超音速火焰喷枪气体温度场和压力场的数值模拟

Numerical Simulation of Temperature Field and Pressure Field in High Velocity Oxygen Fuel Spray Gun

超音速火焰喷涂喷枪内的气体状态(温度、压力等)直接影响喷涂粒子的加热、加速效果,从而决定涂层质量。为获取喷枪内温度场、压力场及气体质量分数分布,采用finite-rate化学模型和Realizable k-ε湍流模型进行流体动力学计算。模拟结果显示:O2和C3H8分布直接影响喷枪内燃烧区的位置,从而影响化学能-动能的转变;燃烧室主燃区的位置、大小与温度梯度、燃烧气体成分梯度密切相关;超音速火焰喷涂喷枪内气体压力呈阶梯状分布,所产生的动态压差迫使燃气沿压力梯度传播;燃烧室内高压气体经拉瓦尔管转换,使压降转变为动能。

Finite-rate chemical model and Realizable k-ε turbulent model were adopted for fluid dynamic computation so as to obtain the distribution of temperature field,pressure field and gas mass fraction inside the high velocity oxygen fuel(HVOF) spray gun.It was found that the distribution of oxygen and propane directly affected the position of burning zones in the gun,which affected the transformation of chemical-kinetic energy.In the combustion chamber,the location and the size of key burning area were closely related with temperature gradient and gas composition gradient.In HVOF spray gun,gas pressure gradient propelled gas to transmit along the pressure gradient,while pressure energy of high pressure gas in the combustion chamber was converted by Laval nozzle into kinetic energy.