基于拉法尔喷嘴的磨料气体射流加速规律研究

Study on acceleration laws of abrasive gas jet based on Laval nozzle

为明确磨料气体射流中磨料的加速规律,基于拉法尔喷嘴,使用FLUENT软件数值模拟了气体和磨料在直管段、拉法尔喷嘴内部、自由射流段的加速过程,以及入口压力15 MPa时不同质量流量磨料的加速过程;分析了磨料质量流量与喷嘴出口磨料速度和磨料最大速度的关系。研究结果表明:高压气体的加速主要在喷嘴收敛段和扩张段,自由射流段气体速度波动较大;磨料的加速过程与气体具有相似性,主要加速过程在喷嘴内部,自由射流段磨料加速相对较小;恒定入口压力条件下,磨料质量流量与喷嘴出口的磨料速度和磨料的最大速度呈二次函数关系;拟合得到15 MPa下磨料质量流量与喷嘴出口磨料速度和磨料最大速度的关系式,经验证模拟结果准确度较高。

In order to clarify the acceleration laws of abrasive in the abrasive gas jet, the FLUENT software was used to nu- merically simulate the acceleration process of gas and abrasive in the straight pipe section, the inside of Laval nozzle and the free jet section, and the acceleration process of abrasive with different mass flowrates under the inlet pressure of 15 MPa based on the Laval nozzle. The relationship between the mass flowrate of abrasive and the abrasive velocity at the nozzle outlet and the maximum abrasive velocity were analyzed. The results showed that the acceleration of high pressure gas was mainly in the convergent and expanding sections of nozzle, and the gas velocity in the free jet section fluctuated greatly. The acceleration process of abrasive was similar to the gas, the main acceleration process was inside the nozzle, and the acceleration of abrasive in the free jet section was relatively small. Under the constant inlet pressure, the relationship between the mass flow rate of abrasive and the abrasive velocity at the nozzle outlet and the maximum abrasive velocity presented the quadratic function. The relationship formulas between the mass flowrate of abrasive and the abrasive velocity at the nozzle outlet and the maximum abrasive velocity under 15 MPa were obtained by the fitting, which had a high accuracy through the verification of simulation results.