Experimental Study of Atomization by Impinging Jets of Liquid and Gelled Green Propellants

Abstract

Gelled propellants are an interesting option for rockets and missiles propulsion systems, since they combine high performance with facility of handling and storage. These characteristics are due to the shear thinning non-Newtonian behavior of gels. High shear rates can lead to extensive liquefaction of gelled fluids. This liquefaction offers the possibility to develop engines that can be throttled like liquid propellant engines. Impinging jet injectors are commonly used in propulsion systems applications since they can be easily manufactured and can provide good atomization and mixing characteristics within a short distance. Green propellants represent a low toxicity and high performance alternative to the conventional hazardous propellants. This work compares analytical solutions with images of the sheet shapes formed by the impingement of two round jets of water, liquid hydrated ethanol and gelled hydrated ethanol. Breakup lengths and maximum widths of the sheet shapes are determined as function of the Reynolds number. The analytical plotted sheet shapes have shown good agreement with experimental data for water and liquid hydrated ethanol, but not for gelled hydrated ethanol. The aspect ratio was approximately constant, around 2, for water and liquid hydrated ethanol, while for gelled hydrated ethanol the breakup length increased exponentially and the aspect ratio increased linearly with Reynolds number.

Hydrous Ethanol Atomization by Impinging Jets

“…The sheet regimes goes from stable closed sheet (u = 2.81 m/s) to impact wave regime (u = 7.36 and 12.45 m/s). According to Dias et al (2019b), stable closed rim for hydrous ethanol can be found until the Reynolds of jet reaches a value around 1700, considering the designed injector. Impact waves starts from the impingement point and grow in amplitude as the distance from the impingement point increase, as seen for u = 4.89 m/s.…”