压气机转子叶片的抑颤设计

Design for Flutter Suppression of Rotor Blade in a Compressor

关键词:  叶片颤振  气动阻尼  抑颤  安装角  弦长  叶尖间隙

Key words:  Blade flutter  Aerodynamic damping  Flutter suppression  Stagger angle  Chord length  Tip clearance

摘要:

为了建立适用于工程设计的叶片抑颤方法，以一高压压气机转子叶片为对象开展了叶片颤振特性与其结构参数的关联性研究。采用基于相位延迟边界条件的能量法和特征值法对原转子叶片模型的气动弹性稳定性进行评估，通过分析近失速工况下的非定常气动功密度分布，对叶片安装角沿径向分布、弦长和叶尖间隙等设计参数进行调整，以明确各参数对气动弹性稳定性的影响，最终达到提高气动阻尼的目的。研究结果表明：叶尖间隙对气动阻尼的影响较大，安装角次之，弦长影响相对较小。叶片气动阻尼随叶尖间隙的变化并非单调，而是存在一个叶尖间隙使其气动阻尼最小，即叶片气动弹性稳定性最差。减小进口气流攻角和增加折合频率，能够提高气动阻尼，设计中可以通过调节安装角来减小气流攻角，增加弦长来增大折合频率。考虑到对叶片气动性能的影响，在调节安装角时通常要保证进口气流攻角的改变量不超过5°，调节弦长和叶尖间隙时要保证各结构构件不发生碰摩。

Abstract:

In order to establish the blade flutter suppression engineering design method, the correlation between blade flutter characteristics and structural parameters of a high-pressure compressor rotor blade was investigated. The energy method based on the phase lagged boundary condition and the eigenvalue method was used to analyze the aeroelastic stability of the prototype blade. By analyzing the unsteady aerowork density distribution under near stall condition, the effects of design parameters such as radial distribution of the blade stagger angle, chord length and tip clearance were investigated to clarify the influence and its extent of each parameter on the flutter, so as to improve the aerodynamic damping. The results show that the tip clearance has the greatest influence on aerodynamic damping, the stagger angle takes the second place, and the chord length is the least. The variation of aerodynamic damping with tip clearance is not monotonous, so there exists a tip clearance to minimize the blade aerodynamic damping, where the blade aeroelastic stability is the worst. Reducing the attack angle and increasing the reduced frequency can improve the aerodynamic damping. In the design phase, the attack angle can be reduced by adjusting the stagger angle, and the reduced frequency can be increased by increasing the chord length. In consideration of the influence on the aerodynamic performance, the change of the attack angle is usually less than 5°. In addition, when adjusting the chord length and tip clearance, ensure that all structural components will not be collided.