Based on the analysis of the natural wind spectra, a new method for generating an air movement with the same velocity spectra as the natural wind is presented. Correspondingly a new device using this method is designed to investigate the velocity fields. The key part of the device is controlled by a digital signal, which can be regulated according to the test needs. The frequency scope of the velocity spectra and the turbulence intensity can be easily changed in order to satisfy the air conditioning need, so a series of modes of the natural wind can be simulated. The investigation shows that is application in dynamic air conditioning is applicable .