Recursos de colección

Caltech Authors (160.010 recursos)

Repository of works by Caltech published authors.

Group = Graduate Aeronautical Laboratories (Fluid Mechanics)

Mostrando recursos 1 - 5 de 5

  1. Analytical Models for the Thrust of a Rotating Detonation Engine

    Shepherd, J.E.; Kasahara, J.
    Two models are proposed for rotating detonation engine performance. The first model is motivated by models of pulse detonation engine performance which are based on the pressure-time history within the detonation tube. The present work extends those ideas to treat rotating detonation engines with a control volume analysis that considers the forces within the combustion chamber. The key scaling parameters for this model are the height of the reactant layer just ahead of the detonation wave and the computed Chapman-Jouguet pressure and velocity. The thrust can be estimated using these parameters and a simple functional form of the pressure history...
    (application/pdf) - 26-sep-2017

  2. Laser Doppler Velocity & Vorticity Measurements in Turbulent Shear Layers

    Lang, Daniel B.; Dimotakis, Paul E.
    A Laser Doppler Velocimeter (LDV) system was developed to measure the instantaneous spanwise vorticity, - ω_z, in a turbulent shear layer. It was necessary to design and fabricate the LDV optics and processing electronics, as no commercially available LDV systems met the specifications of measuring the velocity at four closely spaced points to the requisite accuracy. Measurements were also made of the instantaneous u, v, u', v' and - u'v'. The instantaneous vorticity was processed to obtain an estimate of its probability density function, from which the mean and rms values were estimated. It was also possible to separate the irrotational...
    (application/pdf) - 04-nov-2017

  3. On the Design of Pulse Detonation Engines

    Chao, Tong Wa; Winterberger, E.; Shepherd, J. E.
    This report addresses some basic issues in the structural and performance aspects of Pulse Detonation Engines (PDEs). Performance parameters studied include thrust-specific-fuel-consumption (TSFC), frequency limits, and thrust-to-weight ratio. A design surface is developed that accounts for various design limits. The structural aspects deal with critical parameters, material properties, and phenomena such as engine geometry, mass, yield stress, structural resonance due to flexural wave excitation, critical flaw size, and fracture toughness. Four materials for PDEs were chosen for comparison: silicon nitride, inconel, steel, and aluminum. Estimates of wall thickness and thrust-to-weight ratio are given over a range of operating conditions. Key...
    (application/pdf) - 07-oct-2017

  4. Experimental investigation of planar strained methane-air and ethylene-air flames

    Benezech, Laurent J.-M.; Bergthorson, Jeffrey M.; Dimotakis, Paul E.
    The extinction of planar strained methane-air flames in the stagnation-point flow is studied. A thermal analysis has been conducted in order to build a new copper stagnation plate which can be heated up to 1000K, and allows investigation of downstream heat loss as extinction driving mechanism. Since premixed stagnation flames are mostly sensitive to the composition of the mixture, axial velocity and CH radical profiles are simultaneously measured for different equivalence ratios, using respectively Particle Streak Velocimetry (PSV) and Planar Laser Induced Fluorescence (PLIF). These are compared to simulations using CANTERA stagnation flow code with a multicomponent molecular transport model, with...
    (application/pdf) - 23-sep-2017

  5. Experimental investigation of planar strained methane-air and ethylene-air flames

    Benezech, Laurent J.-M.; Bergthorson, Jeffrey M.; Dimotakis, Paul E.
    The extinction of planar strained methane-air flames in the stagnation-point flow is studied. A thermal analysis has been conducted in order to build a new copper stagnation plate which can be heated up to 1000K, and allows investigation of downstream heat loss as extinction driving mechanism. Since premixed stagnation flames are mostly sensitive to the composition of the mixture, axial velocity and CH radical profiles are simultaneously measured for different equivalence ratios, using respectively Particle Streak Velocimetry (PSV) and Planar Laser Induced Fluorescence (PLIF). These are compared to simulations using CANTERA stagnation flow code with a multicomponent molecular transport model, with...
    (application/pdf) - 26-sep-2017

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