Aerodynamic characteristics of a tip jet fan with a large blade pitch angle
Abstract This work aims to investigate the availability of a tip jet on a ducted fan under large blade pitch angle and high solidity conditions. The aerodynamic performance and flow field of a ducted fan in hover are numerically investigated over a range of blade pitch angles at three operating speeds. A numerical experiment is conducted using the shear stress transport k omega turbulence model with a refined high quality structured grid. The maximum thrust, peak efficiency, and stall margin of the ducted fan with tip jet are the main interests of this investigation. Results indicate a 30% increase in the thrust of the fan with tip jet near stall margin condition. This aerodynamic improvement seems to increase with the blade pitch angle because the separation flow at the front part of the blade becomes uniform and reattaches to the blade surface due to the entrainment effect of the tip jet. The nozzle with an angle in downwash direction can improve tip jet efficiency at a large blade pitch angle. The tip jet is applicable to a fan with a large pitch angle and high solidity.
Aerospace Science and Technology