One-Dimensional design of a three-stage axial compressor with Its 3D numerical simulation

In this research, one-dimensional design of a three-stage axial compressor is performed to reach an adequate pressure ratio and efficiency in design point conditions with rotational speed of 38000 rpm and mass flow rate of 3.2kg/s. At first, some constraints such as Dehaller number more than 0.7 for all sections of rotor and stator, and relative Mach number less than 0.8 at rotor blade tip are considered. In this design, hub diameter is equal to shaft diameter in each stage. In order to reduce rotor blade tip diameter or tip Mach number at the first stage, some inlet guide vanes are utilized. Therefore, the rotor and stator blades can be designed based on reaction coefficient of 0.5. The output of the one-dimensional design program is calculation of all geometric parameters such as blades inlet and outlet angles, blades length and diameter, solidity coefficient, number of blades and blades stagger angles at three different sections of hub, mid and tip in compliance with the constraints. Thus, 3D shape of the blades can be generated. To ensure the performance characteristic of the designed compressor at design and off design conditions, the 3D designed geometry is modeled in BLADE GEN software and then is transferred to TURBO GRID for grid generation. Finally, 3D numerical solution of fluid flow through all blades passages is solved by CFX flow solver. In this approach, compressible flow equations are solved according to the pressure based method with SST turbulence model. The numerical solution results indicate that the designed compressor has a maximum pressure ratio of 1.8 with efficiency of 80% which is acceptable for a primary design.

Keywords:

Axial compressor , One dimensional design , Numerical simulation , Dehaller