10 Arctic Passion Seminar Thursday, March 12 th, 2015, Helsinki

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1 10 Arctic Passion Seminar Thursday, March 12 th, 2015, Helsinki Central Marine Research & Design Institute CNIIMF, Russian Maritime Register of Shipping (RS), St. Petersburg State Polytechnic University Ice certificate principles for double-acting ships (Modern methods to assign permissible speeds under ice conditions proceeding from both hull and propeller operating strength assurance for ice going vessels including DAT and ships fitted with bulb) Within the framework of joint research project Development of methodology and software for determination of ice loads acting on the ships and offshore constructers CNIIMF, Russian Maritime Register of Shipping and St. Petersburg State Polytechnic University) Authorized by: Dr. S.I. Buyanov, General Director, CNIIMF; Dr. M.A. Kuteinikov, Head of Hull department, Russian Maritime Register of Shipping; Dr. A.V. Andryushin, Head of Laboratory, CNIIMF; Dr. G.V. Markozov, Head of Hull structure department, CNIIMF; Dr. A. S. Bolshev, Head of a chair, St. Petersburg State Polytechnic University Under assistance: P.S. Zuev, engineer, CNIIMF; K.S. Verasco, recearcher, CNIIMF.

2 Status of Ice Navigation Ship Certificate ( Ice Certificate ). Official procedure of issue by RS Essential: Ice Navigation Ship Certificate (Ice passport) is indented to establish the safe modes of operations in ice covered waters proceeding from assurance of hull and propulsion complex strength. Official Status: In 2011 Russian Register (RS) entered in force the Ship Certificate Permissible conditions of ice operations regulating safe regimes of the ship operation depending on operating area, ice conditions, icebreaking assistance and technical state of the ship. Ice Certificate has been incorporated into Polar Code as guidelines to specify safe operating modes under ice conditions. Ice Certificate is volunteer for Ship Owner, However : IN accordance with RS Requirements: It is assumed that during service the owner will follow the recommendation of the Ice Navigation Ship Certificate issued by the Register upon ship owner's request and specifying the conditions of safe operation of the ship in ice depending on the ice category mark, the ship's specific features, ice conditions and icebreaker support. (see RS Rules. Part I Classification, 2.2 Class Notation of a ship, ). Ice Certificate is recommended for ship Owner to obtain the permission from the direction of Administration of NSR to operate in ice covered waters of NSR. 2

3 Official procedure of Ice Certificate issue by Russian Register (In accordance with RS requirements) 3 1. The application is to be directed to RS Head office not less than 6 weeks before desired data of receipt. 2. The Organization, authorized by RS, performs the calculations of the permissible operating modes and directs ones to RS Head Office for consideration and approval. 3. RS performs the ship inspection 4. RS Head Office issues the Ice Navigation Certificate based on the results of above mentioned calculations and general inspection.

4 Modern progress trends of arctic shipbuilding 4 Arctic container vessel Norilskiy Nickel with icebreaking bow. Arc7, AZIPOD 13MW Ice - going tanker Tempera type DAS with bulb. I A super, AZIPOD 16MW Ice going supply vessel fitted with bulb Brage Viking IA Super Yamal LNG carrier, Arc7, DAS

5 Main technical approaches to develop Ice Certificate for modern ice going vessels including DAS ships (YAMAL LNGC and DAS large capacity tanker for NOVOPORT) 5 Assurance of operating hull strength for astern and ahead Assurance of operating operability and strength of propulsion complex for astern and ahead Assigning of ice condition parameters including ice strength characteristics. Refined technics to assign permissible speeds both for conventional and DAS ice going vessels proceeding from hull and propulsion complex strength (modified methodologies to assign ice loads acting on the hull and propulsion complex, as well as estimation of operating strength depending on operating speeds, ice conditions). Development of recommendation for safe operating modes (icebreaker assistance, safe distance) based on refined calculation of ice and open water performance (including elaborations of hull forms, propulsion complex and ice performance regimes in more detail).

6 6 Assigning of ice condition parameters: (based on comprehensive database, full scale data, results of numerical calculations. - Ice thickness, type of ice, parameters of ridges - Determination of strength characteristics of first and multi year (FY, MY) ice sheet including fresh ice of Siberian rivers (Ob Bay, Yenicei river) depending on ice thickness and temperature (type of navigation: winter, summer-autumn period). - unconfined ice compressive strength - ice flexure (bending) strength - ice crushing strength - Elastic modulus

7 Procedure for determination of ice strength characteristics of ice sheet (level ice) depending on ice thickness, inviarimenral temperature, type of navigation Distribution of ice unconfined compression strength across ice sheet both at horizontal and vertical loading. Thick FY sea ice. Kara Sea. Ice thickness ~2m. March. Air temperature (-28 0 (-30 0 )). Snow thickness m. Temperature of ice surface is (max. values) 7

8 Procedure for determination of ice strength characteristics for ice typical features: FY and MY ice ridges 8 MY ice feature, Ice thickness is 6m Unconfined compressive strength for MY ice feature, Ice thickness is 6m

9 Investigation of fresh ice strength characteristics for Siberian rives to ensure operating strength of ships calling in Ob Bay and Yenisey Gulf 9 1,3 Relative increasing of design crushing strength of OB BAY fresh ice in comparison with sea first ice. 1,29 1,28 1,27 Relative increasing of ice crushing strength for OB BAY conditions Air temperature -30C 1,26 Air temperature -20C 1,25 1,24 1,23 Air temperature -10C 1,22 Ice thickness, 0 0,5 1 1,5 2

10 Development of scenarios of hull-ice interaction for conventional merchant ships, DAS, Pushing Pulling, ice going vessels fitted with bulb 10 LNG Carrier Type DAT Large capacity tanker with bulb

11 Main Scenarios for DAS Both Astern and Ahead modes are to be considered 11 Astern Ahead

12 Development of Basic hull-ice interaction models and ice crushing strength determination 12 Incline side Well recognized modern technic based on extrusion of ice powder as viscous layer is applied to determine local ice pressure and global ice loads acting on the hull (K. Riska, C. Daley, E. M. Appolonov, A.V. Andryushin) Crushing zone Wall side Typical edge of ice block has been crushed by hull (full scale conditions)

13 Model of ice local pressure acting on of hull (ice crushing strength) The ice-hydrodynamic model of ice extrusion is applied to assign ice local pressure 13 Dimensionless ice contact zone and ice pressure p ice e x e x p ice p p ice ice max x 0,1 p f ( ) ice max comp comp p ice - unconfined compressive strength - ice pressure (i.e. ice crushing strength does not depend on typical speed of hull-ice interaction)

14 Main approaches for assigning ice loads depending on operating speed ( ice contact zone, ice pressure, value of impact ice loads) Based on traditional damage of ice sheet edge by bending 2 ) Impact vertical force of ice sheet damage by bending (based on Papkovich solution) F vertical ) ) tg 2 / 2 h ice ~ design bend ice dyn l ( Fr ( L L f ( Fr ) ice - Characteristic length of ice sheet dyn, parameters ) l( Frice) F vertical F - Length of hull-ice contact zone n cos( 90 ) F n d p ( d) k l( Fr 0 scale ice ) d, p0( d), k scale, l Height of ice contact zone, average local ice pressure (average ice crushing strength), scale factor of ice loads, length of ice-hull interaction 2. Proceeding from penetration into edge of ice sheet without bending damaged into (relatively thick ice, small speed) m eff V 2 2 n F d n

15 0,65 0,6 0,55 0,5 0,45 0,4 0,35 0,3 0,25 0,2 5 4,5 4 3,5 3 2,5 2 1,5 1 0,5 0 Effect of speed for bending damage of ice sheet: Parameters of ice contact zone depending on speed of ice-hull interaction Icebreaker Polar Sea, MY ice, hice=1.8m. (calculations) 15 d,m Contact depth along hull plating vs speed, Polar Sea MY ice, hice=1.8 Length of contact, m. Line load MN/m Contact length, line load vs Polar Sea speed, MY, ice thickness 1.8 contact length,m line load, MN/m ship speed, m/sec ship speed, m/sec Load patch

16 Verification: comparison of design and full scale data Bending Ice impact force does not depend on typical speed of ice-ship interaction 16 Full scale data: OTC Paper Number GPU-Event-Mechanics Evaluation of Ice Impact Load Statistics Claude Daley, Shadi Alawneh, Dennis Peters, Bruce Colbourne / Memorial University

17 Comparison of design and full scale ice loads acting on the hull of Polar sea icebreaker under MY ice conditions 17 line load, MN/m Line load, Polar Sea, MY, hice=1.8m V=4.7m/s V=2.5m/s Polar sea, 1983, MY, hice=1.8m, full sacle data Polar sea, MY, hice=1.8m, d=0.63m, calculation Polar sea, MY,hice= 1.8m, d=0.5m, calculation contact length, m V=1.5m/s 0 0,5 1 1,5 2 2,5 3 3,5 Polar sea, MY,hice=1.8m,d=0.45m, calculation Louis S. St. Laurent, 1994,MY, d=0.6m, full sacale data Poly. (Polar sea, MY,hice=1.8m,d=0.45m, calculation) Full scale data: Robert Frederking, and Ivana Kubat - A Comparison of Local Ice Pressure and Line Load Distributions from Ships Studied in the SAFEICE Project, DRAFT

18 Verification of framing and plating based on IACS requirements in force as well as FEM 18 Consideration: the peak pressure factor, plastic deformation of the framing and shell plating.

19 IACS Project: (determination of safe speed for traditional ahead mode) 19

20 Assurance of hull strength under ice compressive condition 20 Pressure Compression Number Kara sea, typical zones of ice pressure (2.5-5) Up to number (5-20) (1-1.5) number (20-40) (1.5-2) number (40-60) (2-2.5) number (60-80) (2.5-3) number 80 * number and more

21 Ensuring of hull elements strength for DAS under astern conditions 21 Ensuring of skeg strength under ice conditions for astern modes

22 Ensuring of bulb strength under ice conditions 22

23 Impact of ice block from ridge located under edge of ice channel (behind icebreaker) Longitudinal ice load for vertical and horizontal ice loading 23 Horizontal loading of ice sheet Vertical loading of ice sheet

24 Assurance of operating operability and strength of propulsion complex DAS both astern and ahead, assigning of permissible speeds under ice conditions 24 Assurance of the operating load-carrying capability of propulsion complexes ( Azimuth Thrusters) elements proceeding from pyramidal and fatigue strength under action of ice loads : - assigning of operating ice loads on the Azimuth thruster elements (propeller, pod, struts) depending on ship speeds and ice condition parameters; - development of technics for fatigue and pyramid strength assurance Assurance of the operability of main electric engine. It is means that main engine should support propeller speed (rotation) and acceptable propeller thrust and ship movement as well as to prevent propeller stop and his (blade) damage correspondingly under ice conditions

25 Assurance of propeller strength vs ship speed (based on RS project requirements book 12 and 20) 25 Design methodology to assign operating ice blade loads Assurance of the propeller blade strength Q spind Q bend l ice Model tests (KSRI)

26 Assurance of Azimuth thruster reliability, including assignment of ice loads acting on the Azimuth Thruster elements vs operating ship speed (In cooperation with ABB for Yamal LNG) 26 Lognitudinal ice force acting on the propeller cup. Ob bay. Large capacity LNGC Ice thickness - about 2m. Ice force ship speed, m/s Designed curve, OB Bay Norilskiy Nickel, Kara sea Recalculation of NN data for Ob Bay conditions 0 0,5 1 1,5 2 2,5 3 3,5 4 4,5 5 5,5

27 Assurance of operability of main electric engine (main approaches). 27 Overtorque safety factor and propulsion power of main electrical engine are main factors to guarantee required operating operability and icebreaking capability for ahead and astern mode to support safe and effective operation under ice conditions Total torque on the shaft Q total Q hydr Q ice n t Q hydr Q ice n t - hydrodynamic torque - ice torque - inertia component Main criteria : ( Q engine ) lim total max Q max( Q ) total The designed overtorque safety factor and main engine capacity should not restrict the operating ice ship performance (capability)

28 Full scale test data obtained for large capacity tanker type Vasiliy Dincov and icebreaker Arctica under severe ice conditions for astern mode relevant base to ensure Azipod operability for LNGC 28 Astern mode. Ridge Power, Torque Typical ice block ( )m in thickness from consolidated layer of ridge propeller shaft torque and power vs propeller speed under ice conditions for astern (Power )/100, ; shaft torque,%, vs bollard conditions propeller speed Full scale test of Vasiliy Dincov for astern mode under sever ice conditions. Testing of Azipod unit (main engine) operability. Verification and calibration of specified overtorque safety factor.

29 Design and off-design conditions of main electric engine under severe ice conditions. Tanker type Dincov. ASTERN under ridge conditions. Full scale data. 29 Design conditions (load) 0,35 0,30 0,25 0,20 0,15 0,10 0,05 probability Probabilistic distribution of operating speed under ridge conditions. Astern mode. Large capacity tanker type Dincov ship speed, knots 0, OFF-Design conditions (load) Propeller stop. Lockout of control system

30 - Main approaches of technics to assign permissible speeds proceeding from assurance of main engine operability 1. Ice torque acting on the propeller depending on ship and propeller speed (attack angle), ice conditions, as well as propeller parameters 30 Q ice k profile ( r 0.8) 3deg exp( ( r 0.8)) K sice K Hice D 2.6 t( r 0.8) 0.5 ( r 0.8), Q ice const at ( pure cutting) ( r 0.8)) > 3deg (r 0.8)) - attack angle of the blade at relative radius 0.8 Ksice K Hice - ice strength and ice thickness factors t( r 0.8) - propeller blade thickness at relative radius 0.8 k profile - factor depending on form of blade leading edge

31 Q Numerical procedure to calculate the propeller speed and total torque depending on ship speed and ice conditions (to assign safe speed to prevent propeller stop) Total torque n Qtotal Qhydr Qice t n( t dt ) n( t) dn Q total ( n dn ) Q total ( n ) Q total n ( n ) dn Qice ( t) ( Qmax ) ice (1 exp( d t)), t ( n dn ) Q hydr ( n ) Q hydr ( n dn n Qice ( t) ( Qmax ) ice at t ; Qice hudr ) > 0 0, t 0 31 dn Q n ice ( t dt ) Q n ( n ) Q ( n ) 1 dt Q ( n ) Q ( n ) total hydr hydr total Under ridge conditions t l / V ice ice ship Typical time of ice-propeller interaction l ice 3 / 4 * h ice - typical size of ice block in the ridge hice - thickness of thermal ice.

32 Prediction of safe mode (permissible speed) proceeding from main engine operability. Large capacity tanker fitted with Azipod. Astern mode under ridge. 32 0,35 0,30 0,25 0,20 0,15 0,10 0,05 probability Probabilistic distribution of operating speed under ridge conditions. Astern mode. Large capacity tanker type Dincov ship speed, knots 0, Zone of high risk 1,9 1,8 1,7 1,6 1,5 1,4 1,3 1,2 1,1 1 0,9 0,8 0,7 0,6 0,5 0,4 0,3 0,2 0,1 0 Zone of high risk relative propeller speed 0 0,050,10,150,20,250,30,350,40,450,50,550,60,650,70,750,80,850,90,95 1

33 The Permissible value of operating speeds proceeding from assurance of main eclectic engine operability Conventional large capacity ship Arc7 category under ice conditions of Kara sea and OB bay 33

34 Development of recommendations for operating regimes including both independent operation and operation under icebreaker assistance based on refined calculation of ice and open water performance 34

35 Thank You very much for Your attention