Lifting Jet Flow Fields.
Abstract
The control of VTOL aircraft during transition from hover to forward flight is complicated due to the complex airframe-jet interaction. This investigation is concerned with mathematical modelling of asymmetric entrainment of lifting jets. The analysis is for two dimensional augmenters used on VTOL aircraft. The theoretical analysis of the lifting jets was limited to two dimensional curved jets in forward flight and out of ground effects. The aim was to predict the asymmetric entrainment rates of the curved jet along with its decay rate of the maximum velocity, and jet width growth rate. The results were obtained using turbulent curved free jet theory in conjunction with thin jet potential flow models to obtain the jet edge streamwise velocities. To test the effects of asymmetric entrainment the results were inserted in a thick jet potential flow computer program to obtain transition flight performance of a typical VTOL augmenter wing. A concurrent experimental study was undertaken to determine curved jet characteristics issuing from a two dimensional model. Maximum velocity decay, jet curvature, jet width, velocity and pressure profiles were measured. Good agreement has been obtained between the theoretical predicted and experimental measured curved jet characteristics. It was necessary to adjust the constant in the turbulent shear stress model to get this good agreement. Both experiments on the straight and curved jets at West Virginia University and by others have been compared with the theory.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 01, 1975
- Accession Number
- ADA021968
Entities
People
- John L. Loth
- Richard E. Walters
- Subrato Chandra
Organizations
- West Virginia University