Engineering topics

Kendall, James M., Jr.

Publications and source records attributed to Kendall, James M., Jr..

5 records

NASA NTRS1990

Measurement of waves in flows across a surface

A method and apparatus is disclosed for sensing wave flow across a surface wherein at least two pressure levels are sensed and combined to provide a representation of waves within the flow. In the preferred embodiment holes bored through the aircraft surface at an interval of one-half the wavelength of the flow being measured introduce pressure perturbations into a cavity so they may acoustically interfere. The interfering waveform is sensed by at least one microphone disposed in the cavity.

Kendall, James M., Jr.↗

NASA NTRS1990

Some comparisons of linear stability theory with experiment at supersonic and hypersonic speed

Measurements of waves initiated by wind-tunnel sounds are obtained for both supersonic and hypersonic speed. Flat-plate experiments carried out at Mach numbers of 4.5, 3.7, and 2.4 under the condition of laminar tunnel-wall boundary layers whereby a low background fluctuation level prevailed are outlined, as well as flat-plate experiments with sound-induced waves at supersonic speeds. Experimental studies of 'natural' wave growth on sharp cones at zero angle of attack and Mach numbers near 8 are discussed. Attention is focused on experimental research needed on boundary-layer receptivity to eddy Mach-wave radiation, hypersonic speed, and the stability-transition relationship in zero-pressure-gradient layers.

Kendall, James M., Jr.↗

NASA NTRS1990

The effect of small-scale roughness on the main flow profile of a laminar boundary layer

The profile distortion due to a single roughness element, to two such elements, and to many elements is investigated. Signal-averaging of the velocity difference due to the roughness being alternately present or absent is employed in order to improve accuracy. The primary objective of examining the distributed-roughness profiles for any evidence of instability-enhancing form is not met, but the results are reconsidered, and relevant hypotheses and suggestions are presented. It is noted that the reason for not meeting the objective of estimating Tollmien-Schlichting amplification from rough-wall profiles is that much of the distortion occurs close to the wall and below the element tops.

Kendall, James M., Jr.↗

NASA NTRS1987

Experiments in Boundary-Layer Turbulence

Motion in layer highly three-dimensional. Report describes experimental studies of disturbances induced by weak free-stream turbulence in pre-transitional Blasius boundary layer. Asks and partially answers some fundamental questions concerning large-amplitude, low-frequency disturbances.

Kendall, James M., Jr.↗

NASA NTRS1984

Apparatus for forming a continuous lightweight multicell material

An apparatus is described for producing a lightweight structural material (12), by forming gas-filled shells (38) of molten material from a matrix of nozzles (22) that form shells of very uniform size at very uniform rates. The matrix of molten shells coalesce into a multi-cell material of controlled cellular structure. The shells can be of two different sizes (38, 44) that are interspersed, to form a multicell material that has a regular cell pattern but which avoids planes of weakness and localized voids. The gas (50) in the shells can be under a high pressure, and can be a fire extinguishing gas.

Wang, Taylor G.↗