GB970047A - Improvements in and relating to stabilizing devices - Google Patents

Abstract

970,047. Boundary layer control. T. HELMBOLD. Jan. 5, 1961 [Nov. 19, 1960 (2)], No. 474/61. Heading F2R. [Also in Division F1] A device for stabilizing a standing vortex comprises a guiding body formed with a concave surface adapted to lie close to the periphery of the vortex and at least one duct or passage leading from an inlet on the concave surface to an outlet which is downstream of the inlet and is in a region where during operation the pressure is lower than at the concave surface. Fig. 5 shows a diffuser provided with concave members 1, 1a and with slot-forming rings 14, 14a which may be of adjustable position. As shown in Fig. 4a, the flow through the diffuser generates a toroidal free vortex at, each concave member 1, la, the vortex allowing the use of a large diffuser enlargement angle without breakaway of flow from the diffuser walls. The annular slot 2 formed between each concave member 1, 1a and the corresponding ring 14, 14a connects the concave surface of the member 1, 1a with a region of lower pressure, whereby air is drawn through the slot 2 from the vortex and returned to the periphery of the vortex at the region of lower pressure. This stabilizes the position of the vortex. Each vortex may be divided into shorter vortices by means of discs disposed substantially radial to the diffuser axis and corresponding in shape and size to the cross-section of the vortex. The discs may be rotatable about their axes. Each slot 2 may extend over a part only of the circumference of the diffuser. The members 1, 1a may be separate from the body of the diffuser and mounted inside it instead of being formed by the body as shown.