航空发动机插板式进气压力畸变紊流度分布

Statistical Analysis of the Aero-engine Inlet Air Flow Pressure Distortion Turbulence Degree Distribution Using an Inserted-board

根据试验的结果,插板式进气畸变脉动压力在发动机进口可分为未扰动区、掺混区和低压区。紊流的主要能量分布在掺混区内,具有低频和宽泛的幅值特征,基本服从正态分布。其主要能量分布在100 Hz以内,其幅值较低压区高6倍,是影响畸变度的主要区域。对其它两个区域的紊流分布也进行了分析,得到了其统计分析结果。还发现,随插板升高,特别是在发动机接近失稳时,脉动压力能量逐渐向一固定频段收敛,该低频段幅值大幅升高并充满畸变流场,并引起发动机失稳。初步分析认为:可能是进气道内的气流在强烈的紊流扰动下,出现了自激振荡现象。

The inserted- board air flow inlet distortion test shows that dynamic pressure at the engirie inlet exit section can be divided into undisturbed, mixing and low pressure areas. The main turbulence flow power is distributed in mixing areas, with the value characteristics of low frequency distribution and wide range. It is basically in a normal distribution. The main power is distributed within 100 Hz. Its scale is 6 times higher than that of low - pressure area, and is the main area that affects the distortion degree. Also, the turbulence distributions of other two ar- eas are analyzed and an analyzed result is obtained. It is discovered that with the inserted -board raised and especially when the engine operation point is moving to surge boundary, many dynamic pressure frequencies will gather to a small range, the low frequency wave power will increase in large scale, and full of all distortion area. At last, it arouses the engine stall. The primary analysis indicates that in air inlet the airflow presents self-excitation vibration during the trouble by strong distortion.