Measurements on the mean and most of the significant turbulent properties of plane isothermal and heated (but essentially “nonbouyant”) jets are reported. The velocity measurements were made using two-component, frequency-shifted Laser Doppler Anemometry (LDA) and the temperature measurements were made using fast-response resistance thermometry. A simple but effective technique was developed for obtaining accurate velocity measurements from the LDA in a nonisothermal environment. These measurements, some of which are the first of their kind, provide an independent data base with which to compare existing hot-wire data on jets. The LDA measurements indicate lower turbulence intensities and lower turbulent fluxes compared to the hot-wire data.

Measurements in Vertical Plane

No abstract

Compressibility effects on dynamic stall of a NACA 0012 airfoil undergoing sinusoidal oscillatory motion were studied using a stroboscopic schlieren system. Schlieren pictures and some quantitative data derived from them are presented and show the influence of freestream Mach number and reduced frequency on the dynamic stall vortex. This study shows that a dynamic stall vortex always forms and convects over the airfoil upper surface at approximately 0.3 times the freestream velocity for all cases studied. The results also demonstrate that occurrence of deep stall is delayed to higher angles of attack with increased reduced frequency, even when compressibility effects are present, but increasing Mach number alone has the opposite effect.

No abstract