Nowadays precise and reliable tools for designing and optimizing turbomachines have a high impact on industrial and research fields. The design methods of turbomachines follow usually two main paths: direct design, where performances are achieved by iteratively modifying a given geometry, and inverse design where performance characteristics are prescribed and the proper geometry for reaching them is found (usually using analytical methods). Both of these methods are used today in research and development and they are coupled with numerical simulations (CFD) for shorter design cycles. This paper proposes an inverse design approach for low pressure axial fans based upon performance equations, namely the equations for total-to-static pressure and efficiency. To validate our approach we use numerical simulation of the axial fan in a virtual test rig. Combining inverse design with the CFD for its validation offers an integrated approach for improving the design in the development phase. In the first step analytical energy equations are derived for a blade cascade section and then integrated over the blade surface, i.e. from hub to tip radii, providing a dependency of the theoretical performances characteristics such as for the pressure and the efficiency, as a function of the flow-rate, rotating speed and the outer dimensions and blade angles of the machine. The next step computes inversely the main outer dimensions and blade angles of the geometry required for reaching the performance. In the final design step the blade shape is computed inversely using a NACA 4 Digit camber as it will be shown in the paper upon the required blade angles and other constrains of the cascade. The final shape is generated in CAD software-program and then a proper computational grid is generated so that it can be finally simulated with a commercial Navier-Stokes solver for the complete pressure and efficiency characteristics. The aim of this study is to offer general conclusions about the analytical influence of certain geometry parameters on the design and optimization of axial fans of this type. The last step for the proposed design method is typically the experimental validation with prototypes which will be not covered in this study.

This content is only available via PDF.
You do not currently have access to this content.