FAILURE DETECTION ALGORITHMS FOR COMBUSTION INSTABILITY (original) (raw)
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Owing to the feedback coupling of the dominant processes of heat release, dynamic instability occurs in combustion processes. The control of dynamic instability in continuous combustion systems is one of the most successful applications of control technology in computational fluid mechanics. Dynamic data driven applications systems (DDDAS) paradigms relating to propulsion processes entail the ability to dynamically incorporate data into an execution application. Models of combustion instability have been derived using system-identification-based methods. The heat release from the combustion of reactants alters the heat release dynamics closing the loop. The most dominant dynamics that are of concern in combustion systems pertain to the unsteady temperature. This investigation uses input-output data and a system identification approach to determine the underlying model for which active control strategies can be designed and implemented experimentally. The process responsible for energizing the temperature oscillations is heat release. The modelling of heat release dynamics thus constitutes a study of the mechanisms that induce these fluctuations and their quantification. The present work attempts to obtain dynamic descriptions of temperature of a space shuttle main engine for development of a real time failure detection algorithms using multilayer group method of data handling algorithm (GMDH).
Analysis and Control of Combustion Instabilities in Rocket Engines
IJRASET, 2021
Sound is the transmission of energy that is produced when two particles or objects undergo collision. It is one of the forms in which energy modulates and travels in a medium. Vibration is a phenomenon in which an object of mass executes a periodic oscillatory displacement when certain energy is transferred to it. Combustion is a chemical reaction in which a lot of molecules collide. Combustion instabilities occur in a reacting flow. It is a physical phenomenon. Combustion instabilities have mostly been studied in a particular flow but they also occur in real life. Real engines often feature specific unstable modes such as azimuthal instabilities in gas turbines or transverse modes in rocket chambers. Eddy simulation has been the major tool to study this type of instabilities so far but recently it has been proved to be insufficient to completely understand the complex nature of these instabilities [3]. These instabilities involve large Reynolds number, high pressure, densities in real engines. Combustion instabilities can occur at any part of the rocket propulsion system like nozzle, combustion chamber, injectors, feed systems and lines. Theory plays an important role in understanding and analysing these instabilities and the amount of damage they can cause to a particular object. In this paper we will look at different types or modes of combustion instabilities and active and passive ways to control them in real situations.
An adaptive algorithm for control of combustion instability
Automatica, 2004
We propose an adaptive algorithm for control of combustion instability suitable for reduction of acoustic pressure oscillations in gas turbine engines, and main burners and augmentors of jet engines over a large range of operating conditions, and supply an experimental demonstration of oscillation attenuation, the first for a large industrial-scale gas turbine combustor. The algorithm consists of an Extended Kalman Filter based frequency tracking observer to determine the in-phase component, the quadrature component, and the magnitude of the acoustic mode of interest, and a phase shifting controller actuating fuel-flow, with the controller phase tuned using extremum-seeking. The paper also identifies a closed-loop model with phase-shifting control of combustion instability from experimental data; supplies stability analysis of the adaptive scheme based upon the identified model, and stable extremum-seeking designs used in experiments.
Experimental Replication of an Aeroengine Combustion Instability
Volume 2: Coal, Biomass and Alternative Fuels; Combustion and Fuels; Oil and Gas Applications; Cycle Innovations, 2000
Combustion instabilities in gas turbine engines are most frequently encountered during the late phases of engine development, at which point they are difficult and expensive to fix. The ability to replicate an engine-traceable combustion instability in a laboratory-scale experiment offers the opportunity to economically diagnose the problem (to determine the root cause), and to investigate solutions to the problem, such as active control. The development and validation of active combustion instability control requires that the causal dynamic processes be reproduced in experimental test facilities which can be used as a test bed for control system evaluation. This paper discusses the process through which a laboratory-scale experiment was designed to replicate an instability observed in a developmental engine. The scaling process used physically-based analyses to preserve the relevant geometric, acoustic and thermo-fluid features. The process increases the probability that results achieved in the single-nozzle experiment will be scaleable to the engine.
2020
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Investigation of diesel engine combustion instability using a dynamical systems approach
2018
This study investigates the combustion instability of a compression ignition engine using dynamical system analysis in the form of a recurrence plot approach. In-cylinder combustion chamber pressure and crank angle are obtained from a six-cylinder, turbocharged diesel engine with a common-rail direct fuel injection system using a piezoelectric transducer and encoder, respectively. The common-rail system keeps the fuel pressure at a constant rate, which helps to minimise the effect of fuel pressure in this study. Constant speed and 4 loads are investigated. The engine emission and operation can be influenced by combustion instabilities and inter-cycle variability. Previous studies reported that ambient temperature, fuel pressure and injection timing, residual gases and fuel properties significantly alter the combustion instability. This study focus on the effect of biodiesel on this phenomena. Considering the CI engine as a dynamical system, the dynamic state of the combustion can in...
Extraction of Combustion Instability Mechanisms from Detailed Computational Simulations
48th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition, 2010
Previous unsteady computational studies have demonstrated combustion instability for a single-element rocket engine, matching experimental instability trends. The current paper seeks to better understand the mechanisms of combustion instability by demonstrating and evaluating possible diagnostics using computational data. Specifically, the following types of diagnostics are evaluated: point measurements, power spectral density analysis, instantaneous flow plots, Rayleigh index, signal filtering, phase difference analysis, mode shape analysis, and time-averaged flow-field plots. Used together, these various types of diagnostics proved to be effective in better understanding the mechanisms causing combustion instability for the particular configurations. Concerning the instability mechanism, the results suggest that axial velocity fluctuations at the driving frequency (induced by the acoustic field) cause oscillations in the oxidizer post vorticity, which then affect the pulsing of the combustion. For the current configuration, the propagation of these vorticity oscillations into the combustor, along with the subsequent combustion, occurs sufficiently in-phase with the pressure oscillations to permit instability to occur. For the experimental configuration where combustor step height was varied, the stronger instability of the smaller step-height combustor is likely due to the increased mixing and combustion that occurs as the vortices interact more strongly with the combustor wall, providing a greater unsteady heat source for driving instability.
Modeling and Control of Instabilities in Combustion Processes
Anali PAZU, 2022
This paper treats the contr ol of nonstationar y oscillations of acoustic pressur e in the combustion instability process, which appears in the combustion chamber. Two models of nonstationary combustion process control are presented, where first of them is a classic model, which applies the Rayleigh criterium of phase matching between heat-release rate and acoustic pressure. The second model is an alternative van der Pol model exhibiting selfexciting oscillations due to the feedback with a negative damping. The paper outlines the model of fuel control, which is successfully applied for quenching of selfexcited oscillations. Efficiency of fuel control to quench selfexcited oscillations is shown in the phenomenon of competitive quenching, where the influence of various control parameters is explained.