The Effect of Hole Geometry on the Near Field Character of Crossflow Jets
Abstract
Water tunnel experiments were conducted to understand the effect of hole exit geometry on the lift-off characteristics of crossflow jets. Six basic hole shapes were investigated, all having the same cross-sectional area: round, elliptical, square, and rectangular. Laser Induced Fluorescence (LIF) and Particle Image Velocimetry (PIV) were used to visualize the jet structures near the hole, and acquire velocity and vorticity field information, respectively. The flow visualization pictures, and PIV data images, graphs, and vector plots' complement each other to provide a deeper understanding of the basic make-up of the kidney-vortices that are present in a crossflow jet. The vorticity around the circumference of the jet was tracked using LIF and PIV to understand the relative contributions to the kidney-vortices. The jet side-wall boundary layer is responsible for the primary kidney vortex structures. These vortices result from the roll-up of the side-wall boundary layer as the jet exits the hole. Here, hole geometry alone was found to have a distinct influence on the lift-off behavior by affecting the lateral separation of these side-wall vortices.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 1996
- Accession Number
- ADA311883
Entities
People
- Brenda A. Haven
Organizations
- Air Force Institute of Technology