| 摘要 |
There is provided a spray discharge assembly for an aerosol spray device comprising a pressurised or pressurisable container holding a liquid to be discharged from the device by a propellant, the spray discharge assembly adapted to be inserted in a fluid flow path between fluid in the container and a nozzle, the spray discharge assembly incorporating: (i) an approach channel having at least one inlet and an outlet, (ii) a flow conduit upstream of said approach channel in the direction of liquid discharge from the nozzle for supplying fluid to be discharged to the approach channel, (iii) at least one jetting orifice through which fluid from the conduit passes and issues as a jet into the approach channel through the inlet thereof, and (iv) a discharge orifice into which fluid from the approach channel passes via the outlet thereof to issue as a spray from the device, wherein the outlet of the approach channel is surrounded by a sharp edge and the jetting orifice is configured for directing the jet against said edge. The spray discharge assembly may be incorporated into an aerosol device having either a compressed gas propellant or a liquefied gas propellant. Embodiments of the invention allow production of a "bubbly flow" which is such that a flow of ideally homogenous bubbles, with similar diameter, and without stratification across the flow conduit passes into the jetting orifice(s) from which the bubbly flow then issues as turbulent bubble-laden jets which impact on the sharp edge (around the outlet of the approach channel) and enter the discharge orifice. The combination of the bubble laden jets and their impact on the sharp edge combine to give flow separation from the interior surface of the discharge orifice at an upstream region thereof with reattachment (at fluctuating locations) at a relatively downstream region. This results in a highly unsteady turbulent bubbly flow that is beneficial to the atomisation into droplets of the jet emerging from the outlet of the discharge orifice. |
