Flow pattern transition and wave characteristics of impinging jet flow on a spinning disk reactor

A spinning disk reactor is a promising technique of process intensification used in various chemical engineering processes. The flow behaviour of the thin film on the reactor surface dominates the transfer and reaction performance. Using glycerol–water and sodium dodecyl benzene sulphonate–water solutions as medium, this study examined the transition of flow patterns and wave characteristics of film flow using image processing technique. Five types of patterns are identified, and the transition is dominated by impact and centrifugal effects. Transitional flow is characterized as regular or irregular squeeze flow. Irregular waves flow regularly and lead to reverse spiral wave for large flow rates or speeds. The spiral waves originate from concentric wave owing to Rayleigh Taylor instability and form in synchronization zone, and go through long wave, short wave and wavelet stages. The instantaneous distribution rate of spiral waves has periodic characteristic. Due to the reduced surface tension, the waves become more stable and move outward, while larger distribution rates are obtained. The distribution rates decline rapidly at first and then slowly with the increasing viscosity. For a low volume flow rate times rotational speed, the formation radius of spiral waves is easily regulated and a larger distribution rate is obtained. While for high speeds, it is not recommended to blindly further increase the speeds to improve the wave behaviour.