THEORETICAL AND EXPERIMENTAL STUDY OF A SHOCK TUBE PERFORMANCE WITH HOMOGENEOUS NUCLEATION OF WATER VAPOUR

Document Type : Original Article

Author

Department of Mechanical Power Engineering, Faculty of Engineering, Minoufiya University, Shebin El-Kom, EGYPT.

Abstract

Performance characteristics of a shock tube has been investigated here
theoretically and experimentally when the homogeneous nucleation appears in the
expansion fan within the driver section. Nucleation of water vapour is simulated using
the nonisothermal formulation of the classical theory of nucleation. Shock tube
performance is represented with the aid of an analytical model combines its pressure
ratios. A modified shock tube equipped with a convergent section of different
geometries and joined the driven section to the tail pipe is used in the present
experimental program. Pressure traces ahead and behind the convergent section are
measured using three pressure transducers. Both measurement and prediction of shock
tube flows show the dependence of the pressure ratio across the incident moving shock
wzve in the driven section on the tube overall pressure ratio. It is noted also from the
prssent predictions the pronounced effect of the shock tube overall pressure ratio on the
nncleation characteristics (i.e., amount of subcooling, supersaturation ratio, critical size
of nucleated droplets and rate of nucleation) of the water vapour in the driver section.
The validity of the suggested model is tested by comparing between the predicted and
measured pressure ratios. Another comparison has been carried out between the
calculated values of the nucleation rate in a shock tube and the published measured
ones. The two cornparisoils indicate reasonable agreements

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