Combustion Characteristics of an Al/H₂O Mixture with Polyoxyethylene

Abstract

An experimental investigation of the combustion characteristics of an aluminum/water (Al/H 2 O) mixture with the addition of polyoxyethylene (PEO) was conducted in argon at 0.1 MPa. The burning rates were obtained using a constant-pressure strand burner. Ignition and combustion processes of an Al/H 2 O mixture were observed with a high-speed camera. The results show that PEO addition can improve the ignition and combustion performance of an Al/H 2 O mixture. The mixture of nanosized Al powder and H 2 O cannot be ignited in argon at 0.1 MPa, but the mixture of nanosized Al powder and H 2 O with the mass fraction 1% PEO or 3% PEO can be ignited, and the mixture can be self-sustaining combustion. The burning rates are 2.57 mm/s and 3.94 mm/s, respectively. In the mixture of nanosized Al powder and H 2 O with 3% PEO, the ignition can be sustained when 20% nanosized Al powder is replaced by micrometer-sized Al powder, and the burning rate is 3.36 mm/s. However, the mixture would not be ignited when 25% nanosized Al powder is replaced by micrometer-sized Al powder. In addition, the combustion process and flame image characteristics were obtained by using a high-speed photography technique, and the condensed combustion products were characterized by scanning electron microscopy combined with energy dispersive X-ray.

The effects of additives on the combustion characteristics of aluminum powder in steam

“…In addition, the surfaces of coarse blocks are covered by a layer of occules. In our previous study, 50 we have demonstrated that the occules are composed of Al and Al 2 O 3 . As shown in Fig.…”

“…These spherical particles may be composed of Al 2 O 3 as the main products based on our recently research. 50 This can be explained by the fact that nAl with 5 wt% AP addition burns more completely than the original nAl powder due to the high oxidizing ability of the decomposition products of AP. In addition, nAl with 5 wt% AP addition burns much violently as evidenced by the explosion-like intense burning shown in Fig.…”

“…Sundaram et al 31 reported that the combustion ame temperature and linear burning rate of aluminum/water mixtures with addition of alane (AlH 3 ) were lower than those of aluminum/water mixtures without addition of AlH 3 . Sun et al 32 reported that PEO addition improved the ignition and combustion characteristics of aluminum/water mixtures. They found that the mixtures of aluminum and water could hardly be ignited in argon atmosphere, whereas the mixture with addition of 1 wt% or 3 wt% PEO could be ignited.…”

Combustion of Mechanically Alloyed Aluminum‐Magnesium Powders in Steam

“…Commonly,f lame speed is used in laboratory experiments as an indicator of the reaction rate achievable in an energetic system;t he flame speedm easurements have also been used to evaluate various metal-water systems [12][13][14].F or liquid or gelled water-aluminum, the most studied system, the flame speeds vary in the range of mm s À1 to cm s À1 ,d epending on pressure and specifice xperimental conditions. Higher flame speeds areo bserved for nano-aluminum powders;t he flames peedi sr educed rapidly when micron-sized powdersa re added [15,16].…”

Facile Fabrication of Highly Efficient Hollow Ni/Al Bimetal Fuel with Enhanced Thermal Oxidation Behavior

“…Metal powder is often used as a fuel in propellants, explosives, or pyrotechnics because of the high enthalpy of its combustion. − Al powder is a common metal fuel that is relatively inexpensive and safe to handle and has a relatively high volumetric combustion enthalpy. − However, Al powder is difficult to ignite because its high ignition temperature reaches up to ∼2000 °C due to the existence of a dense Al 2 O 3 surface layer. , Moreover, Al powder tends to agglomerate during burning because of its low melting point of ∼660 °C. , Difficult ignition and easy agglomeration cause incomplete oxidation and low heat release activity of Al powder.…”