Jetting Dynamics of Burning Gel Fuel Droplets
Jetting in burning gel fuel droplets is an important process which, in addition to pure vaporization, enables the convective transport of unreacted fuel vapors from the droplet interior to the flame envelope. This aids in accelerating the fuel efflux and enhancing the mixing of the gas phase, which...
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| Format: | Article |
| Language: | English |
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MDPI AG
2022-11-01
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| Series: | Gels |
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| Online Access: | https://www.mdpi.com/2310-2861/8/12/781 |
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| author | Janmejai Sharma Ankur Miglani Jerin John Purushothaman Nandagopalan Javed Shaikh Pavan Kumar Kankar |
| author_facet | Janmejai Sharma Ankur Miglani Jerin John Purushothaman Nandagopalan Javed Shaikh Pavan Kumar Kankar |
| author_sort | Janmejai Sharma |
| collection | DOAJ |
| description | Jetting in burning gel fuel droplets is an important process which, in addition to pure vaporization, enables the convective transport of unreacted fuel vapors from the droplet interior to the flame envelope. This aids in accelerating the fuel efflux and enhancing the mixing of the gas phase, which improves the droplet burn rates. In this study, Schlieren imaging was used to characterize different jetting dynamics that govern the combustion behavior of organic-gellant-laden ethanol gel fuel droplets. To initiate jetting, the gellant shell of the burning gel fuel droplet was subjected to either oscillatory bursting or isolated bursting, or both. However, irrespective of the jetting mode, the jets interacted with the flame envelope in one of three possible ways. Based on the velocity and the degree to which a jet disrupts the flame envelope, it is classified as either a flame distortion, a fire ball outside the flame or a pin hole jet (localized flame extinction), where the pin hole jets have the highest velocity (1000–1550 mm/s), while the flame distortion events have the lowest velocity (500–870 mm/s). Subsequently, the relative number of the three types of jetting events during the droplet lifetime was analyzed as a function of the type of organic gellant. It was demonstrated that the combustion behavior of gel fuels (hydroxypropyl methylcellulose: HPMC at 3 wt.%) that tend to form thin-weak-flexible shells is dominated by low-velocity flame distortion events, while the gel fuels (methylcellulose: MC at 9 wt.%) that facilitate the formation of thick-strong-rigid shells are governed by high-velocity fire ball and pin hole jets. Overall, this study provides critical insights into the jetting behavior and its characterization, which can help us to tune the droplet gasification and the gas phase mixing to achieve an effective combustion control strategy for gel fuels. |
| first_indexed | 2024-03-09T16:32:51Z |
| format | Article |
| id | doaj.art-f130363f74dc49a795d09b65b0cb32c5 |
| institution | Directory Open Access Journal |
| issn | 2310-2861 |
| language | English |
| last_indexed | 2024-03-09T16:32:51Z |
| publishDate | 2022-11-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Gels |
| spelling | doaj.art-f130363f74dc49a795d09b65b0cb32c52023-11-24T15:00:54ZengMDPI AGGels2310-28612022-11-0181278110.3390/gels8120781Jetting Dynamics of Burning Gel Fuel DropletsJanmejai Sharma0Ankur Miglani1Jerin John2Purushothaman Nandagopalan3Javed Shaikh4Pavan Kumar Kankar5Microfluidics and Droplet Dynamics Lab, Department of Mechanical Engineering, Indian Institute of Technology, Indore 453552, Madhya Pradesh, IndiaMicrofluidics and Droplet Dynamics Lab, Department of Mechanical Engineering, Indian Institute of Technology, Indore 453552, Madhya Pradesh, IndiaDepartment of Aerospace Engineering, Korea Advanced Institute of Science and Technology, 291, Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of KoreaDepartment of Aerospace Engineering, Hindustan University, Chennai 603103, Tamil Nadu, IndiaIntel Corporation, Bengaluru 560035, Karnataka, IndiaMicrofluidics and Droplet Dynamics Lab, Department of Mechanical Engineering, Indian Institute of Technology, Indore 453552, Madhya Pradesh, IndiaJetting in burning gel fuel droplets is an important process which, in addition to pure vaporization, enables the convective transport of unreacted fuel vapors from the droplet interior to the flame envelope. This aids in accelerating the fuel efflux and enhancing the mixing of the gas phase, which improves the droplet burn rates. In this study, Schlieren imaging was used to characterize different jetting dynamics that govern the combustion behavior of organic-gellant-laden ethanol gel fuel droplets. To initiate jetting, the gellant shell of the burning gel fuel droplet was subjected to either oscillatory bursting or isolated bursting, or both. However, irrespective of the jetting mode, the jets interacted with the flame envelope in one of three possible ways. Based on the velocity and the degree to which a jet disrupts the flame envelope, it is classified as either a flame distortion, a fire ball outside the flame or a pin hole jet (localized flame extinction), where the pin hole jets have the highest velocity (1000–1550 mm/s), while the flame distortion events have the lowest velocity (500–870 mm/s). Subsequently, the relative number of the three types of jetting events during the droplet lifetime was analyzed as a function of the type of organic gellant. It was demonstrated that the combustion behavior of gel fuels (hydroxypropyl methylcellulose: HPMC at 3 wt.%) that tend to form thin-weak-flexible shells is dominated by low-velocity flame distortion events, while the gel fuels (methylcellulose: MC at 9 wt.%) that facilitate the formation of thick-strong-rigid shells are governed by high-velocity fire ball and pin hole jets. Overall, this study provides critical insights into the jetting behavior and its characterization, which can help us to tune the droplet gasification and the gas phase mixing to achieve an effective combustion control strategy for gel fuels.https://www.mdpi.com/2310-2861/8/12/781gel fuelsethanolorganic gellantsdroplet combustionhybrid rocket |
| spellingShingle | Janmejai Sharma Ankur Miglani Jerin John Purushothaman Nandagopalan Javed Shaikh Pavan Kumar Kankar Jetting Dynamics of Burning Gel Fuel Droplets Gels gel fuels ethanol organic gellants droplet combustion hybrid rocket |
| title | Jetting Dynamics of Burning Gel Fuel Droplets |
| title_full | Jetting Dynamics of Burning Gel Fuel Droplets |
| title_fullStr | Jetting Dynamics of Burning Gel Fuel Droplets |
| title_full_unstemmed | Jetting Dynamics of Burning Gel Fuel Droplets |
| title_short | Jetting Dynamics of Burning Gel Fuel Droplets |
| title_sort | jetting dynamics of burning gel fuel droplets |
| topic | gel fuels ethanol organic gellants droplet combustion hybrid rocket |
| url | https://www.mdpi.com/2310-2861/8/12/781 |
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