Welcome to the Ship Resistance Predictor! The total calm water resistance is given by:

Transcription

1 Welcome to the Ship Resistance Predictor! What does this Excel Sheet do? This Excel sheet helps you calculate the Total Calm Water Resistance for a Ship at a given forward speed It also calculates from the resistance the Effective Power (P E ) required for propulsion Formula R C = R F (1 + k1) + R APP + R W + R B + R TR + R A R F = Frictional Resistance as per ITTC 1957 friction ]formula k1 = Form Factor describing viscous resistance of the Hull Form in relation to R F R APP = Resistance of Appendages R W = Wave Resistance (Wave Making and Wave Breaking Resistance) R B = Additional Pressure Resistance of Bulbous Bow near Water surface R TR = Additional Pressure Resistance of Immersed Transom Stern R A = Model-Ship Correlation Resistance The total calm water resistance is given by: How to use this Excel Sheet The user is asked for some inputs for the Vessel. The Input cells are highlighted in blue. The user has to provide all the inputs highlighted in blue in the Worksheets "Inputs - Vessel" and "Inputs - Appendages". ONLY INPUT THE CELLS HIGHLIGHTED IN BLUE. LEAVE ALL OTHER CELLS UNTOUCHED! For some inputs, Tables and charts are required to be referred. These Tables and charts are provided alongwith for the user to enter these inputs. In the 'Speeds' excel sheet, the speeds at which resistance is to be estimated have to be input. Once all inputs and speeds are provided, the components of the calm water resistance are calculated in different worksheets to give the final Calm Water Resistance for each speed. Then the resistance curve is plotted from the resistance values at different speeds Limitations 1. This application is limited to a displacement vessel, with Hull forms resembling the average ship. It cannot be used for unusual hull forms, high speed crafts and barges References 1. An Approximate Power Prediction Method, J.Holtrop and G.G.J.Mennen, A Statistical Power Prediction Method by J. Holtrop and G.G.J. Mennen, International Shipbuilding Progress, Vol. 25, October Change Log (Rev 02) 1. User can now input design speed at which the report will be generated. The curve will be generated for all speed values input by user in the "Speeds" worksheet 2. Bulbous bow resistance - formula corrected for the case when there is no bulbous bow

2 Company Name: Project Name: SHIP RESISTANCE SHIP RESISTANCE CALCULATION - VESSEL INPUTS Doc. No: Date: Revision No: Prepared By: Page 2 of 14 General Particulars Stern Shapes Stern Shape Code Particular Value Default Value Units Normal Section Shape 1 Acceleration due to Gravity g m/s 2 V-shaped Sections 2 Density of air ρ air kg/m 3 U-Shaped Sections with Hogner Stern 3 Density of Water ρ water kg/m 3 Viscosity of Water ν m 2 /s Vessel Particulars Particular Value Units Vessel Name Barge 1 Principal Dimensions Length Between Perpendiculars (LBP) LBP 200 m Length on Waterline (LWL) L m (Default value 1.02*LBP) Breadth B 32 m Depth D 15 m Longitudinal Center of Buoyancy fwd of Midship (+ve fwd and -ve aft of Midship) lcb m (Default value 0.01*LBP) Floating Status Mean Draft at Midship T 10 m Trim (trim by aft +ve, by fwd -ve) Trim 0 m Coefficients Block Coefficient Cb Midship Section Coefficient C M 0.98 Waterplane Coefficient C W 0.75 Table 1: Stern Shape Types Bow and Stern Information Stern Type (See Table 1 and enter code) 3 Transverse area of immersed part of Transom Stern(only if the stern is transom stern,else input 0) A T m 2 Ratio of Bulb Transverse Section Area to Midship Area A BT /A mid (Default value 0.1) Vertical distance from baseline to center of bow bulb cross sectional area h B m (Default value 0.4T) Angle of Half Entrance (angle of Waterline at bow)* i E degrees (Default Value: See Formula) *The default value of ie (Angle of Half entrance) is given by: i E = exp{-(l/b) (1 - C wp ) (1 - C p lcb) (L R /B) (100D V /L 3 ) }, C p = Prismatic Coefficient, L R = Length of Run, D v = Volumetric Displacement Wetted Surface Area Wetted Surface Area* S m 2 (Default Value: See Formula) *The default value of Wetted Surface is given by S = L (2T + B) C M ( C B C M B/T C WP ) A BT /C B Operational Inputs Forward Vessel Speed V 5.5 m/s

3 SHIP RESISTANCE CALCULATION - APPENDAGE INPUTS Appendages Rudder Type Particular Value Default Value Units Rudder Type Code Rudder Type (Enter code from Table 2) 2 Rudder Behind Skeg 1 Rudder Wetted Area A R m 2 (Default Value = 0.05*LBP*T) Rudder Behind Stern 2 Shafts Wetted Area A SH 0.00 m 2 Twin screw balance rudders 3 Shaft Brackets Wetted Area A SHB 0.00 m 2 Skeg Wetted Area A SK 0.00 m 2 Strut Bossings Wetted Area A STB 0.00 m 2 Hull Bossings Wetted Area A HB 0.00 m 2 Stabilizer Fins Wetted Area A STF 0.00 m 2 Dome Wetted Area A DOME 0.00 m 2 Bilge Keels Wetted Area A BK 0.00 m 2 Bow Thruster Tunnel Openings Particular Value Default Value Units Bow Thruster Tunnel Opening Diameter ( Enter value zero if no bow thruster is present) d BT m Is the Bow Thruster located in the cylindrical part of Bulbous Bow? (Write 'Y' for Yes and 'N' for No,'NA' if no Bow Thruster is present) NA NA Table 2: Rudder Types

4 INPUT VESSEL SPEEDS Please click the 'Input Speeds' button below to input the various vessel speeds at which you want to calculate resistance

5 Doc. No: Date: Revision No: Prepared By: Page 5 of 14 SHIP RESISTANCE CALCULATION - FRICTIONAL RESISTANCE Calculation of Frictional Resistance Frictional Resistance R F = 1/2 ρ water SV 2 X C F ρ water = Density of Water, S = Wetted Surface Area, V = Vessel Fwd Speed (including current speed), C F = Resistance Coefficient as per ITTC 1957 (C F = / [log 10 R)-2] 2 where R = Reynolds Number (R = VL/ν), ν = Viscosity of Water, L = Waterline Length Particulars Notation Value Units Density of Water ρ water 1025 kg/m 3 Viscosity of Water ν m 2 /s Length on Waterline L 205 m Wetted Surface Area S m 2 Vessel Fwd Speed (including Current) V 5.5 m/s Reynolds Number R Friction Coefficient (ITTC 1957) C F = / [log 10 R)-2] Frictional Resistance R F MT Calculation of Form Factor Form Factor (1 + k1) 1+k1 = c 13 { c 12 (B/L R ) (0.95-C p ) (1-C p lcb) ; where L R /L = 1 - C p C p x lcb /(4C p -1); (L R = Length of Run), C p = Prismatic Coefficient c 12 = (T/L) for T/L > 0.05, 48.20(T/L ) for 0.02 < T/L < 0.05, and for T/L < 0.02; C 13 = Cstern, where Cstern = 0 for Normal Stern, -10 for V-shaped Sterns and +10 for U-shaped sections with Hogner Stern Particulars Notation Value Units Length of Waterline L 205 m Breadth B 32 m Prismatic Coefficient C p = C b /C M Longitudinal Center of Buoyancy lcb m lcb as %age of L Length of Run L R m T/L Stern Type U-shaped with Hogner Stern C stern 10 c c Form Factor 1 + k MT

6 SHIP RESISTANCE CALCULATION - APPENDAGE RESISTANCE Calculation of Appendage Resistance Appendage Resistance R APP = 1/2 ρ water (ΣS APP ) V 2 x (1 + k2) eq x C F + ρ water V 2 πd BT 2 C BTO ρ water = Density of Water, ΣSAPP = Total Wetted Surface Area of all Appendages, V = Vessel Fwd Speed (including current speed), C F = Resistance Coefficient as per ITTC 1957 (C F = / [log 10 R)-2] 2 where R = Reynolds Number (R = VL/ν), ν = Viscosity of Water, L = Waterline Length, (1 + k2) = Appendage Resistance Factor = Σ{(1 + k2) S APP }/(ΣS APP ), where (1 + k2) value for different appendages are taken from Table 3, dbt = Diameter of Bow Thruster Tunnel, CBTO = Coefficient ranging from to (0.003 being taken for Bow Thruster Tunnel located in cylindrical part of bulbous bow) Particulars Notation Value Units Appendage Area, S APP 1 + k2 (1 + k2) S APP Density of Water ρ water 1025 kg/m 3 Rudder Viscosity of Water ν m 2 /s Shafts Length on Waterline L 205 m Shaft Brackets Total Surface Area of Appendages ΣS APP m 2 Skeg Vessel Fwd Speed V 5.5 m/s Strut Bossings Reynolds Number R Hull Bossings Friction Coefficient (ITTC 1957) C F = / [log 10 R)-2] Stabilizer Fins (1 + k2) eq 1.5 Dome Bow Thruster Tunnel Opening Diameter d BT 0.00 m Bilge Keels Bow Thruster Opening Coefficient C BTO ΣS APP 50 Σ(1 + k2)s APP 75 Frictional Resistance R F 0.18 MT

7 SHIP RESISTANCE CALCULATION - WAVE RESISTANCE Calculation of Wave Resistance Wave Resistance R W = c 1 c 2 c 5 D V ρ water g exp{m 1 F n d + m 2 cos(λf n -2 )} ρ water = Density of Water, g = Acceleration due to gravity, D V = Volumetric Displacement, F n = Froude Number = V/ gl where L = Waterline Length, V = Vessel speed + Current Speed, c 1 = c (T/B) (90-i E ) , c 7 = (B/L) when B/L < 0.11, B/L when 0.11 < B/L < 0.25, L/B when B/L > 0.25, i E = angle of Half entrance (angle of waterline at the bow in degrees) 1.5 c 2 = exp(-1.89 c 3 ), c 3 = 0.56 A BT / {BT(0.31 A BT + T F - h B ), T F = Fwd Draft, h B = position of centre of transverse area A BT above keel line Particulars Notation Value Units Density of Water ρ water 1025 kg/m 3 Acceleration due to Gravity g 9.81 m/s 2 Length on Waterline L 205 m Breadth B 32 m L/B Ratio L/B Draft(mean) T 10 m Volumetric Displacement D V m 3 Vessel Fwd Speed (including Current) V 5.5 m/s L 3 /D v Ratio L 3 /D v 235 Froude Number F n Angle of Half Entrance i E degrees Bulb Transverse Section Area A BT m 2 Transom Transverse Wetted Area A T 16 m 2 Prismatic Coefficient C p Fwd Draft T F m Position of centre of A BT above keel line h B 4.00 m c c c c λ c m c m c Wave Resistance R W 0.03 MT

8 SHIP RESISTANCE CALCULATION - Additional Resistance due to Bulbous Bow Calculation of Additional Pressure Resistance of Bulbous Bow near Water Surface R B = 0.11 exp(-3p B -2 ) F ni 3 A BT 1.5 ρ water g/(1 + F ni 2 ) ρ water = Density of Water, A BT = Bulb Transverse Section Area, g = Acceleration due to gravity, F ni = Froude number based on immersion, P B is a measure of emergence of the bow P B = 0.56 A BT /(T F h B ), F ni = V/sqrt{g(T F - h B A BT ) V 2 }, T F = Forward Draft, h B = position of centre of transverse Bulb area above keel Particulars Notation Value Units Density of Water ρ water 1025 kg/m 3 Bulb Transverse Section Area A BT m 2 Acceleration due to Gravity g 9.81 m/s 2 Fwd Draft T F m Vessel Fwd Speed V 5.5 m/s Position of centre of A BT above keel line h B 4.00 m Froude Number based on immersion F ni Measure of emergence of Bow P B Additional Resistance of Bulbous Bow R B 0.00 MT

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10 SHIP RESISTANCE CALCULATION - Additional Resistance due to Immersed Transom Calculation of Additional Pressure Resistance of Immersed Transom R TR = 1/2 ρ water V 2 A T c 6 ρ water = Density of Water, A T = Immersed part of transverse transom area, V = Fwd speed of Vessel (including current), F nt = Froude number based on transom immersion, F nt = V/sqrt{2 g A T /(B + B C WP )}, C WP = Waterplane area coefficient c 6 = 0.2(1-0.2 F nt ) when F nt < 5, 0 when F nt >= 5 Particulars Notation Value Units Density of Water ρ water 1025 kg/m 3 Breadth B 32 m Waterplane area Coefficient C WP 0.75 Transom Transverse Section Area A T 16 m 2 Acceleration due to Gravity g 9.81 m/s 2 Fwd Draft T F m Vessel Fwd Speed (including Current) V 5.5 m/s Froude Number based on transom immersion F nt c Additional Resistance of Bulbous Bow R B 2.71 MT

11 SHIP RESISTANCE CALCULATION - Model-Ship Correlation Resistance Calculation of Model-Ship Correlation Resistance R A = 1/2 ρ water V 2 S C A ρ water = Density of Water,g = Acceleration due to gravity, S = Wetted Surface Area,, V = Vessel fwd speed (including current), C A = Correlation Allowance Coefficient C A = 0.006(L+100) (L/7.5) C 4 B c 2 ( c 4 ), c 4 = T F /L when T F /L <= 0.04, 0.04 when T F /L > 0.04 c 2 = exp( c 3 ), c 3 = 0.56 A BT 1.5 / {BT(0.31 A BT + T F - h B ), T F = Forward Draft, h B = position of centre of transverse Bulb area above keel, A BT = Bulb Transverse Section Area Particulars Notation Value Units Density of Water ρ water 1025 kg/m 3 Waterline Length L 205 m Breadth B 32 m Draft(Mean) T 10 m Block Coefficient C B Wetted Surface Area S m 2 Bulb Transverse Section Area A BT m 2 Acceleration due to Gravity g 9.81 m/s 2 Fwd Draft T F m Vessel Fwd Speed (including Current) V 5.5 m/s Position of centre of A BT above keel line h B 4.00 m Ratio T F /L T F /L c c c C A Model-Ship Correlation Resistance R A 4.10 MT

12 Company Name: Project Name: CARGO FORCES AND ACCLERATION CALCULATION Final Forces Doc. No: Date: Revision No: Prepared By: Page 12 of 14 The total calm water resistance is given by: R C = R F (1 + k1) + R APP + R W + R B + R TR + R A R F = Frictional Resistance as per ITTC 1957 friction ]formula k1 = Form Factor describing viscous resistance of the Hull Form in relation to R F R APP = Resistance of Appendages R W = Wave Resistance (Wave Making and Wave Breaking Resistance) R B = Additional Pressure Resistance of Bulbous Bow near Water surface R TR = Additional Pressure Resistance of Immersed Transom Stern R A = Model-Ship Correlation Resistance Results Summary Frictional Resistance R F MT Form factor k Appendage Resistance R APP 0.18 MT Wave Resistance R W 0.03 MT Additional Resistance of Bulbous bow R B 0.00 MT Additional Resistance of Immersed Transom Stern R TR 2.71 MT Model-ship Correlation Resistance Total Calm Water Resistance, R C R A 4.10 MT MT Effective Power, P E = R C x V x g (in kw) Effective Power, P E = R C x V x g (in kw) P E kw

13 Resistance (MT) Speed Resistance Effective Power (P E ) (m/s) (MT) (kw) Resistance vs Speed 30 Resistance vs Speed Speed (m/s) --->

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