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Clarkson, M. H.

Publications and source records attributed to Clarkson, M. H..

11 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1983

Subsonic high-angle-of-attack aerodynamic characteristics of a cone and cylinder with triangular cross sections and a cone with a square cross section

Experiments were conducted in the 12-Foot Pressure Wind Tunnel at Ames Research Center on three models with noncircular cross sections: a cone having a square cross section with rounded corners and a cone and cylinder with triangular cross sections and rounded vertices. The cones were tested with both sharp and blunt noses. Surface pressures and force and moment measurements were obtained over an angle of attack range from 30 deg to 90 deg and selected oil-flow experiments were conducted to visualize surface flow patterns. Unit Reynolds numbers ranged from 0.8x1,000,000/m to 13.0x1,000,000/m at a Mach number of 0.25, except for a few low-Reynolds-number runs at a Mach number of 0.17. Pressure data, as well as force data and oil-flow photographs, reveal that the three dimensional flow structure at angles of attack up to 75 deg is very complex and is highly dependent on nose bluntness and Reynolds number. For angles of attack from 75 deg to 90 deg the sectional aerodynamic characteristics are similar to those of a two dimensional cylinder with the same cross section.

Clarkson, M. H.↗
NASA NTRS1983

Flow visualization studies of bodies with square cross sections

A water-tunnel study was conducted of four bodies. A solution of sodium fluorescein coating the body provided visualization of vortices and feeding sheets and isolated dots of methyl blue dye provided visualization of stream lines. These data, along with published oil-flow photos, were analyzed to develop the topological representation of the flows in cross-flow planes. Presented are the development of the flow along the body at fixed angles of attack and at a fixed body station with changes in angle of attack. Effects of roll angle, body corner radius, and nose bluntness are illustrated.

Chapman, G. T.↗
NASA NTRS1982

The investigation of flow instabilities on a rotating disk with curvature in the radial direction

The major objective is to explore any visible differences of the flow field with wall curvature of the test body, including possible interaction between Taylor-Gortler instabilities present along concave walls and the inflexional instabilities investigated here. An experimental study was conducted with emphasis placed on making visual observations and recording photographically the flow instabilities present under three different rotating bodies: a flat disk, a concave paraboloid, and a convex paraboloid. The data collected for the three test bodies lead to the conclusion that the wall curvature of the concave and convex paraboloids did not alter the observed flow field significantly from that observed on the flat disk.

Intemann, P. A.↗
NASA NTRS1980

Flow visualization of inflexional instabilities on a rotating disk

Experiments were conducted on a rotating disk in water using dye to observe the formation of small vortices in the boundary layer due to the inflexional nature of the boundary layer profiles in the radial and near radial directions. Such vortices have also been detected near the leading edge of swept wings and on the windward side of fuselages at angles of attack using sublimation techniques. In the present investigation, color motion pictures at 300 frames per second were taken and the vortex spacing, angles of inclination of the vortex axes and critical Reynolds numbers were determined from these films. Secondary instabilities were also observed and analyzed.

Clarkson, M. H.↗
NASA NTRS1977

A subsonic flow investigation on a research body at high angles of attack

Tests conducted in the Ames 12-foot pressure wind tunnel on a rotating research body at angles of attack of 45 to 90 deg yielded results that were inconsistent with simple cross-flow theory. Consequently, force and pressure distribution tests along with oil and sublimation flow-visualization studies were conducted in the same tunnel on a nonrotating model to attempt to explain the behavior observed in the rotary tests. These studies indicate that at appropriate conditions of Reynolds number and angle of attack, inflectional instabilities occur in the boundary layer that materially affect separation and, hence, the aerodynamic forces. Calculations of cross-flow Reynolds numbers are made and compared with other works on inflectional instability.

Clarkson, M. H.↗
NASA NTRS1976

Wind-tunnel testing with a rotary-balance apparatus to simulate aircraft spin motions

Experiments have been conducted in the Ames 12-Foot Pressure Wind Tunnel on a simple airplane-like model using a rotary-balance apparatus to simulate a steady spin motion at high angles of attack. Tests were run at Mach numbers of 0.1 and 0.25 over a wide Reynolds number range with the angle of attack varying from 45 to 90 deg. During previous tests of the same research model, some difficulties were experienced with measurement accuracy in the low-to-medium range of Reynolds number because of limitations in the sensitivity of selected force balances. For the present tests, special balances were built to provide accurate measurements of the nose and tail contributions to spin motions and improvements were made to the overall test apparatus. The results of this test, including some interesting hysteresis effects with spin rate, are described. Some of the problems associated with rotary-balance tests at high Reynolds numbers are discussed. A new large-scale rotary apparatus now nearing completion for use in the Ames 12-Foot and 11- by 11-Foot Wind Tunnels is described briefly.

Malcolm, G. N.↗
NASA NTRS1975

Experimental determination of post-stall rotary derivatives for airplane-like configurations at several Reynolds numbers

Military and civilian airplane losses due to out-of-control spin motions are significant. Knowledge of rotary coefficients is necessary to understand the cause of spin entry and to devise proper recovery techniques. An exploratory wind-tunnel investigation has been conducted on simple airplane-like configurations on a rotary sting apparatus at rotation rates up to 10 rps. Rotary coefficients have been measured at unit Reynolds numbers from 2,000,000 to 24,600,000 per m and at angles of attack from 45 to 90 deg. Results show that the aerodynamic characteristics at steady spin rates are highly dependent on both spin rate and Reynolds number.

Clarkson, M. H.↗