Effects of Compressibility, Pitch Rate and Reynolds Number on Unsteady Incipient Leading-Edge Boundary Layer Separation Over a Pitching Airfoil
Abstract
The effects of compressibility, pitch rate and Reynolds number on the initial stages of 2-D unsteady separation of laminar subsonic flow over a pitching NACA-0012 airfoil have been studied numerically. Computations have been performed using two separate algorithms (structured grid algorithm of Beam and Warming, and unstructured grid algorithm employing flux-difference splitting method of Roe) for the compressible laminar Navier-Stokes equations. The simulations show the appearance of a primary recirculating region near the leading edge, followed by a secondary and tertiary recirculating regions. The primary and secondary recirculating regions interact with each other to give rise to the unsteady separation of the boundary layer. Increasing the Mach number from 0.2 to 0.5 causes a delay in the formation of the primary recirculating region. Increasing the pitch rate also delays the formation. Increasing the Reynolds number hastens the appearance of the primary recirculating region and leads to the appearance of a shock on the top surface along with the formation of multiple recirculating regions near the leading edge. A linear stability analysis has shown that the appearance of the primary recirculating region is related to the instability of the flow.
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 30, 1996
- Accession Number
- ADA308347
Entities
People
- Doyle D. Knight
- Nora Okong'o
- Pushkar G. Choudhuri
Organizations
- Rutgers University Department of Mechanical and Aerospace Engineering