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Focuses on a study which examined the mean flow development in dual-stream compressible jets. Description of the planar shear layer model used; Potential core lengths and sonic lengths; Mass flow rates.

Presents a study which characterized the acoustics of axisymmetric high-speed jets at a variety of Mach numbers and velocities and at pressure-matched, overexpanded, and underexpanded conditions. Components of supersonic jet noise; Noise measurements; Correlations of jet noise with engine operating parameters.

Presents a study which demonstrated directional suppression of noise from a high-speed jet using an asymmetric parallel secondary stream. Methodology; Results and discussion; Conclusions.

Presents information on a study that investigated the noise measurements for perfectly expanded coaxial jets composed of a supersonic primary stream at conditions designed to prevent formation of Mach waves. Description of the flow apparatus; Global features of the jet; Noise characteristics.

We present a computational study, validated by mean-flow experiments, of a dual-stream nozzle simulating the exit conditions of a supersonic turbofan engine with noise-suppressing fan flow deflectors. The study is conducted for eight nozzle configurations and two operating conditions: a cold condition at which mean velocity surveys were conducted and against which the computational code was validated and a hot condition that corresponds to the takeoff engine cycle and at which acoustic data were collected. The code predictions successfully replicate the mean velocity fields and the inflectional layers of the experimental flows. The code is then extended to the conditions of the actual engine cycle. The computations reveal a similar velocity profile for the hot and cold conditions when the axial distance is normalized by the potential core length. For both conditions, the vane deflectors reduce the turbulent kinetic energy k on the underside of the jet. An overall noise source strength is modeled as the axial integral of k7/2. A significant correlation is found between the reduction in the noise source strength and the reduction in the peak level of the overall sound pressure level. [ABSTRACT FROM AUTHOR]