Dynamics of Unsteady Flow Past Bluff Bodies With Lofted Bases
Abstract
This report describes a comprehensive four-year effort to characterize the wake downstream of a surrogate cargo aircraft fuselage. The specific configuration is a cylinder with free streamflow-aligned axis, and a base at various upsweep angles. A tightly-integrated experimental computational campaign was conducted. Experiments included high-fidelity point-, planar and volume measurements, while simulations employed very high-order Large-Eddy Simulations. Key findings of the efforts cover the physical three-dimensional mean structure of the wake, unsteadiness associated with vortex meandering and the phenomenon of hysteresis. The effects of Reynolds number and upsweep angle on these features were examined in detail. The primary vortical structure emerging due to separation around the periphery of the base rolls up into a horse-shoe structure which ultimately separates from the base to form a generally streamwise oriented vortex pair. The development of the turbulent flow is characterized by numerous instabilities. The vortices downstream meander at characteristic frequencies designated by their Strouhal numbers based on cylinder diameter. A reduced model shows however, that far downstream, the complex motion can be represented with only a few modes obtained from Proper Orthogonal Decomposition. Hysteresis is observed with Reynolds number as well as upsweep angle varied independently with the two states corresponding to the above described vortex regime, and a separate wake regime characterized by a turbulent.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 31, 2022
- Accession Number
- AD1184980
Entities
People
- Datta V. Gaitonde
- Farrukh S. Alvi
- Rajan Kumar
Organizations
- Ohio State University