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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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At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1960

Static Thrust of an Annular Nozzle with a Concave Central Base

A static test of an annular nozzle with a concave central base, producing a jet in which tangents to the jet streamlines at the exit converged toward a region on the axis of symmetry downstream of the exit, has indicated good thrust performance. A value of nozzle-flow coefficient only slightly less than unity indicates the internal loss to be small. Pressures on the concave central base are relatively large and positive, and a predictable portion of the total thrust of the jet is exerted on the central base.

Corson, Blake W., Jr.↗
NASA NTRS1935

Tank Tests of a Model of a Flying-boat Hull Having a Longitudinally Concave Planing Bottom

The NACA model 11-B, which has a longitudinally concave planing bottom forward of the step, was tested over a wide range of loading. The results of the tests are presented as curves of resistance and trimming moment plotted against speed for various trim angles and as curves of resistance coefficient at best trim angle, and trimming-moment coefficient. The characteristics of the form at the optimum trim are compared with those of NACA model 11-C which has the same form with the exception of a planing bottom longitudinally straight near the step. Photographs of the models being towed in the tank are included for a comparison of the spray patterns. At the best angles of trim in each case model 11-B has lower resistance at high speeds, a higher maximum positive trimming moment near the hump speed, and a more favorable spray pattern than of model 11-C.

Parkinson, J B↗
NASA NTRS1954

On the three-dimensional instability of laminar boundary layers on concave walls

A study is made of the stability of laminar boundary-layer profiles on slightly curved walls relative to small disturbances that result from vortices whose axes are parallel to the principal direction of flow. The result is an eigenvalue problem by which, for a given undisturbed flow at a prescribed wall, the amplification or decay is computed for each Reynolds number and each vortex thickness. For neutral disturbances (zero amplification) a critical Reynolds number is determined for each vortex distribution. The numerical calculation produces amplified disturbances on concave walls only.

FLOW, LAMINAR↗
NASA NTRS1958

Heat-Transfer Measurements on a 5.5- Inch-Diameter Hemispherical Concave Nose in Free Flight at Mach Numbers up to 6.6

The aerodynamic heat transfer to a hemispherical concave nose has been measured in free flight at Mach numbers from 3.5 to 6.6 with corresponding Reynolds numbers based on nose diameter from 7.4 x 10(exp 6) to 14 x 10(exp 6). Over the test Mach number range the heating on the cup nose, expressed as a ratio to the theoretical stagnation-point heating on a hemisphere nose of the same diameter, varied from 0.05 to 0.13 at the stagnation point of the cup, was approximately 0.1 at other locations within 40 deg of the stagnation point, and varied from 0.6 to 0.8 just inside the lip where the highest heating rates occurred. At a Mach number of 5 the total heat input integrated over the surface of the cup nose including the lip was 0.55 times the theoretical value for a hemisphere nose with laminar boundary layer and 0.76 times that for a flat face. The heating at the stagnation point was approximately 1/5 as great as steady-flow tunnel results. Extremely high heating rates at the stagnation point (on the order of 30 times the stagnation-point values of the present test), which have occurred in conjunction with unsteady oscillatory flow around cup noses in wind-tunnel tests at Mach and Reynolds numbers within the present test range, were not observed.

Levine, Jack↗