Numerical simulation of aerial liquid drops of Canadair CL-415 and Dash-8 airtankers

Background Airtankers are able to drop volumes of liquid (suppressant or fire retardant) varying from less than 1 m3 to several tens of cubic metres directly on a fire or with the objective to form barriers of retardant to stop or reduce fire propagation. Aims The objective of this work is to demonstrate that Computational Fluid Dynamics can be used to provide a deep understanding of liquid fragmentation and dispersion when liquid is dropped from an aircraft. Methods A numerical investigation based on the Volume of Fluid method is used for the analysis of airtanker performance and applied here to the biggest airtankers used in Europe: the Canadair CL-415 and Dash-8. Key results Numerical simulations are used to provide an accurate description of tank discharge as well as to study liquid ejection, fragmentation and atomisation in air. From the results, the vertical penetration and lateral expansion of the liquid are described using simple modelling. Conclusions From the numerical simulation, the main characteristics of liquid atomisation and dispersion in air are described and modelled. Implications Computational Fluid Dynamics is an efficient tool that may help to optimise airtanker performance.