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Johnson, L. E.

Publications and source records attributed to Johnson, L. E..

6 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1990

Turbulence in a reacting contact surface

Turbulent features in a shock tube's contact surface with the reversible reaction 2NO2 to N2O4 are explored. Turbulent densities and velocities show an overall power-law dependence in the fluctuation spectra. At fixed reactant percentages, turbulence increases with increasing Reynolds number. At fixed Reynolds numbers, increasing the reactant percentages causes a reduction in turbulence and an increase in the relative strength of discrete high-frequency components in the density fluctuation spectra. The reliability of conventional chemical modeling for this system apparently decreases with increasing turbulence in a manner suggestive of reaction rate distortion, consistent with theoretical speculation.

Johnson, J. A., III↗
NASA NTRS1988

Evidence of Reynolds number sensitivity in supersonic turbulent shocklets

A local shock wave can destroy the evolution of supersonic combustion in a scramjet. The Reynolds number correlation of the systems of internal shock waves produced in such turbulent free shear layers are presently noted to imply that a direct connection with turbulence intensity exists. By way of this connection, as well as the adjustability of the Reynolds number, opportunities emerge for the control of turbulent shocklets; this will in turn allow control of their influence on supersonic mixing.

Johnson, J. A., III↗
NASA NTRS1985

Fast turbulent correlations from phase coherence velocimetry

Flows with coherent structures allow see-free measurements of local velocity and velocity fluctuations. Continuous turbulent velocity histories in ionizing shock waves are obtained at a 10-MHz sampling rate. From this, correlation profiles and frequency spectra are determined which reveal the presence of prominent high-frequency components.

Johnson, J. A., III↗
NASA NTRS1983

Heated Aluminum Tanks Resist Corrosion

Simple expedient of heating foam-insulated aluminum alloy tanks prevents corrosion by salt-laden moisture. Relatively-small temperature difference between such tank and surrounding air will ensure life of tank is extended by many years.

Johnson, L. E.↗
NASA NTRS1972

Backus-Gilbert inversion of travel time data

Application of the Backus-Gilbert theory for geophysical inverse problems to the seismic body wave travel-time problem is described. In particular, it is shown how to generate earth models that fit travel-time data to within one standard error and having generated such models how to describe their degree of uniqueness. An example is given to illustrate the process.

Johnson, L. E.↗