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高速圆舭艇无浅水影响的最小水深衡准 总被引:2,自引:0,他引:2
本文通过5条模型、7种吃水状态的浅水阻力试验,经回归分析得到高速圆舭艇无浅水影响的最小水深条件,包括各种航速下均无浅水影响的“绝对深水”条件和不同航速下的“相对深水”条件,其适用范围可达Fr=0.8。将本文提出的衡准与国内外现有各种衡准进行了比较:在Fr≤0.4~0.5时,本衡准与各国驱逐舰的衡准基本一致,从而证实了本衡准的可靠性;当Fr≥0.5以后,差别较明显,表明目前常用的将驱逐舰浅水衡准用于高速圆舭艇是不合理的。 相似文献
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高速圆舭排水艇的船型设计 总被引:1,自引:0,他引:1
高速圆舭排水艇的船型设计,关键是合理选择尾部线型。本文通过一个船型组系的各种尾部改型试验结果,分析了航行纵倾角、底升角、尾板浸深面积、尾板宽度、尾部纵剖线形状、尾楔块的应用、尾折角线、面积曲线等因素对阻力的影响,从而为高速圆舭排水艇的船型设计提供依据。 相似文献
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本文介绍高速圆舭排水艇一组线型设计和静水阻力试验结果,适用于500~1000t 级高速艇的设计和研究。在 Fr<0.7的航速范围内,在瘦长比 L/Δ~(1/3)相等的基础上与国内外同类型艇作比较,显示出优良的阻力性能。此外,还对船模 M8320进行切除分水踵试验和改成短折角尾型作两个不同尾板宽度的对比试验。 相似文献
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根据排水量长度系数C和排水量纵向分布是影响圆舭快艇静水阻力主要参数的观点,本文对文献国舭快艇阻力试验的系列图谱进行了重新计算和整理后,得出了一组剩余阻力系数C_k=/(C,F_n)曲线图。用此曲线可简单、迅速而比较正确地计算高速国舭快艇的静水阻力,供设计图舭快艇的初始阶段作估算用。 为了使这类艇的阻力性能比较良好,文中还扼要地介绍了一些船型和附体设计的特点供参考。 相似文献
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改善高速排水型艇性能的措施 总被引:1,自引:0,他引:1
一、防溅条的应用高速排水型艇有圆舭型和折角型两种艇型。从阻力观点来看,在F_n<1.0的范围内,圆舭型艇的阻力性能较具有折角线的V型艇为佳[1]、[2]、[3]。因此,在高速排水型艇的设计中,对航速小于F_n=1.0的艇通常选用 相似文献
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本文对三个不同系列的高速圆舭排水艇型进行了模型静水阻力和纵倾试验,直接得出了各艇型阻力性能的比较结果。这三个艇型分别是英国的NPL系列、瑞典的SSPA系列,以及我国的CSSRC组系。文中给出的CSSRC组系M8643模型是从文章[1]中M8320模型再次繁衍派生,同时结合一个产品的具体设计要求而作某些局部修改后获得。修改内容包括:横剖面面积曲线的变化——它对阻力反映有比较显著的影响;对尾板宽度再次作了试验研究,从而验证了[1]文所得的结论,即尾板相对宽度不应限于0.80以下;尾楔块的安装又使艇体阻力性能获得了进一步的改善。 相似文献
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本文根据国内外圆舭快艇系列试验资料和我国的设计经验,分析了圆舭快艇主尺度和系数对阻力的影响。由分析可知:排水量长度系数和排水量的纵向分布(包括方尾浸湿面积比、棱形系数、横剖面面积曲线形状和浮心纵向位置等要素)是影响圆舭快艇静水阻力的主要参数。而方形系数、长宽比、宽吃水比、半进水角和横剖面形状等则是影响阻力的次要参数。 为了能设计出成功的圆舭快艇,需要把圆舭快艇分为高速段(F_n>0.60)和低速段(F_n=0.35~0.45),并使主要参数的选择适合于相应的速度范围。文中列出了高速段和低速段圆舭快艇的横剖面面积曲线和横剖面形状供参考。 相似文献
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浅水中船舶水动力特性数值计算 总被引:1,自引:0,他引:1
本文对浅水中船舶水动力特性进行数值计算研究.采用RANS方程结合RNG K-ε两方程湍流模型,对一方形系数0.6的系列60船模在浅水中的阻力、升沉、纵倾和兴波进行数值计算,其中自由面采用VOF方法处理;计算中,水深Froude数范围0.6~1.8,包含了临界和超临界水深Froude数.数值计算得到的阻力、升沉和纵倾与模型试验结果及采用三维扩展Boussinesq方程的计算结果进行了比较分析,吻合较好,部分计算结果得到改进. 相似文献
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分析9 艘圆舭型快艇船模浅水阻力系列试验资料,寻找每艘船模阻力变化规律,由108 条内插阻力曲线应用回归分析直接计算及依据深水阻力转换的间接计算分别计算浅水阻力曲线。可用于该类船型浅水功率估算及主尺度优化分析计算。对无浅水影响最小水深及超临界纵倾角也作了一定研究 相似文献
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本文提供了一种估算内河船舶浅水阻力的方法。根据184条船模浅水阻力曲线及部分相应的深水阻力曲线,计算了经济航速、临界航速和不同航速下的兴波阻力系数。应用经修正的Prohaska方法计算了深、浅水形状因子。将上述这些量视为H/T、L/B、B/T和C_B的幂函数方程,应用回归分析确定其指数值。利用求得的回归公式即可进行深、浅水阻力计算,协助选择优良船型,进行主尺度分析,选配经济航速以提高营运经济性。本方法具有计算简便、适应范围广、计算精度高等优点。 相似文献
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The ice resistance on ships in escort operations in level ice are investigated using the discrete element method (DEM). A dilated polyhedron—generated by the Minkowski sum of a sphere and a polyhedron—is employed in the DEM; this dilated polyhedron-based DEM (DPDEM) is adopted to simulate the ship–ice interaction, wherein the contact force and bond-failure criterion are considered for the collision and fracture of sea ice, respectively. A three-point bending test was simulated with DPDEM, and a field test was conducted in the Bohai Sea to validate the DEM results. Further, a parametric analysis of flexural strength was conducted to identify the parameters involved in the bond-failure criterion. The ice resistance on icebreakers and cargo ships in level ice are simulated using DPDEM. The simulated ice resistances are compared with the Lindqvist and Riska formulas and the model test, which proves the validity of the DEM simulation. The interaction between ships and level ice is simulated parametrically to investigate the ice resistance on cargo ships with and without the icebreaker escort. Influencing factors such as ship speed, ice thickness, and ship breadth were examined to investigate the ice resistance on the escorted cargo ship. Analysis and change rules of the ice resistance on cargos affected by those factors were given. 相似文献
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A computational method for improving hull form in shallow water with respect to wave resistance is presented. The method involves coupling ideas from two distinct research fields: numerical ship hydrodynamics and nonlinear programming techniques. The wave resistance is estimated by means of Morinos panel method, which is extended to free surface flow and considers the influence of finite depth on the wave resistance of ships. This is linked to the optimization procedure of the sequential quadratic programming (SQP) technique, and an optimum hull form can be obtained through a series of iterations giving some design constraints. Sinkage is an important factor in shallow water, and this method considers sinkage as a hydrodynamic design constraint. The optimization procedure developed is demonstrated by selecting a Wigley (C
B = 0.444) hull and the Series 60 (C
B = 0.60) hull, and new hull forms are obtained at Froude number 0.316. The Froude number specified corresponds to a lower than critical speed since most of the ships operating in shallow water move below their critical speed. The numerical results of the optimization procedure indicate that the optimized hull forms yields a reduction in wave resistance. 相似文献
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高速双体船阻力特征及其应用 总被引:2,自引:0,他引:2
双体船的阻力特点是片体波系间相互有干扰。当处于有利干扰时,双体船的阻力小于两个单独片体的阻力之和。干扰的实质是片体间波系的横渡干扰。作者根据三种不同横剖面形状的高速双体船在不同间距比和排水量长度系数下的阻力试验资料,分析船型、间距比、排水量长度系数对阻力的影响,得到高速双体船的有利干扰起始点Fr0和片体间流动阻塞时的FrR0根据本文推荐的Fr0和FrR计算公式,可以选择恰当的航速、间距比和排水量长度系数以满足Fr0<Fr<FrR,使高速双体船处于低阻的有利干扰状态。 相似文献
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URANS simulations of catamaran interference in shallow water 总被引:1,自引:0,他引:1
Teresa Castiglione Wei He Frederick Stern Sergio Bova 《Journal of Marine Science and Technology》2014,19(1):33-51
This paper investigates the interference effects of wave systems on a multi-hull vessel in shallow water. A numerical analysis is made using the URANS code CFDSHIP-Iowa V.4 on the DELFT Catamaran model 372. The test matrix for numerical computations includes two separation distances (s = 0.17; 0.23) and the depth values of h/T = 8.2, 2.5 and 2, at several speeds ranging within Fr H = 0.775–1.739. Numerical results are compared with the experimental data of the Bulgarian Ship Hydrodynamic Center, and verification and validation for resistance, sinkage and trim are also performed. Results show that, at critical speed (Fr H ≈ 1), the presence of a finite depth significantly affects the catamaran total resistance, which, in shallower water, increases considerably with respect to deep water. At low h/T, small effects of the water depth on resistance occur at subcritical and supercritical speeds. The interference effects seem to be more relevant in shallow, rather than in deep water, with maximum IF values registered at critical speeds (Fr H ≈ 1). Similarly to deep water, the lower the separation distance the greater the interference value. Moreover, in shallow water some negative interference is observed at Fr > 0.5. Wave patterns and wave profiles are analyzed and a comparison is made between several configurations of catamaran and a mono-hull vessel, in order to analyze how water depth and separation distance determine resistance and interference. Finally, a vortex instability study is also included. 相似文献
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关于深水、浅水与限制性航道界定的探讨 总被引:1,自引:1,他引:0
通过对船舶阻力的分析和计算.根据影响阻力的主要因素,航速、水深与船吃水比、断面系数,由换算系数来界定深水、浅水与限制性航道。 相似文献
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Alexander H. Day David Clelland Lawrence J. Doctors 《Journal of Marine Science and Technology》2009,14(3):387-397
This paper covers an extension of the study of Doctors et al. (J Ship Res 52(4):263–273, 2008) on oscillations in wave resistance during the constant-velocity phase of a towing-tank resistance test on a ship model to
the case of relatively shallow water. We demonstrate here that the unsteady effects are very prominent and that it is essentially
impossible to achieve a steady-state resistance curve in a towing tank of typical proportions for a water-depth-to-model-length
ratio of 0.25. This statement is particularly true in the speed region near a depth Froude number of unity. However, on the
positive side, we show here that an application of unsteady linearized wave-resistance theory provides an excellent prediction
of the measured total resistance, when one accounts for the form factor in the usual manner. Finally, a simple application
of the results to the planning and analysis of towing-tank tests is presented. 相似文献