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水下航行体通气超空泡减阻特性实验研究 总被引:7,自引:1,他引:6
为了研究超空泡的减阻效果,保证在较低流速下生成超空泡,在水洞中开展了水下航行体通气超空泡的实验研究.采用通气的方法在较低水速下生成人工通气超空泡,通过改变通气率和弗劳德数,获得了不同条件下通气空泡的长度,以及不同空泡长度下的模型阻力系数.研究表明,来流速度不变时,空泡长度随通气率的增加而增加,阻力系数随空泡长度的增加先递增后递减;空化器直径对阻力系数的影响较大,在大弗劳德数条件下,阻力系数会因空化器直径过大而出现随通气量的增加而变大的趋势.利用商用软件对超空泡形态及阻力系数作了数值仿真,并与实验结果作了对比,两者符合较好. 相似文献
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为了探索通气超空泡的生成机理和获取形态可控有效减阻的超空泡,文章利用中速可持续通气空泡水洞进行了空化器和通气联合生成超空泡的实验研究.详细分析了通气超空泡的生成和发展过程;给出了空化器直径、空化器线形对通气系数门限值和通气超空泡形态的影响.研究表明,在相同条件下,较大直径空化器模型形成通气超空泡需要的通气系数门限值较低,相应的超空泡尺寸也较大;平头倒角形和圆盘形空化器比圆锥形的形成通气超空泡需要的通气系数门限值低,相同条件下前者形成的超空泡尺寸也较后者大;对于圆锥形空化器,锥角较小的不易形成通气超空泡.文中实验研究结果为水下航行体的空化器合理设计提供了重要的参考依据. 相似文献
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针对多种不同锥段线型的航行体,对其自然空泡形态及减阻特性进行了数值模拟研究.得到了各条件下空泡形态随空化数的变化关系、拟合曲线,以及阻力系数随空泡长度的变化关系.通过对比分析,得出了航行体锥段线型对空泡形态及减阻特性的影响规律.结果表明,锥段线型对空泡形态影响不明显;当空泡闭合于航行体锥段时,锥段线型为圆弧的模型阻力系数较小;而当空泡闭合于航行体柱段或形成超空泡时,各模型阻力系数趋于一致,几乎不受锥段线型影响. 相似文献
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水下高速射弹超空泡形态特性的数值模拟研究 总被引:1,自引:0,他引:1
基于均匀多相流假设,建立了水下射弹自然超空化流动的多相流CFD模型,分析了带圆锥和圆盘空化器头部2种高速射弹模型所产生的超空泡形态特性.仿真结果表明,圆盘头形空化器有利于射弹超空泡的形成;超空泡的相对直径与相对长度随空化数增加而减小;空化数越小,超空泡的长细比越大,减阻效果也越好.最后,通过Fluent软件的自定义函数模拟了带圆盘空化器头部射弹超空泡流发展过程,得到了射弹在水下高速航行过程中超空泡形态的变化特性,研究结果为进一步研究水下高速射弹空泡流水动力特性提供了理论参考. 相似文献
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文中研究了锥柱组合体模型在轴向约束加速运动中人工通气量对加速过程中超空泡形态的影响及其变化规律。研究表明模型在加速过程中不通气的情况下,只有锥柱结合面后尚有局部空泡,但未见超空泡形成。在通气量23.4g/s、19.0g/s、14.6g/s、9.3g/s下,均能在研究的σv范围内逐步形成超空泡。对于一定的通气量,随着模型运动速度的逐步提高,自然空化数逐步减小,空泡由短变长;由大片分段脱落不连续的空泡变成连续的空泡;由空泡长度明显的不稳定到稳定;由空泡表面不光滑到光滑;发展成空泡表面光滑透明的超空泡。超空泡随通气量的变化规律与水洞定常试验结果是一致的。 相似文献
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To deal with the effect of compressible fluids on the supercavitating flow over the subsonic disk cavitator of a projectile, a finite volume method is formulated based on the ideal compressible potential theory. By using the continuity equation and Tait state equation as well as Riabouchinsky closure model, an “inverse problem” solution is presented for the supercavitating flow. According to the impenetrable condition on the surface of supercavity, a new iterative method for the supercavity shape is designed to deal with the effect of compressibility on the supercavity shape, pressure drag coefficient and density field. By this method, the very low cavitation number can be computed. The calculated results agree well with the experimental data and empirical formula. At the subsonic condition, the fluid compressibility will make supercavity length and radius increase. The supercavity expands, but remains spheroid. The effect on the first 1/3 part of supercavity is not obvious. The drag coefficient of projectile increases as the cavitation number or Mach number increases. With Mach number increasing, the compressibility is more and more significant. The compressibility must be considered as far as the accurate calculation of supercavitating flow is concerned. 相似文献
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《船舶与海洋工程学报》2015,(3)
To deal with the effect of compressible fluids on the supercavitating flow over the subsonic disk cavitator of a projectile, a finite volume method is formulated based on the ideal compressible potential theory. By using the continuity equation and Tait state equation as well as Riabouchinsky closure model, an "inverse problem" solution is presented for the supercavitating flow. According to the impenetrable condition on the surface of supercavity, a new iterative method for the supercavity shape is designed to deal with the effect of compressibility on the supercavity shape, pressure drag coefficient and density field. By this method, the very low cavitation number can be computed. The calculated results agree well with the experimental data and empirical formula. At the subsonic condition, the fluid compressibility will make supercavity length and radius increase. The supercavity expands, but remains spheroid. The effect on the first 1/3 part of supercavity is not obvious. The drag coefficient of projectile increases as the cavitation number or Mach number increases. With Mach number increasing, the compressibility is more and more significant. The compressibility must be considered as far as the accurate calculation of supercavitating flow is concerned. 相似文献
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《船舶与海洋工程学报》2019,(3)
Ventilated cavitation has been successfully employed as ship drag reduction technology and potentially can mitigate flowinduced vibration. The obtained successes were based on solutions of design problems considered in the framework of ideal fluid theory with their following validation by towing tank tests. However, various aspects of the interaction of ventilated cavities with the viscous flows around the ship hulls remain unclear, whereas there is usually no possibility to simultaneously keep the full-scale Froude number and cavitation number in the test facilities. So, the further progress of the application of ventilated cavitation substantially depends on the ability of computational tools to predict this interaction. This paper briefly describes the state-of-the-art computation of ventilated cavitation and points out the most challenging unsolved problems that appeared in the model tests(prediction of air demand by cavities, ventilation effect on ship drag, on hydrofoil lift, and on the propagation of shock waves in cavities). 相似文献
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为分析来流速度对圆盘空化器产生超空泡的形态,基于粘流理论和有限体积方法,对带有圆盘空化器超空泡航行体流场进行了数值模拟。得到了超空泡形态与航行体速度之间的关系。随着速度的增加,空泡长度逐渐增大。并进一步给出了流场的压力分布云图和速度矢量图。 相似文献