摘要:
水下多点爆炸气泡耦合及形态演化特性一直是被广泛关注的现象。在众多研究方法中,基于离心机的超重力水下爆炸实验因同时满足Mach数和Frude数相似,被认为是大当量水下爆炸原型实验研究的最佳手段之一。本文针对超重力场下水下多点爆炸气泡间耦合规律进行实验和数值研究。首先开展重力加速度为100g的超重力环境下水下两点爆炸实验,通过高速相机高精度捕捉了双气泡形态演化过程。其次,利用基于实验数据验证的超重力水下多点爆炸数值模型进一步探究重力场对水下爆炸双气泡耦合形态演化及特征参数的影响。结果表明,较大重力加速度下,水下爆炸气泡形态演化、脉动和迁移特性与常重力场存在显著差异,超重力这种极端条件会强化压力梯度和浮力效应,导致射流行为呈现独特规律。超重力环境增大了流场中垂向压力梯度,增强了气泡表面的不稳定性、造成更强烈的流体加速运动,促使气泡迁移速度加快;超重力场造成了气泡脉动的“时空压缩效应”同时改变气泡系统浮力-惯性力关系,对气泡射流方向和气泡间相互作用强度有较大影响,进而改变双气泡系统中能量的分布。
关键词:
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水下爆炸 /
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气泡耦合 /
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超重力 /
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气泡脉动 /
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射流
Abstract:
The coupling mechanisms and morphological evolution characteristics of underwater multipoint explosion bubbles have long been a subject of extensive scientific interest due to their complex hydrodynamic behaviors and significant implications in both engineering and defense applications. Among various research methodologies, underwater explosion experiments conducted in centrifugal facilities—commonly referred to as hypergravity experiments—have emerged as one of the most effective approaches, primarily because of the simultaneous satisfaction of both the Mach number and the Froude number which are two critical dimensionless parameters governing dynamic similarity in fluid mechanics. This paper presents a comprehensive experimental and numerical investigation into the coupling dynamics of underwater multipoint explosion bubbles under hypergravity conditions. Specifically, a series of experiments were conducted under an accelerated gravitational field of 100g, enabling high-fidelity observation of the morphological evolution of dual explosion bubbles using high-speed imaging techniques. The captured visual data provided critical insights into bubble interaction processes and served as the foundation for the development and validation of a three-dimensional numerical model simulating underwater dual-bubble explosions in hypergravity environments.Through systematic comparison between experimental results and numerical simulations, the influence of gravitational intensity on the morphological evolution and characteristic parameters of coupled bubbles was thoroughly analyzed. It has been observed that under significantly elevated gravitational acceleration, the morphological evolution, pulsation dynamics, and migration characteristics of underwater explosion bubbles exhibit substantial deviations from those observed under normal gravity conditions. The hypergravity environment, as an extreme physical condition, intensifies both the pressure gradient within the surrounding fluid and the buoyancy forces acting on the bubble, thereby fundamentally altering the underlying hydrodynamic mechanisms. Specifically, the enhanced pressure gradient leads to a more pronounced asymmetry in the pressure distribution around the bubble interface, which in turn accelerates fluid motion and amplifies surface instabilities, resultting in faster and more violent bubble collapse phases, as well as stronger and more focused liquid jets during the rebound stage.Moreover, the increased gravitational acceleration significantly strengthens the buoyancy effect, which governs the direction and magnitude of bubble migration. Consequently, bubbles migrate more rapidly in the direction opposite to the effective gravity vector, and their trajectories become more predictable and less susceptible to small-scale perturbations. This enhanced migration velocity further influences the interaction intensity between multiple bubbles in a multipoint explosion scenario.The pulsation period of the bubble is also notably reduced under hypergravity, a phenomenon referred to as the "temporal compression" effect. Due to the increased restoring forces from both the ambient pressure and gravitational field, the bubble undergoes faster expansion and collapse cycles, resulting in a shorter overall lifetime and fewer oscillation periods. This spatiotemporal compression not only affects the phase relationship between coupled bubbles, thereby modifying their interference patterns and interaction intensity, but also redistribute the energy within the dual-bubble system, leading to distinct energy partitioning patterns compared to normal gravity scenarios.