Ocean Engineering Model Test at Harbin Engineering University. June 2015 Liping Sun

Transcription

1 Ocean Engineering Model Test at Harbin Engineering University June 2015 Liping Sun

2 Outline 1. Introduction to DERC 2. Deepwater Offshore Basin in the World 3. Platform Motion Model Test 4. Riser Model Test

3 Deepwater Engineering Research Center The Deepwater Engineering Research Center (DERC) was established at HEU in the end of In 2006 DERC got funding from Chinese Education Ministry and Foreign Expert Bureau to build Base on Science and Technology of Deepwater Engineering An active team of 15 foreign members and 15 internal members has been established. Domestic members are from HEU whose major in various NA&ME such as hydrodynamics, structure, CFD and so on.

4 Foreign Team Members Academic Master Prof. William C. Webster USA Motion response of floating structures Nonlinear water wave theory Rod Dynamics Some team members

5 International Exchange and Cooperation Domestic faculty members keep contacts with overseas members through a variety of ways. Establish relations of cooperation with MARINTEK LabOceano OTRC Establish relations of cooperation with Univ. and Classification Society such as Univ. of California, Berkeley, Univ. of Michigan, Texas A&M Univ., Osaka Univ. BV GL and so on International cooperation in scientific research project

6 International Conferences

7 Outline 1. Introduction to DERC 2. Deepwater Offshore Basin in the World 3. Platform Motion Model Test 4. Riser Model Test

8 MARIN Basin in Netherlands Built in 2000,main dimensions 45m 36m 10.5m, pit:5mx 30m Simulate wind, wave and current; on the 10.5m depth there is six layers pipe to simulate shear current Carriage moves in both X and Y direction,max. speed 3.2 m/s

9 Main dimensions: 80m 50m 10m Environmental simulation including wind, wave and current; Maximum current velocity approx. 0.2 m/s at 5 m water depth. The carriage system speed up to 5 m/s. MARINTEK Basin ( Norwegian Marine Technology Research Institute) Multiflap wave maker: Regular waves: Maximum wave height: 0.4 m. Wave periods: 0.6 s and above Double flap wave maker: Regular waves. Maximum wave height: 0.9 m. Wave periods: 0.8 s and above.

10 LabOceano Basin in Brazil Main Dimensions: 40mX30mX15m,Pit:5mX15m Simulate wind, wave and current Wave period: s; Max.regular wave height:0.5m; Max. wind velocity:12m/s

11 OTRC Basin (Offshore Technology Research Center) Main dimensions: 150ft*100ft*19ft, Pit:55ft Simulate wind, wave and current

12 Shanghai Jiaotong Univ.Basin Main dimensions: 50mX40mX11.5m, Pit: 5mX40m Wind, current, wave simulation X,Y carriage, max. velocity 3m/s Wave :3-D multiflaps wavemaker Maximum significant wave height :0.3m Current max. velocity:0.1m/s

13 Main dimensions: 50mX30mX10m Wind, current, wave simulation X,Y carriage, max. velocity 3m/s Wave :3-D multiflaps wavemaker Regular, irregular waves in arbitrary direction Maximum wave height :0.3m Current Velocity:0.1m/s ~0.5m/s HEU Deepwater Basin 50m x 30m x 10m

14 Towing Tank 110m 7m 3.5m Model Length: m 2D & 3D Regular and Irregular Waves Max. Wave Height: 0.4m Wave Periods : sec. Max. carriage velocity:6.5m/s

15 Outline 1. Introduction to DERC 2. Offshore Basin in the World 3. Platform Motion Model Test 4. Riser Model Test

16 The Purpose of Model Test To demonstrate proof of concept To verify design assumptions, factors and allowances Substantiate analytical technique Problem difficult to handle analytically To obtain empirical coefficients To verify offshore operation To validate the numerical model and design analysis tools To independently confirm the accuracy of hydrodynamic performance of a particular design

17 Model Tests Considerations Size of model & facility -- depth limitation Physical size of the basin requires mooring line truncation. For a deepwater system of 3000m, the deepest basin(15m) can only model the whole system using a scale of about 1:200 which is far too small Environment generation(e.g. current turbulence) Instruments -- measurement accuracy The number of test cases are limited Scale distortion catenary mooring & taut lines; risers & tendons

18 DEEPWATER MODEL TEST HYBRID APPROACH

19 LINE TRUNCATION CONSIDERATIONS

20 Numerical Simulation and Model Test Study of FPSO and CALM System

21 Model Test Scheme Design Verify the experiment schemes By doing coupling analysis in time domain under same load condition to compare the results between the model system and original system. FPSO model test scheme(1:90) CALM system test scheme(1:40)

22 Verify the truncation design of CALM mooring system The static characteristics of calm mooring system before and after truncation are equivalent. The dynamic characteristics are similar. Top tension of mooring line vs displacement Horizontal tension of mooring line vs displacement

23 Results (1)The coupling of CALM motion to FPSO can be ignored for the FPSO preliminary design because of the far distance of two bodies. (2) The coupling effect of FPSO and OOL(Oil Offloading Line) must be considered in the analysis of FPSO's response because the top tension of the OOL and the mooring line of FPSO have the same order of magnitude. (3)The influence of the FHSR on the movement and the force of the FPSO system is minimal. It s influences on FPSO can be ignored.

24 (4)Under West Africa environment FPSO s motion is controlled by Squall. So it s the ultimate condition for the FPSO strength check. (5)The OOL is strongly influenced by the CALM because the pipeline weight and the drainage volume of buoy have the same order of magnitude. (6) Plane motion of shuttle tanker will increase the motion amplitude of the CALM buoy. But for the ultimate strength check there is no need to consider effect of the shuttle tanker because oil external operation usually done in mild environment.

25 Study on multi-body Interaction during transportation and installation Study on multi-body interaction during lifting Analysis of vertical relative motion and safety during lifting Analysis of safety and relative motion between two bodies during in place

26 Test of multi-body Response Test scale: 1:60 Lifting test In-Place test The experimental purpose is to verify the numerical analysis model of multi floating bodies.

27 In the stage of in-place operation multi-body system including, SPAR tank crane ship upper module

28 Some safe operation environmental conditions are suggested. The maximum significant wave height is suggested to be less than 2.0m both for the lifting and in-place operation

29 Development of Large Crane and Pipelaying Vessel Study on the Global Performance and Model Test of Crane and Pipelaying Vessel Study on Seakeeping Performance in Operation Condition Hydrodynamic Analysis consider Coupling between Pipe and Ship in Pipelaying Condition Stability Ananlysis for 3000m Waterdepth Hydrodynamic Model Test of the Vessel Catenary Pipeline Load Analysis

30 Environmental Conditions 1 Max. Wind and Wave 2 Wind and Swell 3 Standby Condition Wind Velocity:16m/s; Wind Velocity:8m/s; Wind Velocity :26m/s; Wave height:hs=2.5m Wave height:hs=2.0m Wave height:hs=8.2m Wave period: Tp=6.0~9.0s Wave period: Tp=10.0~12.0s Wave period:tp=11~15s Current Velocity:2.0 knot Current Velocity:2.0 knot Current Velocity:3.0 knot Jonswap Spectrum Jonswap Spectrum Jonswap Spectrum

31 Test scale: 1:50 model for deepwater model for shallow water

32 Motion Test in Operation Condition Test the pitch,roll,heave and acceleration response of the ship under dynamic positioning condition. Wave direction 180 degrees, the self-propelled condition Wave direction 165 degrees, 50% pipelaying, shallow water condition

33 1)In the beam condition the heave is significant. So it should be avoided to lay pipe in this condition. 2)During pipelaying the roll motion is less in deepwater than in shallow water. 3) During pipelaying the pitch and heave amplitude are biggest in 150 degrees wave direction. But there is no big difference both in deepwater and in shallow water. 4)The vertical acceleration of the stinger bottom changes most. Followed by the position connected with ship. The smallest position is at the midship.

34 Dynamic Positioning Study of a Deepwater Semisubmersible Overall scheme of DP for a deepwater Semi Capability analysis of DP system Control system design of DP system Simulation of DP control system Developed a dynamic positioning simulation system of semi drilling platform

35 SEMI model test on DP control system The purpose is to verify the DP control system can make sure the surge sway and yaw of the SEMI to satisfy the DP3 requirements under wind,wave and current conditions when the thrusters work normally or two thrusters failed.

36 模型试验的海洋环境条件 Load Conditions load Parameter Standby Condition Operation Condition SEMI 981 model SEMI 981 model Wave Wind Current Spectrum ISSC Spectrum ISSC Spectrum ISSC Spectrum ISSC Spectrum Hs(m) Tp(s) Ts(s) Velocity (m/min) Velocity (m/s)

37 Test Results Surge Sway Yaw

38 Thrust Curve

39 Model Test of FPSO in Enping Field Do model test for two different shape FPSOs to compare the influences on damping, motion and mooring line response and to provide suggestions for the design

40 No. 1 Full load 2 Full load 3 Full load 4 Full load 5 Full load 6 Ballast 7 Ballast 8 Ballast 9 Ballast Environment condition 500years wave,wind,wave,current in the same direction 500years wave,wind,wave in the 0 direction,current in 45 direction 500years wave,wind,wave in the 0 direction,current in 90 direction Monsoon, 500years, wind,wave,current in the same direction Monsoon, 500years, wind,wave in the 0 direction,current in 90 direction 500years wave,wind,wave,current in the same direction 500years wave,wind,wave in the 0 direction,current in 45 direction 500years wave,wind,wave in the 0 direction,current in 90 direction Monsoon, 1 in 500years, wind,wave in the 0 direction,current in 90 direction Wind wave Current speed Hs Tp (m/s) (m/s) (m) (s)

41 Test Results There is visible green water under both ballast and full load conditions. The green water is much for the full load condition than ballast condition. When current and wave in different direction the green water is obvious at the midship. By increasing the height of forecastle there is no green water anymore on the bow but there is no any change at the midship.

42 Model Test of SSCV H206 Series of model tests were carried out in HEU basin to get the motion response, air gap of SSCV H206 under different conditions.

43 Irregular Wave Conditions 15 wave probes were set on SSCV to get the air gaps of different positions. Three load conditions: Survival condition: H S =12m, T p =13.7s, gamma=3.33; Survival condition: H S =10.42m, T p =11.18s, gamma=3.33; Towing condition: H S =3m, T p =9.83s, gamma=3.33

44 Video of SSCV in 45 wave direction under survival condition Slamming on SSCV in 45 wave direction The response under survival conditions was severe, the air gap was 0cm, and obvious slamming was found on the lower deck.

45 Outline 1. Introduction to DERC 2. Offshore Basin in the World 3. Platform Motion Model Test 4. Riser Model Test

46 Design and Analysis of FSHR 1. Global design of Free Standing Hybrid Riser 2. Global Strength Analysis 3. Fatigue Analysis 4. Design of Buoyance Can 5. Sensitivity Parameters Analysis

47 Vortex-induced vibration suppression device model test Three kinds of VIV suppression devices are tested, uniform current from 0.2m/s~0.6m/s,interval 0.1m/s

48 Experimental results Without suppression device, the biggest amplitude appeared under current velocity of 0.2 ~ 0.3 m/s,which is the lock area, when the velocity is greater than 0.4 m/s, amplitude decreases. With suppression device,it was founded the double set of double helix work best,a single set of double helix is the second,fiber is the last

49 Model test study on double degree of freedom VIV of cylinder Φ20 120cm Φ11 120cm Φ 5 120cm 垂向运动机构 测桥 固顺流向电位器定架 垂向运动机构 滑车 滚珠轴承 横向电位器 水平导轨 滚珠轴承 卡块 水平导轨 弹簧 滑车 连接板 水池 加速度传感器 圆柱体 连接板 圆柱体 水池

50 Cylinder motion trajectories results Cylinder motion trajectories corresponding to different natural vibration frequencies are completely different. That is, they respectively appear to be D shape, egg shape, rain drop shape and figure 8 shape.

51 Cylinder motion trajectories results When f x / f y is large, the cylinder appears to have a D -shape trajectory. When the natural vibration frequency ratio f x / f y is reduced to the lowest value 0.474, at the tip of the motion trajectory, i.e., the lower half of 8 -shape trajectory, gradually appears.

52 Cylinder motion trajectories results with a decrease of f x / f y, the original egg -shape trajectory gradually changes. At the tip of the motion trajectory of the cylinder, another tight loop appears and grows, leading to the beginnings of 8 -shape trajectory forms.

53 Cylinder motion trajectories results The rain drop forms a tight loop at the tip. The tight loop at the upper end becomes larger and finally resulting in an oblique figure 8 -shape. Different fx, fy and Ur are the main causes of the various changes in the form of the cylinder VIV trajectory.

54 Two cylinders VIV test

55 Test Matrix Exp No Spacing (spacing ratio) 60.5 cm (L/D=5.5) 54.2 cm (L/D =4.9) 39.3 cm (L/D =3.6) 32.5 cm (L/D =3.0) Velocity (m/s) arrangement Spacing (spacing ratio) side by side arrangement absolute value (cm) spacing ratio T/D

56 Two cylinders in tandem arrangement A new amplitude reaction format totally different from single cylinders VIV reaction was found.

57 Amplitude results When the spacing ratio of two cylinders in tandem arrangement is large enough, there is no influence between two cylinders.

58 Amplitude results When the two cylinders spacing ratio is less than the critical value, the dual-peaks phenomenon appears with the cross flow vibration of the left and right cylinders.

59 Thank you for your attention