The results show that nonparallel demihulls cause total resistance to increase at froude numbers below 0. The ittc, hughes, katsui and grigson lines are defined and discussed in the final report of the resistance committee to the 26th ittc. C x 103 according cf x 103 according to 1957 ittc line. Employing froude scaling, the ittc 1957 frictional resistance coefficient, and a correlation allowance of 0.
Froude number g l v fr depth froude number gh v frh reynolds number. There have been successive discussions in ittc conferences whether ittc 1957 line is an appropriate line to estimate frictional resistance of ship hull forms. The wavemaking resistance coefficient, cw is then given by the pressure integral over the wetted hull surface. As computer technologies develop over time, cfd tools are used for calculating total resistance of a ship at full scale without establishing any dynamic. Only two different formulations for the frictional resistance coefficient cf are used in the results pre the 1947 attc schoenherr sented in this paper formulation and the 1957 1 ttc formulation. Armed with this information, it is possible to estimate the frictional resistance of a model. The ittc57 correlation line, which is derived based on the assumption that the water in which ships advance is infinite deep and wide. A study on the effect of flat plate friction resistance on. In the 23rd ittc propulsion committee ittc, 2002, the validity of the ittc1957 skin friction line was suspected. The frictional resistance was calculated using the ittc 1957 line. Model tests are often conducted by researchers in a real or a numerical towing tank to calculate residuary resistance of a ship by the aid of froude similarity.
Common ittc1957 formula is usually employed to calculate frictional resistance. Experimental and numerical studies on resistance of a. F calculated model frictional resistance coefficient from step 2. Even if they might not create major activities of research work, it is truly a fundamental. Frictional resistance coefficient ittc modelship correlation line log 2 0. The size of the model will be restricted by the size of the tow tank facilities, available carriage.
A model for prediction of propulsion power and emissions. The frictional resistance r f derived from the use of either the ittc or attc lines should be viewed as an instrument of the calculation process rather than producing a definitive magnitude of the skin friction associated with a particular ship. Fr frictional resistance according to ittc 1957 formula 1k form factor of bare hull wr wave making resistance br additional pressure resistance of bulbous bow near the water surface trr additional pressure resistance due to. Therefore, the ittc line is a horizontal line equal to 1. Frictional resistance coefficient ittc 57 model ship correlation. This designer will then use a frequently quoted correlation allowance of 0. Cf is calculated according to the ittc1957 international towing tank conference1957. Resistance characteristics of small and fast monohull vessels. These methods were based on the results of experiments andor numerical simulations with an unrestricted incoming flow.
Ittc recommended procedures and guidelines page 1 of 11. Procedures for resistance, propulsion and propeller open water tests of 23rd ittc 2002 23rd ittc 2002 date date 2002 table of contents 1. Ittc international towing tank conference, rt total resistance, rf frictional resistance, rr residuary resistance, ct total resistance coefficient, cf frictional resistance coefficient, cr residuary resistance coefficient, rn reynolds number, u ship speed, s hull wetted. One popular correlation line is the ittc 1957 line, 0. The thrust is assumed to remain constant throughout at its original equilibrium value before the ship reaches the gate. Investigation on correlation lines through the analyses of. As a consequence, when using a froude analysis based on these, or indeed any friction line data, it is necessary to introduce a correlation allowance. Figure 2 reproduced from the article demonstrates the effect of separation ratio on resistance. Frictional resistance coefficient of ship according to ittc1957 formula.
The ittc 1957, 1963 line, attc 1947, 1957 line and the froudes ship resis tance. Based on ittc 1957 shipmodel frictional resistance coefficient line a scheme was taken to compute and compare the extrapolated full scale resistance per unit displacement and effective horsepower requirements of the three hull forms under investigation. Comments on reliable prediction accuracy hydrocomp. Now calculate the value of the reynolds number for the ship and take it as 11957 ship. The specific residual resistance coefficient has been determined from cea crm crm 5. Calculate the ship frictional resistance coefficient c fs for a smooth hull using the ittc 57 modelship correlation line at each speed. Geosim model test results using ittc 1957 line increased when the larger model was used. Numerical prediction of total resistance using full. A major change is underway regarding the coefficient of friction for tile, the frequently cited and specified measurement of a tiles frictional resistance and the parameter most closely related to traction and slipperiness.
The proposal of a new friction line request pdf researchgate. Paper open access computational and experimental works. Hydrodynamic analysis of ship resistance following ittc. The coefficient of frictional resistance the coefficient of frictional resistance can be given by the formula. Skin friction lines some comparisons boat design net. He introduced a new wave resistance coefficient, 2 fn r c w 4 in which, l b t g r r w 2 2 8 r p and r w is the wave resistance. The ittc 1957 modelship corre lation line has been used to determine the fric tional resistance coefficient 0. As described in the above, the validity of the ittc1957 was suspected and then new friction resistance curves were proposed by grigson equation 1993 and katsui et al. Ittc78 method the total resistance coefficient of a ship without bilge keel is 9.
Ittc1957 was used as the plate friction line that has been generally applied to the expansion process of fullscale ships in the methods including the ittc. Calculate the residuary resistance coefficient c r at each speed. Comparison of the mariner schilling rudder and the mariner. As described in the above, the validity of the ittc1957 was suspected and then new friction resistance curves were proposed by grigson equation 1993 and.
Calculate the ship frictional resistance coefficient c fs for a smooth hull using the ittc57 modelship correlation line at each speed. Taking for example the ittc 1957 formula for cf, the reynolds numbers log is used, which for me seems to be almost insensitive to length variations of the hull, in the order of a couple of meters. The frictional resistance is updated continuously using the ittc 1957 formula with an empirical velocityincrease correction. The following new waveresistance coefficient was introduced. The frictional resistance is calculated using ittc 1957 line. Appendage resistance coefficient app 2 app sv r c 2. A modification of the ittc57 correlation line for shallow. In this equation the frictional resistance rf is calculated according to the 1957 ittc friction formulation, equation 12. Ittc recommended procedures page 1 of 17 resistance. 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 rf frictional resistance as per ittc 1957 friction formula k1 form factor describing viscous resistance of the hull form in relation to rf. Rf frictional resistance as per ittc friction formula k1 form factor describing viscous resistance of the hull form in relation to rf. Comparative study of air resistance with and without a.
C t total measured resistance coefficient from step 1. To include the effect of hull shape and viscous pressure drag a form factor is estimated and applied to the frictional resistance coefficient to make a viscous resistance coefficient. A proposed method for determining propulsion coefficient. Wetted surface of the hull the frictional resistance coefficient, cf is given by the ittc 1957 modelship correlation line formula. Finally, the frictional resistance of the catamaran from the ittc 1957 correlation line is calculated and compared with cfd frictional resistance. Procedures for resistance, propulsion and propeller open water tests 23rd ittc 2002 date date 2002. Plus, if we think about the dimensional skin friction resistance rfcf0. Frictional resistance coefficient of model according to ittc1957 formula.
From this, the total resistance r t of the catamaran can be found by. In addition to calculating the resistance and ehp, this method also calculates the propulsive coefficients for each of. This value is subtracted from the total resistance of the model to obtain its residual resistance. A study on the effect of flat plate friction resistance on speed. Re cf air resistance coefficient v s v a c c 2 v d 2 a a aa. The residual resistance is then scaled up to give that of the fullsized. Resistance and wake prediction for early stage ship design. Fujiwaras wind force coefficient surge, sway, and yaw c l. Ittc 1957 frictional coefficient is calculated and the total resistance and effective horsepower computed, for high speed round bilge hull forms in the froude number range 0. The procedure ittc1957 to determine the total resistance for the ship, rts, is as follows 1, 6, 7. Calculations for variables used in table iii are shown below 5, 11. The results for one of the loading conditions are shown as figures 7 and 8. Morrall national physical laboratory, ship division, 1970 frictional resistance hydrodynamics 16 pages. Numerical prediction of total resistance using full similarity technique article in china ocean engineering 334.
Ittc recommended procedures and guidelines page 1 of. Resistance tests of high speed marine vehicles hpmv ittc. At an international meeting of the testing pool administrations international towing tank conference ittc1957, it was agreed that, instead of the william froudes equation 2, the following equation can. Where cfm is derived from the ittc 1957 correlation line. Values of c according to 1947 attc and 1957 ittc lines. C t 1 k c f c r c f c aa 1 0,074 0,00 0,00057 0,00015 0,00066 0,00262, where k form factor c f frictional coefficient of the ship according to the ittc1957 shipmodel correlation line c r. The wetted surface is normally calculated by hydrostatic programs. A short description of the three updated parameters is given in the following. However, for ships sailing in the waterway with limited water depth, the frictional resistance will be influenced leading to a decreasing accuracy of the prediction with this correlation line. The viscous component uses the 1957 ittc friction line to estimate a frictional resistance coefficient. Evaluation of submarine model test in towing tank and.