ONE-DIMENSIONAL DESIGN OF A THREE-STAGE AXIAL COMPRESSOR WITH ITS 3D NUMERICAL SIMULATION

The purpose of this study is to design a three-stage axial compressor with identical pressure ratio which makes an adequate pressure ratio and efficiency in design point conditions with rotational velocity of 38000rpm and mass flow rate of 3.2kg/s. First of all, considering some restrictions such as Dehaller number more than 0.7 in all sections of the stator and the rotor, and relative Mach number less than 0.8 at the tip of the rotor blade [1], one dimensional design is performed. In this design, blade base diameter is considered the same in all stages, regarding shaft diameter. In order to reduce casing diameter, inlet guide vanes are utilized so that the relative Mach number at the tip of the first stage rotor blade decreases. Therefore, the design of the rotor blades and the stator are based on reaction coefficient of 0.5. According to calculated input and output angles, adequate profile for each section is selected from NACA-Mellor diagrams. The output of the one dimensional design program is calculation of all the geometric parameters including blades input and output angles, blades length and diameter, solidity coefficient, number of blades and installation angle at three different sections of hub, mid and tip in compliance with the constraints. Thus, the three-dimensional shape of the blades is created. To investigate the performance of the designed compressor at design point, an appropriate grid is selected on the three-dimensional geometry of the compressor and the three-dimensional numerical solution is obtained using a full Navier-Stokes program.