ESPI was proposed to test airflow speckle shift. N frames of speckle patterns along temporal sequence were collected by CCD, phase field of correlated patterns were obtained after calculating the temporal correlated patterns using a FFT program, which does Fourier transformation, filtering, inverse Fourier transformation and phase unwrapping. Then the instantaneous speckle shift could be worked out and the variation process of airflow filed could be also redisplayed. A new experimental analytical method for fast dynamic processes in testing of engineering thermodynamical parameters was put forward.
