SCIENCE CHINA Technological Sciences © Science China Press and Springer-Verlag Berlin Heidelberg 2014 tech.scichina.com link.springer.com *Corresponding author (email: lifch@hit.edu.cn)  Article  November 2014 Vol.57 No.11: 2115–2130 doi: 10.1007/s11431-014-5631-0 Experimental study on the performance of a rotational supercavitating evaporator for desalination LIKHACHEV Dmitriy S 1 , LI FengChen 1* & KULAGIN Vladimir A 2 1 School of Energy Science and Engineering, Harbin Institute of Technology, Harbin 150001, China; 2 Department of Heat Technology and Fluid Dynamics, Siberian Federal University, Krasnoyarsk 660041, Russia Received May 8, 2014; accepted July 31, 2014; published online October 10, 2014 Efforts have been made on experimental research of a supercavitation device for desalination, which is named rotational su- percavitating evaporator (RSCE). The RSCE is characterised by the simple construction and responsive capacity control, and only requires rough filtration of the source water for scaling- and fouling-free operations. The present study has been conduct- ed for the water flow at temperature of around 22–30°C and atmospheric pressure as the first step for investigation of the per- formance characteristics of RSCE. The multiply factor extremal experiments conducted with the Box-Wilson’s method have revealed the salinity of the condensate, the temperature of steam inside the supercavity, and dependence of the shape of super- cavity on the rate of steam extraction and rotation speed of impeller. The shape of impeller and the expected supercavitating effects it generates have been confirmed by experimental results at the rotation speed of 5430 rpm (round per minute). The de- sign of the steam extraction openings has been approved during the evacuation of steam. The experimental dependencies have been obtained in form of statistically valid regression equations, which can be used for engineering design of RSCE. desalination, cavitation technology, thermal method, steam extraction, regression analysis Citation: Likhachev D S, Li F C, Kulagin V A. Experimental study on the performance of a rotational supercavitating evaporator for desalination. Sci China Tech Sci, 2014, 57: 2115–2130, doi: 10.1007/s11431-014-5631-0 1 Introduction The central contribution of this paper is an experimental investigation of the performance characteristics of the rota- tional supercavitating evaporator (RSCE) [1] for desalina- tion. The details of steady-state heat and mass transfer characteristics between water and water steam, hydrody- namics of the supercavity formed behind the rotational su- percavitating impeller with two wedge-shaped blades rotat- ing in cold water, and the impact of steam extraction on the performance of RSCE are presented. The spatial character- istics of supercavity and technological performance of the RSCE are revealed. During last century, growth of global water consumption ratio more than two times exceeded the population upsurge ratio. Therefore, the main focus of the program “Water for Life”, declared by who for 2005–2015 years, is to halve the number of people without access to safety water resources. Moreover, according to the data presented by hydrologists, projected water use together with diversions to non-agri- cultural sectors was 897 km 3 in the year 2000 and will be a predicted volume of 2216 km 3 in the year 2050 worldwide [2]. More than 97% of water available for human use is from the easily accessible oceans and salted, and desalination is considered as the most perspective solution for the world’s supply of fresh water. According to the data presented in the report [3], beside the thermal distillation technologies pro- ducing over 35% world’s volume of the freshened water,