Characterizing the Effect of Sinusoidal Wall Amplitude on Turbulent Wall Jet Flow Parameters

Abstract

Abstract The influence of wavy wall amplitude on the turbulent wall jet flow parameters has been investigated experimentally. For the present study, a sinusoidal wavy wall (y=A* sin(ωx)) has been used where “A=Amp/a” is the amplitude, which is normalized by the nozzle height “a.” The amplitude of the wavy wall is varied as 0.2, 0.4, and 0.6, and the results are compared with the results of plane wall jet. The constant temperature anemometer (CTA) has been used for the measurement of flow by using a transverse mechanism. The results for the mean velocity profile, turbulent intensity, and power spectral density are plotted at the crest and trough separately for more clear discussions. From the velocity profile, it is noticed that the formation of self-similar profile is delayed as the amplitude increases from 0.2 to 0.6, which means flow takes longer time to develop. There is an increase in the local maximum streamwise velocity Umax at crests for increasing amplitude. At the first crest, the rise in Umax is maximum, i.e., Umax is increased by 26%, 37%, and 60% for the amplitudes 0.2, 0.4, and 0.6, respectively, with respect to the plane wall case. In the near flow field, the turbulent intensity also becomes larger for the higher amplitude, which shows higher intermixing of fluid within the jet. This paper also produces the benchmark results which can be used for the validation of the numerical model dealing with the turbulent wall jet flowing over a wavy surface.