Numerical simulation of the pneumatic elasticity for the blade of a big axial-flow fan

It is very important to study fluid–solid coupling problems of turbomachines which occur in the large revolving fluid machinery. Especially, the coupling between the fluid and the elastic solid is the most difficult problem in fluid–solid coupling of turbomachines. In order to solve this, the effect of the deformation and vibration of the elastic solid on the flow field and the reaction from the vibrating flow field on the solid need to be considered. The No. 18 axial-flow fan in Beijing’s subway is selected as illustration to discuss the computational method for solving the fluid–solid coupling problem by considering the interaction of the blade deformation and the flow field using a numeric simulation analysis of the blade’s pneumatic elasticity. The kind of coupling used is partitioned but loosely coupled with the software CFX to describe the flow field and the software ANSYS to describe the reaction of the structure. Both computational results will be shared on the exchanging platform MFX-ANSYS/CFX and compared with the situation where no elastic deformation is considered. It is indicated that the maximum stress including the pneumatic elasticity is twice the maximum stress without the pneumatic elasticity considered. The minimum safety coefficients approximate the permitted safety coefficients with the pneumatic elasticity considered. Contrarily, the actual minimum safety coefficients are far over the permitted safety coefficient, this is not consistent with the real situation and will magnify the safety of the blade structure, which demand the necessity of the pneumatic elastic analysis.