The Study On The Influence Of Reynolds Number On The Wind Load In Model Tests Of Offshore Platforms

Offshore platforms always face much critical environment with the exploitation of oil and gas resources in blue sea. The wind load, as a sort of environment loads, is important for offshore platform so that people always think much of it. At present, physical model test is also the major method for the study of offshore platform’s wind load. Furthermore, model test can be as criteria for the result of numerical simulation due to its accuracy.However, the similarity of the fluent can’t be satisfied because Froude number Fr and Reynolds number Re in model test are not equal to the prototype value in model tests of offshore platforms’ wind loads. Generally Fr is used for the model design and then the wind speed for model tests can be calculated according to the Froude similarity. Then the experimental results can be carried out with different scale model test. The influence of Reynolds number on the wind load in model tests of offshore platforms can be obtained.First of all, the study of Reynolds number effect in model tests of columns are studied because offshore platform are consist of different columns, in which different number, different space between columns and different wind angle considered. Then Reynolds number effect in model tests of Semi-submersible and Spar platforms are obtained. The results show that the Reynolds number effect increases with the scale reduction. The wind load by a smaller scale model test is larger than the prototype wind load. At the same time, the influence of wind angle, inclination angle of platform and wind speed for Reynolds number effect are also considered. The results indicate that the influence of wind angle and wind speed is much more obvious, but the influence of the platform inclination is small comparatively. As a whole, the wind loads of model tests are also larger than the prototype value. For the Semi-submersible and Spar platform considered, the wind load is30percent higher than prototype value when model scale is smaller than1:70. Therefore the results of model tests and simulations must be corrected when they are used for prototype load.