FD生成的PMM数据在初步设计阶段进行评估英文文献和中文翻译(8)
sed on above, the objective of the current work is to be able to perform standard deep water IMO maneuvering simulations in the early design phase purely based on computed input data, i.e. without using experimental data. This also includes investigations on how the numerical PMM test can be reduced to minimize the computational effort, while still producing sufficient information to give reliable maneuvering simulations. Approach All the experimental and numerical activities in the present work are focused on the appended KCS containership, which, according to the 24th Maneuvering Committee ITTC Report, is appointed as one of the benchmark ships within the maneuvering community. A full standard test matrix for the PMM test is defined and the PMM test is conducted in FORCE Technology’s towing tank in Denmark. Based on this full data set, a mathematical model for the simulator is made and the IMO maneuvers are simulated. A reduction of the full test matrix is then made by removing points from the matrix and corresponding maneuvering simulations are performed to study the influence on the maneuvers, which will be quantified by overshoot angles and turning circle diameters. For each of the simulations the resulting maneuvers will be compared to the initial reference case obtained with the full matrix to quantify the changes. Based on this work, the test matrix for the computational work will be chosen. With the reduced test matrix, CFD computations will be made for all the conditions and the resulting X and Y forces and the yaw moment for each condition will be compared with data from the measurement as a point to point comparison. The computations are performed with the RANS solver Star-CCM+. Finally, all the computed force and moment results will be included in the simulator model in order to rerun the maneuvering simulations based on the numerical data input. The simulated maneuvers will be compared with the results from the previous simulations based on the measured data with full and reduced test matrix. The structure of the paper is as follows. First the model test is presented. This is followed by a presentation of the CFD work. In this connection, point to point comparison of all measured and computed quantities will be made. Next part covers the maneuvering simulations, i.e. the applied mathematical model and simulations based on measured PMM data and the reduction of test matrix. Finally, simulations will be made where the EFD data from the static conditions in the reduced test matrix are replaced with data computed with CFD. The result based on EFD and CFD will be compared to conclude about how well the CFD based input data performs. Data generation based on model testing The model testing is carried out in FORCE Technology’s towing tank with a scale model of the KCS container ship using a scale of 1:53.667. The towing tank is 240m long, 12m wide and 5.5m deep. Figure 1. PMM model test setup at FORCE Technology. The main particulars and propeller data for the ship are shown in Table 1. The approach speed for the manoeuvres is U0=1.701 m/s (24.0 knots full scale) corresponding to a Froude number of 0.26. The test is described in detail in Larsen (2012), so only a brief summary is given here. Table 1: Hull and propeller data. Lpp [m] 4.3671 B [m] 0.6114 T [m] 0.2051 S [m2] 3.4357 CB [-] 0.651 DP [m] 0.150 Z [no. of blades] 5 P/D0.7 [-] 1.300 The considered experimental test conditions cover a set of tests, which are representative for a 1st quadrant 4 DOF PMM test and which can be used for assessment of the experimental uncertainty for representative conditions. The PMM testing technique enables various test conditions to be studied inpidually. The conditions, which are considered in this work, are “static rudder”, “static drift”, “static drift and rudder”, “static heel” “static heel and drift”, “pure sway”, “pure yaw” “yaw and rudder”, “yaw and drift” and “yaw and heel”. In the static test the model is towed in the same steady condition through the tank. The other tests are dynamic, i.e. the model is oscillating harmonically. In the present paper focus is placed on 3 DOF simulations, which means that only a subset of the conditions is covered, leaving all quantities related to heel and roll out. The contents of the considered test tests can be summarized as follows: 29th Symposium on Naval Hydrodynamics Gothenburg, Sweden, 26-31 August 2012 “Static rudder”: The model travels straight ahead through the tank with the rudder in a given angle δ. “Static drift”: The model travels through the tank in oblique flow due to a given drift angle β. “Static drift and rudder”: Same as “Static drift” but the rudder is deflected. “Pure sway”: The model travels through the tank on straight ahead course while it is oscillated from side to side. With u, v and r being the surge velocity, the sway velocity and the yaw rate in the ships local coordinate system, the pure sway motion can also be expressed in terms of the velocities, i.e. u=Uc (carriage speed), r=0 and v oscillates harmonically.