一种基于双喷嘴模型的涡轮等效流通面积计算方法

摘要

基于双喷嘴模型,利用反动度求静叶喷嘴出口压力,对等效涡轮流通面积计算方法进行了研究.将计算结果输入经校核的GT-Power仿真模型中反算得到不同转速下涡轮前后的气体状态参数,绝大部分仿真值与试验值误差小于4%;计算得出的涡轮特性曲线与实测曲线误差低于9%,高膨胀比时涡轮未出现阻塞,优于简单喷嘴模型.利用此方法计算的变海拔涡轮等效流通面积可实现3000 m范围内最大扭矩点转速到标定功率转速的柴油机增压压力恢复.表明此模型具有较高精度,能适应较宽的膨胀比范围,可用于描述涡轮的工作状态和工作过程,表征涡轮流通特性和做功能力,进一步服务于增压系统与柴油机的匹配过程.%This paper presented a modified method to calculate the effective flow area of radial turbine based on the previous double-nozzle model.The reaction degree has been discussed and the outlet pressure of stator nozzle has been obtained.The ver-ified GT-Power simulation model has applied the calculated effective area to compute the state parameters of turbine,most of which approximate to experimental value with a tiny error less than 5%.The error between the fitting and measured character-istic curves of turbine is lower than 9%,and there is no choke at high expansion ratio,which shows better performance than simple nozzle model.This paper also calculated effective flow area of turbine at different altitudes,which recover the boost pressure of diesel engine at 3 000 m from maximum torque speed to the rated power speed.Therefore,with high accuracy and wide validity,this modified model is able to describe the flow characteristic and work capabilities of radial turbine,contributing to the match between turbocharging system and diesel engine.