Combustion instabilities arise owing to a two-way coupling between acoustic waves and unsteady heat release. Oscillation amplitudes successively grow, until nonlinear effects cause saturation into limit cycle oscillations. Feedback control, in which an actuator modifies some combustor input in response to a sensor measurement, can suppress combustion instabilities. Linear feedback controllers a...

Active control has been pursued vigorously for combating thermoacoustic instabilities in combustion processes. Most experimental investigations employ empirical design procedure for determining the characteristic parameters of the filter and phase-shifter of the controller. Such procedure has been observed to result in resonance at frequencies which were not excited in the power spectrum of the...

To understand working features of a micro combustor, a computer code has been developed to study combustion of hydrogen–air mixture in a series of chambers with same shape aspect ratio but various dimensions from millimeter to micrometer level. The prepared algorithm and the computer code are capable of modeling mixture effects in different fluid flows including chemical reactions, viscous and ...

The central recirculation zone (CRZ) in a swirl stabilized gas turbine combustor has a dominant effect on the fuel air mixing process and flame stability. Most of state of the art swirlers share one disadvantage; the fixed swirl number for the same swirler configuration. Thus, in a mathematical sense, Reynolds number becomes the sole parameter for controlling the flow characteristics inside the...

Combustion noise comprises two components: direct combustion noise and indirect combustion noise. The latter is the lesser studied, with entropy noise believed to be its main component. Entropy noise is generated via a sequence involving diverse flow physics. It has enjoyed a resurgence of interest over recent years, because of its increasing importance to aero-engine exhaust noise and a recogn...

Thermoacoustic instability is frequently found in continuous combustion processes in propulsion, power generation, and heating. Active control has been increasingly pursued in recent years to suppress the pressure oscillations which result from this instability, while maintaining performance objectives such as low NOx emission and high efficiency. This thesis considers the physics behind the th...

This paper presents an Artificial Neural Network (ANN)-based modeling technique for prediction of outlet temperature, pressure and mass flow rate of gas turbine combustor. Results obtained by present modeling were compared with those obtained by experiment. The results showed the effectiveness and capability of the proposed modeling technique with reasonable accuracies of about 95 percent. This...

The e ect of initial nonequilibrium dissociated air constituents on the combustion of hydrogen in highspeed ows for a simulated Mach 17 ight condition was investigated by analyzing the results of comparative combustion experiments performed in a re ected shock tunnel test gas and in a shock expansion tunnel test gas. The results were analyzed and interpreted with a one-dimensional quasi-three-s...

Since a large number of physical variables are involved in the combustion process occurring in complex swirl stabilized combustors, simple systems (burner stabilized laminar flat flames) were initially studied (see chapters 5 and 6). Having understood the dynamics of laminar flat flames and developed methodologies to build reduced order flame dynamic models, the technique developed to measure t...

The detonation initiation characteristics of a single tube liquid-fueled pulse combustor (PDC) is investigated at different inlet air temperatures in this paper. inner diameter the PDC 62 mm. Gasoline and are used as fuel oxidant, respectively. temperature 288–523 K operating frequency 10~30 Hz. experimental results show that deflagration to transition (DDT) distance, time, DDT time jet ignitio...