Rectangular supersonic flow nozzle and design method thereof

Abstract

The invention relates to a rectangular supersonic flow nozzle and a design method thereof. A moving principle of a compressible fluid in a one-dimensional variable-sectional pipe and a Mach wave reflection principle are combined to design an inner cavity of the nozzle; the upper surface of a cavity curved surface and the lower surface of the cavity curved surface are symmetrical with respect to ahorizontal plane; the left surface of the cavity curved surface and the right surface of the cavity curved surface are symmetrical with respect to a perpendicular plane; and the upper surface of the cavity curved surface, the right surface of the cavity curved surface, the lower surface of the cavity curved surface and the left surface of the cavity curved surface are closed to form a rectangularbarrel in a flat seam shape. The rectangular supersonic flow nozzle is formed by combining a contraction section subsonic velocity accelerating region, a throat part sonic velocity region, an expansion section front-end supersonic velocity accelerating region and an expansion section rear-end supersonic velocity accelerating region. During spray processing, the interlapping of spraying particles can be greatly reduced, the uniformity of a surface coating of a workpiece is improved, and the cold spraying quality is improved; and a supersonic jet flow with uniform speed and temperature distribution can be obtained with a small pressure difference of an inlet and an outlet, and internal and external flow fields of the nozzle are shock-free, so that an ideal air blasting or spraying effect isachieved.

Description

technical field [0001] The invention relates to a supersonic nozzle, in particular to a rectangular supersonic nozzle and a design method thereof. Background technique [0002] At present, supersonic nozzles are widely used. For example, in supersonic cold spraying technology, supersonic nozzles are used to accelerate spray particles to 300m / s-1200m / s through supersonic carrier gas, and then hit the substrate and deposit on its surface, thus forming A dense coating. [0003] However, the circular cross-section supersonic nozzles currently widely used have disadvantages such as little room for adjustment of the outlet radius and difficulty in spraying thinner-diameter rotating workpieces; The layer is not uniform, so that the quality of cold spraying is greatly reduced. [0004] The existing three-segment broken-line circular supersonic nozzle has non-parallel airflow direction at the outlet when it is working, the airflow is not easy to concentrate and the wind speed atten...

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Problems solved by technology

[0003] However, the circular cross-section supersonic nozzles currently widely used have disadvantages such as little room for adjustment of the outlet radius and difficulty in spraying thinner-diameter rotating workpieces; Inhomogeneous layer, which greatly reduces the quality of cold spray

[0004] The existing three-segment broken-line circular supersonic nozzle has non-parallel airflow direction at the outlet when it is working, the airflow is not easy to concentrate and the wind speed attenuates rapidly, and when using this nozzle to jet quench long-length steel, the diameter of the outlet section is limited. The effect of blowing wind causes the surface temperature and hardness of the section steel to change unevenly

In the spraying process, because the nozzle outlet section is circular, the particles on the surface of the workpiece overlap seriously when spraying the surface of the workpiece, resulting in uneven coating on the surface of the workpiece

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