：
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作者：
W. L. Howes
利用均匀出口速度的圆形亚音速射流的相似关系，对湍流流体中不可压缩波动方程进行半经验分析，以预测沿射流平均速度边界沿着的时均波动压力分布的形状。预测的分布与喷嘴出口沿着混合区下游的距离无关，与沿沿着平均速度自保持区下游的距离成反比，与沿沿着充分发展区下游的距离的平方反比成正比。实验结果与理论基本一致。然而，所测得的脉动压力分布被发现是非常敏感的射流温度和射流喷嘴轮廓的变化，特别是在喷嘴附近。这些因素都没有包含在理论中。射流温度的增加会导致压力波动增加，并违反相似条件。喷嘴型线的修改可能会导致违反理论中规定的均匀出口速度要求。
A semiempirical analysis of the equation for incompressible fluctuations in a turbulent fluid, using similarity relations for round subsonic jets with uniform exit velocity, is used to predict the shape of the time-averaged fluctuation-pressure distribution along the mean-velocity boundary of jets. The predicted distribution is independent of distance downstream of the nozzle exit along the mixing region, inversely proportional to the distance downstream along the region of mean-velocity self-preservation, and proportional to the inverse square of the distance downstream along the fully developed region. Experimental results were in fair agreement with the theory. However, the measured fluctuation-pressure distributions were found to be very sensitive to changes in jet temperature and jet-nozzle profile, especially near the nozzle. These factors are not included in the theory. Increased jet temperatures produce increased pressure fluctuations and violation of similarity conditions. Nozzle-profile modifications may lead to violation of the uniform-exit-velocity requirement imposed in the theory.