压力敏感涂料测量技术在掠型叶栅表面测压中的应用

Application of pressure-sensitive paint measurement technology in pressure measurement of swept blade surface

关键词:  压力敏感涂料  光路布局  掠型叶片  压力测量  角区分离  掠角

Key words:  Pressure-sensitive paint  Optical path layout  Swept blade  Pressure measurement  Corner separation  Sweep angle

摘要:

为了获得某掠型叶片吸力面压力分布，对一稠度为1.53，掠角为10.7°的掠叶栅进行了光路布局以及压力敏感涂料（PSP）压力测量，利用图像处理和三维重构算法得到了可读性高、便于数据提取的三维叶片吸力面压力分布，并和测压孔测量结果进行了对比。结果表明：利用自主发展的光路布局方法，有效解决了叶片表面光照辐照度不均匀、拍摄视角受限的问题；得到了高信噪比的原始压敏图像以及宽范围多工况的掠叶栅吸力面全域压力分布。与测压孔测量相比，PSP测量误差在5%以内，并且PSP测量结果还捕捉到了峰值等熵马赫数位置沿弦向的迁移以及叶片尾缘的气流分离现象。对不同攻角和来流马赫数下的掠型叶片吸力面压力分布进行分析：掠型叶片在零攻角和正攻角下存在明显的径向压力梯度，促使后掠型叶片气流向前掠迁移，增加了前掠下流低能流体的能量，使得前掠更有利于延迟角区分离，后掠则更容易发生角区分离；掠型叶片在低来流马赫数下展向压力对称性良好，掠设计的影响不显著，高来流马赫数则放大了前后掠对角区分离控制效果的不同。相比传统测压孔有限的压力分辨率，PSP测量可为掠型叶片设计和流动机理分析提供丰富可靠的压力实验数据。

Abstract:

In order to obtain the pressure distribution on the suction surface of the swept blade， the optical path layout and pressure-sensitive paint （PSP） pressure measurement were carried out for a swept blade cascade with a solidity of 1.53 and a sweep angle of 10.7°. The three-dimensional pressure distribution on the suction surface of the blade，which was easy to extract pressure data and highly readable， was obtained by using image processing and three-dimensional reconstruction algorithms， and was compared with the measurement results of the pressure taps. The results show that the independently developed optical path layout method effectively solved the problems of uneven illumination irradiance on the blade surface， and the limited shooting angle. The original pressure-sensitive images with high signal-to-noise ratio and the pressure distribution on the suction surface of the swept cascade in a wide range of operating conditions were obtained. Compared with the pressure taps， the PSP measurement error was within 5%， and the PSP measurement results also captured the migration of the peak isentropic Mach number position along the chord and the flow separation phenomenon at the trailing edge of the blade. The pressure distribution on the suction surface of the swept blade at different incidence angles and incoming Mach numbers was analyzed. At zero and positive incidence angles， the swept blade has obvious radial pressure gradient， which makes the flow on forward sweep move forward， increases the energy of low energy fluid in the forward swept downflow， and makes forward sweep more helpful to delay corner separation. However， backward sweep is more prone to corner separation. The spanwise pressure symmetry of the swept blade is good at low inlet Mach number， and the influence of the swept design is not significant. The high incoming Mach number magnifies the difference of corner separation control effect between forward and backward sweep. Compared with the limited pressure resolution of traditional pressure taps， PSP measurement can provide abundant and reliable pressure experimental data for the design of swept blades and the analysis of flow mechanism.