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Results for “conventionally neutral boundary layer”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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NASA NTRS1984

Correlations of supersonic boundary-layer transition on cones including effects of large axial variations in wind-tunnel noise

Transition data on sharp tip cones in two pilot low disturbance wind tunnels at Mach numbers of 3.5 and 5 were correlated in terms of noise parameters with data from several conventional wind tunnels and with data from supersonic flight tests on a transition cone. The noise parameters were developed to account for the large axial variations of the free stream noise and the very high frequency noise spectra that occurred in the low disturbance tunnels for some test conditions. The noise could be varied in these tunnels from high levels, approaching those in conventional tunnels, to extremely low levels. The correlations indicated that transition in the low disturbance tunnels was dominated by the local stream noise that was incident on the cone boundary layer unstream of the neutral stability point. The correlation results also suggested that high frequency components of the low disturbance tunnel noise spectra had significant effects on transition when the noise was incident on the boundary layer both upstream and downstream of the neutral stability point.

Chen, F. J.↗
NASA NTRS1984

Effects of streamwise variations in noise levels and spectra on supersonic boundary-layer transition

Transition data for sharp cones in two quiet wind tunnels at Mach numbers 3.5 and 5.0 have been correlated in terms of noise parameters with data from several conventional wind tunnels and from the flight data for the AEDC transition cone. The noise parameters were developed to account for the large axial variations of the rms stream noise and the high frequency noise spectra that occurred in the quiet tunnels for some test conditions. The correlation results indicated transition in the quiet tunnels was dominated by the local stream noise that was incident on the cone boundary layer upstream of the neutral stability point. The correlation results also suggested that the energy in high frequency components of the quiet tunnel noise spectra had significant adverse effects on transition when the noise was incident on the boundary layer both upstream and downstream of the neutral stability point.

Chen, F.-J.↗
NASA NTRS1986

Ocean surface pressure fields from satellite-sensed winds

The University of Washington's planetary boundary layer model is inverted to use remotely sensed satellite scatterometer-derived surface winds as input to calculate maritime surface pressure fields. The analysis of three different synoptic storm situations is performed using the model and is then compared to conventional National Weather Service analyses. Agreement is good. Isolation of the PBL secondary flow, stratification and thermal wind effects in the model revealed that each may be significant under certain conditions. However, the model shows sensitivity to the thermodynamic features only in a general sense and even a neutral stratification solution gives a good approximation. The high density of the scatterometer data produces mesoscale (hundreds of kilometers) dynamic details, which cannot be confirmed by conventional data at this stage.

Brown, Robert A.↗