Mitigating combustion driven oscillation thermoacoustic instability in industrial combustors combustion processes generate a bandlimited pseudorandom sound that is often referred to as combustion roar. Active control of combustion instability using pilot and. In real devices, combustion instability suppression takes a number of forms 3 acoustic damping fuel splitting symmetry breaking active control bulat, ghenadie. Ghoniem department of mechanical engineering massachusetts institute of technology cambridge, ma 029 abstract active control using periodic fuel injection has the potential of suppressing combustion instability without. This active instability control aic method uses external acoustic excitation by a loudspeaker to suppress. The benefits of this multiplefuelnozzle system are. Amplitude and phase control in active suppression of. Combustion instability results from complex dynamic interactions between acoustics, heatrelease, and vortex dynamics. Modeling and control of combustion instability using fuel injection j. Helmholtz resonator for a gas turbine combustion chamber. Active combustion instability control via fuel modulation highfrequency fuel valve phase shift controller fuel. The addition of diluent injection to this design for nox control did not cause a significant increase in dynamic pressure activity. Combustion instabilities in modern highperformance propulsion systems are often manifested as large amplitude pressure oscillations and can result in serious. Combustion instability suppression can also achievable by breaking any part of this feedback loop 4 flame heat release fluctuations q combustor acoustic fluctuations p,u coupling mechanism.
Pdf modeling and control of combustion instability using fuel. Active control using periodic fuel injection has the potential of suppressing combustion instability without radically changing the engine design or sacrificing performance. Prediction and control of combustion instabilities in real engines core. This paper provides a description of why combustion instability will be a significant problem in future aeroengines.
Organic no x formation is less well understood than thermal no x formation. Description of active control of an instability with the rayleigh based acs. Editors 1995 liquid rocket engine combustion instability, vol. The stability of a combustion chamber is determined by the balance between the energy gained from the flameacoustic interactions and various dissipation.
Dynamic instability has long been recognized as a problem in continuous combustion systems. Larger burners have combustion control systems ccss which should be tuned periodically. The model developed is physically based and includes the acoustics, the heat release. At higher levels of fbn, the conversion efficiency decreases. Both of these approaches offer the potential for improving the viability of active combustion control for practical applications. Active control techniques always involve a complex control system and the actuator.
Jacob university of tennessee space institute, eric. Following this problem statement are details on the combustion instability control approach. Pdf plasma control of combustion instability in a lean. Therefore, the degree to which combustion destabilizes a mode depends on the frequency of the mode itself. Increasing acoustical damping within the combustion. Design results show that the imc controller has good disturbance rejection capability, but the method should be improved to achieve better performance for the active control of combustion instability. The book then goes on to examine the fundamental mechanisms, the combustor modeling, and control approaches. Models of combustion instability have been derived using both physically based and systemidentificationbased methods. But while high heat release and high pressure coincide roughly throughout the combustion chamber in an ice, they coincide at a particular region or regions during a combustion instability. Pdf active control using periodic fuel injection has the potential of suppressing combustion instability without radically changing the engine design. Passive techniques were developed to control the combustion characteristics by. Amplitude and phase control in active suppression of combustion instability dimitry gorinevsky, nick overman y, and jerry goeke american control conference june 2012, montreal, qe, canada abstractthis paper provides stability analysis for phase shifting active combustion control system where modulation of.
Instabilities, transitions and turbulence the control. Combustion instability problems analysis for high pressure. Key words combustion instability, thermoacoustic instability, active control, closedloop control, adaptive control. Robust feedback control of combustion instability with. Feedback control of combustion instabilities from within limit cycle. Active control of high frequency combustion instability in. Combustion instability has also acquired increased urgency in recen t years.
Figure 1 shows the ms7001 multifuelnozzle cap arrangement for such a combustion liner. Heckl controlled the noise from an electrical rijke tube using loudspeaker as the actuator2. Propellant rocket combustion instability, nasa sp194. As large scale structures issued from the air system associated with the injection system, control the mixing between fuel and air, they could lead to unsteady combustion and interactions with the acoustic waves in order to produce selfexcited combustion oscillation. Hydrodynamic instability modes can also differ as well as the combustion regimes, which can require very different simulation models. It is typically caused by a coupling between acoustic waves and unsteady heat release from unsteady combustion. The effectiveness of perforated liner with bias flow on the control of combustion instability is investigated.
Experimental diagnostics for the study of combustion. Dynamic instability occurs in combustion processes due to the feedback coupling between two dominant processes, acoustics and heat release see fig. Widerange robust control of combustion instability boeshong hong, asok ray, and vigor yang department of mechanical engineering, the pennsylvania state university, university park, pa 16802, usa this paper presents the concept and design of a twolayer robust control system for suppression of combustion instabilities over a wide range of. The ones marked may be different from the article in the profile. The understanding and control of combustion instabi lity is important in a variety of systems such as liquid fuel rockets and ramjets. If the energy gain due to combustion response is greater than energy damping, then an instability of the particular mode results.
Plane wave solutions were given for velocity and pressure disturbances both upstream and downstream of a flame confined in a tube with a small mean flow mach number and with open and closed ends. They power package boilers, start up larger furnaces with fluidized beds and grates, and heat many other processes. Measurements or estimates of key variables such as pressure and velocity models of the heat release and acoustic phenomena that, in approximated form, can be implemented online actuation capabilities. We present a survey of the existing theory that includes modeling and control of pressure instability in combustion systems and the practical applications of active control to date in small. Active control of combustion instability in a liquid. Combustion instabilities are a major concern in groundbased gas turbine engines because of nox emissions. One of the most successful applications of control technology in fluid systems is in the context of dynamic instability in continuous combustion systems. A commonly used thermoacoustic model with sensors and monopolelike actuators is linearized and formulated in a statespace form. This type of combustion is very sensitive to thermoacoustic instabilities causing high pressure sound waves.
Overview of combustion instabilities in liquidpropellant. Aiaa cfd for combustion modeling day 2, lecture 6, suresh menon, georgia tech fuel modulation of combustion instability ge lm6000. Control of combustion instability with a tunable helmholtz. Active combustion control for ultra low emissions in aircraft gasturbine engines john delaat controls and dynamics branch ph. Thermoacoustic instability in gas turbines gas turbine combustors. Lecture 6 combustion instability and lean blow out. The case studies section speaks to specific manufacturer and user experiences with combustion instabilities in the development stage and in fielded turbine engines. This signal is filtered, processed, amplified, and sent to the loudspeaker. The process is unstable and thus difficult to control. Combustion instabilities are often suppressed by either active or passive methods. Imaging of combustion radicals has been a cornerstone diagnostic for the field of combustion for the past two decades which allows for visualization of flame structure and behavior. This paper applies the internal model control imc method in the control of the combustion instability, with the aim of finding effective control structures and methods for this kind of system.
The two prongs of a combustion instability, the acoustic field which acts as the host oscillator. A practical active control system for the mitigation of combustion instability has been designed and demonstrated in a lean, premixed, singlenozzle combustor at realistic engine operating conditions. Active control of combustion instability sciencedirect. In real devices, combustion instability suppression takes a number of forms.
This cited by count includes citations to the following articles in scholar. In active control, incipient instability is dynamically detected and corrected. Davis and black, dry low no x combustion systems for ge heavyduty gas turbines. Issue 11 june 01 investigation and modeling of combustion instabilities in aero engines al11092 this equation states that the acoustic energy increases only if the source term due to combustion is larger than the acoustic losses on the combustor inlet and outlet surface. Ghoniem department of mechanical engineering mit cambridge, ma introduction one of the most successful applications of control technology in fluid systems is in the context of dynamic instability in continuous combustion. The tendency is to run lean, an equivalence ratio less than 1, to reduce the combustion temperature and thus reduce the nox emissions. Control of combustion instabilities reducing the feedback from the combustion process in the main chamber to the fuel injectors can control instability. Likewise, a stronger driving of a combustion instability happens when the heat is released at a higher pressure. Feedback of combustion instabilities on the injection of gaseous fuel 1 march 2004 journal of engineering for gas turbines and power, vol. Combined with statistical methodologies and control theories, these techniques allow for an efficient survey of flow evolution and combustion dynamics, with special attention to the identification. The integration of chambers in real engines implies that compressor and turbine impedances control. Active control of combustion instabilities in lean. In the first part of this paper, results are presented from a study of the use of secondary fuel with subharmonic modulation for the suppression of combustion dynamics.
Specific pollution control problems will be addressed in detail. Pdf modeling and control of combustion instability using. Plasma control of combustion instability in a lean direct injection gas turbine combustor. Questions of flame stability, detonations, and several other important aspects ofcombustion science are beyond the scope ofthe present discussion and will not be treated. This active instability control aic method uses external acoustic excitation by a loudspeaker to suppress the oscillations of a flame.
Pdf a passive method to control combustion instabilities. It is important to note that the reduction of flame temperatures gas turbine emissions and control ge. Combustion instability is a phenomenon that happens in a gas turbine when the lean premixed combustion mode is used to reduce the nox emissions. Robust feedback control of combustion instability with modeling uncertainty boeshong hong, vigor yang, and asok ray department of mechanical engineering, the pennsylvania state university, university park, pennsylvania 16802 this paper presents the design of a robust feedback controller for suppressing combustion instabilities in. Observerbased sliding mode control of combustion instability in a rijketype thermoacoustic system is considered. The main purpose of this work was the experimental investigation of helmholtz resonators and baffles to control acoustic instabilities in combustion chambers. A study of nonlinear combustion instability eric j. The excitation signal is provided by a microphone located upstream of the flame.
Thus, combustion instability co ntinues to plague the industry and deserves attention. Mitigating combustiondriven oscillation thermoacoustic. Understanding and controlling the onset and propagation of combustion instability is therefore critical to the development of clean and efficient combustion systems. Modeling and control of combustion instability using fuel. Although combustion roar sound is moderately intense but it is rather straight forward. Active combustion control for ultra low emissions in.
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