stroemungskoerper, especially quertriebsflaeche, by blow of stroemungsmittelstrahlen beeinflussbarer circulation

摘要

933,223. Centrifugal and transverse-flow fans and pumps. N. LAING. July 31, 1959 [Aug. 1, 1958], No. 13685/63. Divided out of 933,222. Class 110 (1). [Also in Groups XXVIII and XXXIII] In apparatus comprising a flow machine producing a first region wherein the pressure is lower than ambient pressure or than a second region of the apparatus, a hollow flow guide in the first region has a slot in its trailing portion, and ambient medium or medium from the second region is led into the interior of the guide, the arrangement being such that medium is ejected from the guide through the slot and medium flowing over the guide is given a change of direction or has a swirl imparted to it. Fig. 1 shows a centrifugal fan or pump in which swirlcreating guides 5 are mounted in a belled portion 3a of the inlet duct 3 downstream of a throttle valve 4 and supported at their inner ends by a dome-shaped deflector 5a. As shown in Fig. 2, each guide 5 is symmetrical in crosssection about a partition 6. Means are provided to connect to ambient fluid either the chambers 7 of all guides 5 or the chambers 8 whereby the difference between ambient pressure and the reduced pressure (as controlled by the throttle valve 4) in the inlet duct 3 causes ejection of ambient fluid from the guides either through slots 9 in the direction 11 or through slots 10 in the direction 12. The ejected fluid produces in co-operation with the guide profile a " jet flap " effect which in turn imposes a swirl (in one direction or the opposite direction) upon fluid entering the impeller 1. The "jet flap " effect is that already proposed for aircraft wherein air is ejected from a slot at the trailing edge of an aerofoil to form an air jet having the effect of a flap but with greatly reduced losses. The air jet changes the lift coefficient of the aerofoil and reduces losses due to flow separation on the suction side. Instead of being ambient fluid, the fluid supplied to the guides 5 may be derived from the pressure side of the fan or pump. Fig. 3 shows an elbow through which fluid flows in the direction of the arrow 32, two hollow arcuate guides 34 being pivoted to help deflect the fluid. Fluid is ejected in the direction of the arrows 35, 36 from the interior of the guides 34 and from a duct 33a at the inside of the elbow to provide a " jet flap " effect which reduces the losses which would otherwise occur. In a further embodiment, a hollow arcuate guide similar to one of the guides 34 is provided to guide the flow of fluid through the interior of the rotor of a transverse-flow machine. The pressure in the interior of the rotor is lower than the pressure of the ambient fluid supplied to the guide and is inversely related to the throughput. The amount of fluid ejected from the guide (and consequently the " jet flap " effect thereof) therefore automatically varies with the throughput.