Unsteady Flows and Airfoil-Vortex Interaction
Abstract
Unsteady flows past two airfoils in tandem placed in a shock tube flow field have been studied using Navier-Stokes equations. An implicit Global Newton iterative procedure is applied for time-accurate solution of the transient flow field. This study is primarily motivated by a need to understand the aerodynamic implications of the blade-vortex interaction in the rotor flow field of a helicopter. To simulate the vortex effects in 2D, a streamwise moving shock wave is imposed immediately upstream of the leading edge of the lead airfoil, which is pitched at an angle of attack of -20 degrees. The lead airfoil is used to generate a vortex that can be lifted off and convected downstream until it reaches the trailing test airfoil. After the passage of the shock wave over the lead airfoil, a nearly symmetric vortex is generated. This vortex then separates at the trailing edge and convects downstream at the freestream velocity towards the aft airfoil. To avoid numerical dissipation, a refined grid is used along the vortex path. For the aft airfoil, it is observed that the passage of the vortex has notable effects upon its aerodynamic characteristics. It is further noted that the vortex is followed by the lead airfoil wake, which splits later on into a series of smaller vortices. Owing to the high angle of attack of the lead airfoil, the viscous flow underneath seems to progressively grow behind the shock wave resulting in a separation. The flow field is seen to comprise a complex pattern of incident and reflected compressibility waves from the walls, which interact with the separated flow present on the lower airfoil surface. (12 figures, 10 refs.)
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 01, 2003
- Accession Number
- ADA418870
Entities
People
- Haowei Xu
- M. Mamou
- Muhammad Khalid
Organizations
- National Research Council Canada