Abstract: The model of time--frequency mired processing and the towing experimental results are discussed in the paper for the fractional beamforming of a dense spacing array. The results show that the theoretical model is correct and it can be realized in the engineering mode. The Performance Figure of the experimental sub--array system is increased by about 17 dB ill comparison with that of traditional array with half wavelength spacing between elements under same conditions, when the flow noise is a dominant component in the background noise received by a sub-array.