Experimental testing to determine stability thresholds for partially submerged vehicles at different flow orientations

Abstract

Vehicles exposed to flooding and losing stability may be washed away, causing potential injuries and fatalities. Such vehicles cause additional disruption to traffic already affected by flooding, which may lead to significant indirect economic impacts, especially in urban areas. Therefore, it is important to analyze the stability of vehicles exposed to flooding to make decisions for reducing damage and hazards. In this study a series of experiments were conducted with a small passenger vehicle, Polo GTI, a large passenger vehicle, Audi A6L, and a large four-wheel drive (4WD) vehicle, Range Rover models with a scale of 1:18. The buoyancy forces of the model-scale vehicles were measured by buoyancy experiments, which allowed for the calculation of the buoyancy force as a function of the flow depth. The drag forces and transverse forces at different flow orientations were determined experimentally using a hydraulic flume, and the drag coefficients (1.22 ≤ CD ≤ 6.82) and transverse force coefficients (0 ≤ CT ≤ 2.40) of the three vehicles were determined by fitting data from all experiments at the same flow direction (from 0° to 180°). Corresponding forces on the full-scale (prototype) vehicles were computed based on the Froude similarity laws. Then stability thresholds and stability curved surfaces for prototype vehicles exposed to flooding were derived based on the experimental results and force analysis of vehicles exposed to flooding. The study results provide valuable information for decision-makers in the field of urban flood risk management to consider the impact of urban road runoff on vehicle stability thresholds.