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Showing 1 to 10 of 10 for “"Acoustic Forcing"”.
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Analyses of flame response to acoustic forcing in a rocket combustor
… to real rocket engines. The chamber features an acoustic excitation system that imposes an acoustic disturbance representative of a high frequency instability upon a cluster of five coaxial injection elements in the center of the chamber. The response of the elements to the imposed acoustic …
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Linear Stability Analysis of a Rijke Tube and Modeling of Turbulent Combustion Using Dynamic Well-Stirred Reactors
… predicted for a Rijke tube with a new two-term acoustic forcing term derived from a one-dimensional flame dynamics model. The new two-term acoustic forcing term, which is comprised of the summation of chemical heat release rate and heat transfer due to convection, correctly predicts instability …
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Effects of Thermoacoustic Oscillations on Spray Combustion Dynamics with Implications for Lean Direct Injection Systems
Thermoacoustic instabilities in modern high-performance, low-emission gas turbine engines are often observable as large amplitude pressure oscillations and can result in serious performance and structural degradations. These acoustic oscillations can cause oscillations in combustor through-flows …
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Receptivity to free stream acoustic disturbances due to a roughness element on a flat plate
The boundary-layer receptivity resulting from acoustic forcing over a flat plate with a surface irregularity is investigated. The unsteady free-stream disturbances couple with the steady perturbations resulting from the surface irregularity to form a traveling-wave mode. The resonance condition …
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Evolution of an Acoustic Disturbance to Transition in the Boundary Layer on an Airfoil
… of establishing the mean flow conditions, forcing two-dimensional Tollmien-Schlichting (T-S) waves in the boundary layer using modulated acoustic bursts in the free-stream, and acquiring the mean boundary-layer data and fluctuating disturbance data using hot-wire probes. The acoustic …
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EXPERIMENTAL INVESTIGATION OF THE RESPONSE OF FLAMES WITH DIFFERENT DEGREES OF PREMIXEDNESS TO ACOUSTIC OSCILLATIONS
… (i.e. different mixture patterns) to acoustic forcing using the same burner configuration and varying only the fuel injection strategy. Special emphasis was placed on the amplitude dependence of their response. Also, the behaviour of self-excited fully premixed flames was examined. kHz …
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Scale Interactions within a Perturbed Plane Wall Jet
… of large-scale perturbations through acoustic forcing. The corresponding interactions because of forcing are characterized using single hot-wire measurements. The nearwall response of the PWJ over a range of large-scale forcing showed that the friction velocity Uτ decreased for all …
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Forcing of globally unstable jets and flames
In the analysis of thermoacoustic systems, a flame is usually characterised by the way its heat release responds to acoustic forcing. This response depends on the hydrodynamic stability of the flame. Some flames, such as a premixed bunsen flame, are hydrodynamically globally stable. They respond …
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Large eddy simulations of premixed turbulent flame dynamics : combustion modeling, validation and analysis
… in premixed flames, can couple with the acoustics of the combustion system. This acoustic coupling creates a feedback loop with the heat release that can lead to severe thermoacoustic instabilities that can damage the combustor. Understanding these dynamics, predicting their onset and …
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Turbulent flame microstructure, dynamics, and thermoacoustic instability in swirl-stabilized premixed combustion : measurements, statistics, and analysis
… oscillations which link the combustor acoustics to the combustion process-can result in significant levels of thermal and mechanical stress on combustion systems, leading to reduced operational lifetime, potentially dangerous failure modes, and significant deviations from the desired …