组合管中气粉流的临界管长

根据气粉流运动的基本定律，考虑收缩喷管的等熵流动以及等截面管中的摩擦流动，建立了描述组合管中气粉流的数学模型．考虑气粉流摩擦壅塞现象，用马赫数检验法确定了组合管的临界管长．计算结果表明，组合管的临界管长随粉气比的增大而减小；在不同粉气比下，组合管中气体速度和粉粒速度均沿程逐渐增大，而粉粒终速随粉气比的增大而减小；组合管的临界管长比等截面管的临界管长小得多，且组合管中的压降比等截面管中的压降明显减小

Critical Duct Length of Gas particle Flow in Combined Duct

According to the basic laws of gas particle flow and considering frictional flow in a constant area duct preceded by an isentropic convergent nozzle,a mathematical model has been developed to describe the behavior of the gas particle flows in combined duct. Considering the friction choke phenomenon of gas particle flow,and using Mach number checkout method,the critical duct length of gas particle flow in combined duct has been determined. The calculation results show that the critical duct length increases with reduction of the ratio of mass flow rate of particles to total mass flow rate;the gas and particle velocities gradually increase with duct length at a different ratio,while the particle terminal velocity decreases with the increase of the ratio;the critical duct length of combined duct is much less than that of constant area duct,and the pressure drop of combined duct is much less than that of constant area duct.