1. INTERNATIONAL TECHNOLOGICAL SCIENCES AND DESIGN SYMPOSIUM, Giresun, Turkey, 27 - 29 June 2018, pp.782-795
The present study experimentally investigates the fluid flow characteristics of a swirling coaxial impinging (swirling and round) air jet issuing from a nozzle having an inner circular flow passage and three outer swirling flow passages. Experiments have been conducted at different dimensionless nozzle-to-plate distances (H* = 0.2, 0.4 and 0.6), and dimensionless flowrate ratios (Q* = 0.1, 0.3 and 0.6) at a constant total flowrate of 1.66 x 10-3 m3 s-1 (100 L/min). The distribution of the pressure coefficient (CP) is obtained against the dimensionless radial distance (R*) for each test condition. The results show that the flowrate ratio is a very important parameter influences the pressure distribution on the impingement plate. The magnitude of the pressure value at the stagnation point decreases with increasing flowrate ratio, and for Q* = 0.6, the maximum value of the local wall pressure occurs at nearly R* = 0.2. On the other hand, in the stagnation region, the magnitude of the local pressure values decreases with increasing nozzle-to-plate distance. For Q* = 0.6, a significant subatmospheric region is obtained.