• <tr id="yyy80"></tr>
  • <sup id="yyy80"></sup>
  • <tfoot id="yyy80"><noscript id="yyy80"></noscript></tfoot>
  • 99热精品在线国产_美女午夜性视频免费_国产精品国产高清国产av_av欧美777_自拍偷自拍亚洲精品老妇_亚洲熟女精品中文字幕_www日本黄色视频网_国产精品野战在线观看 ?

    WAVE DISSIPATING PERFORMANCE OF AIR BUBBLE BREAKWATERS WITH DIFFERENT LAYOUTS*

    2010-05-06 08:22:18ZHANGChengxing

    ZHANG Cheng-xing

    State Key Laboratory of Coastal and Offshore Engineering, Dalian University of Technology, Dalian 116024, China

    College of Urban Planning and Environmental Science, Xuchang University, Xuchang 461000, China, E-mail: zhangchengxing19@163.com

    WANG Yong-xue, WANG Guo-yu

    State Key Laboratory of Coastal and Offshore Engineering, Dalian University of Technology, Dalian 116024, China

    YU Long-mei

    Dalian Port Construction Supervision and Consultation Co. Ltd., Dalian 116015, China

    WAVE DISSIPATING PERFORMANCE OF AIR BUBBLE BREAKWATERS WITH DIFFERENT LAYOUTS*

    ZHANG Cheng-xing

    State Key Laboratory of Coastal and Offshore Engineering, Dalian University of Technology, Dalian 116024, China

    College of Urban Planning and Environmental Science, Xuchang University, Xuchang 461000, China, E-mail: zhangchengxing19@163.com

    WANG Yong-xue, WANG Guo-yu

    State Key Laboratory of Coastal and Offshore Engineering, Dalian University of Technology, Dalian 116024, China

    YU Long-mei

    Dalian Port Construction Supervision and Consultation Co. Ltd., Dalian 116015, China

    (Received December 28, 2009, Revised March 30, 2010)

    The wave dissipating performance of air bubble breakwaters with different layouts is studied by experimental and numerical methods in this article. Based on the assumpation that the mixture of air and water is regarded as a variable density fluid, the mathematical model of the air bubble breakwater is built. The numerical simulation results are compared with the experimental data, which shows that the mathematical model is reasonable for the transmission coefficient Ctm. The influencing factors are studied experimentally and numerically, including the incident wave heightHi, the incidentt wave period T , the air amount Qm, the submerged pipe depth D and the single or double air discharging pipe structure. Some valuable conclusions are obtained for further research of the mechanism and practical applications of air bubble breakwaters.

    Air bubble breakwater, wave dissiptating performance, experiments, variable density fluid

    1. Introduction

    The air bubble breakwater is composed of an air compressor and pipes with orifices. The pipes are often placed at the sea bottom, or at a certain depth in a deep water area. The air compressor is usually installed on the shore or on a boat[1]. The air bubble breakwater is used for protecting a harbor, the entrance of a port, a part of sea water against wave induced wrecks. The air bubble breakwater is one of mobile breakwaters, with several specific features such as mobility, temporality, and low cost. Besides, it may be pointed out that, with the use of the air bubble breakwater, from an environment point of view, one need not interrupt the exchange of water in harbors[2].

    The first air bubble breakwater appeared in 1907, which was used by Brasher of New York to protect civil engineering works. The second was built in 1915 at El Segundo, California, under Brasher’s patent. With some more projects of that nature, the results, however, were not promising and the method fell into disuse. Fundamental tests were conducted by the Admiralty in 1924, by Russian scientists in 1935 and by Professor Thysse of Delft in 1936. During the Second World War, the research and analysis on air bubble and water jet breakwaters were carried out by White and Taylor[3].

    In the early 1950’s, a wide publicity was given to an air bubble breakwater designed by Laurie to protect a train ferry dock entrance at Dover. Before that, Carr and Schiff studied the air bubbles breakwater in a model tank at the California Institute of Technology. With the use of the Dover installation, Evans conducted a series of model tests in 1954 in conjunction with the theoretical work by Taylor. Bulson reviewed the analytical and experimental studies carried out by himself and others, and in was concluded that the surface currents produced by the air bubble motion were the main mechanism of wave dissipation in the system of the air bubble breakwater. The empirical formulae were presented for the surface velocity and the thickness of the horizontal current produced by an air bubble curtain; and for the amount of free air required to suppress waves with certain length and height. Zhang et al.[4]studied the horizontal current generated by air bubble curtain in still water with a numerical simulation technique, which gave a further explanation of the wave dissipating mechanism of the air bubble breakwater. Furthermore, Zhang[5]carried out a preliminary study of the performance of the air bubble breakwater, and the results demonstrated the effects of air amount as well as incident wave period on the air bubble breakwater system.

    Despite of those experimental and theoretical researches done in past years, due to the complexity of the interactions between air bubbles and water, the air bubble breakwater remains a topic of studies and the practical application data are very much in demand. This article presents our experimental and numerical studies of the wave dissipating performance of the air bubble breakwaters with different layouts.

    Fig.1 The schematic diagram of the tests for the air bubble breakwater

    2. Experiment

    2.1 Equipment

    The length scales 1:10 and 1:15 are adopted in our experiments in the large wave tank of the State Key Laboratory of Coastal and Offshore Engineering, Dalian University of Technology. The large wave tank is 69.0 m long, 2.0 m wide and 1.8 m deep. The pipe to discharge air with orifices is made of plexiglass, with the length of 2.0 m, the orifice diameter of 0.0008 m and the distance between two orifices of 0.01 m. The compressed air is supplied by the air compressor up to the maximum amount of 3.0 m3/min. Figure 1 showes the schematic diagram of the tests for the air bubble breakwater.

    Four wave gauges of capacitance type are installed as shown in Fig.1. The transmission coefficient Ctmof the air bubble breakwater is calculated by the Goda method[6]. In the tests, the same case is tested for three times, to obtain the average value.

    Table 1 The parameters of tests with different length scales

    Fig.2 The apparatus of the air bubble breakwater system

    The prototype parameters include the incident wave height H=3.55 m, the incident wave period T=4s , 5 s and 6 s, and the water depth d=12 m. With respect to two length scales, the incident waves are governed by the law of gravity similarity, the corresponding parameters in model tests are shown in Table 1. The subscript of m and p means the model and prototype, respectively, in the article.

    During the tests, the air is pushed by the air compressor to the pipe, and then the air bubbles are produced continuously from the orifices and an air bubble curtain will appear across the tank width. The incident wave passes the air bubble curtain, and the wave dissipation occurs due to the wave deformation and the wave break. In the tests, the flow meter is installed at different locations along the pipe for the measurement of air amount Qm. Figure 2 shows the apparatus of the air bubble breakwater.

    2.2 Results and discussions

    The incident wave height Hiand the transmitive wave height Htcan be obtained from the test data by the Goda’s method. The transmission coefficient Ctmis expressed as Ctm=Ht/Hi. The impacts of the incident wave period T and the air amount Qmon the wave dissipating performance of the air bubble breakwater are compared and analyzed.

    Figure 3 shows the relations of the transmission coefficient Ctmversus the air amount Qmwith different length scales and different incident wave periods T. It is found that the wave dissipating performance of the air bubble breakwater is closely related with the air amout Qm, and it can be improved by the increase of air amount Qm.

    From Fig.3, it is seen that the incident wave period T is the key factor influencing the wave dissipating performance of the air bubble breakwater. Take Fig.3(a) for example, the incident waves with three different wave periods are dissipated with various air amounts Qm. In the case of the incident wave period T =1.26s, the transmission coefficient Ctmchanges from 0.87 to 0.48 when the air amount increases from 5 m3/h·m to 20 m3/h·m. However, the

    transmission coefficient Ctmchanges but little for the cases of the incident wave period T =1.58s and T =1.91s. It is demonstrated that the wave dissipating performance of the air bubble breakwater is affected evidently for short period waves with a given air amount Qm, and the wave dissipating performance of the air bubble breakwater is good for short period waves.

    Fig.3 Test data of Ctmagainst different air amountsQm

    3. Numerical simulation

    3.1 Mathematical formulation

    The mixture of air and water is considered as a fluid of variable density. The density and the dynamic viscosity coefficient of the fluid are defined as

    where a0,ρ0, μ0are the volume fraction, density and the dynamic viscosity coefficient of water, and a1,ρ1, μ1are the corresponding parameters for air. The volume fractions of both phases aq(q =0,1) can be solved from Eqs.(3) and (4)

    The continutiy equation is expressed as Eq.(5), and the momentum equation is the Reynolds averaging equation in the form[7-10], as shown in Eqs.(6) and (7), in which the density and the dynamic viscosity coefficient of the fluid is defined by Eqs.(1) and (2). The pressure pattern and the velocity pattern take the average values.

    where μtis the turbulent viscosity coefficient, μ =ρC k2/ε, C is a constant, C=0.09, the

    tμμμ turbulent kinetic energy k and the turbulent diffusionε are governed by Eqs.(8) - (9)[11,12]. As mentioned previously, it is assumed that the mixture of air and water is regarded as a variable density single phase liquid, so the standard k?ε equation can be used in this condition.

    where Gkis the turbulent kinetic energy produced

    Fig.4 A schematic diagram of the numerical simulation model of the air bubble breakwater

    3.3 Model validation

    In order to verify the rationality of the numerical model of the air bubble breakwater presented in the article, numerical computations are conducted and the schematic diagram of the numerical simulation model is shown in Fig.4. The length scales 1:10 and 1:15 are selected, the wave parameters and the air amounts Qmare the same as the experimental cases, as shown in Table 1. transmission coefficient Ctmof the test results would be smaller than those in other cases.

    It is seen from Figs.5 and 6 that the air amount Qmplays an important role in the wave dissipating performance of the air bubble breakwater, at the same time, the transmission coefficient Ctmis reduced with the increase of air amout Qm. It is also found that the incident wave period T affects the performance of wave dissipating, and the air bubble breakwater would have good wave dissipating performance when the incident wave has a short period T. All these are verified by experimental results.

    3.4 Results and discussions

    The factors that influence the wave dissipating performance of the air bubble breakwater are studied by numerical simulations, including the incident wave height H, the pipe submerged depth D and the spacing between two air discharging pipes dsfor the air bubble breakwater with double air discharging pipes. Based on the results obtained from numerical simulations, various influencing factors are analyzed to determine their impacts on the wave dissipating performance of the air bubble breakwater. A schematic diagram of the numerical wave tank is shown in Fig.4. The wave tank is 330 m long and 15 m deep, and the grids are refined in the region from X =110 m to X =130 m, with the air bubble curtain located at X =120 m. The transmission coefficientCtpis obtained at the monitor #3 as the numerical results.

    3.4.1 Incident wave height

    The cases considered in the numerical simulations include various incident wave heights H, incident wave period T and air amount Qpas shown in Table 2, and the results are illustrated in Fig.7.

    Figure 7(a) shows the variation of the transmission coefficient Ctpwith incident wave heights Hiand the air amount Qpfor T=4s. It is found that the transmission coefficientCtpdecreases with the increase of air amount Qp. But the reduction of transmission coefficient Ctpvaries with different incident wave heights Hi, the smaller the incident wave height Hi, the smaller the transmission coefficientCtpbecomes. The same results can be seen from the Figs.7(b) and 7(c) for T=5s and T=6s.

    Fig.5 The comparison of Ctmbetween experimental experimental and numerical simulations(Length scale, 1:10)

    Fig.6 The comparison of Ctmbetween and numerical simulations (Length scale, 1:15)

    Figures 5 and 6 show the comparisons of transmission coefficient Ctmbetween experimental and numerical results. It can be seen from Figs.5 and 6 that the maximum deviation of transmission coefficient Ctmbetween numerical results and experimental results is 9% except the case of the length scale 1:10, the incident wave periodT =1.26s and the air amount Q=20 m3/h· m . In the

    m experiments, the incident wave will be broken with the horizontal flow produced by a large air amount Qm, but the wave broken phenomenon is not considered in the numerical simulation. So the

    Table 2 Cases for numerical simulations with different incident wave heights Hi

    Fig.7 Transmission coefficient Ctpversus air amounts Qpfor different incident wave heights Hi

    It is demonstrated from Fig.7 that the transmission coefficient Ctpis reduced by a large amount with a small incident wave height Hifor the same air amountQp. which means that the wave dissipating performance of the air bubble breakwater is good for the small incident wave height Hiwith a given air amount Qp, the reason of which may be illustrated from the view of wave energy.

    When the water depth d and the incident wave period T are constants, the greater the incident wave height Hi, the greater the wave energy will be. The wave dissipating performance of the air bubble breakwater is not good when the incident wave height is large at a certain air amountQp.

    3.4.2 Submerged pipe depth

    The different submerged pipe depths D are considered with different air amounts Qpand different incident wave periods. The submerged pipe depth is defined as the vertical distance from the location of air discharging pipe in the water to the water surface. Three submerged pipe depths are considered in the article. The cases with different parameters in numerical simulations are shown in Table 3.

    Figure 8 shows the variation of the transmission coefficient Ctpwith the increase of air amount Qpfor different submerged pipe depths D and the incident wave periods T=4 s, 5 s and 6 s, respectively.

    Figure 8(a) shows the variation of the transmission coefficient Ctpversus the air amount Qpfor various submerged pipe depths D. It is found that the transmission coefficient Ctpdecreases with the increase of air amount Qpfor different submerged pipe depths D. The greater the submerged pipe depth D , the smaller the transmission coefficient Ctpwill be. The sameresults can be seen from Figs.8(b) and 8(c). transmission coefficient Ctpdecreases with the increase of the submerged pipe depth D for the same air amount Qp, which means that the submerged pipe depth D is one of influencing factors related to wave dissipation in the air bubble breakwater system. It is also seen that when the incident wave period T is short, the effect of the submerged pipe depth D is significant. Furthermore, the air amount Qpplays an important role in the wave dissipating performance of the air bubble breakwater, which is consistent with the experiment results.

    Table 3 The numerical simulation cases with different submerged depths of air discharging pipe D

    Fig.8 Transmission coefficient Ctpversus air amounts Qpfor different submerged pipe depths D

    Fig.9 The profile of Vmversus water depth ( X =134 m, t=67 s , Q=500 m3/h· m )

    Figure 9 shows the variation of the horizontal flow velocity Vmgenerated by the air bubble curtain versus the water depth d at the locationX =134 m in the calm water, when the water depth d =12 m,air amount Q=500 m3/h· m , the time

    p

    t=67 s and the submerged pipe depthD=6 m and 12 m, respectively. It can be found that the flow velocity Vmproduced by the pipe with the submergence D=12 m is greater than that with the submergence D=6 m under the same air amountQpin the calm water. According to the wave dissipating mechanism of the air bubble breakwater, as the effects of the horizontal flow velocity Vmon the incident waves, the greater the horizontal flow velocity Vm, the better the wave dissipating performance will be. It is seen that the wave dissipation of the air bubble breakwater is affected by the submerged pipe depthD.

    3.4.3 Double air discharging pipes

    The air bubble breakwater with double air discharging pipes is designed and its schematic diagram is shown in Fig.10 for studying the wave dissipating performance of the air bubble breakwater. Two different spacings between air discharging pipes ds=6 m and 10 m are considered in the article. The locations of air discharging pipes are atX =117 m and X=123m for ds=6 m and atX =115 m and X =125 m for ds=10 m , respectively.

    Fig.10 Schematic diagram of the air bubbles breakwater with double air discharging pipes

    The wave dissipating performance of the air bubble breakwater with double air discharging pipes are studied, considering different spacings between double air discharging pipes dsand different air amounts Qp, which are taken as the total air amounts of both pipes for the case of double air discharging pipes. The incident wave period T=5s, the incident wave height H=3.55 m and the water depth d=12 mare adopted in the numerical simulations. The total air amountQpis selected from 100 m3/h·m to 580 m3/h·m with increment of 80 m3/h·m.

    Figure 11 shows the comparison of transmission coefficient Ctpbetween single and double air discharging pipe structures with various total air amounts Qp, where (a) for ds=6 m and (b) for ds=10 m . It is found from Fig.11(a) that the transmission coefficientCtpof the single and double air discharging pipe structures sees no significant difference for various total air amounts Qpfor ds=6 m , which means that the wave dissipating effects of the air bubbles breakwaters of both structures are similar. It is also found from Fig.11(b) that the transmission coefficient Ctpof the single air discharging pipe structure is smaller compared with that of the double air discharging pipe structure for ds=10 m for various total air amountsQp, which means that the spacing between double air discharging pipes affects the wave dissipating performance to a certain extent.

    Fig.11 The comparison of transmission coefficient Ctpbetween single and double air discharging pipe structures with various total air amounts Qp

    Figure 12 shows the pattern of velocity vector generated by the double air discharging pipes in the calm water at the time t=67 s with the air amount Q=500 m3/h· m , the spacing d=6 m and 10 m,

    p s and the water depth d=12 m. Figure 13 shows the distribution of the horizontal flow velocity Vmalong the water depth at the position X =134 m with the the same condition referred above. It is found from Fig.12(a) that the pattern of the circulation flow produced by the air bubble’s motion is similar to that by the single air discharging pipe for the spacing ds=6 m , so the wave dissipating capability isnearly the same between two kinds of structures. But for the spacing ds= 10 m, on the other hand, as shown in Fig.12(b), there are two minor vortexes between twoair discharging pipes. The existence of the two minor vortexes affects the distribution of the part of the total energy generated by the air bubble’s motion, which would reduce the horizontal flow velocity Vm. Figure 13 also shows obviously that the horizontal flow velocityVmdecreases with the increase of the spacing ds. It is seen that the wave dissipating performance of the air bubble breakwater with double air discharging pipes may not be improved as compared with the air bubble breakwater with a single air discharging pipe, especially, when the spacing between double air discharging pipes dsis large.

    Fig.12 The pattern of velocity vector with different spacings between double air discharging pipes dsin the calm water (t =67 s , Q=500 m3/h· m )p

    Fig.13 The profile of Vmversus water depth ( X =134 m, t=67 s ,Q=500 m3/h· m )p

    4. Conclusions

    In the article the wave dissipating performance of the air bubble breakwater and the influencing factors are studied by experiments and numerical computations. In the numerical model, the mixture of water and air is regarded as a variable density liquid, the Reynolds averaging equation and the standard k?ε equations are adopted as the governing equations, the method of VOF is used to track the two-phase interface; an additional mass source is added in the continuity equation and an additional momentum source is added in the momentum equations. The following conclusions are drawn.

    (1) By the comparison of experimental results and numerical simulation results, it is demonstrated that the mathematical model in this article is reasonable.

    (2) The wave dissipating performance of the air bubble breakwater depends closely on the air amount Q. With the increase of the air amount Q, the wave dissipating performance of the air bubble breakwater is improved.

    (3) The wave dissipating performance of the air bubble breakwater is affected significantly by the incident wave period T, especially, for the incident wave with short period T.

    (4) With the increase of the incident wave height Hi, the wave dissipating performance of the air bubble breakwater becomes worse.

    (5) The increase of the submerged pipe depth D would improve the wave dissipating performance of the air bubble breakwater.

    (6) With the same total air amount Q, the wave dissipating performance of the air bubble breakwater with double air discharging pipes may not be improved in comparison with the air bubble breakwater with a single air discharging pipe, especially, when the spacing between the double air discharging pipesdsis large. It may be a good choice to use the single air discharging pipe structure instead of the double air discharging pipe structure.

    [1] WANG Guo-yu. Investigation on the structure type and performance of the special breakwaters[D]. Ph. D. Thesis, Dalian: Dalian University of Technology, 2005(in Chinese).

    [2] TONG Chao-feng, YANG Yi-xin. Study on the decaying wave feature of floating breakwater[J]. Port and Waterway Engineering, 2002, 343(8): 32-35(in Chinese).

    [3] WANG Guo-yu, WANG Yong-xue and LI Guang-wei. Experimental study on the performance of air bubbles breakwater[J]. Shipbuilding of China, 2004, 45(z1): 103-109(in Chinese).

    [4] ZHANG Cheng-xing, WANG Yong-xue and WANG Guo-yu et al. Numerical simulation study on the horizontal current generated by air bubbles curtain in still water[J]. Chinese Journal of Hydrodynamics, 2010, 25(1): 59-66(in Chinese).

    [5] ZHANG Cheng-xing, WANG Guo-yu and WANG Yong-xue. Study on the peirformances of air curtain breakwater by numerical simulation study[J]. Chinese Journal of Hydrodynamics, 2009, 24(5): 543-549(in Chinese).

    [6] YU Yu-xiu. Random wave theories and engineering applications[M]. Dalian: Dalian University of Technology Press, 2000(in Chinese).

    [7] HAN Zhan-zhong, WANG Jing and LAN Xiao-ping. Fluids engineering simulation examples and applications of Fluent[M]. Beijing: Beijing Institute of Technology Press, 2004(in Chinese).

    [8] CHANG K. A., HSU T. J. and LIU P. L. F. Vortex generation and evolution in water waves propagating over a submerged rectangular obstacle: Part II: Cnoidal waves[J]. Coastal Engineering, 2005, 52(3): 257-283.

    [9] CHEN G., KHARIF C. and ZALESKI S. et al. Two-dimensional Navier-Stokes simulation of breaking waves[J]. Physics of Fluids, 1999, 11(1): 121-133.

    [10] LUBIN P., VINCENT S. and ABADIE S. et al. Three-dimensional large eddy simulation of air entrainment under plunging breaking waves[J]. Coastal Engineering, 2006, 53(8): 631-655.

    [11] LIU Zhen, HYUN Beom-soo and KIM Moo-rong et al. Experimental and numerical study for hydrodynamic characteristics of an oscillating hydrofoil[J]. Journal of Hydrodynamics, 2008, 20(3): 280-287.

    [12] WANG Rui-jin, ZHANG Kai and WANG Gang. The technical bases and application examples of Fluent[M]. Beijing: Tsinghua University Press, 2007(in Chinese).

    [13] LI Ling. The numerical simulation of interaction of water waves and floating structures in a viscous fluid[D]. Master Thesis, Shanghai: Shanghai Jiao Tong University, 2007(in Chinese).

    [14] LI Sheng-zhong. Study on 2-D numerical wave tank based on the software Fluent[D]. Master Thesis, Harbin: Harbin Institute of Technology, 2006(in Chinese).

    [15] LI Ling, LIN Zhao-wei and YOU Yun-xiang et al. The numerical wave flume of the viscous fluid based on the momentum source method[J]. Journal of Hydrodynamics, Ser. A, 2007, 22(1): 76-82(in Chinese).

    [16] WANG Yan, YOU Yun-xiang. Numerical simulation of interaction of viscous wave fields with a semi-submersible platform[J]. Chinese Journal of Hydrodynamics, 2009, 24(6): 793-799(in Chinese).

    [17] ZHANG Hong-sheng, YU Xiao-wei and YANG Jian-min et al. Verification and application of the improved numerical model for nonlinear wave propagation[J]. Chinese Journal of Hydrodynamics, 2009, 24(3): 364-373(in Chinese).

    [18] DONG Zhi, ZHAN Jie-min. Comparison of existing methods for wave generating and absorbing in VOF-based numerical tank[J]. Journal of Hydrodynamics, Ser. A, 2009, 24(1): 15-21(in Chinese).

    [19] LU Chang-na, WANG Ru-yun and CHEN Ping-ping. A keeping volume fraction method for moving interfaces reconstruction of VOF using triangle meshes[J]. Chinese Journal of Hydrodynamics, 2008, 23(3): 255-260(in Chinese).

    [20] DONG Zhi, ZHAN Jie-min. Numerical modeling of wave evolution and runup in shallow water[J]. Journal of Hydrodynamics, 2009, 21(6): 731-738.

    10.1016/S1001-6058(09)60102-5

    * Project supported by the National Natural Science Foundation of China (Grant No. 50809015).

    Biography: ZHANG Cheng-xing (1977-), Male, Ph. D., Lecturer

    在线观看人妻少妇| 中文精品一卡2卡3卡4更新| 91精品伊人久久大香线蕉| 青春草国产在线视频| 久久精品熟女亚洲av麻豆精品| 亚洲经典国产精华液单| 草草在线视频免费看| 色视频在线一区二区三区| 欧美日韩av久久| 国产亚洲av片在线观看秒播厂| av有码第一页| 伊人亚洲综合成人网| 最黄视频免费看| 久久久久视频综合| 久久人人爽av亚洲精品天堂| 国产69精品久久久久777片| 两个人免费观看高清视频| 国产免费福利视频在线观看| 大码成人一级视频| 男人爽女人下面视频在线观看| 极品少妇高潮喷水抽搐| 夫妻性生交免费视频一级片| 人人妻人人澡人人看| 久久精品久久精品一区二区三区| 久久久久久久国产电影| 少妇高潮的动态图| 极品人妻少妇av视频| 啦啦啦视频在线资源免费观看| 亚洲精品中文字幕在线视频| 精品酒店卫生间| 哪个播放器可以免费观看大片| 久久人人爽av亚洲精品天堂| 飞空精品影院首页| 免费av不卡在线播放| 国产欧美日韩综合在线一区二区| 亚洲高清免费不卡视频| av在线老鸭窝| 男的添女的下面高潮视频| 一级片'在线观看视频| 国内精品宾馆在线| 久久久国产欧美日韩av| 两个人的视频大全免费| 亚洲欧洲精品一区二区精品久久久 | 一级黄片播放器| 精品一品国产午夜福利视频| 国产精品国产三级专区第一集| 丰满乱子伦码专区| 婷婷色av中文字幕| 亚洲av二区三区四区| 国产极品粉嫩免费观看在线 | 午夜视频国产福利| 国产午夜精品久久久久久一区二区三区| 久久久久人妻精品一区果冻| 亚洲国产成人一精品久久久| 精品国产一区二区三区久久久樱花| 精品一区二区免费观看| 亚洲av免费高清在线观看| 在线观看一区二区三区激情| 成人毛片60女人毛片免费| 自拍欧美九色日韩亚洲蝌蚪91| 大香蕉97超碰在线| 一区二区日韩欧美中文字幕 | 一区在线观看完整版| 日本爱情动作片www.在线观看| 成人二区视频| .国产精品久久| 精品熟女少妇av免费看| 日本vs欧美在线观看视频| 亚洲婷婷狠狠爱综合网| 青春草视频在线免费观看| 国产女主播在线喷水免费视频网站| 久久久国产一区二区| 成年人午夜在线观看视频| 男人添女人高潮全过程视频| 免费人妻精品一区二区三区视频| 黄色毛片三级朝国网站| 在线观看人妻少妇| 91午夜精品亚洲一区二区三区| 激情五月婷婷亚洲| 久久久久久久大尺度免费视频| 国产在线视频一区二区| 99热国产这里只有精品6| 18禁在线播放成人免费| 国产爽快片一区二区三区| 日本黄色日本黄色录像| 亚洲一级一片aⅴ在线观看| 美女cb高潮喷水在线观看| 亚洲av成人精品一区久久| 亚洲av日韩在线播放| 亚洲内射少妇av| 狂野欧美白嫩少妇大欣赏| 欧美老熟妇乱子伦牲交| 久久精品久久久久久噜噜老黄| 久久韩国三级中文字幕| 男人添女人高潮全过程视频| 街头女战士在线观看网站| 观看美女的网站| 香蕉精品网在线| 日韩熟女老妇一区二区性免费视频| 精品久久久久久电影网| 亚洲欧美清纯卡通| 亚洲精品久久成人aⅴ小说 | 日韩亚洲欧美综合| 亚洲精华国产精华液的使用体验| av播播在线观看一区| 日韩成人av中文字幕在线观看| 香蕉精品网在线| 久久女婷五月综合色啪小说| 少妇的逼好多水| 51国产日韩欧美| 亚洲无线观看免费| 亚洲综合色惰| 日韩 亚洲 欧美在线| 97超碰精品成人国产| 国产精品一国产av| 亚洲综合精品二区| 国产精品不卡视频一区二区| 成人黄色视频免费在线看| 91精品国产国语对白视频| 久久精品国产鲁丝片午夜精品| 一级毛片黄色毛片免费观看视频| 亚洲欧洲精品一区二区精品久久久 | 亚洲精品一二三| 黄片无遮挡物在线观看| 嫩草影院入口| 久热这里只有精品99| 免费人妻精品一区二区三区视频| 91久久精品国产一区二区成人| 高清在线视频一区二区三区| a级毛片在线看网站| 青青草视频在线视频观看| 免费黄网站久久成人精品| 美女脱内裤让男人舔精品视频| 亚洲综合色网址| 久久久久国产精品人妻一区二区| 久久久国产精品麻豆| 成人国语在线视频| 99热全是精品| 99视频精品全部免费 在线| 高清av免费在线| 久久人人爽人人片av| 日韩,欧美,国产一区二区三区| 亚洲综合色惰| 天堂俺去俺来也www色官网| 精品酒店卫生间| 成人国产av品久久久| 三级国产精品欧美在线观看| 日本av手机在线免费观看| 久久精品国产a三级三级三级| 午夜福利在线观看免费完整高清在| 有码 亚洲区| 热re99久久精品国产66热6| 成人免费观看视频高清| 97在线视频观看| 婷婷成人精品国产| 亚洲精品aⅴ在线观看| 亚洲国产精品一区三区| 少妇精品久久久久久久| 黄片无遮挡物在线观看| 能在线免费看毛片的网站| 男人添女人高潮全过程视频| 69精品国产乱码久久久| 男人爽女人下面视频在线观看| 国产伦理片在线播放av一区| 各种免费的搞黄视频| 少妇人妻精品综合一区二区| 久久久久久久久久久免费av| 成人影院久久| 久久久a久久爽久久v久久| 欧美精品人与动牲交sv欧美| 亚洲高清免费不卡视频| 熟女av电影| 一区二区av电影网| 少妇熟女欧美另类| 免费观看在线日韩| 高清不卡的av网站| 国产不卡av网站在线观看| 男女边摸边吃奶| 如日韩欧美国产精品一区二区三区 | tube8黄色片| 国产精品一区二区在线观看99| 少妇人妻 视频| 99久久综合免费| 超碰97精品在线观看| 欧美激情极品国产一区二区三区 | 七月丁香在线播放| 最后的刺客免费高清国语| 三上悠亚av全集在线观看| 麻豆成人av视频| 国产午夜精品久久久久久一区二区三区| 午夜久久久在线观看| 精品一区二区三区视频在线| 一个人免费看片子| 国产av精品麻豆| 成人国产麻豆网| 国产av国产精品国产| 久热久热在线精品观看| 日本91视频免费播放| 美女视频免费永久观看网站| 久久久a久久爽久久v久久| 色94色欧美一区二区| 国产精品国产三级专区第一集| 久久ye,这里只有精品| 免费日韩欧美在线观看| 免费黄网站久久成人精品| 免费大片黄手机在线观看| 91国产中文字幕| 有码 亚洲区| 亚洲国产精品成人久久小说| 欧美成人午夜免费资源| 成年人免费黄色播放视频| 亚洲精品视频女| 国产男人的电影天堂91| 免费观看无遮挡的男女| 国产69精品久久久久777片| 少妇被粗大的猛进出69影院 | 三上悠亚av全集在线观看| 国产伦理片在线播放av一区| 男的添女的下面高潮视频| 中国三级夫妇交换| 中文字幕av电影在线播放| 另类精品久久| 久久亚洲国产成人精品v| 这个男人来自地球电影免费观看 | 91久久精品国产一区二区成人| 亚洲综合精品二区| 一个人免费看片子| 国产免费一级a男人的天堂| 国国产精品蜜臀av免费| 黄色视频在线播放观看不卡| 日韩精品免费视频一区二区三区 | 免费黄频网站在线观看国产| 人妻一区二区av| 久久热精品热| 亚洲综合色惰| 亚洲高清免费不卡视频| 老女人水多毛片| 在线天堂最新版资源| 国产伦精品一区二区三区视频9| 久久午夜福利片| 妹子高潮喷水视频| av专区在线播放| 午夜视频国产福利| 美女大奶头黄色视频| 2022亚洲国产成人精品| 中文欧美无线码| 丰满乱子伦码专区| 九色亚洲精品在线播放| 两个人免费观看高清视频| 三级国产精品欧美在线观看| 久久久久视频综合| 欧美 亚洲 国产 日韩一| 乱码一卡2卡4卡精品| 亚洲国产精品一区二区三区在线| 国产国拍精品亚洲av在线观看| 2021少妇久久久久久久久久久| 亚洲第一av免费看| 国产精品国产三级专区第一集| 9色porny在线观看| 国语对白做爰xxxⅹ性视频网站| 青春草国产在线视频| 久久毛片免费看一区二区三区| 你懂的网址亚洲精品在线观看| 各种免费的搞黄视频| 18禁在线无遮挡免费观看视频| 国产欧美日韩一区二区三区在线 | 亚洲一级一片aⅴ在线观看| 午夜91福利影院| 久久精品国产a三级三级三级| 在线播放无遮挡| 伦理电影大哥的女人| av播播在线观看一区| 制服人妻中文乱码| 美女国产高潮福利片在线看| 日本欧美视频一区| 高清午夜精品一区二区三区| 最近最新中文字幕免费大全7| 久久久国产一区二区| 97精品久久久久久久久久精品| h视频一区二区三区| 日韩av在线免费看完整版不卡| 人人澡人人妻人| 狠狠精品人妻久久久久久综合| 亚洲精品一二三| 亚洲av国产av综合av卡| 精品久久久久久电影网| 国产高清国产精品国产三级| 水蜜桃什么品种好| 精品一品国产午夜福利视频| 亚洲欧美精品自产自拍| 亚洲av成人精品一二三区| 午夜免费鲁丝| 亚洲人与动物交配视频| 午夜免费观看性视频| 国产黄频视频在线观看| 午夜福利视频精品| 在线观看一区二区三区激情| 男的添女的下面高潮视频| 18禁在线播放成人免费| 熟妇人妻不卡中文字幕| 人成视频在线观看免费观看| 黄片播放在线免费| 国产乱人偷精品视频| 波野结衣二区三区在线| 亚洲伊人久久精品综合| 久久韩国三级中文字幕| 丝袜脚勾引网站| 一个人免费看片子| 欧美xxⅹ黑人| 久久午夜综合久久蜜桃| 热re99久久精品国产66热6| 99re6热这里在线精品视频| 如日韩欧美国产精品一区二区三区 | 国产精品蜜桃在线观看| www.av在线官网国产| 成人免费观看视频高清| 亚洲av电影在线观看一区二区三区| 又黄又爽又刺激的免费视频.| 男女边摸边吃奶| 国产精品国产av在线观看| 日韩不卡一区二区三区视频在线| 免费观看无遮挡的男女| 乱码一卡2卡4卡精品| 男女边摸边吃奶| 成人无遮挡网站| 日韩电影二区| 蜜臀久久99精品久久宅男| 午夜老司机福利剧场| 精品人妻一区二区三区麻豆| freevideosex欧美| 人妻人人澡人人爽人人| 18+在线观看网站| 99热网站在线观看| 丝袜在线中文字幕| av.在线天堂| 9色porny在线观看| 丝袜喷水一区| 欧美人与性动交α欧美精品济南到 | 99热全是精品| 亚洲精品美女久久av网站| 免费不卡的大黄色大毛片视频在线观看| 日本欧美国产在线视频| 免费看光身美女| 中文精品一卡2卡3卡4更新| 国产精品蜜桃在线观看| 亚洲av国产av综合av卡| 老司机影院成人| 久久女婷五月综合色啪小说| 国产日韩一区二区三区精品不卡 | 一级,二级,三级黄色视频| 亚洲国产最新在线播放| 久久这里有精品视频免费| 只有这里有精品99| 国产免费一区二区三区四区乱码| 人妻一区二区av| 国产精品三级大全| videos熟女内射| av福利片在线| 久久久久国产精品人妻一区二区| 伦理电影大哥的女人| 搡老乐熟女国产| 欧美97在线视频| 人人妻人人澡人人看| 简卡轻食公司| 免费大片黄手机在线观看| 日韩三级伦理在线观看| 熟女人妻精品中文字幕| 成人亚洲欧美一区二区av| 9色porny在线观看| 国产一区有黄有色的免费视频| 国产黄色免费在线视频| 丰满少妇做爰视频| 另类亚洲欧美激情| 大陆偷拍与自拍| 人人澡人人妻人| 国产精品国产av在线观看| 国产精品国产三级国产av玫瑰| 国产深夜福利视频在线观看| 国产永久视频网站| av免费在线看不卡| 性色av一级| 国产av码专区亚洲av| 国产精品免费大片| 内地一区二区视频在线| 高清午夜精品一区二区三区| 国产高清有码在线观看视频| 午夜免费男女啪啪视频观看| 亚洲精品色激情综合| 高清毛片免费看| 亚洲精品视频女| 久久久久精品性色| av.在线天堂| 卡戴珊不雅视频在线播放| 久久亚洲国产成人精品v| 日韩av免费高清视频| 精品亚洲乱码少妇综合久久| 婷婷色麻豆天堂久久| 国产精品一区www在线观看| 国产精品一区二区三区四区免费观看| 成人18禁高潮啪啪吃奶动态图 | 亚洲精品aⅴ在线观看| 99九九在线精品视频| 不卡视频在线观看欧美| 青青草视频在线视频观看| 久久亚洲国产成人精品v| 啦啦啦在线观看免费高清www| 国产乱人偷精品视频| 看非洲黑人一级黄片| 少妇熟女欧美另类| 国产av精品麻豆| 日日摸夜夜添夜夜爱| 色5月婷婷丁香| 大片电影免费在线观看免费| 午夜影院在线不卡| 亚洲怡红院男人天堂| 欧美3d第一页| 久久热精品热| 一本大道久久a久久精品| 精品酒店卫生间| 久久综合国产亚洲精品| 久久久精品免费免费高清| 国产精品国产三级国产av玫瑰| 熟妇人妻不卡中文字幕| 国产黄频视频在线观看| 国产老妇伦熟女老妇高清| 久久久国产精品麻豆| 9色porny在线观看| 午夜免费观看性视频| 成人国产av品久久久| 99久国产av精品国产电影| 精品人妻熟女毛片av久久网站| 日本猛色少妇xxxxx猛交久久| 91成人精品电影| 人人妻人人澡人人看| 飞空精品影院首页| 婷婷色麻豆天堂久久| 女性被躁到高潮视频| 久久国产精品大桥未久av| 国产高清有码在线观看视频| 熟女av电影| 国产亚洲午夜精品一区二区久久| 丝袜喷水一区| 国产成人免费观看mmmm| 18禁动态无遮挡网站| 天堂中文最新版在线下载| 多毛熟女@视频| 蜜桃在线观看..| 久久久久久久精品精品| 大陆偷拍与自拍| 国产老妇伦熟女老妇高清| 这个男人来自地球电影免费观看 | 女人精品久久久久毛片| h视频一区二区三区| 18禁在线播放成人免费| 国产精品一区二区在线观看99| 亚洲av免费高清在线观看| 亚洲精品乱码久久久久久按摩| 欧美3d第一页| 久久久久久久久大av| 国产淫语在线视频| 色视频在线一区二区三区| 久久女婷五月综合色啪小说| av女优亚洲男人天堂| 婷婷色麻豆天堂久久| 亚洲国产毛片av蜜桃av| 亚洲国产欧美在线一区| 国产又色又爽无遮挡免| 一二三四中文在线观看免费高清| 亚洲第一区二区三区不卡| 老司机影院成人| 超色免费av| 中文字幕免费在线视频6| 七月丁香在线播放| 少妇被粗大的猛进出69影院 | 能在线免费看毛片的网站| 亚洲精品aⅴ在线观看| 欧美丝袜亚洲另类| 久久精品国产自在天天线| tube8黄色片| 国产亚洲最大av| 一个人看视频在线观看www免费| 热re99久久国产66热| 国产成人精品无人区| 天堂俺去俺来也www色官网| 一区二区av电影网| 大又大粗又爽又黄少妇毛片口| 国产日韩一区二区三区精品不卡 | 人人妻人人添人人爽欧美一区卜| 免费av不卡在线播放| 美女国产高潮福利片在线看| 亚洲熟女精品中文字幕| 久久久国产欧美日韩av| 国产亚洲最大av| 女人久久www免费人成看片| 亚洲四区av| 大香蕉久久成人网| 新久久久久国产一级毛片| 欧美国产精品一级二级三级| 两个人免费观看高清视频| 亚洲欧洲日产国产| 亚洲丝袜综合中文字幕| 精品午夜福利在线看| 久久久久久久久久久丰满| 欧美日韩精品成人综合77777| 丰满饥渴人妻一区二区三| 国产极品天堂在线| 亚洲五月色婷婷综合| 亚洲精品视频女| 99热全是精品| av在线观看视频网站免费| 午夜福利影视在线免费观看| 亚洲成色77777| 男男h啪啪无遮挡| 五月开心婷婷网| 日日爽夜夜爽网站| 看十八女毛片水多多多| 青青草视频在线视频观看| 99国产精品免费福利视频| 9色porny在线观看| 久久精品国产亚洲av涩爱| 国产精品女同一区二区软件| 蜜桃在线观看..| 亚洲情色 制服丝袜| 久久久久久久久久成人| 啦啦啦中文免费视频观看日本| 大香蕉久久网| 好男人视频免费观看在线| 人体艺术视频欧美日本| 国产免费一区二区三区四区乱码| 成人亚洲欧美一区二区av| 春色校园在线视频观看| 日本黄大片高清| 狂野欧美激情性bbbbbb| 久久精品久久久久久噜噜老黄| 免费人成在线观看视频色| 亚洲欧美日韩卡通动漫| 人成视频在线观看免费观看| 18禁观看日本| 激情五月婷婷亚洲| 色网站视频免费| 97精品久久久久久久久久精品| 国产精品秋霞免费鲁丝片| 99久久精品一区二区三区| 黄色毛片三级朝国网站| 久久久亚洲精品成人影院| 黑人巨大精品欧美一区二区蜜桃 | 亚洲精品第二区| 少妇人妻久久综合中文| 欧美老熟妇乱子伦牲交| 最后的刺客免费高清国语| 汤姆久久久久久久影院中文字幕| 在线观看人妻少妇| 日韩成人av中文字幕在线观看| 亚洲欧美一区二区三区黑人 | 亚洲精品第二区| 美女国产视频在线观看| 亚洲性久久影院| 热99国产精品久久久久久7| 69精品国产乱码久久久| 秋霞伦理黄片| 一区二区三区免费毛片| 日本与韩国留学比较| 久久久久久久亚洲中文字幕| 日本av手机在线免费观看| 亚洲精品aⅴ在线观看| 久久久久久人妻| 久久久精品94久久精品| 成人亚洲欧美一区二区av| 建设人人有责人人尽责人人享有的| 十分钟在线观看高清视频www| 久久久久久久久久成人| 精品一区二区三区视频在线| 日韩精品有码人妻一区| 国产不卡av网站在线观看| 国语对白做爰xxxⅹ性视频网站| 亚洲美女黄色视频免费看| 青春草视频在线免费观看| 毛片一级片免费看久久久久| 一级,二级,三级黄色视频| videos熟女内射| 黄色怎么调成土黄色| 欧美精品一区二区大全| 成年av动漫网址| av天堂久久9| 亚洲欧美一区二区三区黑人 | 久久99热6这里只有精品| 各种免费的搞黄视频| www.av在线官网国产| 在线免费观看不下载黄p国产| 99久久中文字幕三级久久日本| 久久亚洲国产成人精品v| 热99国产精品久久久久久7| 免费播放大片免费观看视频在线观看| 18+在线观看网站| av不卡在线播放| 久久久久精品久久久久真实原创| 亚洲精华国产精华液的使用体验| 国产精品久久久久成人av| 欧美bdsm另类| 免费看不卡的av| 我要看黄色一级片免费的| 26uuu在线亚洲综合色| 亚洲欧美成人精品一区二区| 我要看黄色一级片免费的| 最新的欧美精品一区二区| 欧美日韩亚洲高清精品| 欧美日韩视频精品一区| 欧美日韩精品成人综合77777| 国产亚洲av片在线观看秒播厂| 亚洲欧洲日产国产| 精品人妻熟女毛片av久久网站| 国产免费一区二区三区四区乱码| 国产精品 国内视频| 亚洲精品国产av蜜桃| 黑人高潮一二区|