Features of High-Velocity Pulsating Liquid Jets
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Journal of Engineering Physics and Thermophysics, Vol. 93, No. 4, July, 2020
FEATURES OF HIGH-VELOCITY PULSATING LIQUID JETS A. N. Semkoa and O. V. Kazakb
UDC 532.5:518.5
Processes proceeding in a pulsed liquid-jet generator were investigated in the acoustic and gasdynamic approximations. In the acoustic approximation, the problem on the one-dimensional movement of the liquid in the generator with no movement of its piston and no liquid outflow from it was considered. In the gasdynamic approximation, the problems on one-dimensional and axisymmetric liquid flows in the generator were solved numerically with regard for the movement of the generator piston, the liquid outflow from the generator, and the cavitation of the liquid in it. A onedimensional liquid flow in the generator was calculated using the potential method, a scheme with introduction of artificial viscosity, the Godunov method, and modifications of this method. Results of calculations of the movement of the liquid in the generator by different models were compared, and corresponding conclusions have been made. Keywords: pulsed liquid-jet generator, liquid compressibility, wave process, cavitation, numerical simulation, velocity pulsations, liquid outflow, liquid disks. Introduction. The process of pulsed outflow of the liquid from a liquid-jet generator with pressure pulsations is distinctly wave in character, and this process should be defined with regard for the compressibility of the liquid even in the case where the velocity of the liquid jets emanating from the generator and the pressure in it are low. A pulsed outflow of the liquid from such a generator leads to the formation of a radial liquid flow and liquid regions of increased thickness (liquid disks) in the jet emanating from it. The waves propagating in the generator give rise to the pulsations of the pressure in it, the pulsations of the velocity of the liquid outflowing from the generator, and the cavitation of the liquid near the generator piston and at the closed end of the generator. The equations of gas dynamics for pulsed generators of high-velocity pulsating liquid jets are solved using the method of characteristics, the mesh-characteristic method, the method of S. K. Godunov and its modifications, a scheme with introduction of an artificial viscosity, compact difference schemes, the splitting scheme of V. M. Coveney and N. N. Yanenko, and TVD schemes [1–27]. Each of these methods has advantages over the others and weaknesses compared to them, but there is no unique universal method of solving the indicated gas dynamics equations. The solutions obtained by the methods listed differ in their approximation order as well as in the degree of conservation, monotony, and homogeneity. At present, preference is given to computational schemes providing the obtaining of homogeneous, conservative, and monotonic or quasi-monotonic high-order solutions. In the present work, the method of characteristics and its modifications, the Godunov and Rodionov methods, and a scheme with introduction of
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