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The acoustic emission from the combustion of turbulent mixtures of several gaseous fuels and oxygen was measured to determine the effect of burner diameters, flow velocities and reactant chemistries. The data are presented in the form of acoustic pressure spectra and over-all sound pressure levels. The experiment consisted of a geometrically simple pre-mixed burner with five interchangeable nozzles whose diameters varied from 0.117 cm to 0.541 cm. The fuels examined in the experiment were acetylene, methane and propane. Three flow velocities were tested for each fuel. Methane was tested within a velocity range of 10 m/s to 25 m/s while propane was examined within a range of 20 m/s to 40 m/s. Acetylene was tested at somewhat higher velocities ranging from 50 m/s to 100 m/s. The resulting data base consisted of 23 unique test conditions. The data were evaluated based on peak frequency and overall sound pressure level. The experimental data are also compared to a predictive model.

The acoustic emission from the combustion of turbulent mixtures of several gaseous fuels and oxygen was measured to determine the effect of burner diameters, flow velocities and reactant chemistries. The data are presented in the form of acoustic pressure spectra and over-all sound pressure levels. The experiment consisted of a geometrically simple pre-mixed burner with five interchangeable nozzles whose diameters varied from 0.117 cm to 0.541 cm. The fuels examined in the experiment were acetylene, methane and propane. Three flow velocities were tested for each fuel. Methane was tested within a velocity range of 10 m/s to 25 m/s while propane was examined within a range of 20 m/s to 40 m/s. Acetylene was tested at somewhat higher velocities ranging from 50 m/s to 100 m/s. The resulting data base consisted of 23 unique test conditions. The data were evaluated based on peak frequency and overall sound pressure level. The experimental data are also compared to a predictive model.

The simulation of an algorithm for the active control of combustion noise generated by a turbulent flame produced by an open burner is developed in this thesis. The simulation includes (1) an autoregressive model of real combustion noise, (2) a feedback loop based on the "observer" method, (3) a model of the transfer function between the acoustic driver and the sensor through the flame, and (4) a method to take into account the time-delay due the calculation of the algorithm. A practical implementation of the control strategy is also proposed. An attenuation of up to 40 dB is obtained in the 0 - 3000 Hz band, decreasing with the time-delay required for creation of the feedback signal. The influence of the order of the autoregressive model is studied, and it is shown that better results are obtained by increasing the order. The choices for the location of the activator and for the type of sensor are investigated and discussed. Further analytical research on the method of computing the feedback signal in the presence of time-delay is identified.

Many small scale agricultural operations such as greenhouses, peanut drying and tobacco curing, use significant quantities of thermal energy. Direct combustion of biomass is a potential source of heat energy for those agricultural applications to substitute for the electricity or fossil fuels (principally LP gas) currently used. However, small scale combustion equipment often operates with low efficiency and high emissions. A prototype chunkwood combustor was installed and tested. The basis for controlling heat output, was the modulation of air supplied to the primary and secondary combustors. Exhaust gas CO and CO₂ concentrations, combustor efficiency, and useful heat output were measured. The cleanest burn was achieved during a forty minute test, where 50 percent of stoichiometric air was introduced at the primary, and 170 percent at the secondary, for a total of 220 percent stoichiometric. The overall average CO/CO₂ ratio for this test was 0.084, and 0.1 is considered to be an average rating for a combustion in a wood stove. Moreover, the efficiency during this test was 52 percent.