The effect of heat content and composition of fuel on pulse combustor performance

Kushari, Abhijit; Rosen, Lee; Jagoda, J.; inn, B.T.

doi:10.1016/s0082-0784(96)80184-6

Cited by 12 publications

(6 citation statements)

References 3 publications

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“…Moreover, the frequency for a particular equivalence ratio increases with the increase of inlet flow rate, which is very clear from Figure 4. The total ignition delay time in the pulse combustor is contributed by three different processes: (1) s species , the time required for air and fuel to mix; (2) s mixing , the time required for the fresh cold reactants to mix with the hot combustion products from earlier cycles, which act as the ignition source for the incoming mixture; and (3) s kinetic , the post-mixing chemical ignition time (Keller et al, 1989;Kushari et al, 1996). The total ignition delay time, s ignition , is then given by s ignition ¼ f(s species , s mixing , s kinetic ).…”

Section: Dynamic Characterization Of a Pulse Combustor 143mentioning

confidence: 99%

Dynamic Characterization of a Laboratory-Scale Pulse Combustor

Mondal

Mukhopadhyay

Sen

2014

Combustion Science and Technology

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Pulse combustion is a self-sustained and self-oscillating process driven by combustion, coupled with resonant oscillation of the flow in the tailpipe. This article describes the investigation of the effects of different parameters in a laboratory-scale pulse combustor and analyzes them using concepts of nonlinear dynamics. Two orientations of the fuel injection holes were used. In one orientation, the fuel comes in vertically in parallel and counter-flow with the air stream, while in the other orientation the fuel is injected horizontally at cross-flow with the air stream. For the vertical orientation, the frequency slightly decreased with decrease of global equivalence ratio and inlet flow rate. With change of lean to rich air/fuel mixture, the dynamics changes from non-pulsating to pulsating combustion. The transition from noise-dominated to periodic oscillation has also been verified by evaluating the correlation dimension. In the horizontal orientation of the fuel inlet, the pulsating behavior has been obtained even under fuel-lean conditions due to better mixing of air and fuel, and phase and fast Fourier transform plots indicate quasi-periodic behavior.

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Section: Dynamic Characterization Of a Pulse Combustor 143mentioning

confidence: 99%

Dynamic Characterization of a Laboratory-Scale Pulse Combustor

Mondal

Mukhopadhyay

Sen

2014

Combustion Science and Technology

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“…Changes in fuel composition can affect any of these variables. Fuel composition effect, in particular hydrogen, on dynamic instabilities has been investigated by several researchers [101][102][103][104][105][106][107]50,106] and briefly reviewed as well [8,10]. It is agreed that changes in the fuel do have an influence on the dynamic characteristics of the combustion system.…”

Section: Dynamic Instabilitiesmentioning

confidence: 99%

“…It is agreed that changes in the fuel do have an influence on the dynamic characteristics of the combustion system. A simple time scale approach (change in chemical reaction time scale as well as the convection time scale) carried by Kushari et al [107] and later by Janus et al [101] showed that it is expected to see different dynamic response when fuel composition is modified. Fuel composition changes can affect combustion instabilities primarily by changing the flame shape and local dynamics, or the flame location thus the phase between heat release and pressure fluctuations for a same flame shape.…”

Section: Dynamic Instabilitiesmentioning

confidence: 99%

“…This has the important implication that the effect of changing fuel composition can not only be destabilizing but in some case stabiizing. By relying on a similar time scale approach as the one followed by Kushari et al [107], Lieuwen et al [10] highlighted that fuel In their study they focused on flame-vortex driven combustion dynamics in a swirl stabilized combustor operating with mixtures of natural gas and hydrogen. When fuel is changed by increasing the hydrogen content, the dynamically stable range was reduced and instability occurred starting at a lower equivalence ratio making it difficult to operate at the same equivalence ratio.…”

Section: Dynamic Instabilitiesmentioning

confidence: 99%

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Fuel flexibility, stability and emissions in premixed hydrogen-rich gas turbine combustion: Technology, fundamentals, and numerical simulations

et al. 2015

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“…Kushari et al [6] studied the fuel effect on the dynamics of pulse combustors using methane, methane-carbondioxide and methanehydrogen-carbondioxide fuel blends. They found that the addition of hydrogen extends the rich flammability limit but decreases the amplitude of oscillations.…”

Section: Introductionmentioning

confidence: 99%

Effects of inlet conditions on dynamics of a thermal pulse combustor

Mondal

Mukhopadhyay

Sen

2012

Combustion Theory and Modelling

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To increase the pulse combustor load, a higher amount of fuel-air mixture has to be supplied. This increases the flow rate or equivalently, the flow time is reduced. However, an increase in flow rate leads to an early extinction. This implies that obtaining pulsating combustion is difficult at higher loads. The objective of the present work is to explore the possibility of extending the regime of pulsating combustion at higher flow rates by preheating and diluting the reactants. In this work, the effects of preheating and dilution are examined by varying the inlet temperature and inlet fuel mass fraction. Varying these parameters, a map, presenting regime of pulsating combustion from steady combustion to extinction for each value of flow time considered, has been made. Lastly, Hopf bifurcation points of the system have been investigated by determining the eigenvalues of Jacobian matrix of the coupled non-linear system at the fixed point using a specialised package for bifurcation analysis, MATCONT. It has been found that at higher load, pulsating combustion can be achieved at higher inlet temperature and lower inlet fuel mass fraction. Comparing the Hopf points with mapping, it is found that existence of Hopf bifurcation agrees with the birth and death of pulsating combustion. The results indicate that altering the mixture condition at the inlet can be used for controlling chaos and stabilising periodic solutions in thermal pulse combustors and thus increase the range of pulsating combustion to higher power regimes. Nomenclature ACombustor surface area (m 2 ) A e Combustor cross-sectional area (m 2 ) BPre-exponential factor (s −1 ) C p Specific heat at constant pressure (J/kgK)1 First characteristic length (V/A) L c,2 Second characteristic length (V/A e ) L TP Length of tailpipe (m) m i Mass flow rate at combustor inlet (kg/s) * Downloaded by [University of Tennessee, Knoxville] at 08:55 22 December 2014 60 S. Mondal et al. m e Mass flow rate at combustor exit (kg/s) PPressure (Pa) P 0 Ambient pressure (Pa) P p/p 0 (dimensionless) p e Pressure in tailpipe (bar) P e p e /p 0 (dimensionless) T Temperature (K) T a Activation temperature (K)Fuel mass fraction (dimensionless) y fi Inlet fuel mass fraction (dimensionless)Ratio of specific heats (dimensionless) κ P Planck mean absorption coefficient ρ 0 Ambient density (kg/m 3 ) σStefan-Boltzmann constant (W/m 2 K 4 ) τ c Characteristic flow time (s) τ f Characteristic heat transfer time (s) τ h Characteristic chemical reaction time (s) ω f Fuel consumption rate (kg/m 3 s) IntroductionPulse combustors are known to have high thermal efficiency, high heat transfer rates and lower pollutant emission than steady flow combustors. These differences from steady state combustors are generally attributed to the self-sustained oscillations, which are caused by the strong coupling between the combustor dynamics and the flow in the tailpipe (cf. Figure 1). Keller and Hongo [1] showed that lower NO x production was due to reduced residence time at peak temperature, caused by mixing ...

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The effect of heat content and composition of fuel on pulse combustor performance

Cited by 12 publications

References 3 publications

Dynamic Characterization of a Laboratory-Scale Pulse Combustor

Dynamic Characterization of a Laboratory-Scale Pulse Combustor

Fuel flexibility, stability and emissions in premixed hydrogen-rich gas turbine combustion: Technology, fundamentals, and numerical simulations

Effects of inlet conditions on dynamics of a thermal pulse combustor

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