عنوان مقاله [English]
نویسندگان [English]چکیده [English]
High pressure gas flow at the outlet of the nozzle jet and rocket engines and gas engines in the combustion chamber is one of the factors affecting driving force, fuel consumption, emissions and engine efficiency. Hence its study is very important. High pressure gas from the nozzle exit and the process of mixing with ambient air, depending on the flow properties of compressibility and density barrel shaped like waves, creating shock waves and the stopper. The purpose of this article is the numerical study of these properties. The Mach disk contours, speed and pressure profile that is the effective parameters in the gas flow exit from the nozzles are presented in this paper. Gas jet flow simulation results showed that high pressure ratio of 81.4:1, the formation of the gas jet boundary due to the high amount of kinetic energy is independent of viscosity or turbulent flow in the gas jet. Also the results showed that if the pressure ratio is higher than 18.6:1 the characteristics of the local Mach number and the dimensionless pressure P/Pn is independent of the pressure ratio between the nozzle and the environment, which it depends only on dimensionless distance x/d.
 S. Pai, Fluid Dynamics of Jets, New York: D. Van Nostrand, 1954.
 T. C. Adamson Jr, J. A. Nicholls, On the structure of jets from highly underexpanded nozzles into still air, Journal of the Aerospace sciences, Vol. 26, No. 1, pp. 16-24, 1959.
 P. L. Owen, C. K. Thornhill, The flow in an axially symmetric supersonic jet from a nearly sonic orifice into a vacuum, Ministry of Supply, Armament Research Establishment, Physical Research Division, 1948.
 E. S. Love, C. E. Grigsby, L. P. Lee, M. J. Woodling, Experimental and theoretical studies of axisymmetric free jets, Technical Report, NASA-TR-R-6, 1959.
 D. K. Mather, R. D. Reitz, Modeling the effects of auxiliary gas injection on diesel engine combustion and emissions, No. 2000-01-0657, SAE Technical Paper, 2000.
 F. P. Ricou, D. B. Spalding, Measurements of entrainment by axisymmetrical turbulent jets, Journal of Fluid Mechanics, Vol. 11, No. 01, pp. 21-32, 1961.
 G. N. Abramovich, L. Schindel, General properties of turbulent jets, MIT press, 1963.
 P. O. Witze, impulsively started incompressible turbulent jet, No. SAND-80-8617, Sandia Labs, Livermore, CA (USA), 1980.
 H. Schlichting, Boundary layer theory, fourth edition, McGraw-Hill, 1960.
 P. S. Cumber, M. Fairweather, S. A. E. G. Falle, J. R. Giddings, Predictions of the structure of turbulent, highly underexpanded jets, Journal of Fluids Engineering, Vol 117, No. 4. pp: 599-604, 1995.
 A. T. Hsu, M. S. Liou, Computational analysis of underexpanded jets in the hypersonic regime, Journal of Propulsion and Power, Vol. 7, No. 2, pp. 297-299, 1991.
 C. B. Laney, Computational gasdynamics, Cambridge university press, 1998.
 C. R. Ferguson, A. T. Kirkpatrick, Internal combustion engines: applied thermosciences, John Wiley & Sons, 2015.
 J. Abraham, What is adequate resolution in the numerical computations of transient jets?, No. 970051. SAE Technical Paper, 1997.
 S. Post, V. Iyer, J. Abraham, A study of near-field entrainment in gas jets and sprays under diesel conditions, Journal of Fluids Engineering, Vol. 122, No. 2, pp. 385-395, 2000.
 Y. Li, A. Kirkpatrick, C. Mitchell, B. Willson, Characteristic and computational fluid dynamics modeling of high-pressure gas jet injection, Journal of Engineering for Gas Turbines and Power, Vol. 126, No. 1, pp. 192-197, 2004.