基于图像信噪比的PSP图像平均幅数确定方法

PSP image average number determination method based on image signal-to-noise ratio

摘要:

压敏漆测压技术具有非接触、全域测量的优点,广泛应用于模型表面压力分布测量；压敏漆试验中采用连续采集多幅图像求平均的方式降低图像噪声,一般根据经验确定图像采集幅数；对CCD相机的噪声类型进行分析,判断PSP测量系统随机噪声的主要来源为CCD光散粒噪声；提出了一种基于划分子区域的比图像信噪比计算方法,对比分析了某翼型和三角翼模型PSP试验数据不同图像平均幅数的处理结果,结果表明图像平均幅数增加到一定值后信噪比会趋于收敛,图像平均幅数减半后依然可以满足PSP测压试验精度要求,可通过分析信噪比确定每个工况采集的图像幅数,进而达到合理控制风洞试验时间的目的。

Abstract:

Pressure sensitive paint measurement technology has the advantages of non-contact, full range measurement, widely used in model surface pressure distribution measurement. Pressure sensitive paint test using continuous acquisition of multiple images and calculating the average image to reduce the noise, the number of the images is generally determined by experience. Scientific CCD camera’s noise type was analyzed, come to the collusion that the PSP measurement system’s main noise source is the CCD’ s optical scattering noise which could be reduced by averaging the images. A calculation method of image’s signal-to-noise ratio based on sub region is proposed, and the results of different average number of PSP test images of airfoil and delta wing model are compared and analyzed. The results show that the signal-to-noise ratio tends to converge when the average number of images is increased to a certain value, and the result can still meet the accuracy requirements of PSP pressure test when the average number halved. The required number of images could be determined by analyzing the signal-to-noise, and the test time could be controlled reasonable.