Aerodynamic Design, Analysis and Optimization of Transonic Axial Compressor Blade with the Combination of NACA 65,Double Circular Arc (DCA) and Multiple Circular Arc Airfoil (MCA)

Abstract

This paper deals with the Design, Analysis and optimizing a single stage axial transonic compressor. The recent trend to increase the capacity of modern heavy duty gas turbine compressors requires high performance transonic rotors with increasing tip Mach numbers. When developing a transonic compressor, an important subject is to design an airfoil shape which gives good performance in transonic flow region. NACA-65 aerofoil is best suitable for subsonic regime. While Multi Circular Arc (MCA) airfoil design and DCA aerofoil design are suitable in transonic regimes. Therefore an attempt is made to design and study the aerodynamic characteristics of a transonic compressor stage with NACA-65, MCA and DCA aerofoil combinations.CF-turbo is used to design the aerofoil and computational analysis is carried out in Ansys CFX. The air mass flow rate is considered of 5kg/sec at 10,000 RPM, blade tip speed 454 m/sec rotor hub to tip speed ratio=0.7. Overall performance of all the combinations were inlet totalpr =1 atm. Comparatively good having the isentropic efficiency ranging from 77.9 % to 84.8% having MCA-DCA combinations the lowest & NACA-MCA being the highest but overall pr.ratio is observed to be 1.244 in MCA-MCA and MCA-DCA combinations while NACA-MCA is only 1.23. Flow coefficient and head coefficient being the highest in MCA-MCA & MCA-DCA combinations of 24.87 and 13.62 respectively. Blade loading co efficient is observed as -8.7 and it is nearly flat over the upper surface of rotor as well as stator in MCA-DCA combinations, while NACA-MCA having uneven behavior of -7.86. Thereby through my study i conclude that NACA-65 aerofoil with MCA for the rotor and  NACA-65 with DCA for stator as the best combination among all the different cases studied in this attempt.