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一、引言 在各种颗粒状原料的热等离子体加工过程中,努曾数(定义为气体粒于的平均自由程长度与颗粒直径之比)可能在广泛的范围内变化.如在近年来受到重视的低压等离子体喷涂中,努曾数可以达到一以至更大的数值.低压下原料颗粒的加热往往比大气压下困难,我们曾采用所谓的“热传导势跳跃近似”,分析过小努曾数(<0.5左右)下压力对热等离子体向颗粒传热的影响,指出努曾效应是低压下颗粒加热恶化的原因。对于努曾
I. INTRODUCTION Nobel (defined as the ratio of the mean free path length of a gas particle to its particle diameter) may vary over a wide range of thermal plasma processes for various particulate materials, as has been encountered in recent years In low-pressure plasma spraying where the emphasis is on, the number of numerics can reach a value of one or greater and the heating of raw material pellets at low pressure tends to be more difficult than atmospheric pressure. We used the so-called “thermal conduction potential jump approximation” (<0.5 or so) on the heat transfer from the hot plasma to the particles. It is pointed out that the Nuson effect is the cause of the deterioration of the particle heating under low pressure. For Nzo