The influence rule of near-field wake vortex of tanker and the evaluation of dangerous area

The development of wake vortex of refuelling aircraft includes two stages: near-field and far-field. In the near-field stage, wake vortex is in the phase of rolling up and maturity. The evolution mechanism of wake vortex is complex and the resulting wake vortex is of great strength, which will adversely affect the safety and stability of downstream aircraft, especially small and medium-sized unmanned aircraft, so it is necessary to focus on the study of the development and influencing law of the wake vortex. The potential hazardous area is evaluated by analysing the tail vortex field. The Reynolds average method is used to simulate the near-field distribution of the wake vortex of the hypothetical tanker by using CRM aircraft, and the position of the vortex core and the influencing law and range of the wake vortex of the tanker under different incoming Mach numbers and crosswind conditions are analysed. On this basis, the configuration of the following UAV is selected as the research object of the receiver, and the coefficient of critical rolling moment is selected as the criterion of the dangerous area. The dangerous area of the wake vortex of the following aircraft behind the CRM refuelling machine is evaluated by using the calculation and analysis. The results show that increasing the Mach number makes the longitudinal position of the vortex core lower, the radius of the vortex core larger, and the circulation of the wake vortex at the same flow direction larger. The crosswind makes the vortex core position shift obviously. The larger the crosswind is, the larger the shift is, and the wake vortex dissipation will be accelerated at the same time. Under the influence of the wake vortex field of the refuelling aircraft, the potential dangerous area faced by the following UAV is mainly affected by the circulation of the wake vortex and the characteristic parameters of the following UAV, and the position of the dangerous area is consistent with the position of the vortex core.