Combustion of micron-sized Al-Mg alloy wires in hot H2O/O2/N2 flows
(2024) In Fuel 357.- Abstract
The use of aluminum-magnesium (Al-Mg) alloy particle as energetic additive in solid propellants was previously shown to have many advantages over pure Al particle, such as relatively low ignition temperature, high reaction rate and low particle agglomeration rate. In this paper, the combustion of Al-Mg alloy in hot H2O/O2/N2 flows was experimentally studied using wires with a diameter of 200 µm. The employment of wires instead of particles provided a unique opportunity to obtain fundamental insights into the combustion process due to the spatial stabilization and large size of the sample. High-speed imaging showed that the combustion of Al-Mg alloy wire could be divided into three stages, namely... (More)
The use of aluminum-magnesium (Al-Mg) alloy particle as energetic additive in solid propellants was previously shown to have many advantages over pure Al particle, such as relatively low ignition temperature, high reaction rate and low particle agglomeration rate. In this paper, the combustion of Al-Mg alloy in hot H2O/O2/N2 flows was experimentally studied using wires with a diameter of 200 µm. The employment of wires instead of particles provided a unique opportunity to obtain fundamental insights into the combustion process due to the spatial stabilization and large size of the sample. High-speed imaging showed that the combustion of Al-Mg alloy wire could be divided into three stages, namely pre-heating, ignition, and combustion. Spectral measurements suggested that the chemiluminescence emissions from Mg, MgO and MgOH dominated the collected spectra, in spite of only 3% Mg (by weight) existed in the alloy. Additionally, it was observed that moderate gaseous reactions could occur well before the breakup of the passive oxide coating, generating obvious fine oxide smokes. Moreover, consumption rates of the wire in different hot oxidizers were obtained and compared. It was shown that O2 featured more significant promotion of the reaction than H2O. Nevertheless, without O2, much less metal-oxide particles were generated. Temperature measurements indicated that the ignition temperature lied within 2160 ∼ 2220 K, which was lower than the melting points of Al2O3 (2350 K) and MgO (3125 K). Large single burning Al-Mg alloy droplets (∼200 µm diameter) were generated after the micro-explosion inside the wire. It was found that the combustion of Al-Mg alloy in both H2O/O2/N2 and H2O/N2 atmospheres were diffusion-controlled with a stand-off distance around 150 µm (stand-off ratios at ∼ 1.3). Finally, SEM and EDS measurements revealed that Al, Mg and O elements coexisted on the surface of the burnt wires. Nevertheless, it was observed that the oxidization of Mg started before Al, and the reaction of alloy was more intense when O2 existed. This led to the generation of much thicker oxide layers and larger number of nanoparticles.
(Less)
- author
- Ruan, Can LU ; Wu, Zhiyong LU ; Stiti, Mehdi LU ; Snellman, Markus LU ; Qiu, Yue LU ; Ahamed Subash, Arman LU ; Berrocal, Edouard LU ; Aldén, Marcus LU and Li, Zhongshan LU
- organization
- publishing date
- 2024-02-01
- type
- Contribution to journal
- publication status
- published
- subject
- keywords
- Carbon-free fuel, Metal combustion, Metal fuel, SEM/EDS analysis, Two-color pyrometry
- in
- Fuel
- volume
- 357
- article number
- 129719
- publisher
- Elsevier
- external identifiers
-
- scopus:85170844321
- ISSN
- 0016-2361
- DOI
- 10.1016/j.fuel.2023.129719
- language
- English
- LU publication?
- yes
- additional info
- Publisher Copyright: © 2023 The Author(s)
- id
- 170b78cf-79df-43c9-a0d4-945503eab1ab
- date added to LUP
- 2023-10-23 08:37:18
- date last changed
- 2023-12-01 11:09:10
@article{170b78cf-79df-43c9-a0d4-945503eab1ab,
abstract = {{<p>The use of aluminum-magnesium (Al-Mg) alloy particle as energetic additive in solid propellants was previously shown to have many advantages over pure Al particle, such as relatively low ignition temperature, high reaction rate and low particle agglomeration rate. In this paper, the combustion of Al-Mg alloy in hot H<sub>2</sub>O/O<sub>2</sub>/N<sub>2</sub> flows was experimentally studied using wires with a diameter of 200 µm. The employment of wires instead of particles provided a unique opportunity to obtain fundamental insights into the combustion process due to the spatial stabilization and large size of the sample. High-speed imaging showed that the combustion of Al-Mg alloy wire could be divided into three stages, namely pre-heating, ignition, and combustion. Spectral measurements suggested that the chemiluminescence emissions from Mg, MgO and MgOH dominated the collected spectra, in spite of only 3% Mg (by weight) existed in the alloy. Additionally, it was observed that moderate gaseous reactions could occur well before the breakup of the passive oxide coating, generating obvious fine oxide smokes. Moreover, consumption rates of the wire in different hot oxidizers were obtained and compared. It was shown that O<sub>2</sub> featured more significant promotion of the reaction than H<sub>2</sub>O. Nevertheless, without O<sub>2</sub>, much less metal-oxide particles were generated. Temperature measurements indicated that the ignition temperature lied within 2160 ∼ 2220 K, which was lower than the melting points of Al<sub>2</sub>O<sub>3</sub> (2350 K) and MgO (3125 K). Large single burning Al-Mg alloy droplets (∼200 µm diameter) were generated after the micro-explosion inside the wire. It was found that the combustion of Al-Mg alloy in both H<sub>2</sub>O/O<sub>2</sub>/N<sub>2</sub> and H<sub>2</sub>O/N<sub>2</sub> atmospheres were diffusion-controlled with a stand-off distance around 150 µm (stand-off ratios at ∼ 1.3). Finally, SEM and EDS measurements revealed that Al, Mg and O elements coexisted on the surface of the burnt wires. Nevertheless, it was observed that the oxidization of Mg started before Al, and the reaction of alloy was more intense when O<sub>2</sub> existed. This led to the generation of much thicker oxide layers and larger number of nanoparticles.</p>}},
author = {{Ruan, Can and Wu, Zhiyong and Stiti, Mehdi and Snellman, Markus and Qiu, Yue and Ahamed Subash, Arman and Berrocal, Edouard and Aldén, Marcus and Li, Zhongshan}},
issn = {{0016-2361}},
keywords = {{Carbon-free fuel; Metal combustion; Metal fuel; SEM/EDS analysis; Two-color pyrometry}},
language = {{eng}},
month = {{02}},
publisher = {{Elsevier}},
series = {{Fuel}},
title = {{Combustion of micron-sized Al-Mg alloy wires in hot H<sub>2</sub>O/O<sub>2</sub>/N<sub>2</sub> flows}},
url = {{http://dx.doi.org/10.1016/j.fuel.2023.129719}},
doi = {{10.1016/j.fuel.2023.129719}},
volume = {{357}},
year = {{2024}},
}