The interplays between acoustic and intrinsic modes in a model of Rijke burner are revealed their influence on the prediction thermoacoustic instabilities is demonstrated. To this end, system examined for range time delays, temperature ratios reflection coefficients as adjustable parameters. A linear network used all with frequency below cut-on non-planar waves considered. results show that when reduced, presence pure ITA mode limits reduction growth rate usually from coefficients. In...

A prospective method to assess thermo-acoustic instabilities based on two reflection coefficients measured from the upstream side of burner is presented and experimentally validated. In order compose a model which allows predicting onset instability combustion in practical appliance, one has characterize properties including flame as an acoustically active element acoustic all other (usually passive) components appliance both well downstream burner. This kind modeling strategy usually faces...

In this paper the nonlinear dynamics of pure Intrinsic Thermo-Acoustic (ITA) modes are experimentally investigated for burner stabilized premixed flames by decoupling them from acoustic modes. Thereto, a setup is used with up- and downstream mufflers that provide close to anechoic boundary conditions. This enables investigation self-excited oscillations flame, without influences reflections. An experimental bifurcation analysis conducted systematically investigate different asymptotic...

This dissertation is related to experimental research of the response Bunsen type laminar premixed methane-air flames an acoustic excitation flow. study stimulated by problem instability burners and combustors used in domestic industrial heating devices where combustion organized via flames. The accordingly can be divided into two parts. first part concentrated on a detailed parametric heat release rate conical tent shaped perturbation gas mixture flow velocity. A Transfer Function (TF)...

We apply binary classification theory to assess the (in)stability prediction accuracy of thermoacoustic models. It is shown that by applying such methods compare a large set stability predictions and experiments it possible gain valuable qualitative insight in different aspects quality. The approach illustrated with 2-port model experimental data set. presented framework provides an unified practical tool answer questions as (i) What chance stable will be correct? (ii) How conservative...

The study of Intrinsic Thermo-Acoustic (ITA) instability behavior flames anchored to a burner deck is performed by introducing mapping between the Flame Transfer Function, FTF(s), defined in complex (Laplace) domain and experimentally measured frequency response, FTF(iω). conventional approach requires system identification procedure obtain FTF(s) from FTF(iω); next, root-finding techniques are applied define eigenfrequencies. purpose present work establish criteria which directly applicable...

Surface-stabilized combustion is credited with high burning rates, extended lean flammability limits, wide modulation range and other advantages. This makes it an attractive technology for compact low-emission combustors. The experimental gas turbine surface burners reported to this date are produced from compressed sintered Fe-Cr-Al fiber mats. authors have developed a new concept of burner fabricated by braiding ceramic cords around frame. simple method produces basket-type suitable...

System theory methods are developed and applied to introduce a new analysis methodology based on the stability criteria of active two-ports, problem thermo-acoustic instability in combustion appliance. The analogy between thermo-acoustics small-signal operation microwave amplifiers is utilized. Notions unconditional conditional stabilities an (active) two-port, representing burner with flame, introduced analyzed. Unconditional two-port means absence autonomous oscillation at any embedding...

In this paper, the design, construction and results of experiments performed on a generic combustion system are presented. The setup is supplemented by various weakly frequency-dependent variable reflection coefficient (RC) devices as upstream downstream acoustic terminations. main objective building such terminations to provide method study burner/flame stability when it placed between configurations (RC: 0.1-0.9) determine figure merit burner based evaluation its map (in-)stability....