Experimental and quantitative investigation of a free round jet

Zaouali, Yassine; Ammar, Sinda; Kechiche, Nahla; Jacques, Jean; Aïssia, Habib Ben

doi:10.1051/epjap/2010128

Cited by 3 publications

(4 citation statements)

References 29 publications

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“…GC analysis of volatile compounds was carried out according to Zaouali et al [14] using an Agilent 6980 gas chromatograph equipped with a lame ionisation detector (FID) and an electronic pressure control (EPC) injector attached to HP-INNOWAX polyethylene glycol capillary column (30 m 0.25 mm). The flow of the carrier gas (N 2 ) was 1.6 mL min −1 .…”

Section: Gas Chromatography (Gc) Analysis Of Aniseed Essential Oilmentioning

confidence: 99%

On the effect of initial drying techniques on essential oil composition, phenolic compound and antioxidant properties of anise (Pimpinella anisum L.) seeds

et al. 2019

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The efect of drying methods (sun, oven and shade drying) on aniseeds was investigated in terms of their essential oils, phenolics and antioxidant activities. The optimum yield of essential oil was found in shade drying (2.62%). Fourteen volatile compounds were determined in all samples with variation of the main component proportions depending on drying methods. Thus, trans-anethole (84.21%) and estragole (3.82%) proportions signiicantly increased in shade drying. The highest total phenol and lavonoid contents of aniseeds were recorded in shade drying (42.70 mg of GAE/g and 53.55 mg of QE/g, respectively) while the lowest contents in oven drying at 60 °C (31.15 mg of GAE/g and 46.20 mg of QE/g, respectively). In all drying methods, naringin (41.04-43.76%), chloroginic acid (23.13-27.19%) and rosmarinic acid (12.26-15.95%) were the predominant phenol compounds. Although shade drying increased the antioxidant activity, aniseed extracts exhibited higher radical scavenging (IC 50 = 10.15 µg/mL), reducing power (EC 50 = 187.24 µg/mL) and chelating (IC 50 = 6.85 mg/mL) capacities than essential oils (IC 50 = 114.87 µg/mL, EC 50 = 548.05 µg/mL and IC 50 = 58.65 mg/mL, respectively). In conclusion, Shade drying method was found to enhance essential oils, phenols and antioxidant activities in aniseeds.

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Section: Gas Chromatography (Gc) Analysis Of Aniseed Essential Oilmentioning

confidence: 99%

On the effect of initial drying techniques on essential oil composition, phenolic compound and antioxidant properties of anise (Pimpinella anisum L.) seeds

et al. 2019

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“…The characteristic frequency obtained from this analysis has a value around 9 Hz. A comparison between our results and that obtained using the Laser Tomography [22] (by determining the phase velocity and the average wavelength) was carried out. Both results obtained for the frequency of the primary transition in the round jet, caused by the antisymmetric mode (sinuous mode), show a satisfactory agreement.…”

Section: Discussionmentioning

confidence: 89%

“…The extracted part presents two antisymmetric boundaries in sinusoidal form. Each boundary presents convex parts (creast) and concave parts (trough) [22]. Indeed, the results of the jet profiles velocity, obtained using the Laser Tomography technique, [12] velocity is about 0.46 m.s −1 with an uncertainty value 0.08 and the average wavelength is approximately 54 mm for a Reynolds number equal to 830.…”

Section: Resultsmentioning

confidence: 99%

Spectral analysis of round jet instabilities at low Reynolds number

Kechiche¹,

Abbassi²,

Filali³

et al. 2009

Mécanique & Industries

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For the study of round jet flow at low Reynolds number, a fine analysis of instabilities is necessary. In this paper, we present a frequency analysis of temporal and spatial velocity variations in a round jet with a Reynolds number equal to 830. The data were obtained from Laser Doppler Anemometry (LDA) measurements for various downstream positions. Attention is focused on the characteristics of the instantaneous signal of the longitudinal velocity component u(t) in order to characterize the transition from laminar state to turbulent state. The spectral analysis of the LDA signals of the axial component of the exit velocities highlights the presence of a single peak of energy around a characteristic frequency f0. This frequency corresponds to the amplified mode of the instability. The jet develops a sinuous mode which is the most unstable anti-symmetric mode. The results obtained in this study concerning the sinuous mode frequency, agree well with those obtained by laser tomography technique and images analysis.

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“…The width of rings varies until L/D ≈ 1.2 with a peak of 33% at L/D ≈ 1. It should be noted that, using the relationship established by Zaouali et al (2010), which gives the convective velocity U C of vortex rings on the jet edge (U C = 0.65U 0 ), the average displacement of the ring structures is about D/2 during t = 1/220 s. This excludes the passage of several vortex rings at a given axial position for this time interval.…”

Section: Probability Distribution Of the Jet Widthmentioning

confidence: 89%

Flow structure generated from an axisymmetric natural air jet at a moderate Reynolds number

Zaouali¹,

Filali²,

Aïssia³

et al. 2011

Fluid Dyn. Res.

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This paper reports on an experimental study of a free air jet evolving naturally and discharging from a round nozzle at a Reynolds number of 1600. By using flow visualization images and time-series analysis, the details of the flow behavior are clarified. In particular, the length of the transition zone of the jet is measured and its temporal evolution is investigated. We show that the vortex structures interact with each other, thus producing different sizes in the flow. The probability distribution and temporal evolution of the jet width at various distances from the nozzle exit are studied. The occurrence frequency of vortex rings and the Strouhal number of the jet were also determined at different positions from the nozzle exit. The results obtained are compared with those reported in the literature.

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Experimental and quantitative investigation of a free round jet

Cited by 3 publications

References 29 publications

On the effect of initial drying techniques on essential oil composition, phenolic compound and antioxidant properties of anise (Pimpinella anisum L.) seeds

On the effect of initial drying techniques on essential oil composition, phenolic compound and antioxidant properties of anise (Pimpinella anisum L.) seeds

Spectral analysis of round jet instabilities at low Reynolds number

Flow structure generated from an axisymmetric natural air jet at a moderate Reynolds number

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