Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.

Experience as a consultant to the Safety Office at Norton AFB led to compiling the engineering tools presented so that this report can be used by engineering personnel to investigate future incidents/accidents and existing USAF operations that are impacted by the vortical wake hazard. The approach presented is amenable to easy hand computations. Mixed airplane/helicopter operations can be assessed, since the engineering tools to determine the location and strength of the rotor downwash field behind a helicopter are presented. Finally, a simplified mathematical model is given to represent this hazard for use in USAF simulators, to make pilots aware of the problems associated with operating in wake-contaminated airspace.

An investigation has been undertaken to develop a theoretical model of the incompressible jet injection process. The discharge of a turbulent jet into a cross flow was mathematically modeled by using an integral method which accounts for natural fluid mechanisms such as turbulence, entrainment, buoyancy, and heat transfer. The analytical results are supported by experimental data and demonstrate the usefulness of the theory for estimating the trajectory and flow properties of the jet for a variety of injection conditions. The capability of predicting jet flow properties, as well as two- and three- dimensional jet paths, was enhanced by obtaining the jet cross-sectional area during the solution of the conservation equations (a number of previous studies assume a specific growth for the area). Realistic estimates of temperature in the jet fluid were acquired by accounting for heat losses in the jet flow due to forced convection and to entrainment of free-stream fluid into the jet.

An experimental investigation of a subsonic round jet exhausting perpendicularly from a flat plate into a subsonic crosswind of the same temperature was conducted. Velocity and pressure measurements were made in planes perpendicular to the path of the jet for ratios of jet velocity to crossflow velocity ranging from 3 to 10. The results of these measurements are presented in tabular and graphical forms. A pair of diffuse contrarotating vortices is identified as a significant feature of the flow, and the characteristics of the vortices are discussed.