Aerodynamic performance prediction method for reflecting air permeability of parachute structure

Abstract

The invention relates to an aerodynamic performance prediction method for reflecting the air permeability of a parachute structure. Only on the basis of the aerodynamic configuration of a general parachute, a parachute canopy structure model is built in a blocking mode, the fabric air permeability and the structure air permeability of a completely-opened part are expressed by relative air permeability, and the relative air permeability is expressed by an air permeability coefficient on the basis of the porous medium theory. On the basis, a ventilation domain flow field model is established, and the thickness of the ventilation domain is determined by the jet theory. Then, through numerical calculation of the ventilation domain flow field model and the general domain flow field model, prediction of the aerodynamic performance of the parachute is realized. According to the method, the fabric air permeability of all parts of the parachute canopy can be conveniently adjusted, more importantly, various slotted parachutes do not need to be modeled again, the modeling efficiency is greatly improved, and the method has extremely important significance in parachute aerodynamic performance prediction and optimization design.

Description

technical field [0001] The invention relates to an aerodynamic performance prediction method reflecting the air permeability of a parachute structure, and belongs to the technical field of parachute local aerodynamic performance testing. Background technique [0002] In order to improve stability, reduce the dynamic load of parachute opening, and improve the performance of maneuvering and gliding, certain structural ventilation holes are often opened on the parachute. And the slit position and the slit mode of the parachute are varied: there are warp slits, weft slits, symmetrical slits and asymmetrical slits. Structural ventilation holes have a great influence on the aerodynamic performance of the parachute (such as drag coefficient, stability, parachute opening performance) (Gan Helin, Rong Wei. Sensitivity analysis of variable parameters of ring sail parachute to design deviation[J]. Aerospace return and Remote Sensing, 2014, 35(02):14-24). At present, the theoretical p...

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Problems solved by technology

[0003] In order to fully simulate the air permeability of canopy fabric materials, some scholars later adopted the porous medium jumping model (Chen Xiaodong, Zhou Yuncheng, Wang Depeng. Macroscopic fluid analysis of laminated fabric air permeability [J]. Woolen Technology, 2016, 44 (05): 5-8), fabric air-permeable domain flow field model (Zheng G., Richard D. Charles, and Xiaolin L. (2017). "Numerical Modeling of Flow Through Porous Fabric Surface in Parachute Simulation", AIAA Journal, Vol.55, No. 2, pp.686-690) carried out numerical simulation of a parachute with fabric ventilation, which improved the accuracy of aerodynamic performance analysis, but did not give a method for determining the ventilation domain

It is especially worth noting that the above method is only for more accurately simulating the fabric air permeability of the canopy, and for the opening of the canopy structure, it is necessary to establish a canopy model of the real opening state

During the design process, if you need to adjust the opening position or opening area of ​​the canopy, you need to re-model every time you make a change, which greatly increases the modeling workload and reduces the efficiency of design analysis

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