1. Institute of Fluid Physics, China Academy of Engineering Physics, P.O. Box 919-101, Mianyang 621900, P.R. China (corresponding author).
2. School of Mechanical, Aerospace and Civil Engineering, Univ. of Manchester, Pariser Building, Manchester M13 9PL, UK.
3. Institute of Process Equipment, Zhejiang Univ., Hangzhou 310027, P.R. China.