Ocean conditions will cause ships to be affected by rolling, heave and other motions, which introduce additional inertial forces to the ship's power system, introduce additional pressure drop to the fluids in each loop, bring errors to the measurement of thermal hydraulic parameters such as pressure difference and flow rate. Therefore, the measurement of pressure difference and flow rate under ocean conditions is studied and corrected in this paper. The experimental measurement results of the same velocity and different swinging period show that the larger the swinging period is, the smaller the additional pressure drop is, and the measured value shows that the additional pressure drop is inversely proportional to the square of the swinging period when the swinging Angle is fixed, which is consistent with the theoretical derivation formula.&nbsp;Through analysis, the relationship between differential pressure, flow fluctuation and swaying, undulating and other movements under moving conditions was obtained. Besides, the calculation method of attached pressure drop was analyzed, and the following conclusions were obtained: The influence of motion on differential pressure and flow rate is mainly composed of two parts: the attached pressure drop generated by swinging motion in the loop and working medium inside the pressure primer, and the periodic fluctuation of friction pressure drop caused by the periodic fluctuation of flow velocity caused by swinging motion. The attached pressure drop caused by motion can be calculated through theoretical analysis and is mainly related to the acceleration of motion. Through the analysis of experimental data and the comparison of theoretical calculation methods, it is found that the experimental measurement of the attached pressure drop coincides with the theoretical calculation of the fitting of the attached pressure drop, and the modification scheme of pressure difference under ocean conditions is feasible to some extent.&nbsp;Based on the above conclusions, suggestions are made for the measurement methods of pressure difference and flow under ocean conditions: Main pipelines, pressure pipes and other pipelines shall be arranged parallel to the pendulum shaft as far as possible; The length perpendicular to the pendulum pipe shall be reduced as far as possible; Symmetrical arrangement of the pipework shall be adopted as far as possible; Use the instrument with stable measurement and fast response speed; Properly arrange the accelerometer to obtain the real acceleration to calculate and eliminate the influence of additional acceleration.

Study on Influence of Rolling and Heaving Motions on Differential Pressure and Flow Rate Measurements

Paper Proceedings: https://asmedigitalcollection.asme.org/ICONE/ICONE28/volume/85246

2021 28th International Conference on Nuclear Engineering (ICONE28)

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