造波机主动吸收技术研究
发布时间:2018-04-29 21:08
本文选题:造波机 + 主动吸收 ; 参考:《大连理工大学》2016年博士论文
【摘要】:在海岸工程和海洋工程等领域中,物理模型试验是研究问题的一种重要手段和方法。但是在实施试验的过程中,水槽或水池等设施与真实的海洋环境相比存在着一个主要问题——二次反射。二次反射波是指造波机产生的行进波在遇到高反射率模型后产生反射波,该反射波传向造波板后产生二次反射波并叠加到行进波中。一段时间后,反射波在模型和造波机之间不断产生和传播,此时所得的测试数据不能准确的反应波浪对建筑物的作用。为此,研究人员提出了一种利用造波机在产生波浪的同时吸收反射波的方法,称之为“主动吸收”。这类造波机可根据水动力学的反馈信息,通过控制系统以数学模型来驱动造波板运动,达到消除反射波的作用。不但如此,主动吸收技术还可以有效避免水槽和水池内的共振现象产生,极大的缩短两次实验间的静水时间,并减少伪谐波的产生。目前对主动吸收技术的研究并未完善,尤其是对三维造波机主动吸收技术的研究属起步阶段。因此,开展造波机主动吸收技术的研究,在模型实验领域有重要意义。本文以线性造波理论为基础,针对规则波的单频率特点,给出了二维规则波主动吸收造波板冲程解的离散形式。在原有的造波机控制系统上搭建了吸收式造波机系统,并通过物理实验验证了该离散解对规则波吸收的有效性,其波高稳定性误差小于6%。针对该过程中出现的造波板漂移现象,可采用一阶高通滤波的方法滤除造波信号中的低频长波。针对不规则波的多频率特点,给出了二维不规则波主动吸收造波板冲程的频域解。通过对传递函数的频率特性分析得出传递函数在零频率的无穷大幅值易于引起造波板的漂移,并给出了消除造波板漂移的传递函数修正方法。由于该传递函数无解析解,本文采用一维数字滤波器逼近传递函数频率特性的方法,将频域传递函数转化为时域线性差分方程。基于IIR滤波器模型,提出了一种递归重加权最小二乘法求解模型逼近问题,结果表明该方法较常规最小二乘法可将逼近精度提高约3倍。为提高系统的吸收效率和波浪模拟精度,针对控制系统中各个环路存在的延时,提出了更加精确的带延时补偿的主动吸收控制方程。实验证明其较非延时补偿在波浪精度上有明显改善,并提高了系统在小周期波浪下的稳定性,扩大了系统主动吸收的频率适用范围。在三维水池造波机主动吸收方面,给出了带延时补偿的三维主动吸收造波板冲程的频域解。由于三维主动吸收传递函数幅值特性和相位特性的空间复杂性,模型逼近精度难以保证。本文提出了更加稳定有效的基于二维吸收传递函数与三维修正函数的模型,并给出了一种通过造波板前波高数据实时估计反射波主方向角的角度估计方法,实现了造波机完全三维主动吸收。通过建立三维物理实验,考虑不同周期、角度的入射波浪,验证了该方法在水池吸收中的有效性和精度。实验结果表明,本文方法可使用于实际三维物理模型实验,能够保证实验精度的提升。
[Abstract]:In the fields of coastal engineering and marine engineering, the physical model test is an important means and method to study the problem. But in the process of carrying out the test, there is a major problem in comparison with the real marine environment, such as the water tank or the pool, and the two reflection. The two counter wave is the traveling wave produced by the wave maker. The reflection wave is generated after the high reflectivity model. The reflected wave is transmitted to the wave maker and produces two reflection waves and superposed into the traveling wave. After a period of time, the reflected wave is produced and propagate between the model and the wave maker, and the measured data can not accurately reflect the effect of wave on the building. Using the wave maker to absorb the reflected wave at the same time, it is called "active absorption". This kind of wave maker can drive the wave plate motion by the control system by the feedback information of hydrodynamics and control the motion of the wave plate by the control system. Not only so, the active absorption technology can also effectively avoid the water tank and water. The resonance phenomenon in the pool can greatly shorten the hydrostatic time between the two experiments and reduce the generation of the pseudo harmonic. At present, the research on the active absorption technology is not perfect, especially the research on the active absorption technology of the three-dimensional wave maker. Therefore, the research on the main dynamic absorption technology of the wave maker is heavy in the field of model experiments. In this paper, based on the linear wave making theory, the discrete form of the two dimensional regular wave active absorption wave plate is given. The absorption type wave maker system is built on the original wave maker control system, and the validity of the discrete solution to the regular wave absorption is verified by the physical experiment. The wave height stability error is less than 6%. in response to the wave plate drift in the process. The first order high pass filter can be used to filter the low frequency long wave in the wave making signal. According to the multi frequency characteristic of irregular wave, the frequency domain solution of the two-dimensional irregular wave active absorption wave plate is given. It is concluded that the infinite large value of the transfer function at zero frequency can easily cause the drift of the wave plate, and gives the correction method of the transfer function to eliminate the drift of the wave plate. Because the transfer function has no analytical solution, the frequency domain transfer function is converted into a linear difference time domain by a one dimensional digital filter. Based on the IIR filter model, a recursive heavy weighted least square method is proposed to solve the model approximation problem. The results show that the method can improve the approximation accuracy by about 3 times compared with the conventional least square method. In order to improve the absorption efficiency and wave simulation accuracy of the system, it is more accurate for the delay of each loop in the control system. The active absorption control equation with time delay compensation has been proved to be better than the non delay compensation in the wave precision, and the stability of the system under the small periodic wave is improved and the frequency range of active absorption of the system is enlarged. The three-dimensional active absorption with delay compensation is given in the active absorption of the three-dimensional pool maker. Due to the spatial complexity of the amplitude and phase characteristics of the three dimensional active absorption transfer function, the approximation accuracy of the model is difficult to guarantee. In this paper, a more stable and effective model based on the two-dimensional absorption transfer function and the three-dimensional correction function is proposed, and a real-time estimation of the front wave height data of the wave plate is given. An angle estimation method for the main direction angle of the reflected wave is used to realize the full three-dimensional active absorption of the wave maker. By establishing a three-dimensional physical experiment and considering the incident waves of different periods and angles, the validity and accuracy of the method in the absorption of the water pool are verified. The experimental results show that the method can be used in the actual three-dimensional physical model experiment. To improve the accuracy of the experiment.
【学位授予单位】:大连理工大学
【学位级别】:博士
【学位授予年份】:2016
【分类号】:P75;P731.2
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本文编号:1821553
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