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The self propulsion computation is to be carried out at the ship point following the experimental procedure. Propeller open test data is provided HERE.
Thus, the rate of revolutions of the propeller \(n\) is to be adjusted to obtain force equilibrium in the longitudinal direction considering the applied towing force (Skin Friction Correction, SFC): \(T = R_{T(SP)}-SFC\)
Where \(T\) is the computed thrust, \(R_{T(SP)}\) is the total resistance at self propulsion and SFC = 18.1[N] (from the test).
Report rate of revolutions \(n\), thrust and torque coefficients \(K_T\), \(K_Q\) and resistance components \(C_{T(SP)}\), \(C_{P(SP)}\), \(C_{F(SP)}\).
In case this procedure cannot be carried out, set \(n\) to the measured value \(7.5\)[rps] and report towing force \((R_{T(SP)}-T)\), \(K_{T}\), \(K_{Q}\), \(C_{T(SP)}\), \(C_{P(SP)}\), \(C_{F(SP)}\).
Table/Figure# | Items | EFD Data | Submission Instruction | ||
---|---|---|---|---|---|
Data file | Image | Image files | Sample + Tecplot layout file | ||
1.6a-1 | V&V of \(n\), \(K_T\), \(K_Q\) \(C_{T(SP)}\), \(C_{P(SP)}\), \(C_{F(SP)}\) or (for given \(n\)) \((R_{T(SP)}-T)\), \(K_{T}\), \(K_{Q}\), \(C_{T(SP)}\), \(C_{P(SP)}\), \(C_{F(SP)}\) |
Refer to sample file for detail | Filename: [Identifier]_V&V_1.6a.xls (MS Excell file) |
[Identifier]_V&V_1.6a.xls updated on July, 3, 2015 |
Note: a positive (+) sinkage value is defined upwards and a positive (+) trim value is defined bow up.
All quantities are non-dimensionalized by denstiy of water (\(\rho\)), ship speed (\(U\)), and length between parpendiculars (\(L_{PP}\)): \begin{align*} F_r = \frac{U}{\sqrt{g \cdot L_{PP}}}, \quad R_e = \frac{U \cdot L_{PP}}{\nu} \end{align*} where \(g\) is the gravitational acceleration and \(\nu\) is the kinematic viscosity.
All CFD predicted force coefficients should be reported using the provided wetted surface area at rest (\(S_0\)), propeller diameter (\(D_P\)), and propeller rate of revolution (\(n\)).
Force coefficients are defined as follows: \begin{align*} C_T = \frac{R_T}{ \frac{1}{2} \rho U^2 S_0 }, \quad C_F = \frac{R_F}{ \frac{1}{2} \rho U^2 S_0 }, \quad C_P = \frac{R_P}{ \frac{1}{2} \rho U^2 S_0 }, \quad K_T = \frac{T}{ \rho n^2 {D_P}^4 }, \quad K_Q = \frac{Q}{ \rho n^2 {D_P}^5 } \end{align*}