A Physical Interpretation of Stagnation Pressure and Enthalpy Changes in Unsteady Flow
A Physical Interpretation of Stagnation Pressure and Enthalpy Changes in Unsteady Flow
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非定常流中停滞压力和焓变的物理解释
DOI：
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发表时间：
2012
期刊：
影响因子：
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通讯作者：
C. Tan
中科院分区：
文献类型：
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作者：
H. Hodson;T. Hynes;E. Greitzer;C. Tan
本文从物理上解释了非定常流动引起的工质滞止焓和滞止压力变化的机理，非定常流动是工质与无粘流体之间全部功传递的媒介。首先给出的例子来说明一个给定的流体粒子的静压的时间变化和该粒子的滞止焓的变化率之间的直接联系。这些包括涡轮机转子叶尖泄漏流中的绝对滞止温度升高、通过下游叶片排的尾流传输以及尾流相位对压气机功输入的影响。流体动力学的情况下，然后构建来解释不稳定的影响，包括如何滞止压力的变化是由静态压力的时间变化创建的物理解释;在这一点上，它表明，不稳定的静态压力起着与时间相关的体力潜力的作用。它进一步表明，当不稳定性是由于在恒定的速度平移的空间不均匀性，如在一个crackine，不稳定的压力变化可以被看作是局部功率输入每单位质量从这个体力的流体粒子瞬间在该点。© 2012美国机械工程师协会。
This paper provides a physical interpretation of the mechanism of stagnation enthalpy and stagnation pressure changes in turbomachines due to unsteady flow, the agency for all work transfer between a turbomachine and an inviscid fluid. Examples are first given to illustrate the direct link between the time variation of static pressure seen by a given fluid particle and the rate of change of stagnation enthalpy for that particle. These include absolute stagnation temperature rises in turbine rotor tip leakage flow, wake transport through downstream blade rows, and effects of wake phasing on compressor work input. Fluid dynamic situations are then constructed to explain the effect of unsteadiness, including a physical interpretation of how stagnation pressure variations are created by temporal variations in static pressure; in this it is shown that the unsteady static pressure plays the role of a time-dependent body force potential. It is further shown that when the unsteadiness is due to a spatial nonuniformity translating at constant speed, as in a turbomachine, the unsteady pressure variation can be viewed as a local power input per unit mass from this body force to the fluid particle instantaneously at that point. © 2012 American Society of Mechanical Engineers.