Kinetic energy evolution and injury assessment of high-speed tear jets.

High-speed tear liquid ejectors, as novel less-lethal weapons, demonstrate significant potential in public security, counter-terrorism, and riot control applications. However, critical gaps persist in understanding their kinetic energy dissipation dynamics and associated injury risks, particularly when using traditional specific kinetic energy methods. Therefore, this study establishes an integrated experimental framework combining transient trajectory acquisition systems, ballistic gelatin targets, and dynamic impact force measurements. Key findings reveal that as the launch distance varies from 10 cm, 30 cm to 100 cm, and 200 cm, the trajectory transitions from a coherent stream to dispersed filaments with unstable energy density evolution. Initially, the jet velocity rises from 93.3 m/s to 101.1 m/s, then decreases to 91.7 m/s and 80.8 m/s. Additionally, the penetration depth in the ballistic gelatin decreases progressively with launch distance, measuring 91 mm, 80 mm, 38 mm, to 0 mm respectively, and the depths of penetration at 10 and 30 cm are similar to those of a 4.5 mm steel ball at 180 m/s. The transient impact force follows a similar pattern with velocity, first increasing and then decreasing, to 464 N, 518 N, 95 N, and 48 N respectively, underscoring potential injury risks within 100 cm ranges. This work establishes a framework for evaluating high-speed jet injuries and informs safety protocols for less-lethal weapon deployment.