The effect of tip-blade cutting on the performance of a large scale axial fan was investigated using computational fluid dynamics(CFD)methods.Experiments verified the numerical simulations.The original fan was compare...The effect of tip-blade cutting on the performance of a large scale axial fan was investigated using computational fluid dynamics(CFD)methods.Experiments verified the numerical simulations.The original fan was compared with the one with tip-cutting in terms of dimensionless characteristic and aerodynamic performance in tip region under the conditions of the maximum efficiency point and near-stall point.The results showed that double leakage flow occurred in tip clearance at maximum efficiency point and spillage of leakage flow from leading edge occurred in tip-blade region at near-stall point for the both two fans;and that tip-cutting with 6% of blade height could reduce the intensity of tip-leakage vortex and increase flow capacity in tip blade region,and hold the stall margin almost the same as the original fan.The maximum efficiency of the fan with tip-cutting was improved by1%,and the ability of total pressure rising was obviously greater than the original fan.展开更多
叶片振动参数是影响航空发动机、燃气轮机等重大旋转装备工作效率和运行安全的关键,基于叶尖定时的叶片振动测量方法已成为监测旋转叶片健康状态的标配技术。介绍了叶尖定时(Blade Tip Timing,BTT)测量原理,阐述了系统典型结构及常用测...叶片振动参数是影响航空发动机、燃气轮机等重大旋转装备工作效率和运行安全的关键,基于叶尖定时的叶片振动测量方法已成为监测旋转叶片健康状态的标配技术。介绍了叶尖定时(Blade Tip Timing,BTT)测量原理,阐述了系统典型结构及常用测量流程,归纳了叶尖定时测量的4大关键技术,包括叶片到达时刻高精度提取、高信噪比的叶片振动位移测量、极度欠采样的叶片振动参数辨识、基于小样本叶尖定时信号的叶片故障诊断,详细分析了叶尖定时测量方法在叶尖定时传感技术、振动参数辨识技术、叶片故障诊断技术方面取得的重大进展,提出了叶尖定时技术的发展趋势与展望,从传感信号复用、不确定度分析与校准、系统的机载应用、数字孪生及智能运维4个方面总结了叶片振动非接触测量领域的未来重点研究方向,有望为叶尖定时测量技术的科学发展与工程应用提供重要参考。展开更多
旋转叶片是航空发动机的关键易损件,需要对其进行状态监测。叶端定时(Blade tip timing,BTT)是一种有效的旋转叶片非接触监测方法。然而,传统的叶端定时严重依赖键相信号,叶端定时信号存在严重的欠采样问题。对此,提出了一种基于叶片振...旋转叶片是航空发动机的关键易损件,需要对其进行状态监测。叶端定时(Blade tip timing,BTT)是一种有效的旋转叶片非接触监测方法。然而,传统的叶端定时严重依赖键相信号,叶端定时信号存在严重的欠采样问题。对此,提出了一种基于叶片振动差的正交匹配追踪(Orthogonal matching pursuit,OMP)方法来提取叶片固有频率。首先,使用叶端定时传感器计算叶片振动差。然后,构建叶片振动差的稀疏模型,在变转速情况下使用正交匹配追踪方法对叶片振动差信号进行分解,提取叶片振动振幅和固有频率。通过数值仿真验证了该方法的有效性和鲁棒性,并在叶端定时试验台上进行试验。结果表明,该方法可以准确识别叶片异步振动的振幅和固有频率。展开更多
叶端定时是航空发动机叶片叶端振动非接触测量的有效手段,但其采样模式决定了所采信号具有高度欠采样特征,需要进行抗混叠频谱分析从而提取转子叶片固有频率这一关键指标。利用了前向平滑策略的改进多重信号分类法(multiple sIgnal clas...叶端定时是航空发动机叶片叶端振动非接触测量的有效手段,但其采样模式决定了所采信号具有高度欠采样特征,需要进行抗混叠频谱分析从而提取转子叶片固有频率这一关键指标。利用了前向平滑策略的改进多重信号分类法(multiple sIgnal classification,MUSIC)能实现抗混叠但无法充分发挥平滑方法的优势。因此,提出适用于叶端定时信号处理的前后向平滑MUSIC法,通过建立传感器的对称布局条件,利用前后向平滑方法代替前向平滑方法,得到更准确的自相关矩阵估计,进而提高叶片固有频率估计性能,并通过仿真和试验验证了在样本数量、算法参数等相同的情况下,前后向平滑MUSIC法的混叠与噪声抑制能力得到了提升。展开更多
基金supported by the Specialized Research Fund for the Doctoral Program of Higher Education (No. 20113218120006)
文摘The effect of tip-blade cutting on the performance of a large scale axial fan was investigated using computational fluid dynamics(CFD)methods.Experiments verified the numerical simulations.The original fan was compared with the one with tip-cutting in terms of dimensionless characteristic and aerodynamic performance in tip region under the conditions of the maximum efficiency point and near-stall point.The results showed that double leakage flow occurred in tip clearance at maximum efficiency point and spillage of leakage flow from leading edge occurred in tip-blade region at near-stall point for the both two fans;and that tip-cutting with 6% of blade height could reduce the intensity of tip-leakage vortex and increase flow capacity in tip blade region,and hold the stall margin almost the same as the original fan.The maximum efficiency of the fan with tip-cutting was improved by1%,and the ability of total pressure rising was obviously greater than the original fan.
文摘叶片振动参数是影响航空发动机、燃气轮机等重大旋转装备工作效率和运行安全的关键,基于叶尖定时的叶片振动测量方法已成为监测旋转叶片健康状态的标配技术。介绍了叶尖定时(Blade Tip Timing,BTT)测量原理,阐述了系统典型结构及常用测量流程,归纳了叶尖定时测量的4大关键技术,包括叶片到达时刻高精度提取、高信噪比的叶片振动位移测量、极度欠采样的叶片振动参数辨识、基于小样本叶尖定时信号的叶片故障诊断,详细分析了叶尖定时测量方法在叶尖定时传感技术、振动参数辨识技术、叶片故障诊断技术方面取得的重大进展,提出了叶尖定时技术的发展趋势与展望,从传感信号复用、不确定度分析与校准、系统的机载应用、数字孪生及智能运维4个方面总结了叶片振动非接触测量领域的未来重点研究方向,有望为叶尖定时测量技术的科学发展与工程应用提供重要参考。
文摘旋转叶片是航空发动机的关键易损件,需要对其进行状态监测。叶端定时(Blade tip timing,BTT)是一种有效的旋转叶片非接触监测方法。然而,传统的叶端定时严重依赖键相信号,叶端定时信号存在严重的欠采样问题。对此,提出了一种基于叶片振动差的正交匹配追踪(Orthogonal matching pursuit,OMP)方法来提取叶片固有频率。首先,使用叶端定时传感器计算叶片振动差。然后,构建叶片振动差的稀疏模型,在变转速情况下使用正交匹配追踪方法对叶片振动差信号进行分解,提取叶片振动振幅和固有频率。通过数值仿真验证了该方法的有效性和鲁棒性,并在叶端定时试验台上进行试验。结果表明,该方法可以准确识别叶片异步振动的振幅和固有频率。
文摘叶端定时是航空发动机叶片叶端振动非接触测量的有效手段,但其采样模式决定了所采信号具有高度欠采样特征,需要进行抗混叠频谱分析从而提取转子叶片固有频率这一关键指标。利用了前向平滑策略的改进多重信号分类法(multiple sIgnal classification,MUSIC)能实现抗混叠但无法充分发挥平滑方法的优势。因此,提出适用于叶端定时信号处理的前后向平滑MUSIC法,通过建立传感器的对称布局条件,利用前后向平滑方法代替前向平滑方法,得到更准确的自相关矩阵估计,进而提高叶片固有频率估计性能,并通过仿真和试验验证了在样本数量、算法参数等相同的情况下,前后向平滑MUSIC法的混叠与噪声抑制能力得到了提升。
