喷气发动机起动点火过程中的流动相似

一、概述 空中起动时,点火包线如图1所示,从点火的贫油边界看出.随着高度增加,点火所允许的速度是增加的。当采用电嘴附近补氧时.它的贫油边界虽然扩大了,仍然保持这一趋势。而在经典的点火理论中,当点火能量一定时,空气的温度T_σ、密度ρ_o降低,点火的流速V_o下降。为此,本文企图解释.当高度增加时,贫油点火边界的流速也增加这一试验结果。

FLOW SIMILARITY IN IGNITION PROCESS OF JET ENGINE

An analytical study on the flow similarity in ignition process is completed inrespect to the effects of the air flow on the local fuel and oxygen distribution near the plug. For lean light off limitation, a momentum criteria is derived from the motion equation of fuel droplet. The criteria states that the ignition velocity rises with the increase of altitude. It is in quite good agreement with the experimental data. Moreover, it can be explained as that the ignition process changes gradually with the decrease of pa into-optimum range when the fuel flow is kept constant. This case is a very conventional fuel control scheme for ignition ot the jet engine.