Semi Analytical Solution to Transient Start of Weakly Underexpanded Turbulent Jet

Chitsaz, Iman; Saidi, Mohammad Hassan; Mozafari, A.

doi:10.1115/1.4004835

Cited by 8 publications

(5 citation statements)

References 25 publications

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“…Several research works have already paid attention to the spray properties of bio-fuels and their key roles on the mixture formation, combustion, and environmental issues [22][23][24][25][26][27][28][29]. In the present work, spray pattern and mixture formation of bio-ethanol and its blends with conventional gasoline have been examined, and in uences of a number of parameters on spray characteristics of several blends have been performed.…”

Section: Fuel Properties and Injection Systemmentioning

confidence: 99%

Experimental and theoretical investigation on spray characteristics of bio-ethanol blends using a direct injection system

Ghahremani¹,

Jafari²,

Ahari³

et al. 2017

Scientia Iranica

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Abstract. In the present work, the spray characteristics of bio-ethanol and its blends have been experimentally and theoretically investigated. To have a comprehensive study, the e ects of ambient condition and injection pressure on the spray of di erent blends have been considered. Macroscopic and microscopic characteristics of spray such as tip penetration length, cone angle, projected area, volume, Sauter Mean Diameter (SMD), and Ohnesorge number are investigated precisely. Besides, air entrainment and atomization analyses have been carried out to improve mixture formation process. Using curve tting and least squares method, theoretical correlations have been suggested in such a way to predict experimental results with the accuracy of 9.9%. To have a good estimation of the calculated parameters, uncertainty analysis has been performed. The results demonstrate that enhancing the injection pressure or decreasing the ambient pressure improves the atomization characteristics of spray. Moreover, outcomes of this study indicate that spray tip penetration is enhanced by increasing the injection pressure or bio-ethanol percentage in the blend, while spray cone angle showing the opposite behavior.

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Section: Fuel Properties and Injection Systemmentioning

confidence: 99%

Experimental and theoretical investigation on spray characteristics of bio-ethanol blends using a direct injection system

Ghahremani¹,

Jafari²,

Ahari³

et al. 2017

Scientia Iranica

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“…Due to the complexity of the transient set of equations, the transient imperfectly expanded jet flow has not been investigated in detail by analytical methods. Chitsaz et al 9 solved the transient under-expanded jet flow semi-analytically using Hankel transform. They solved the equation of pressure but did not propose any solution for the velocity domain.…”

Section: Introductionmentioning

confidence: 99%

“…Chitsaz et al 9 showed that the radial and axial derivatives of pressure are in the same order of magnitude and the following dimensional analysis is considered…”

Section: Introductionmentioning

confidence: 99%

“…1 Imperfectly expanded jet is a complicated process containing different compression and expansion waves which forms a diamond shape. 2,3 This phenomenon has been extensively studied experimentally, [4][5][6][7][8] numerically, 2 and analytically [9][10][11][12] ; however, each of the methods has its own limitations to explain the phenomenon completely. The position of the Mach disk is the key subject of experimental works in this area.…”

Section: Introductionmentioning

confidence: 99%

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An analytical investigation of transient imperfectly expanded turbulent jet

Ghahremani

Aramfard

Saidi

2022

Proceedings of the Institution of Mechanical Engineers, Part G:

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Supersonic turbulent high-pressure jet flows, which are discharging in low-pressure quiescent ambient, are recognized as imperfectly expanded turbulent jet. Steady-state imperfectly expanded jet flow has been already studied analytically; however, the transient flow has not been thoroughly studied. In the present study, the transient imperfectly expanded jet flow with focus on fuel spray in combustion is investigated analytically employing two-step separation of variables method and Fourier-Bessel expansion. The results are validated using available experimental data. The effects of different parameters such as eddy viscosity and pressure ratio on the behavior of the jet are studied. Results show that increasing the eddy viscosity decreases the velocity magnitude and required time to reach fully developed jet. Increasing the pressure ratio almost linearly increases the required time to reach steady state. The density distribution which affects the combustion performance is reported for different axial and radial positions. In the transient region, tip penetration is obtained and validated with the experimental results in the literature, and the velocity profile at different times is presented. The simplicity and accuracy are key advantages of the developed method compared with the experimental and numerical methods. The analytical method proposed in the present research helps to understand the behavior of jet flows from transient to steady state condition without using expensive and time-consuming numerical or experimental techniques.

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“…Spray behaviors and atomization level of bio-fuels and their influences on emissions and engine performance have been recently investigated [15,16]. Based on the bio-ethanol fuel and in order to enhance the energy content of the fuel, modified bio-ethanol (MBE) with chemical formulation of C 11 H 24 OH has been produced in the present work.…”

Section: Introductionmentioning

confidence: 99%

Experimental and theoretical study on spray behaviors of modified bio-ethanol fuel employing direct injection system

et al. 2017

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One of the key solutions to improve engine performance and reduce exhaust emissions of internal combustion engines is direct injection of bio-fuels. A new modified bio-ethanol is produced to be substituted by fossil fuels in gasoline direct injection engines. The key advantages of modified bio-ethanol fuel as an alternative fuel are higher octane number and oxygen content, a long-chain hydro-carbon fuel, and lower emissions compared to fossil fuels. In the present study spray properties of a modified bio-ethanol and its atomization behaviors have been studied experimentally and theoretically. Based on atomization physics of droplets dimensional analysis has been performed to develop a new non-dimensional number namely atomization index. This number determines the atomization level of the spray. Applying quasi-steady jet theory, air entrainment and fuel-air mixing studies have been performed. The spray atomization behaviors such as atomization index number, Ohnesorge number, and Sauter mean diameter have been investigated employing atomization model. The influences of injection and ambient conditions on spray properties of different blends of modified bio-ethanol and gasoline fuels have been investigated performing high-speed visualization technique. Results indicate that decreasing the difference of injection and ambient pressures increases spray cone angle and projected area, and decreases spray tip penetration length. As expected, increasing injection pressure improves atomization behaviors of the spray. Increasing percentage of modified bio-ethanol in the blend, increases spray tip penetration and decreases the projected area as well.

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Semi Analytical Solution to Transient Start of Weakly Underexpanded Turbulent Jet

Cited by 8 publications

References 25 publications

Experimental and theoretical investigation on spray characteristics of bio-ethanol blends using a direct injection system

Experimental and theoretical investigation on spray characteristics of bio-ethanol blends using a direct injection system

An analytical investigation of transient imperfectly expanded turbulent jet

Experimental and theoretical study on spray behaviors of modified bio-ethanol fuel employing direct injection system

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