Research On Supersonic Quench Flow Field And Temperature Field Of U75V Heavy Rail

Railway development concerns national economy and people’s livelihood.The construction of high-speed heavy-haul railway puts forward higher requirements on the comprehensive performance(especially the strong toughness)of the rail.It is one of the most effective and economical methods to improve the comprehensive performance of hundred-meter rail.Heavy rail U75 V 60 kg/m is the most widely used rails,but the current of U75 V hectometer heavy rail quenching air cooling air spraying apparatus design parameters and the quenching process of study is less,and the cooling speed(1℃/s-3℃/s)is low,and is closely related to the performance and U75 V rail quenching cooling rate,with the increment of cooling speed,pearlite lamellar spacing decreases,organizational performance improvement,thus improve the cooling speed of U75 V heavy rail so as to further improve the rail comprehensive performance has important research significance.For this reason laval nozzle is used to improve the velocity of air jet and thus the cooling speed of rail.A Mach 2 Laval nozzle was designed based on the contractive nozzle used in a steel plant.In order to make the study comparable,the inlet pressure of laval nozzles was adjusted to ensure the same mass flow rate of the two nozzles.On this basis,the finite element models of jet cooling from two nozzles to the disk were established respectively.The fluid-solid thermal coupling analysis was carried out with ANSYS-CFD(FLUENT)software respectively,and the laws of radial flow and heat transfer were obtained and compared.It was proved that the cooling capacity of Laval nozzles was higher than that of contractions.Then the finite element model of the two nozzles for the integral air quenching of the heavy rail was established respectively and the fluid-solid thermal coupling analysis was carried out.The flow field,temperature field and cooling speed of the heavy rail were obtained and the comparative study was carried out.It was proved that laval nozzles could improve the cooling speed of the heavy rail.Finally studied the supersonic air cooling quenching nozzle set parameters(wind spray height,Angle and distance)for heavy rail flow field,temperature field and the influences of cooling rate,and the heavy rail rail head cooling rate and cooling uniformity index for nozzle set parameters optimization,get a better set of nozzle set parameters(Height 40 mm,Angle 50° and spacing 25mm).This study provides important reference value for exploring the application of supersonic technology in heavy rail cooling quenching and the design of supersonic jet device,and has important practical significance for improving the quality of heavy rail quenching.