Part I. Convective Thermal Transfer in a Steady, Nearly Uniform Flow of Air Between Parallel Plates. Part II. A Study of Organ-Pipe Combustion Oscillations of Premixed Gases in a Combustor with Variable Length at Atmospheric Pressure

Citation

Chia, Wu-sun (1969) Part I. Convective Thermal Transfer in a Steady, Nearly Uniform Flow of Air Between Parallel Plates. Part II. A Study of Organ-Pipe Combustion Oscillations of Premixed Gases in a Combustor with Variable Length at Atmospheric Pressure. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/DMCW-1391. https://resolver.caltech.edu/CaltechETD:etd-10072002-140720

Abstract

NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document. PART I Measurements of the total viscosity and total conductivity were made as a function of position and Reynolds number for the flow of air between two parallel plates with a separation of approximately 0.75 in. The temperature of the upper plate was 103.0[degrees]F and that of the lower plate 70.0[degrees]F. The investigations were carried out at Reynolds numbers from 40,000 to 100,000 and were in good agreement with earlier data obtained at Reynolds numbers up to 40,000. The results obtained indicate little change in the total Prandtl number with increasing Reynolds number from the value of the molecular Prandtl number. PART II The effect of varying the length of the combustor upon the frequency and the amplitude of the organ-pipe oscillations has been investigated in a cylindrical combustor 3.836 in. in diameter and approximately 162 in. in length. Measurements of the perturbations in pressure were made in a premixed flame of air and natural gas at a mixture ratio of about 90 per cent stoichiometric. Results indicate some discontinuous variations in frequency, along with the presence of some quiet regions, as the length of the combustor is systematically changed. A driving mechanism of the combustion oscillation is proposed and is examined in the light of Rayleigh's criterion. The calculated results based upon this driving mechanism turn out to be in good agreement with the experimental data.

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