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Inverse Jet Flame Based Swirl Combustor
Published in Debi Prasad Mishra, Advances in Combustion Technology, 2023
A combustor, in the context of gas turbine engines, is a sub-entity/region within the engine where the mixing of fuel with oxidizer leading to an exothermic chemical reaction takes place. A reliable combustor should be capable of anchoring a stable flame established from the oxidation of reactants and ensure complete combustion within a compact volume. Importantly, a combustor should help in establishing a near uniform temperature distribution at the turbine entry for preventing hot spots and uneven thermal load on rotating turbine blades. In addition, reliable and hassle-free ignition of the reactants (fuel-air) during engine start-up and subsequent relighting after unexpected flame blowout in high altitudes are the major requirements expected of a combustor. Apart from this, enhanced flame stability limit over a wide range of air-fuel ratio within the combustor along with fuel flexibility are other essential requirements sought. The combustor should also incur low pressure loss and ensure low pollutant emissions such as NOx, CO and soot in the exhaust through optimum air-fuel ratio.
Localized vs Central Station Power Generation
Published in Neil Petchers, Combined Heating, Cooling & Power Handbook: Technologies & Applications, 2020
The other basic thermodynamic cycle used by electric utility plants to generate electric power is the open-cycle gas turbine, which operates on the Brayton cycle. Whereas steam cycle plants are used for base and intermediate load applications, gas turbine cycle plants are used by many utilities to serve peaking power requirements. Whereas the steam cycle operates essentially on a closed loop, the gas turbine uses air in a once-through open cycle. Since air is essentially a non-condensable fluid at normal operating temperatures, the gas turbine cycle does not use a boiler and condenser. Instead, a combustor burns fuels such as natural gas or oil in direct contact with compressed air, directing the mixture into a power turbine, which then expands the gases and exhausts them directly into the atmosphere. While the steam cycle uses boiler feed pumps to elevate feedwater to the required operating pressures, the gas turbine uses a multiple-stage compressor to elevate the pressure of the incoming air stream to operating pressure. The power turbine, through a common shaft, supplies the energy required for this air compression.
High Mass Transfer Rate Theory
Published in Anthony F. Mills, Heat and Mass Transfer, 2018
In many furnaces and combustion chambers liquid fuels are atomized to form a spray of small droplets that burn rapidly and efficiently. Examples include fuel oil in a power plant furnace, kerosene in a gas turbine combustor, and hydrazine in a rocket motor. Although the practical problem involves a spray, it has proven useful to understand the behavior of a single isolated droplet. Analysis of single-droplet combustion assists interpretation of experimental data for single-droplet combustion, and also yields results that can be extended to spray combustion. Of particular importance is the lifetime of the droplet, because the required size of the combustion chamber depends in part on the time required for burning.
A Comparative Study of Natural Gas and Biogas Combustion in A Swirling Flow Gas Turbine Combustor
Published in Combustion Science and Technology, 2022
Asif Hoda, Tariq M. R. Rahman, Waqar Asrar, Sher Afghan Khan
Gas turbine combustor design and development have been focused on achieving higher combustion efficiency, proper flame temperature and gas concentrations, lower and balanced emissions, lower pattern factor, and minimized entropy generation (Elbaz and Roberts 2016; Elbaz et al. 2019; Jerzak and Kuźnia 2016; Santhosh and Basu 2016; Shanbhogue et al. 2016; Taamallah, Shanbhogue, Ghoniem 2016). Both conventional fuels like kerosene (Chmielewski and Gieras 2017; Li et al. 2016), propane (Krieger et al. 2015; Wankhede, Bressloff, Keane 2011), methane or natural gas, some liquid-fuels (Kahraman, Tangöz, Akansu 2018; Motsamai, Snyman, Meyer 2010), and non-conventional fuels like biogas, hydrogen (Bothien et al. 2019; İlbaş, Karyeyen, Yılmaz 2016; Rohani and Saqr 2012), syngas (Iqbal et al. 2016; Safer, Ouadha, Tabet 2017) have been used in gas turbine combustors. All these investigations have been conducted in different mixing uniformities such as premixed, partially premixed and non-premixed.
Nonlinear Dynamic Analysis of the Transition from MILD Regime to Thermoacoustic Instability in a Reverse Flow Combustor
Published in Combustion Science and Technology, 2022
Atanu Dolai, Santanu Pramanik, Pabitra Badhuk, Ravikrishna RV
To the best of the authors’ knowledge, the transition of combustion dynamics from MILD to combustion instability in a reverse flow combustor has not been reported in the literature. Combustion instability affects the combustor performance, reduces the operating range and combustor lifetime. It arises from the interaction between unsteady heat release and acoustic modes of the combustion chamber, particularly when heat released from the chemical reactions provides energy for driving the acoustic modes (Huang and Yang 2009; Lieuwen 2003). As a result, pressure oscillations from the combustor have high amplitude with a predominant oscillation frequency, which may even lead to the structural failure of the combustor (Lieuwen 2003). The fundamental aspects of self-excited acoustic oscillations and acoustic-flame interaction are reviewed in the seminal work by Lieuwen (Lieuwen 2003), whereas the sensitivity of thermoacoustic oscillations to design parameters have been discussed in a short review by Juniper and Sujith (Juniper and Sujith 2018).
Flashback Characteristics of Kerosene Spray in Cross Flow under High Temperature and High Pressure
Published in Combustion Science and Technology, 2022
Yongsheng Zhao, Xiaohu Tian, Yuzhen Lin
The fuel of aero-engine low-emission combustor is liquid hydrocarbon fuel. The flashback problem occurs at high temperatures and high pressures, coupled with complex physico-chemical processes such as injection, breakup, atomization, evaporation, and chemical reactions. Therefore, the induced mechanism and critical conditions of flashback must be unique. Marek, Papathnkos, and Verbulecz (1977), Marek and Bakw (1983) study the flashback of aviation fuel/air premixed gas using a circular tube flow reactor. The flashback process and critical conditions are obtained by the thermocouple and high-speed camera. However, the influence of fuel atomization and evaporation is not considered in this study. Scha¨fer, Koch, and Wittig (2003) study the spray flashback of aviation fuel under normal pressure non-swirl conditions. The results show that the local equivalent ratio, spray particles and flame propagation velocity have great influence on the flashback. This further confirms that the mechanism of spray flashback may be different from that of gas. Therefore, the study of spray flashback is very meaningful. The study of kerosene spray flashback characteristics in cross flow under high temperature and high pressure has not been found in the open literature. However, this problem is crucial for predicting and evaluating the risk of flashback and developing low-emission combustor.