Accession Number : ADA321732

Title :   Numerical Study of Shear-Induced Heating in High-Speed Nozzle Flow.

Descriptive Note : Technical rept. Aug 93-May 96,

Corporate Author : JOHNS HOPKINS UNIV BALTIMORE MD DEPT OF MECHANICAL ENGINEERING

Personal Author(s) : Shi, Xiyan ; Knio, Omar M. ; Katz, Joseph

PDF Url : ADA321732

Report Date : 03 DEC 1996

Pagination or Media Count : 207

Abstract : During high-speed injection in small-diameter nozzles, a combustible mixture may experience high enough temperature for premature ignition to occur. Among the various physical mechanisms which may lead to such an undesirable effect, shear-induced heating is believed to play an important role. In this effort, the impact of shear heating is analyzed theoretically and numerically. The first part of the study focuses on short-duration events, for which shear heating remains confined to thin laminar boundary layers. This situation is analyzed using computational codes which numerically integrate the parabolized vorticity transport and energy equations. The codes are applied to predict the peak temperatures, and to analyze the effects of injection speed, inlet mixture temperature, and variable mixture properties . The second part of the study considers continuous injection modes. In these situations, boundary layer transition is expected to occur, and one must characterize the mean flow and temperature field, and fluctuations around the mean. To this end, the mean temperature solutions are constructed using well-established empirical correlations for the mean velocity field. Meanwhile, the impact of temperature fluctuations is evaluated in light of direct simulation of isotropic turbulence and transitional channel flow.

Descriptors :   *HEATING, *NOZZLES, SHEAR PROPERTIES, VELOCITY, SIMULATION, INJECTION, PEAK VALUES, TEMPERATURE, COMPUTATIONS, IMPACT, PHYSICAL PROPERTIES, HIGH VELOCITY, ENERGY, NUMERICAL ANALYSIS, TURBULENCE, VORTICES, MIXTURES, VARIABLES, VARIATIONS, SHORT RANGE(TIME), CODING, COMBUSTION, CORRELATION, SOLUTIONS(GENERAL), PREMATURE FUNCTIONING(ORDNANCE), ISOTROPISM, TRANSPORT, PARABOLAS, THINNESS, IGNITION, TRANSITIONS, FLOW, MEAN, EQUATIONS, BOUNDARY LAYER TRANSITION, CHANNEL FLOW, INLETS, LAMINAR BOUNDARY LAYER.

Subject Categories : Fluid Mechanics
      Thermodynamics

Distribution Statement : APPROVED FOR PUBLIC RELEASE