Design And Simulation Of Air Cooling Quench Rectangular Supersonic Nozzle

Air-cooled quenching technology is developed rapidly in recent decades,a heat treatment process,which is the high-pressure air through the jet device to accelerate to high-speed airflow,then the workpiece surface convection forced convection to cool the workpiece quickly to improve the surface hardness and Corrosion resistance,while the workpiece core still has good strength and toughness.Air-cooled quenching process because of its compressed air for the media,with environmental protection,economy,wide range of adjustable cooling rate and other advantages,especially in the large-scale steel on-line heat treatment process has been applied in recent years.As the key of air-cooled quenching technology lies in how to increase the wind speed so as to improve the quenching and cooling rate,developing the supersonic nozzle has become one of the focuses of the research on air-cooled quenching technology.In this paper,a new type of curved rectangular cross-section supersonic speed is proposed based on the shortcomings of wide range of used round-section supersonic nozzles such as small outlet radius adjustment space,non-parallel exit air velocity and small wind speed width.Nozzle design method and CFD numerical simulation of the nozzle designed by the method to study in detail the characteristics of the flow field inside and outside the rectangular section of the supersonic nozzle and the simulation results were compared with the numerical simulation results of the circular section supersonic nozzle.The results show:1)The nozzle exit speed and size of the nozzle design mach number and inlet airflow temperature are related to the nozzle exit speed and inlet temperature is proportional to the square root.When the temperature of the inlet is constant,only the nozzle design Mach number is changed,there is a maximum limit of velocity (?).2)The ratio of the nozzle inlet pressure to the outlet back pressure determines the expansion of the gas flow inside the nozzle,which affects the uniformity of the flow field inside the nozzle.For the same design Mach number,different cavity curve of the supersonic nozzle,when the outlet back pressure is the same,the curved nozzle designed by Vythosky method and the characteristic line method,the internal inlet pressure required to achieve uniform flow to Much smaller than ordinary broken line ultrasonic nozzle.3)The velocity field distribution and outlet mass flow at the outlet section of therectangular supersonic nozzle are not significantly different from the circular nozzle with the same cross-sectional area.However,the boundary layer thickness of the former is obviously smaller and the distribution of the internal flow field is more uniform.4)The results show that the characteristic line method rectangle supersonic nozzle is more flexible in the aspect ratio selection,the internal flow field uniformity and inlet minimum pressure are better than the ordinary circular supersonic nozzle.The research will be of great reference value for the design of supersonic speed and the application in the fields of spraying and quenching.