| 摘要 |
<p>1513921 Controlling boundary layer in jet pumps F R HILLIS 9 Oct 1975 [17 Oct 1974] 45078/74 Heading F2R [Also in Divisions B7 F1 and B1] A propulsion device for accelerating fluid flow through the device or for propelling the device through a fluid, has a duct 13, and primary and secondary orifices 37 and 55 for discharging a pressurized working fluid into the duct. The primary discharge is in the form of a cone 40 which has a semi-conical angle 44 of between 18 and 35 degrees, and converges to a theoretical apex 42 which lies on or near the plane of the secondary orifice. The secondary discharge 60 has a shallower semi-conical angle 61 of between 5 and 10 degrees. The actual discharges, when fluid is present in the duct, are shown at 48 and 64. The duct is in three axially-spaced parts 20, 21, 22 and the orifices are formed between chamfered edges of the duct parts. The axial spacing, and therefore the width of the orifices, can be varied. The working fluid is supplied through a pipe 15 and a manifold 14. The orifices may alternatively be in the form of peripheral nozzles (174, 190) Fig. 7 (not shown), and the nozzles may also be inclined in such a manner as to provide a slight whirling effect. In an alternative embodiment, Fig. 5 (not shown), the device is provided with an inner body (119) which lies on the central axis of the duct, and which is provided with corresponding primary and secondary orifices (133) and (136).</p> |
