Persistence of Laminar Flamelet Structure Under Highly Turbulent Combustion

Yamamoto, Kazuhiro; Nishizawa, Yasuki; Onuma, Yoshiaki

doi:10.1299/jsmeb.46.408

Cited by 7 publications

(9 citation statements)

References 22 publications

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“…The sampling frequency is 50 kHz. Here, we obtain the reaction variable, a, whose value is unity inside the reaction zone, and zero outside the reaction zone (11), (12) . Then, we determine the probability of reaction zone existing, p, which is the time-averaged value of reaction variable at the specified location.…”

Section: Fig 3 Combustion Diagram For Turbulent Premixed Flamesmentioning

confidence: 99%

“…Here, we determine the probability of reaction zone existing, p. An example of signal waveform of ion current is shown in Fig. 7 for U m = 15 m/s at r = 9 mm and Z = 20 mm (12) . We use simple threshold procedure.…”

Section: Mean and Rms Velocity Profilesmentioning

confidence: 99%

“…It has been experimentally confirmed that the reaction zone is kept thin while the preheat zone is thickened, which is in accordance with consideration that small eddies can penetrate into the preheat zone but not into the reaction zone. In our experiments, we use a cyclone-jet combustor to investigate the premixed flame structure in a highly turbulent flow (11), (12) . The estimated reaction zone thickness is almost constant even for Ka > 1, and the persistence of laminar flamelet structure is observed.…”

Section: Introductionmentioning

confidence: 99%

“…Figure 1 shows a cyclone-jet combustor used in this study. It is possible to investigate turbulent flames over a wide range of turbulence intensities (11), (12), (17,) (18) . It consists of a combustion chamber with a main jet nozzle and four cyclone nozzles for pilot flames.…”

Section: Introductionmentioning

confidence: 99%

“…These characteristics are similar to that of a so-called Bunsen flame. The experimental conditions have been evaluated in our previous experiments (12) …”

Section: Introductionmentioning

confidence: 99%

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Flow Field of Turbulent Premixed Combustion in a Cyclone-Jet Combustor

Yamamoto

Inoue

Yamashita

et al. 2007

JTST

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The flow field in highly turbulent premixed combustion has been examined, using a cyclone-jet combustor. The shear-strain rate is obtained by PIV system. Results show that, in combustion field, mean axial velocity does not decay along center axis and RMS fluctuation velocity is much lower, compared with those in cold flow. The reaction zone detected by an ion probe well corresponds to region of large shear-strain rate. In combustion, turbulence is small around reaction zone to have the undiminished jet velocity, which leads to an increase in length of potential core, although the flame generated turbulence is observed through flow expansion.

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Section: Fig 3 Combustion Diagram For Turbulent Premixed Flamesmentioning

confidence: 99%

Section: Mean and Rms Velocity Profilesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…These characteristics are similar to that of a so-called Bunsen flame. The experimental conditions have been evaluated in our previous experiments (12) …”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Flow Field of Turbulent Premixed Combustion in a Cyclone-Jet Combustor

Yamamoto

Inoue

Yamashita

et al. 2007

JTST

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PIV measurement and turbulence scale in turbulent combustion

Yamamoto¹,

Inoue²,

Yamashita³

et al. 2006

Heat Trans. Asian Res.

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We have investigated turbulent combustion by PIV (Particle Image Velocimetry) technique. Comparing with LDV data, the validity of PIV measurements has been confirmed. Particularly, the conditions of sampling number and spatial resolution have been shown to yield reliable data using PIV. Based on the velocity fields in cold flow and combustion, the interaction between flame and flow has been discussed. It was observed that the flow field is changed by combustion and the turbulence is reduced. In order to determine statistical quantities such as mean velocity and RMS of velocity fluctuation, a sampling number of 1000 is needed. Moreover, the velocity correlation coefficient was evaluated to obtain the integral length scale of the flow. For both cold flow and combustion, the PIV estimated scale is very close to that of LDV based on the assumption of Taylor's hypothesis. As a result, the spatial resolution in this study is about 6 times smaller than the integral length scale.

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