黃小華,王芳芳,,劉海陽,胡 昱,王占行,王紹敏,趙云鵬
系泊和壓載方式對半潛式漁場平臺動力特性的影響
黃小華1,王芳芳1,2,劉海陽1,胡 昱1,王占行3,王紹敏1,趙云鵬2
(1. 中國水產(chǎn)科學研究院南海水產(chǎn)研究所,廣東省網(wǎng)箱工程技術(shù)研究中心,農(nóng)業(yè)部外海漁業(yè)開發(fā)重點實驗室,廣州 510300;2. 大連理工大學海岸和近海工程國家重點實驗室,大連 116024;3. 中國水產(chǎn)科學研究院漁業(yè)工程研究所,北京 100141)
為了解漁場平臺的耐波性及穩(wěn)性,為漁場平臺主體結(jié)構(gòu)設計和海上安裝提供理論依據(jù)和數(shù)據(jù)支撐,該研究針對一種半潛式桁架結(jié)構(gòu)漁場平臺開展了模型比尺為1:30的波浪水池試驗,通過試驗分別研究了漁場平臺在3種系泊方式(錨鏈長度2.67、5.34、5.34 m并懸掛200 g重塊)、3種壓載狀態(tài)(空載、半載和滿載)和6種波況(波高為16.7~23.3 cm,周期為1.64 s和2.01 s)條件下的動力響應情況,比較分析了不同條件下漁場平臺系泊力、升沉、縱搖和橫搖的試驗結(jié)果。結(jié)果表明,選用5.34 m長度錨鏈并懸掛200 g重塊的單點系泊系統(tǒng),能夠更好的降低漁場平臺的系泊力。在所有波況條件下,漁場平臺的各運動分量的峰值均比較小,最大升沉峰值為4.21 cm,僅占波高的約1/5,縱搖峰值僅為6.55°,橫搖峰值僅為1.19°,表明漁場平臺具有較好的穩(wěn)性。比較3種不同壓載狀態(tài),其中滿載狀態(tài)下漁場平臺的系泊力、縱搖及橫搖峰值最大,但在空載狀態(tài)下漁場平臺的升沉峰值最大。隨著波高的增大,漁場平臺的運動受力均有所增大。研究結(jié)果有助于為今后我國半潛式漁場平臺發(fā)展提供一定的理論參考。
水產(chǎn)養(yǎng)殖;波浪;動力學;漁場平臺;單點系泊;壓載狀態(tài)
中國遠離大陸的深遠海水域水質(zhì)優(yōu)良、無污染、水體交換速度快、養(yǎng)殖病害發(fā)生率低,是發(fā)展現(xiàn)代水產(chǎn)養(yǎng)殖業(yè)和海洋漁業(yè)經(jīng)濟的新空間[1-2]。近年來,中國灘涂及近海養(yǎng)殖業(yè)面臨空間壓縮、環(huán)境破壞的嚴峻挑戰(zhàn),而外海20 m以深海域的資源利用率不到1%,充分利用深遠海廣闊的海域資源發(fā)展設施工程化養(yǎng)殖,提供大量優(yōu)質(zhì)安全的海產(chǎn)品,是加快轉(zhuǎn)變漁業(yè)生產(chǎn)方式、建立現(xiàn)代海洋養(yǎng)殖新模式、有效保障糧食安全的重要舉措,也是推進實施國家海洋戰(zhàn)略的重要組成部分[3]。
國內(nèi)外深遠海養(yǎng)殖起源于網(wǎng)箱養(yǎng)殖,當前主流養(yǎng)殖設施為大型高密度聚乙烯(high density polyethylene,HDPE)深水網(wǎng)箱。為了掌握深水網(wǎng)箱在大浪強流沖擊下的安全可靠性,國內(nèi)外已有眾多學者通過計算機數(shù)值模擬[4-10]、小比例尺模型試驗[11-15]和海上實測[16-18]方法開展了深水網(wǎng)箱水動力特性研究,研究內(nèi)容除涉及到網(wǎng)箱各主要部件如框架系統(tǒng)、網(wǎng)衣系統(tǒng)及系泊系統(tǒng)的動力學特性之外,也涉及到網(wǎng)箱材料性能[19]、疲勞破壞評估[20]等,至今已較全面的建立了深水網(wǎng)箱工程技術(shù)理論,為中國深水網(wǎng)箱產(chǎn)業(yè)的快速發(fā)展發(fā)揮了工程技術(shù)理論指導作用。截止到2017年底,中國深水網(wǎng)箱數(shù)量規(guī)模約1.2萬個,養(yǎng)殖產(chǎn)量13.5萬t[21],其中HDPE網(wǎng)箱約占90%。由于大型HDPE網(wǎng)箱柔性易變形的特點,其規(guī)?;B(yǎng)殖過程管理的高效性必須依賴于專有的養(yǎng)殖管理平臺或?qū)I(yè)化養(yǎng)殖工作船,配備先進的機械化、自動化裝備[22-23]。但由于養(yǎng)殖元素及個體的分散,管理的海域面積比較大,該養(yǎng)殖模式如進一步拓展應用至更深更遠的無屏障外海海域,其面臨的臺風災害風險必然會更大, 同時造成深遠海養(yǎng)殖涉及到的運輸補給、管理、配套的問題越來越突出。因此,為充分利用更廣闊的外海海域資源,解決深遠海設施結(jié)構(gòu)安全和養(yǎng)殖一體化管理的技術(shù)瓶頸問題,近兩年國內(nèi)外開始研發(fā)集養(yǎng)殖生物、養(yǎng)殖設施、養(yǎng)殖裝備等各元素于一體具備現(xiàn)代化養(yǎng)殖方式及管理模式的大型漁場平臺[24],包括挪威的“海洋漁場1號”,中國的“深藍1號”、“德海1號”漁場等[25],有效引領和推動了中國深遠海養(yǎng)殖產(chǎn)業(yè)的發(fā)展?!暗潞?號”為半潛式桁架結(jié)構(gòu)漁場平臺,采用單點系泊系統(tǒng),是一種環(huán)境友好節(jié)約型養(yǎng)殖裝備,可以隨著漲落潮的變化在以錨泊點為中心的區(qū)域內(nèi)漂移運動,使得漁場平臺養(yǎng)殖魚類的排泄物及未吃完的飼料能夠在更大海域范圍內(nèi)分解,大大減輕了局部海洋環(huán)境的惡化,已于2018年9月完成建造并投放至廣東珠海萬山附近海域進行養(yǎng)殖試驗示范。
本研究圍繞“德海1號”漁場研發(fā)開展前期試驗研究,重點圍繞漁場平臺動力響應特性,通過模型比尺1:30的波浪水池試驗,研究探討了不同波浪條件,系泊方式和壓載狀態(tài)對漁場平臺運動受力的影響,旨在了解漁場平臺的耐波性及穩(wěn)性,為漁場平臺主體結(jié)構(gòu)設計和海上安裝提供理論依據(jù)和數(shù)據(jù)支撐。
研究在中國水產(chǎn)科學研究院江蘇如東試驗基地波浪試驗水池進行。水池長50 m、寬26 m、深1.2 m。水池前端配備造波機,造波機總寬度24 m,單塊造波板寬度0.5 m,可產(chǎn)生試驗要求的規(guī)則波和不規(guī)則波。水池側(cè)端設直立式消能網(wǎng),尾端安裝斜坡式消能網(wǎng),用于吸收波浪能量以減少波浪反射,減弱邊界效應。波浪測量采用LYL-Ⅲ型浪高儀,應用計算機進行波高率定、采樣及數(shù)據(jù)處理,儀器線性及穩(wěn)定性均良好,試驗前后均對儀器標定校準,測試相對誤差小于0.5%。漁場平臺的系泊力測量采用LA1型水下拉力傳感器。該測力計為應變式,使用350 Ω應變計組成全橋電路,具有良好的溫度特性和靈敏度,可以在水下測量軸向力,測力計量程為200 N,測試相對誤差小于1%。漁場平臺的運動響應測量采用非接觸式運動姿態(tài)測量系統(tǒng)(Untouched 6-D Measurement System),該系統(tǒng)是由光學、機械、電子線路等硬件控制系統(tǒng)以及軟件圖形分析系統(tǒng)組成的一種測試測量設備,可用于對漁場平臺6個自由度(縱蕩、橫蕩、升沉、縱搖、橫搖、回轉(zhuǎn))的運動姿態(tài)進行測量,測量結(jié)果角度分辨率為0.1°、線位移為0.1 mm。以上介紹的3種測量儀器均為中交天津港灣工程設計院有限公司研制。
“德海1號”漁場由中國水產(chǎn)科學研究院南海水產(chǎn)研究所和天津德賽環(huán)??萍加邢薰韭?lián)合設計研發(fā),采用全錨鏈單點系泊系統(tǒng)。漁場平臺為半潛式桁架結(jié)構(gòu),可根據(jù)養(yǎng)殖過程的操作需求,通過平臺前、后端浮體壓載水來實現(xiàn)平臺的整體上浮和下潛,前后浮體通過鋼管桁架連接成整體(見圖1)。原型漁場平臺總長度91.3 m、寬27.6 m、高10.3 m,設計吃水6.5 m,空載吃水2.4 m,空載質(zhì)量414 t。
圖1 “德海1號”漁場平臺
根據(jù)試驗水池的實際尺寸,采用重力相似準則,確定模型試驗的模型比尺為1:30,則動力相似比尺為1:27 000。試驗水深設定為0.67 m,模型主要尺寸及相關(guān)參數(shù)見表1。由于原型網(wǎng)衣的網(wǎng)線直徑和網(wǎng)目尺寸較小,若嚴格遵循幾何相似,在模型比尺為1:30的情況下,制作同步縮放的試驗網(wǎng)衣往往難以實現(xiàn)。為此采用變尺度的網(wǎng)衣模型設計原則,對于網(wǎng)衣三維空間長度選取大比尺為1/30,對于網(wǎng)目及目腳直徑選取小比尺為1,關(guān)于網(wǎng)衣相似準則具體介紹可參考文獻[11],試驗網(wǎng)衣材質(zhì)與原型相同均為PE,網(wǎng)衣底部與桁架底端連接固定。圖2為漁場平臺的模型布置圖,為了最大減少水池的邊界效應,將模型設置于水池的正中央。測力計設于錨鏈末端,用于測量試驗平臺的系泊力,錨鏈上系有浮筒和重塊,重塊質(zhì)量為200 g(原型5 400 kg)。波浪傳播方向沿軸正方向。
表1 漁場平臺主要參數(shù)
圖2 漁場平臺模型布置圖
設定大浪條件測試漁場平臺的系泊及運動特性。根據(jù)試驗設備的性能技術(shù)參數(shù)和水池條件,選定6組波浪要素見表2。依據(jù)幾何比尺1:30和運動比尺1:5.48,換算得到試驗工況對應值,波浪為規(guī)則波。試驗時波浪通過LYL-Ⅲ型浪高儀測定,待波浪穩(wěn)定后開始采集數(shù)據(jù),采集時間大于10個波浪周期,采樣頻率為1 024 Hz,間隔為0.02 s[26],試驗數(shù)據(jù)由電腦軟件自動讀取。每組工況重復3次,取平均值。
表2 試驗波浪參數(shù)
為了比較不同系泊方式下漁場平臺在波浪作用下的錨鏈受力,便于海上安裝固定提供一種安全可靠的系泊形式,本研究設定圖3所示的3種不同的單點系泊方案。第一種系泊方式設定模型錨鏈長度2.67 m(原型80 m);第二種系泊方式設定模型錨鏈長度5.34 m(原型160 m);第三種系泊方式設定模型錨鏈長度5.34 m(原型160 m),并在距離錨泊點1/4錨鏈長度位置處懸掛一個質(zhì)量為200 g的重塊。在3種系泊方式中,錨鏈均系有浮桶,浮桶設定在距離漁場平臺前端1/8錨鏈長度的位置處,吃水深度均為0.22 m。設計在錨鏈上懸掛浮桶和重塊,其依據(jù)主要是基于將錨鏈劃分為三段形成折線型系泊系統(tǒng),通過試驗分析折線型系泊系統(tǒng)是否可以更好的為漁場平臺在高海況條件下起到緩沖作用從而減小錨鏈受力[27]。
注:L代表錨鏈長度,Gw代表錨鏈上懸掛的重塊質(zhì)量,下同。
通過試驗結(jié)果比較確定錨鏈受力最小的系泊方式。然后基于此系泊方式,分析壓載狀態(tài)對漁場平臺運動受力的影響。該漁場平臺根據(jù)實際生產(chǎn)需求設計,可以通過調(diào)節(jié)吃水深度來實現(xiàn)漁場平臺的上浮和下沉,便于更好的日常養(yǎng)殖管理。為了解不同工作狀態(tài)下漁場平臺的動力響應特性,共設定漁場平臺3種不同壓載狀態(tài),分別為空載(吃水深度2.4 m)、半載(吃水深度4.0 m)和滿載(吃水深度6.5 m)。
該研究針對的半潛式漁場平臺由于采用的是單點系泊系統(tǒng),平臺在實際情況下必然會隨著漲落潮的變化在以錨泊點為中心的區(qū)域內(nèi)漂移運動,產(chǎn)生的縱蕩、橫蕩及回轉(zhuǎn)與漁場平臺的穩(wěn)性關(guān)聯(lián)度不高,為此這3個運動分量在本文中不做專門研究,僅重點針對漁場平臺的系泊力、縱搖、橫搖及升沉開展試驗研究。
圖4為3種不同系泊方式的漁場平臺在波高16.7 cm、周期1.64 s波浪條件下的錨鏈受力歷時曲線。從圖中可以看出,當錨鏈長度為2.67 m時的系泊力最大,最大峰值247.58 N。當錨鏈長度增加一倍為5.34 m時,錨鏈受力顯著減小,系泊力最大峰值為161.73 N,減小幅度為34.7%。當在5.34 m長度的錨鏈上懸掛質(zhì)量為200 g的重塊時,錨鏈受力會進一步減小,系泊力最大峰值相應減小為132.69 N。
注:波高為16.7 cm,周期為1.64 s,漁場平臺為滿載狀態(tài)。
此外,從圖4中也可以看出,3種系泊方式下對應系泊力峰值處的波形曲線均比較尖,而且各個峰值數(shù)據(jù)不相同。這主要是由于漁場平臺波浪試驗過程中采用的錨鏈,因其自身剛度大而沒有彈性的特點,導致在波浪沖擊下會將錨鏈拉直而使得錨鏈受力脈沖式的達到峰值,這種脈沖式峰值通常會使得各個峰值的大小不一樣。采用的第三種系泊方式通過在錨鏈上懸掛重塊,有效增加了整個系泊系統(tǒng)的彈性,當系泊力達到峰值時會起到一定的緩沖作用,相比第二種系泊方式最大峰值減少29.04 N,最大系泊力降低幅度達18%;相比第一種系泊方式減少114.89 N,最大系泊力降低幅度達46.4%。對應其他波況如波高20.0 m、周期1.64 s或者2.01 s條件時,比較漁場平臺在3種系泊方式下的錨鏈受力,發(fā)現(xiàn)均是第三種系泊方式的錨鏈受力最小,而第一種系泊方式的錨鏈受力最大,與上述比較結(jié)果一致,故不對其他波況再做重復性介紹。
高海況下漁場平臺的穩(wěn)定性是平臺設計者、養(yǎng)殖者等所關(guān)注的焦點,穩(wěn)定性評估其重要依據(jù)來源于平臺的運動響應數(shù)據(jù)。表3為滿載狀態(tài)時漁場平臺在6種波況條件下的運動分量試驗結(jié)果,各運動分量數(shù)值取試驗結(jié)果的平均峰值。從表中可以看出,隨著波高的增大,平臺的升沉、縱搖及橫搖峰值均增大。在相同波高條件下,波浪周期2.01 s時的漁場平臺升沉和縱搖峰值要大于周期1.64 s的情況。此外,在所有不同波況條件中,當波高23.3 cm、周期2.01 s(原型波高7 m、周期11 s)時的漁場平臺升沉、縱搖及橫搖峰值均是最大的,升沉峰值為4.21 cm,僅占波高的約1/5,縱搖峰值僅為6.55°,橫搖峰值僅為1.19°,表明漁場平臺即使在高海況條件下,各運動分量值均比較小,漁場平臺具有較好的穩(wěn)性。
表3 漁場平臺運動響應的試驗結(jié)果
注:系泊方案采用錨鏈長度5.34 m并懸掛200 g重塊的單點系泊方案(下同)。為波高,為波浪周期。漁場平臺為滿載狀態(tài)。
Note: The single-point mooring system with anchor chain length of 5.34 m and a weight of 200 g is used (the same below).is wave height,is wave period. The offshore fish farm is in full-load status.
圖5為各波況條件下3種不同壓載狀態(tài)對漁場平臺運動受力的影響比較,其中系泊力峰值比較結(jié)果見圖5a所示。可以看出,對應不同波況條件空載狀態(tài)下錨鏈受力均最小,而滿載狀態(tài)下錨鏈受力最大。以波高23.3 cm、周期2.01 s為例,滿載狀態(tài)時系泊力峰值為142.10 N,約為半載狀態(tài)時117.40 N的1.21倍,空載狀態(tài)時66.82 N的2.13倍。根據(jù)這一研究結(jié)果,實際中的漁場平臺在養(yǎng)殖收獲完成后,可以將漁場平臺上浮以便減小錨鏈受力,增加高海況漁場的安全性。
圖5b~圖5d為不同壓載狀態(tài)下漁場平臺各運動分量的比較。從圖5b所示的升沉比較結(jié)果可以看出,空載時漁場平臺的升沉峰值最大,而圖5c~圖5d所示的縱搖和橫搖的比較結(jié)果則相反,滿載時漁場平臺的縱搖和橫搖的峰值最大。在相同壓載狀態(tài)下,漁場平臺的系泊力、升沉、縱搖及橫搖峰值均隨著波高的增大而增大。如以半載為例,在波浪周期為1.64 s時,漁場平臺的系泊力從波高16.7 cm時的62.99 N增大到波高23.3 cm時的132.95 N,增加幅度為111%;相應的漁場平臺升沉、縱搖及橫搖峰值的增加幅度分別達到18%、58%和110%。當波浪周期由1.64 s增大至2.01 s時,對應不同壓載狀態(tài),漁場平臺的系泊力峰值均有所減小,縱搖峰值均相應增大。在周期2.01 s時,不同壓載狀態(tài)下漁場平臺的升沉峰值相差較小。圖5d所示的橫搖結(jié)果表明,雖然滿載狀態(tài)下漁場平臺的橫搖峰值最大,但數(shù)值很小,這可能與漁場平臺采用的單點系泊方式有關(guān),在試驗過程中能夠明顯觀察到波浪傳播方向基本與漁場平臺的縱向始終保持一致,表明單點系泊系統(tǒng)對于降低漁場平臺的橫搖響應具有一定效果。
圖5 不同壓載狀態(tài)下漁場平臺運動受力峰值比較
本文對一種半潛式桁架結(jié)構(gòu)漁場平臺在大浪條件下的動力響應特性進行了試驗研究,比較分析了漁場平臺分別在不同波況(波高16.7~23.3 cm,周期1.64和2.01 s)、系泊方式及壓載狀態(tài)下的運動受力情況,得到如下幾點結(jié)論:
1)錨鏈長度由2.67 m增加至5.34 m時,漁場平臺的系泊力會顯著減小,減小幅度為34.7%。當在錨鏈上懸掛質(zhì)量為200 g的重塊時,可有效增加系泊系統(tǒng)的彈性,錨鏈受力會進一步減小,系泊力峰值相比沒有懸掛重塊時降低幅度18%。
2)在所有波況條件中,波高23.3 cm、周期2.01 s(原型波高7 m、周期11 s)時的漁場平臺升沉、縱搖及橫搖峰值均是最大的,但升沉峰值僅占波高的約1/5,縱搖峰值為6.55°,橫搖峰值僅為1.19°,漁場平臺的各運動分量值均比較小,漁場平臺具有較好的穩(wěn)性。
3)對應不同波況條件空載狀態(tài)下系泊力均最小,而滿載狀態(tài)下系泊力最大。在相同壓載狀態(tài)下,漁場平臺的系泊力、升沉、縱搖及橫搖峰值均隨著波高的增大而增大。漁場平臺的縱搖及橫搖峰值在滿載狀態(tài)下最大,漁場平臺的升沉峰值在空載狀態(tài)下最大。
[1] 賈敬敦,蔣丹平,楊紅生,等. 現(xiàn)代海洋農(nóng)業(yè)科技創(chuàng)新戰(zhàn)略研究[M]. 北京:中國農(nóng)業(yè)科學技術(shù)出版社,2014.
[2] 徐皓,諶志新,蔡計強,等. 我國深遠海養(yǎng)殖工程裝備發(fā)展研究[J]. 漁業(yè)現(xiàn)代化,2016,43(3):1-6.
Xu Hao, Chen Zhixin, Cai Jiqiang, et al. Research on the development of deep sea aquaculture engineering equipment in China[J]. Fishery Modernization, 2016, 43(3): 1-6. (in Chinese with English abstract)
[3] 麥康森,徐皓,薛長湖,等. 開拓我國深遠海養(yǎng)殖新空間的戰(zhàn)略研究[J]. 中國工程科學,2016,18(3):90-95.
Mai Kangsen, Xu Hao, Xue Changhu, et al. Study on strategies for developing offshore as the new spaces for mariculture in China[J].Engineering Sciences, 2016, 18(3): 90-95. (in Chinese with English abstract)
[4] Fredriksson D W, Swift M R, Irish J D, et al. Fish cage and mooring system dynamics using physical and numerical models with field measurements[J]. Aquacultural Engineering, 2003, 27(2): 117-146.
[5] DeCew J, Fredriksson D W, Bugrov L, et al. A case study of a modified gravity type cage and mooring system using numerical and physical models[J]. IEEE Journal of Oceanic Engineering, 2005, 30(1): 47-58.
[6] Zhao Y P, Li Y C, Dong G H, et al. A numerical study on dynamic properties of the gravity cage in combined wave-current flow[J]. Ocean Engineering, 2007, 34(17): 2350-2363.
[7] Tang H J, Huang C C, Chen W M, et al. Dynamics of dual pontoon floating structure for cage aquaculture in a two-dimensional numerical wave tank[J]. Journal of Fluids and Structures, 2011, 27(7): 918-936.
[8] Lee C W, Lee J, Park B. Dynamic behavior and deformation analysis of the fish cage system using mass-spring model[J]. China Ocean Engineering, 2015, 29(3): 311-324.
[9] Kristiansen T, Faltinsen O M. Experimental and numerical study of an aquaculture net cage with floater in waves and current[J]. Journal of Fluids and Structures, 2015, 54: 1-26.
[10] 黃小華,劉海陽,胡昱,等. 深水養(yǎng)殖網(wǎng)箱浮架變形模擬及結(jié)構(gòu)改進設計[J]. 農(nóng)業(yè)工程學報,2018,34(15):44-49.
Huang Xiaohua, Liu Haiyang, Hu Yu, et al.Deformation simulation and structural improvement design for floating collar of deep-water aquaculture net cage[J].Transactions of the Chinese Society of Agricultural Engineering (Transactions of the CSAE), 2018, 34(15): 44-49. (in Chinese with English abstract)
[11] 桂福坤. 深水重力式網(wǎng)箱水動力學特征研究[D]. 大連:大連理工大學,2006.
Gui Fukun. Hydrodynamic Behaviors of Deep-water Gravity Cage[D]. Dalian: Dalian University of Technology, 2006. (in Chinese with English abstract)
[12] 鄭國富,黃桂芳,魏觀淵,等. 波流作用下圓柱形近??癸L浪網(wǎng)箱纜繩的張力特性[J]. 水產(chǎn)學報,2007,31(1):84-89.
Zheng Guofu, Huang Guifang, Wei Guanyuan, et al.Study on the characters of tension in mooring lines of anti-stormy-wave cage with cylindrical net under the combined action of waves and currents[J].Journal of Fisheries of China, 2007, 31(1): 84-89. (in Chinese with English abstract)
[13] 黃六一,梁振林,萬榮,等. 波流作用下網(wǎng)格錨泊的單個重力式網(wǎng)箱纜繩張力[J]. 中國水產(chǎn)科學,2011,18(3):636-645.
Huang Liuyi, Liang Zhenlin, Wan Rong, et al.Tension of anchor lines of single gravity grid mooring cage under combining effects of wave and current[J]. Journal of Fishery Sciences of China, 2011, 18(3): 636-645. (in Chinese with English abstract)
[14] Lader P F, Enerhaug B. Experimental investigation of forces and geometry of a net cage in uniform flow[J]. IEEE Journal of Oceanic Engineering, 2005, 30(1): 79-84.
[15] Stranda I M, Sfrensena A J, Volentb Z, et al. Experimental study of current forces and deformations on a half ellipsoidal closed flexible fish cage[J]. Journal of Fluids and Structures, 2016, 65: 108-120.
[16] 郭根喜,黃小華,胡昱,等. 高密度聚乙烯圓形網(wǎng)箱錨繩受力實測研究[J]. 中國水產(chǎn)科學,2010,17(4):847-852.
Guo Genxi, Huang Xiaohua, Hu Yu, et al. In-situ measurement on the forces of mooring lines of circular net cages with high density polyethylene[J].Journal of Fishery Sciences of China, 2010, 17(4): 847-852. (in Chinese with English abstract)
[17] Colbourne D B, Allen J H. Observations on motions and loads in aquaculture cages from full scale and model scale measurements[J]. Aquacultural Engineering, 2001, 24(2): 129-148.
[18] Gansel L C, Oppedal F, Birkevold J, et al. Drag forces and deformation of aquaculture cages: Full-scale towing tests in the field[J]. Aquacultural Engineering, 2018, 81: 46-56.
[19] 劉海陽,王紹敏,黃小華,等. 深水網(wǎng)箱護欄力學性能分析及優(yōu)化[J]. 農(nóng)業(yè)工程學報,2017,33(4):248-257.
Liu Haiyang, Wang Shaomin, Huang Xiaohua, et al. Mechanical property analysis and optimization of deep-water net cage guardrail[J]. Transactions of the Chinese Society of Agricultural Engineering (Transactions of the CSAE), 2017, 33(4): 248-257. (in Chinese with English abstract)
[20] Bai X D, Xu T J, Zhao Y P, et al. Fatigue assessment for the floating collar of a fish cage using the deterministic method in waves[J]. Aquacultural Engineering, 2016, 74: 131-142.
[21] 農(nóng)業(yè)農(nóng)村部漁業(yè)漁政管理局. 2018中國漁業(yè)統(tǒng)計年鑒[M]. 北京:中國農(nóng)業(yè)出版社,2018.
[22] 郭根喜,黃小華,胡昱,等. 深水網(wǎng)箱理論研究與實踐[M].北京:海洋出版社,2013.
[23] 王紹敏,劉海陽,郭根喜,等. 基于動特性分析法的海上養(yǎng)殖平臺多點系泊系統(tǒng)設計[J]. 農(nóng)業(yè)工程學報,2017,33(5):217-223.
Wang Shaomin, Liu Haiyang,Guo Genxi, et al. Design of multi-point mooring system for marine breeding barge based on dynamic analyses[J]. Transactions of the Chinese Society of Agricultural Engineering (Transactions of the CSAE), 2017, 33(5): 217-223. (in Chinese with English abstract)
[24] 何皛磊,張海文. “深海漁場”的應用前景[J]. 船舶,2018,2:1-6.
He Xiaolei, Zhang Haiwen. Application prospect of “deep-sea fishing ground[J]. Ship Boat, 2018, 2: 1-6. (in Chinese with English abstract)
[25] 何勇. 國內(nèi)新型深遠海漁業(yè)養(yǎng)殖裝備技術(shù)動向[J]. 中國船檢,2018(8):102-104.
[26] 波浪模型試驗規(guī)程:JTJ/T234-2001[S].
[27] 鄭艷娜,董國海,桂福坤,等.圓形重力式網(wǎng)箱錨碇系統(tǒng)的受力研究[J]. 應用力學學報,2007,24(2):180-187.
Zheng Yanna, Dong Guohai, Gui Fukun, et al. Wave force on mooring system of gravity cage[J].Chinese Journal of Applied Mechanics, 2007, 24(2): 180-187. (in Chinese with English abstract)
Effects of mooring systems and ballast status on dynamic behaviors of semi-submersible offshore fish farm
Huang Xiaohua1, Wang Fangfang1,2, Liu Haiyang1, Hu Yu1, Wang Zhanhang3, Wang Shaomin1, Zhao Yunpeng2
(1.,,,,510300; 2.,116024,; 3.,100141,)
In recent years, due to various environmental problems and resource conflicts in coastal areas, nearshore mariculture in China has been increasingly confronted with the severe challenge of space compression. However, in more exposed sea areas with the depth exceeds 20 m, the water quality is much better and the water utilization rate is much lower, less than 1%.With the development of aquaculture technology and equipment engineering, it is an inevitable trend for fish farms to transfer to offshore areas. To reduce the risk of fish farming in open sea areas with strong waves and current, offshore fish farm that having the distinct advantages with moderlization of culture and management were encouraged to develop in the past two years in China. Generally, offshore farm was considered as an integrated farming system composed of cultured fish, floating structure, automatic equipments, various facilities, which was expected to play a positive role in leading and promoting the offshore aquaculture industry. In this study, we conducted a series of physical model tests for a semi-submersible offshore fish farm called “Dehai No.1” in waves, in which the model scale was set as 1:30 and the scale of 1:1 was set for the net mesh size. The “Dehai No.1” offshore fish farm with truss structure was co-designed by South China Sea Fisheries Research Institute and Tianjin De-Sai Environmental Protection Technology Co.,Ltd in the year of 2018. The main experimental parameters of the offshore farm were as follows: length 3.04 m, width 0.92 m, height 0.34 m, designed draft of 0.22 m, no-load weight of 15.33 kg. Considering the actual production requirements, three kinds of single point mooring systems (=2.67,=5.34 or=5.34 plusG=200 g) and three kinds of ballast status (no-load, half-load or full-load) as well as different regular waves conditions (=16.7-23.3 cm,=1.64-2.01 s) were set as the test conditions for the fish farm. Through physical model experiments, the dynamic behaviour of the fish farm under different conditions were studied, and the results of mooring force and motion response were given and compared. Owing to the characteristics of the single point mooring system, the fish farm in practice inevitably drift within the scope of sea area in the center of mooring point on seabed with the variation of low-to-high water surface, studying the sway and surge as well as yaw for the fish farm could not testify its good stability. Therefore, we chose the heave, pitch and roll for analyzing the motion characteristics of the fish farm. The experimental results showed that the single-point mooring system with anchor chain length of 5.34 m and a weight of 200 g could better reduce the mooring force of the fish farm in waves. Among all of the wave conditions, the peak value of each movement component of the fish farm was relatively small. When the fish farm was subjected to the sea loads with wave height of 23.3 cm (7 m in full-scale) and wave period of 2.01 s (11 s in full-scale), the peak value for the heave, pitch and roll was 4.21 cm, 6.55° and 1.19°, respectively, which indicated that the fish farm had good performance for the stability of floating state. Comparing the maximum motion and mooring force of the fish farm under various floating conditions, including no-load and half-load as well as full-load, we found that, in the full-load floating state, the peak value for the mooring force, pitch and roll was biggest, but the peak value of the heave was biggest under the no-load floating state for the fish farm. With increasing wave height, both of the mooring force and motion of the fish farm became larger. The results provide a basis for further understanding the dynamic characteristics of fish farm, and help to provide theoretical and data reference for the structure design and installation of fish farm.
aquaculture; wave; kinetics; offshore fish farm; single-point mooring; ballast status
10.11975/j.issn.1002-6819.2019.15.007
S969
A
1002-6819(2019)-15-0048-06
2019-02-18
2019-05-15
國家自然科學基金項目(31772897,31402349);海南省重大科技計劃項目(ZDKJ2016011);海洋經(jīng)濟創(chuàng)新發(fā)展區(qū)域示范專項(Bhsfs012);
廣州市珠江科技新星專項(201710010168);廣東省現(xiàn)代農(nóng)業(yè)產(chǎn)業(yè)技術(shù)體系創(chuàng)新團隊建設專項資金
黃小華,副研究員,主要研究方向為漁業(yè)設施工程技術(shù)。Email:huangx-hua@163.com
黃小華,王芳芳,劉海陽,胡 昱,王占行,王紹敏,趙云鵬. 系泊和壓載方式對半潛式漁場平臺動力特性的影響[J]. 農(nóng)業(yè)工程學報,2019,35(15):48-53. doi:10.11975/j.issn.1002-6819.2019.15.007 http://www.tcsae.org
Huang Xiaohua, Wang Fangfang, Liu Haiyang, Hu Yu, Wang Zhanhang, Wang Shaomin, Zhao Yunpeng. Effects of mooring systems and ballast status on dynamic behaviors of semi-submersible offshore fish farm[J]. Transactions of the Chinese Society of Agricultural Engineering (Transactions of the CSAE), 2019, 35(15): 48-53. (in Chinese with English abstract) doi:10.11975/j.issn.1002-6819.2019.15.007 http://www.tcsae.org