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Showing 1 to 16 of 16 for “"Combustion noise"”.
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A turbulent combustion noise model
A turbulent combustion noise model based on first principles is developed in this thesis. The model predicts (1) the pressure time series, (2) Sound Pressure Level (SPL) spectrum, (3) Over-All Sound Pressure Level (OASPL), (4) the thermoacoustic efficiency, (5) the peak frequency, and (6) the sound …
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Simulation of an algorithm for the active control of combustion noise
… 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 …
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Experimental measurement of combustion noise and comparison 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. …
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Verbrennungsgeräusch des direkteinspritzenden Hubkolbenmotors
Noise radiated by a piston engine can be divided into mechanical noise which depends mainly on engine speed, and combustion noise which is influenced by load and the boundary conditions of the combustion process, respectively. Within this thesis, a new model for the excitation of different …
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An experimental and analytical study of noise production and propagation in burners
Turbulent combustion in burners causes low frequency broadband combustion noise. Before the noise from such burners can be reduced, the generating mechanisms must be understood. Noise generation by a simple can-type burner has been investigated. Several parameters are varied to study their effect …
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Hydrogen Enrichment Effects on Thermoacoustics of Turbulent Partially Premixed Flames
… incorporation of hydrogen into the existing combustion infrastructure. This doctoral thesis addresses the challenges of hydrogen combustion and thermoacoustic instability in Gas Turbine Model Combustors (GTMC). A bimodal thermoacoustic instability where two different modes are excited are …
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Acoustical behavior of a turbulent, ducted, premixed, hydrogen- flame burner
… within a duct. A main goal in the study of noise generated by turbulent combustion is to characterize the structure of the flame as an acoustic source. Data describing the farfield and duct terminating conditions allow for the testing of combustion noise models. The acoustic farfield of a …
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On entropic and compositional sound and its sources
Combustion noise is relevant to current aviation, rocket, and ground-based gas turbine engines, as it contributes to environmental noise pollution and can trigger thermoacoustic instabilities. These consequences are particularly prevalent in lean, premixed, prevaporised combustors, which are …
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Scattering of an entropy disturbance into sound by a linear cascade of turbine stator blades
… known that modern turbofan engines produce more noise from their exhaust than can be accounted for by jet noise alone. Part of the extra noise coming from the exhaust of the engine is associated with the combustor. Apart from direct combustion noise, the combustor is known to have an indirect …
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The Development of a Monitoring and Control System for a Pulverised Coal-Fire Burner Using Neural Network Approach
… and Control System (FMCS) to optimise the combustion of a pulverised coal flame.<br/><br/>A series of experiments were conducted on a 150 kW pulverised fuel burner rig based at Casella CRE Ltd. in the United Kingdom. These experiments systematically varied the burner swirl number and the …
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Probabilistic machine learning for the elimination of thermoacoustic instabilities
… pulses from the spectrum of 100 millisecond combustion noise samples, thus enabling us to monitor the combustor's thermoacoustic stability in real time. We then apply these ideas to predict instabilities in an experimental rocket chamber, where we use the history of sensor data, including …
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Sound produced by entropic and compositional inhomogeneities
Combustion noise is central to several efforts to curb aircraft emissions. Indeed, acoustic waves originating in the combustor are a major contributor to aircraft noise. Moreover, they can act as a trigger for thermoacoustic instabilities, the consequences of which may range from decreased …
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Laseroptische Untersuchungen des Verbrennungsprozesses in einem PKW-Dieselmotor
The process of the conventional diesel combustion in small-size passenger car engines is an object of research. The combustion process can be divided in the sub-processes injection, mixture formation, auto-ignition and combustion. In the present work different laser-optical measurement technologies …
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Behaviour of accelerating entropy spots
Combustion noise has become a major research interest within the aerospace community. Stricter pollutant emission regulations have forced the introduction of lean premixed pre-vaporised combustors, which produce less NOx but burn more unsteadily, generating more noise and creating the potential for …
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Indirect noise in non-isentropic flows
… makes the combustor susceptible to unsteady combustion. Along with improper mixing and air cooling, the unsteady combustion process gives rise to flow inhomogeneities. The acceleration of these inhomogeneities in the nozzle downstream of the combustor generates indirect combustion noise. …