Abstract: Atomization mechanism of a type of nozzle is analyzed. The nozzle has a circular exit orifice, which is preceded by a swirl chamber with a multi-slotted, in-line distributor. Using three-dimensional phase doppler particle anemometer (3D-PDPA), water mist’s velocity and Sauter mean diameter (SMD) is measured. Experimental result shows that the spray status at low working pressure can be explained by the wave breakup theory. When at high pressure, the spray is forced to a hollow cone by the distributor in a very short distance at first, and become a solid cone under stretch-jet way finally, such distance decrease with the rise of working pressure. On the status of hollow cone spray, with the extension of spray distance, water mist’s axial and radial velocity decay exponential in the edge of spray cone. Mist inside the cone is caused by the splash of spray, so its axial velocity conform to the general rule of common spray, and a steady radial velocity is non-existence. Water mist’s SMD is far less than 100 μm in every section of the spray.

Key words: Distributor nozzle, PDPA, Water mist diameter, Water mist velocity, Induction velocity, Installation angle, Local tip speed ratio, Optimum angle of attack, Vertical axis wind turbine