Thermal effect on surrounding combustibles in minivan passenger car fires

In the fire safety design of parking lots and buildings, estimating the possibility of fire spreading to surrounding combustibles, such as neighboring buildings and cars, is essential. The ignition possibility to surrounding combustibles can be predicted from the heat flux from a burning car to the combustibles. In this study, we conducted 2 full‐scale car fire experiments using minivan passenger cars and measured the heat fluxes to their surroundings. The cars were ignited at the rear bumper with 80 g of alcohol gel fuel. The windows were closed. Heat flux gauges were placed around the car to measure the heat flux in various directions. Cedar boards were placed next to the gauges, and burn damage to the boards was observed. When the windows shattered in succession, combustion in the passenger compartment became larger. At a distance of 50 cm from the burning car, the heat flux was greater than 40 kW/m², and most of the cedar boards were completely burned. At a distance of 1 m, the heat flux was 10 to 20 kW/m², and some of the cedar boards were burned. We devised a method for modeling the shape and temperature of flames in the burning cars. Furthermore, we propose a method for calculating heat fluxes in the lateral direction of the burning minivan passenger car, and we compared the calculated and measured heat fluxes as a means of verifying the proposed method. The shape of flame in the burning car was approximated as a rectangular prism to calculate the heat flux. The calculation results were in good agreement with the experimental results. The proposed method is expected to be useful for fire safety engineering.