Abstract Physical experimental and 3D numerical free decay tests are performed for a stationary oscillating water column (OWC) device with various underwater opening heights and power take-off (PTO) mechanisms. Numerical model results are verified with experimental data. Equivalent linear damping of the system is found by using logarithmic decrement method. Natural and resonant frequencies and added mass are calculated. For the OWC with the orifice, it is found that damping ratio decreases quadratically with increasing orifice ratio and linearly with increasing relative opening. Resonant frequency is found to be a linear function of both opening size and PTO damping. Calculated natural frequency values are compared with extensively used formulas, which are found to overestimate the OWC natural frequency. For the first time, an empirical formula for the natural frequency of a fixed OWC is proposed. Added mass is found to be independent of orifice size and underwater opening height. For the OWC with the porous layer, no noteworthy change is observed for the natural frequency and added mass compared to those of OWC with orifice. However, damping of the system is quite altered, while its change due to the variations in the permeability and under water opening height has similar characteristics.

中文翻译：

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通过实验和数值自由衰减测试确定固定 OWC 的流体动力学参数

摘要 对具有各种水下开口高度和动力输出 (PTO) 机构的固定式振荡水柱 (OWC) 装置进行了物理实验和 3D 数值自由衰减测试。数值模型结果用实验数据验证。采用对数递减法求得系统的等效线性阻尼。计算自然和共振频率以及附加质量。对于带孔口的 OWC，发现阻尼比随着孔口比的增加呈二次方下降，随着相对开度的增加呈线性下降。发现共振频率是开口尺寸和 PTO 阻尼的线性函数。计算出的固有频率值与广泛使用的公式进行比较，发现这些公式高估了 OWC 固有频率。首次，提出了固定 OWC 固有频率的经验公式。发现增加的质量与孔口尺寸和水下开口高度无关。对于具有多孔层的 OWC，与具有孔口的 OWC 相比，在固有频率和附加质量方面没有观察到显着变化。然而，系统的阻尼变化很大，而其由于渗透率和水下开口高度的变化而发生的变化具有相似的特征。