A N A L Y T I C A L I N V E S T I G A T I O N O F E F F E C T O F S T A T E E Q U A T I O N S A N D T H E R M O-P H Y S I C A L P R O P E R T I E S O N A S U P E R S O N I C T W O-P H A S E S T E A M F L O W
Author(s):
Abstract:
Water vapor contains liquid droplets at low pressure stages of a steam turbine, and this two-phase flow can be modeled analytically (mathematically) in a one dimensional convergent-divergent nozzle. The main goal of this paper is to investigate the effect of different state equations and thermo-physical properties of water vapor on modeling the performance of a supersonic two-phase flow. In this research, for the first time, the virial equations of state proposed by Vukalovich, and the related steam properties, have been compared with the state equations and the equations of the thermo-physical properties of vapor in ASME steam tables published in 2006. The principal gas-dynamic differential equations of the two-phase flow are solved by the Runge-Kutta technique. In this regard, the proposed nucleation and droplet growth equations, and, also, the equations of state and thermo-physical properties from the two above mentioned references are used. The results have been compared with the experimental data, including the pressure ratio and droplet diameter. According to the results, for inlet stagnation pressures and temperatures less than 1.5 bars and 400 Kelvin, respectively, the equations proposed in the ASME steam tables are more accurate than the other equations. But, for higher inlet pressures and also inlet temperatures up to 600 Kelvin,Vukalovich's virial equation of state and related steam properties are suggested.
Keywords:
Language:
Persian
Published:
Mechanical Engineering Sharif, Volume:30 Issue: 2, 2015
Pages:
3 to 13
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