波瓣穿透率对波瓣混合排气系统性能影响

Effects of lobe penetration ratio on performance of mixer exhaust system

关键词:  波瓣混合器  排气系统  穿透率  热混合效率  总压恢复系数  推力系数

Key words:  Lobed mixer  Exhaust system  Lobe penetration ratio  Thermal mixing efficiency  Total-pressure recovery coefficient  Thrust coefficient

摘要:

基于Navier-Stokes方程组对某型涡扇发动机波瓣强迫混合排气系统进行了数值模拟,获得了波瓣长度以及扩张角分别不变时,不同穿透率模型的流场、涡量场的变化规律,揭示了通过不同方法改变穿透率对强迫排气系统混合性能的影响。模拟结果表明,在排气系统出口处,当瓣长一定时,热混合效率随穿透率的增加先增加而后逐渐趋于不变,当波瓣扩张角不变时,热混合效率随穿透率的增加而增加；总压恢复系数和推力系数随穿透率的增加均不断降低。

Abstract:

Geometric models with respective change of length and expansion angle of lobe in the forced mixing exhaust system of turbofan engine were created and numerical simulation based on Navier-Stokes equations was carried out. Through 3-D simulation the principle of effects of different lobe penetration ratio (h/h₀) was obtained. The results show that that at the exit of the force mixing exhaust system, when length of lobe is constant, the mixing efficiency increases at first and then tends to be unchanged as h/h0 augments. Moreover, when expansion angle of lobe is invariable, the mixing efficiency increases with rise of h/h₀. Besides, total-pressure recovery factor and thrust coefficient decrease, as h/h0 augments. 