Transformation of initially unatomized fire-extinguishing liquid arrays at free fall from different heights

Anastasia Islamova, Svetlana Kropotova, Pavel Tkachenko, Ivan Voitkov, Geniy Kuznetsov

Research output: Contribution to journalArticlepeer-review


This paper presents experimental results on disintegration of initially unatomized extinguishing liquid arrays in the free fall from a variable height. In laboratory conditions, the discharge height varied in the range of 0.5-3 m, and in field tests it was 3-15 m. The initial volume of unatomized liquid varied in the range of 0.05-1 l. The following compositions were considered: Pure water, bentonite suspension, foam agent emulsion, magnesium chloride, antipyrene, and flame-retardant solutions. When processing the research results, four stages of transformation of liquid arrays, leading to the formation of an aerosol, were determined. Data obtained in the experiments served to establish the dependences of the surface area covered by the discharged liquid. Using such dependences, the transformation characteristics of non-sprayed liquid arrays with volumes of up to 5000 l (maximum for helicopters) and 20,000 l (maximum for airplanes) at discharge heights of up to 100 m were calculated. General approximation expressions for water, suspension, solution, and emulsion were obtained to describe these dependences, taking into account the influence of the properties of liquids (viscosity, density, and surface tension) through the Ohnesorge number. These expressions allow predicting the minimum discharge heights of non-sprayed arrays with different component composition and volume, sufficient for the formation of an aerosol cloud with virtually unchanged dimensions (the forest coverage area, respectively) and dispersion.

Original languageEnglish
Pages (from-to)71-91
Number of pages21
JournalAtomization and Sprays
Issue number1
Publication statusPublished - 2021


  • Fire extinguishing liquids
  • Free fall
  • The area of coverage
  • Transformation
  • Unatomized arrays

ASJC Scopus subject areas

  • Chemical Engineering(all)

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