Characteristics of Wall Jets Induced by Single and Dual Supersonic Impinging Jets for Ground Safety Analysis

Vertical Take-Off and Landing (VTOL) aircraft can achieve the required lift using impinging jets. However, such operations often require ground crew to work in close proximity to the aircraft. The high-speed wall jets generated by jet impingement can pose significant safety risks to ground personnel due to intense drag forces. Additionally, the presence of multiple jets leads to the formation of fountain flow, which may further exacerbate these risks. Understanding the characteristics of wall jets is therefore essential for ensuring safe ground operations. In the present study, wall jets and fountain flow produced by single and dual supersonic impinging jets - issued from Mach 1.5 and sonic nozzles - are investigated. Particle Image Velocimetry (PIV) is employed to acquire velocity profiles near the ground plate and to analyze wall jet behavior. For safety assessment, the PAXman model is utilized to quantify the forces exerted on ground personnel by the impinging flow.