Nozzle corner vortex generator capable of inhibiting low-frequency pressure pulsation of opening jet-flow wind tunnel

Abstract

The invention discloses a nozzle angular vortex generator for suppressing low-frequency pressure pulsation in an open jet wind tunnel, which comprises a nozzle (2), and two turbulent bodies (1) are fixedly installed on each wall of the nozzle; wherein, the The turbulence body is an arc-shaped structure composed of a rectangular turbulence body bottom surface (11), two turbulence body side surfaces (14) and a flow direction surface (12). The angular vortex generator conducts a long-distance corner diversion of the nozzle airflow, changes the direction of the vortex, destroys the large-scale vortex structure caused by the instability of the shear layer, and suppresses the low-frequency pressure fluctuation to a large extent , which can greatly reduce the low-frequency pressure fluctuations in the wind tunnel.

Description

technical field [0001] The invention relates to a nozzle angular vortex generator, in particular to a nozzle angular vortex generator for suppressing low-frequency pressure fluctuations in an open jet wind tunnel, and belongs to the technical field of wind tunnel experiments. Background technique [0002] Due to the instability of the shear layer (Kelvin-Helmholtz) at the jet boundary, the free jet will generate a large-scale vortex structure at a certain distance downstream of the nozzle due to the instability of the shear layer. These vortex structures interact with the collector downstream of the test section of the open jet wind tunnel and its reflected pressure pulsations, resulting in low-frequency pressure pulsations in the flow field of the test section. Low-frequency pressure fluctuations damage the quality of the flow field and seriously affect the accuracy of the aerodynamic and aeroacoustic measurements of the test model. In order to carry out high-quality aerod...

AI Technical Summary

Problems solved by technology

The disadvantages brought by this type of vortex generator are: 1) Whether it is a spoiler or a spoiler, there are many edges and corners on the shape, which brings its own high-frequency noise and seriously affects the acoustic measurement; 2) The way of circumferential distribution and The large number of installations (about 20 to 30 nozzles per week) not only reduces the core area of ​​the laminar flow in the test measurement section, but also destroys the quality of the flow field, such as increasing the direction field and turbulence, which seriously affects the aerodynamic measurement. Moreover, the superimposed high-frequency noise is more serious; 3) the material is mostly metal, and the installation is complicated, which will cause certain damage to the existing wind tunnel nozzle; Forced vibration, strong high-frequency noise

In general, this type of method has the following disadvantages: first, the control effect is limited, and the amplitude of low-frequency pressure fluctuations cannot be greatly reduced; second, the traditional vortex generator makes the jet boundary layer after transition have a higher flow rate. Mixing efficiency, the expansion speed of the jet boundary is faster, so the area of ​​the core part of the laminar flow that can be used for the test will be reduced; the third is that the vortex generator causes high-frequency noise after the flow transition, which has an adverse effect on the acoustic measurement

In addition, with the enhancement of test methods and the improvement of the test index requirements of the design under test, the existing eddy current generator control methods can no longer meet the high-precision and high-quality test results of advanced aircraft / high-speed trains / automobiles. needs

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