共查询到20条相似文献,搜索用时 156 毫秒
1.
弧板式透空堤消浪性能影响因素数值研究 总被引:1,自引:0,他引:1
弧板式透空堤是由弧型板组成的新型防波堤结构。为探讨其透射系数的影响因素,利用Fluent软件基于N-S方程构建了波浪与板式透空堤相互作用的数值模型,讨论了相对潜深、入射波周期、相对波高、相对板宽和结构型式对透射系数的影响。结果表明:弧板式透空堤的透射系数随着相对波高和入射波周期的增大而增大,在静水面附近透射系数最小,尤以静水面和略高于静水面时的消浪效果最佳;在相同波浪要素条件下,静水面及其上0.02 m和0.04 m位置处,弧板式透空堤的消浪效果明显优于平板式透空堤。 相似文献
2.
3.
4.
5.
本文提出了一种倾斜挡浪板式桩基透空型防波堤,通过物理模型试验对规则波作用下防波堤的消浪性能进行了研究。试验中观测了桩基透空型防波堤迎浪侧和背浪侧波面的变化过程,探讨了不同入射波浪条件下防波堤挡浪板的开孔率ε和布置形式B对其消浪性能的影响,分析了防波堤的反射系数Kr、透射系数Kt以及波能耗散系数Kd随着相对波高H/D和相对堤宽W/L的变化关系,并从波浪能量分布的角度分析此种防波堤的消浪机理。研究结果表明,单层挡浪板的开孔率自30%降低至10%,平均透射系数可减小约24.3%,平均耗散系数可增长约12.8%;双层挡浪板防波堤的反射系数取决于前排挡浪板的开孔率,透射系数取决于挡浪板组合中的最小开孔率。 相似文献
6.
7.
浮式防波堤在港口海岸工程、近海工程、海洋工程和水产养殖等诸多领域有广阔的应用前景。与单浮箱式浮式防波堤相比,多浮箱式浮式防波堤可提高其消浪性能。对双浮箱式浮式防波堤进行了二维波浪物理模型试验,分析了浮箱宽度、前后浮箱连接方式、前后浮箱间距以及浮箱入水深度等因素对浮式防波堤消浪性能的影响。研究结果表明:对于单浮箱式浮式防波堤,试验范围内浮箱宽度增大一倍后消浪效果改善并不相对明显;前后浮箱刚性连接的双浮箱式浮堤的波浪透射系数均小于前后浮箱自由的双浮箱式浮堤和相同浮箱宽度的单浮箱式浮堤,浮堤消浪性能提高;由于前后浮箱相对间距太大时前后浮箱的相互作用减弱,浮堤的波浪反射系数变小,而不同前后浮箱相对间距的波能损耗系数整体上差别较小,双浮箱式浮堤的波浪透射系数整体上随着前后浮箱相对间距D/2B的增大先减小然后变大,在相对间距D/2B为1.0~1.5时双浮箱式浮堤的波浪透射系数相比最小;不同波高和波浪周期下,浮堤的波浪透射系数均随着浮箱相对入水深度的增大而减小。 相似文献
8.
9.
在现有的矩形方箱和透空结构的基础上,提出一种由立管和水平板组合而成的消浪结构。利用波浪水槽物理模型试验,测试该结构在单向规则波作用下的消浪性能。分别探讨了其单排布置和双排布置时的透射系数随结构宽度、相对吃水深
度、相对间距等因素的变化规律。结果表明:单排布置时,透射系数随结构宽度的增大而减小,总体上随吃水深度的增大而减小;双排布置时,透射系数相对总宽度相同的单体结构减少 10 %,透射系数随吃水深度的增大而减小,前后间距对透射系数的影响不明显。对试验结果数据进行曲线拟合,得到了透射系数关于各影响因素的函数表达式。 相似文献
10.
透空式防波堤周围的非线性波浪传播的数值模拟 总被引:1,自引:0,他引:1
对非线形波浪在透空式防波堤周围的波浪变形进行了数值模拟,在Boussinesq波浪方程中加入与透空建筑物有关的新的耗散项,从而界定了透空建筑物引起的部分反射和透射,波浪折射衍射的传播过程通过控制方程求解。波浪控制方程通过有限差分方法求解。模型应用于模拟波浪经过具有部分反射的群桩式透空结构,结果表明透空式防波堤可以有效地衰减波浪,是重力式结构的一种替代形式。 相似文献
11.
Numerical prediction of performance of submerged breakwaters 总被引:1,自引:0,他引:1
The results of a numerical model study on the transmission characteristics of a submerged breakwater are presented. Study aimed to determine the effect of depth of submergence, crest width, initial wave conditions and material properties on the transmission characteristics of the submerged breakwater. The results highlight the optimum crest width of the breakwater and optimum clear spacing between two breakwaters. A submerged permeable breakwater with ds/d=0.5, p=0.3 and f=1.0, reduces the transmission coefficient by about 10% than the impermeable breakwater. The results indicates an optimum width ratio of B/d=0.75 for achieving minimum transmission. By restricting the effective width ratio of the series of breakwaters to 0.75, studies were conducted to determine the effect of clear spacing between breakwaters on transmission coefficient, suggesting an optimum clear spacing of w/b=2.00 to obtain Kt below 0.6. 相似文献
12.
Wave interaction with T-type breakwaters 总被引:1,自引:0,他引:1
The wave transmission, reflection and energy dissipation characteristics of partially submerged ‘T'-type breakwaters (Fig. 1) were studied using physical models. Regular and random waves, with wide ranges of wave heights and periods and a constant water depth were used. Five different depths of immersions of the ‘T'-type breakwater were selected. The coefficient of transmission, Kt, coefficient reflection, Kr, were obtained from the measurements and the coefficient of energy loss, Kl is calculated using the law of conservation of energy. It is found that the coefficient of transmission generally reduces with increased wave steepness and increased relative water depth, d/L. This breakwater is found to be effective closer to deep-water conditions. Kt values less than 0.35 is obtained for both normal and high input wave energy levels, when the horizontal barrier of the T type breakwater is immersed to about 7% of the water depth. This breakwater is also found to be very efficient in dissipating the incident wave energy to an extent of about 65% (i.e. Kl>0.8), especially for high input wave energy levels. The wave climate in front of the breakwater is also measured and studied.
Fig. 1. Schematic view of the T-type breakwater. 相似文献
Full-size image (12K) |
13.
O.S. Rageh 《Ocean Engineering》2009,36(14):1112-1118
The efficiency of the breakwater, which consists of caissons supported on two or three rows of piles, was studied using physical models. The efficiency of the breakwater is presented as a function of the transmission, reflection and the wave energy dissipation coefficients. Regular waves with wide ranges of wave heights and periods and constant water depth were used. Different characteristics of the caisson structure and the supporting pile system were also tested. It was found that, the transmission coefficient (kt) decreases with increasing the relative breakwater draft D/L, increasing the relative breakwater width B/h, and decreasing the piles gap-diameter ratio G/d. It is possible to achieve kt values less than 0.25 when D/L≥0.1. The reflection coefficient takes the opposite trend especially when D/L≤0.15. The proposed breakwater dissipates about 10-25% of the incident wave energy. Also, simple empirical equations are developed for estimating the wave transmission and reflection. In addition, the proposed breakwater model is efficient compared with other floating breakwaters. 相似文献
14.
Experimental investigations on perforated hollow piles in two rows were conducted in a two dimensional wave flume. The influence of water depth, incident wave steepness, clear spacing between the piles and the spacing of pile rows on transmission coefficient have been studied. The effect of staggering of piles in rows is investigated. The results are also compared with the results of experiments on piles without perforations. The investigations have revealed that perforated piles attenuate more wave energy than non-perforated piles. The transmission coefficient Kt decreases as the wave steepness increases for both non-perforated and perforated piles. For non-perforated piles as relative clear spacing between the piles (b/D) decreases, for waves of higher steepness, Kt decreases while for perforated piles as b/D decreases, Kt is decreasing for all the steepness considered. As the relative clear spacing between the pile rows (B/D) increases Kt initially decreases till B/D is around one and later it starts increasing for both non-perforated and perforated piles. Staggering of piles has little effect on Kt. It is also found that water depth has insignificant influence on transmission coefficient at higher steepness for both perforated and non-perforated piles. Wave period alone does not directly influence transmission coefficient Kt. 相似文献
15.
The wave transmission, reflection and energy dissipation characteristics of ‘’-type breakwaters were studied using physical models. Regular and random waves in a wide range of wave heights and periods and a constant water depth were used. Five different depths of immersion (two emerged, one surface flushing and two submerged conditions) of this breakwater were selected. The coefficient of transmission, Kt, and coefficient of reflection, Kr, were obtained from the measurements, and the coefficient of energy loss, Kl was calculated using the law of balance of energy. It was found that the wave transmission is significantly reduced with increased relative water depth, d/L, whether the vertical barrier of the breakwater is surface piercing or submerged, where ‘d’ is the water depth and ‘L’ is the wave length. The wave reflection decreases and energy loss increases with increased wave steepness, especially when the top tip of the vertical barrier of this breakwater is kept at still water level (SWL). For any incident wave climate (moderate or storm waves), the wave transmission consistently decreases and the reflection increases with increased relative depth of immersion, Δ/d from −0.142 to 0.142. Kt values less than 0.3 can be easily obtained for the case of Δ/d=+0.071 and 0.142, where Δ is the height of exposure (+ve) or depth of immersion (−ve) of the top tip of the vertical barrier. This breakwater is capable of dissipating wave energy to an extent of 50–80%. The overall performance of this breakwater was found to be better in the random wave fields than in the regular waves. A comparison of the hydrodynamic performance of ‘’-type and ‘T’-type shows that ‘T’-type breakwater is better than ‘’-type by about 20–30% under identical conditions. 相似文献
16.
Performance of solid and perforated U-type breakwaters under regular and irregular waves 总被引:1,自引:0,他引:1
An experimental investigation of U-type breakwaters was carried out in a laboratory channel. Both regular and irregular waves were used during testing. Two types of breakwaters such as solid and perforated were studied to analyse the porosity effect of structures. In order to investigate performance of these breakwaters for different immersion depths, four depths of immersions of the solid and perforated breakwaters were selected. Different wave groups were generated over these breakwaters, and the transmission, reflection and energy dissipation characteristics of each breakwater were determined. Three coefficients such as transmission, reflection and energy dissipation coefficients, which were named as Ct, Cr, and Cl, respectively, were used during the evaluation of the test results. The most important parameters governing performance of these breakwaters were determined by using earlier investigations and experimental results. These parameters were expressed as a dimensionless group by using π theory. Based on the test results, empirical expressions were formulated to describe the Ct, Cr, and Cl for different immersion depths of solid and perforated breakwaters under regular and irregular waves. 相似文献
17.
The wave transmission characteristics and wave induced pressures on twin plate breakwater are investigated experimentally in regular and random waves.A total of twenty pressure transducers are fixed on four surfaces of twin plate to measure the wave induced dynamic pressures.The spatial distribution of dynamic wave pressure is given along the surface of the twin plate.The uplift wave force obtained by integrating the hydrodynamic pressure along the structure is presented.Discussed are the influence of different incident wave parameters including the relative plate width B /L,relative wave height /i H a and relative submergence depth s /a on the non-dimensional dynamic wave pressures and total wave forces.From the investigation,it is found that the optimum transmission coefficient,t K occurs around B /L 0.41 ~ 0.43,and the twin plate breakwater is more effective in different water depths.The maximum of pressure ratio decreases from 1.8 to 1.1 when the relative submergence depth of top plate is increased from 0.8to +0.8. 相似文献
18.
Interaction Between Waves and A Comb-Type Breakwater 总被引:2,自引:1,他引:2
The characteristics of wave transmission, reflection and energy dissipation of comb-type caisson breakwaters are studied through laboratory physical model tests. Regular and irregular waves, with a wide range of wave heights and periods and a constant water depth, are considered. Different dimensions of each portion of the comb-type caisson breakwater are tested. Empirical formulae for calculating the reduction coefficient k, which is the ratio of horizontal wave force on unit length of the comb-type breakwater to that on unit length of the vertical wall breakwater, and for calculating the reflection coefficient of waves k, are obtained from the measurements. The comb-type caisson breakwater has been found to be very efficient in dissipating incident wave energy and in reducing wave reflection, and has already been used for the construction of an island breakwater in the Dayao Bay of Dalian Port, Liaoning Province, China. Compared with the cost of a common caisson breakwater, about 24. 5% of the investm 相似文献
19.
Fifteen formulae of wave transmission coefficient for submerged breakwaters obtained during last 3 decades are presented,compared,and analyzed in this paper.The dimensionless parameters mainly involved in this discussion are the relative submerged depth Rc/h,relative wave height Rc/Hi,relative rubble size B/D50,relative breakwater width B/HiL0 and wave breaker index ξ.It indicates that there exist notable differences among the computed results,which mainly originate from the limited experimental conditions and different analytical methods,even though the major tendency keeps similar.It is necessary to conduct more systematic studies to obtain better understanding about the mechanism of wave transmission over submerged breakwaters. 相似文献
20.
针对海工作业平台、海洋养殖网箱等海洋装备的安全防护问题,提出了一种带空气透平的后弯管浮式防波堤,该空气透平既可将作用在防波堤上的波浪能转化成机械能并用于发电,还可显著减小防波堤的锚链力。在介绍了防波堤原理和结构特点的基础上,设计了物理实验模型,并在实验室造波池内进行了模型试验,研究了波浪周期、波高、吃水深度与弯管数量等因素对后弯管浮式防波堤透射系数和锚链力的影响规律。研究结果表明,波浪周期越短,波高越低,防波堤的透射系数越小,锚
链力越小,其消波性能优于传统的浮式防波堤. 相似文献