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A Thermodynamic Cavitation Model for Cavitating Flow Simulation in a Wide Range of Water Temperatures
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A thermodynamic cavitation model is developed to simulate the cavitating water flow in a wide temperature range. The thermal effect on bubble growth during cavitation is introduced in the developed model by considering both pressure difference and heat transfer between the vapor and liquid phase. The cavitating turbulent flow over a NACA0015 hydrofoil has been simulated at various temperatures from room temperature to 150°C by using the present cavitation model, which has been validated by the experimental data. It is seen that the thermodynamic effects of cavitation, vapor depression and temperature depression are much more predominant in high temperature water compared with those in room temperature water. These results indicate that the proposed thermodynamic cavitation model is reasonably applicable to the cavitating water flow in a wide temperature range. 相似文献
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空化水动力学非定常特性研究进展及展望 总被引:1,自引:0,他引:1
空化作为一种重要的复杂水动力学现象,具有明显的三维流动特征与剧烈的非定常特性,在水力机械、船舶推进器、水利工程中广泛存在,且通常会带来不利的影响,长期以来一直是水动力学领域研究的重点与难点课题之一.本文首先从实验测量和数值模拟两个角度,综述了空化水动力学非定常特性研究的发展概况, 分析了当前存在的问题.在空化实验研究中,主要介绍了空化水洞、空化流场测量以及多物理场同步测量等方面所取得的进展.在数值模拟方法中, 对目前的空化模型和湍流模型进行了分类介绍,并重点讨论了大涡模拟、验证和确认等在空化流模拟中的应用.之后以附着型空化为主, 同时兼顾云状空泡、空蚀、涡空化等,梳理了其研究中存在的几个关键科学问题,包括空化演变、空化流动的三维结构、失稳机制、空化不稳定性及其与低频压力脉动的联系、空化与旋涡的相互作用、空化与弹性水翼的流固耦合、空化对尾流场影响等.最后展望了空化水动力学的研究方向和未来发展趋势. 相似文献
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A three-component model based on mass transfer equation is proposed to simulate both the natural and ventilated cavitations. In the present cavitation model, the content of nuclei in the local flow field is updated synchronously, and is coupled with the Rayleigh-Plesset equation so as to capture the cavity development. The proposed model is applied for simulating the cavitating flow around a super-cavitating vehicle in different cavitation conditions. In the ease of the natural cavitation simulation, the predicted cavitation characteristics including the cavity length and cavity diameter agrees fairly well with the analytical results. In the case of the mixed cavitation simulation, the gas ventilation obviously influences the development of cavity. With the increase of the gas ventilated rate, the natural cavitation is suppressed remarkably, and a super cavitation is formed even at a relatively larger natural cavitation number. 相似文献
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空化作为一种重要的复杂水动力学现象,具有明显的三维流动特征与剧烈的非定常特性,在水力机械、船舶推进器、水利工程中广泛存在,且通常会带来不利的影响,长期以来一直是水动力学领域研究的重点与难点课题之一.本文首先从实验测量和数值模拟两个角度,综述了空化水动力学非定常特性研究的发展概况,分析了当前存在的问题.在空化实验研究中,主要介绍了空化水洞、空化流场测量以及多物理场同步测量等方面所取得的进展.在数值模拟方法中,对目前的空化模型和湍流模型进行了分类介绍,并重点讨论了大涡模拟、验证和确认等在空化流模拟中的应用.之后以附着型空化为主,同时兼顾云状空泡、空蚀、涡空化等,梳理了其研究中存在的几个关键科学问题,包括空化演变、空化流动的三维结构、失稳机制、空化不稳定性及其与低频压力脉动的联系、空化与旋涡的相互作用、空化与弹性水翼的流固耦合、空化对尾流场影响等.最后展望了空化水动力学的研究方向和未来发展趋势. 相似文献
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梢涡空化是螺旋桨最早发生的空化类型,其一旦发生会显著增强舰船辐射噪声水平.因此,螺旋桨梢涡空化初生的预报是军舰临界航速确定的关键,长期以来受到船舶领域诸多专家学者的重点关注.微观气核受涡心低压作用而发生暴发式生长是梢涡空化初生的重要机制,而传统欧拉框架下的宏观空化模型用经验参数模化了微观气核的影响而无法对该过程准确模拟,影响对螺旋桨空化初生的准确预报.为了弥补传统模拟方法的不足,本研究发展并使用一种基于气泡动力学并考虑水相可压缩效应的欧拉-拉格朗日空化初生数值预报方法对螺旋桨梢涡空化初生进行了数值模拟研究.与实验结果对比表明,该模型能够准确地预报螺旋桨梢涡空化初生.此外,本研究不仅从微观气核角度探究不同来流气核尺寸对空化初生的影响,还进一步研究梢涡流动特性对气核演变的影响机制,初步探究初生空化在螺旋桨梢涡流场中的发声机理.在空化初生光学判断准则下尺寸越大的气核越容易被梢涡捕获而暴发式生长.气核在梢涡卷吸作用下逐渐靠近涡心低压区.在涡心低压区的持续作用下气核开始暴发式生长,并在半径达到最大后迅速收缩溃灭,产生强烈的正声压脉冲信号. 相似文献
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