Three-dimensional inward turning type air inlet flow field distortion suppression method based on RBF (Radial Basis Function) network

Abstract

The invention discloses a three-dimensional inward turning type air inlet channel flow field distortion suppression method based on an RBF network, and the method comprises the steps: preliminarily designing an air inlet channel model based on an osculating flow principle, recognizing a low-energy flow form, obtaining a low-energy flow distribution condition on each section, and adjusting the osculating surface pressure based on the RBF network; replacing original coordinates by position coordinates passing through RBF interpolation points, forming a new air inlet channel model. Extra energy loss and flow field distortion caused by too large circumferential pressure gradient of the air inlet channel can be avoided on the design level, and in combination with the distance attenuation characteristic of a radial basis (RBF) network, on the premise that second-order derivability of an osculating plane contour line and continuous flow field parameters are guaranteed, And pressure correction is conducted on the distortion generation area, the flow loss in the air inlet channel is reduced by eliminating the circumferential pressure gradient, the effective flow area is enlarged, and the comprehensive compression efficiency of the air inlet channel is improved.

Description

technical field [0001] The invention relates to the technical field of performance optimization design of a high-speed inlet, in particular to a method for suppressing flow field distortion of a three-dimensional inward turning inlet based on an RBF network. Background technique [0002] The three-dimensional internal rotation inlet has become the mainstream development direction of the high-speed inlet due to its advantages of high compression efficiency, high flow capture, low external resistance, and weakened corner flow. One of the important internal flow performance indicators; the impact of distortion on performance is mainly reflected in three aspects: 1) The pressure field generated by distortion drives the further development of low-energy flow near the wall, which aggravates the total pressure loss; 2) Distortion interferes with the flow field 3) Due to the increase of low-energy flow ratio, the internal flow field of the inlet is destroyed, which reduces the anti-...

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Problems solved by technology

[0002] The three-dimensional internal rotation inlet has become the mainstream development direction of the high-speed inlet due to its advantages of high compression efficiency, high flow capture, low external resistance, and weakened corner flow. One of the important internal flow performance indicators; the impact of distortion on performance is mainly reflected in three aspects: 1) The pressure field generated by distortion drives the further development of low-energy flow near the wall, which aggravates the total pressure loss; 2) Distortion interferes with the flow field 3) Due to the increase of low-energy flow ratio, the internal flow field of the inlet is destroyed, which reduces the anti-backpressure ability of the inlet and increases the internal resistance; Under the conditions of sonic flow and leading edge passivation, the thickness of the low-energy flow increases suddenly, which is very likely to cause more severe distortion; therefore, suppressing the distortion of the internal flow of the inlet is the key to ensuring the efficient operation of the air-breathing propulsion system in a wide speed range

[0003] The essence of inlet distortion is the convergence and growth of low-energy flows driven by pressure gradients; current methods of suppressing distortion mainly include boundary layer suction, setting circular / elliptical inlet outlets, and improving inlet velocity field, etc.: 1) The core of boundary layer suction is to discharge the low-energy flow near the wall through the pressure difference, but for the case of thicker low-energy flow, the area of ​​the suction port is larger, which not only increases the structural complexity, but also easily produces serious hidden dangers of strength; 2) The core of improving the inlet velocity field is to use the bulge to generate the lateral pressure gradient to displace the low-energy flow, which can take into account both the displacement of the low-energy flow and the uniformity of the inlet flow field, but the distortion has not been eradicated according to the transition between the internal and external flow fields, and the applicability of the method is limited; 3) The core of setting the outlet of the circular / elliptical inlet is to increase the pressure at the location of the low-energy flow so that the low-energy flow does not converge. However, since this method only considers the pressure gradient at the outlet, it is a purely geometric correction, and The elliptical shape limits the flexibility of the inlet design; the above methods have suppressed the distortion of the inlet to a certain extent, but have not fundamentally eliminated the causes of the distortion

[0004] At present, the three-dimensional inwardly rotating inlet generally adopts the principle of kiss-cut flow design (simplifies the design of three-dimensional complex surfaces to a series of two-dimensional kiss-cut surfaces arranged in the circumferential direction). Although the kiss section guarantees equal wave intensity at the entrance (that is, no circumferential pressure gradient), there is still a circumferential pressure gradient at each kiss section, which drives the low-energy flow to migrate along the circumferential direction, so a three-dimensional inward rotation method based on RBF network is urgently needed. Inlet flow field distortion suppression method to solve the above problems

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