Thickness distribution and fluctuation characteristics of swirling liquid film after corrugated deformation of the tube wall

After long-term operation under high temperature and high pressure, the scrubbing-cooling tube undergoes corrugated deformation, which reduces the stability of turbulent liquid film flow along the tube wall. The swirling liquid film can make the liquid film adhere to the wall and improve the circumferential distribution uniformity of the liquid film. This paper employed the ultrasonic Doppler velocimeter to investigate the effects of corrugated wall surface structural parameters （amplitude and wavelength） and liquid film Reynolds number （Re_L） on the thickness distribution and fluctuation characteristics of swirling liquid film under turbulent conditions. The results show that when the wall undergoes corrugated deformation, except for the inlet, crests, and troughs, the swirling liquid film thickness at other locations is generally thinner than that on the smooth wall. Compared with the smooth wall, the disturbance wave frequency of the swirling liquid film on the corrugated wall increases overall, the dimensionless maximum film thickness ε_max increases, the dimensionless minimum film thickness ε_min decreases, and the spatial fluctuation of the liquid film is enhanced. When the amplitude increases or the wavelength decreases, the liquid film fluctuation becomes more intense. The increase in Re_l enhances the centrifugal force, thereby suppressing liquid film fluctuations. The established liquid film thickness prediction model can satisfactorily predict the average thickness of the swirling liquid film on corrugated walls （amplitude-to-wavelength ratio = 0.015 ~ 0.03） under turbulent conditions （Re_L = 8.73 × 10³ ~ 1.22 × 10⁴）, and can particularly predict the minimum film thickness, providing a reliable theoretical basis for the stable operation of the device.