声呐部位水声场的机械自噪声传播分析
发布时间：2018-11-13 08:35
【摘要】：声呐是利用声波在水中的传播特性,对水中的目标进行探测、定位、跟踪、导航和通讯的一种设备。它在舰船上起着重要的作用,提高声呐的探测能力和舰船自身的隐蔽性,可以有效的避免危险事故的发生,增强舰船在海水中的生存能力。国内外许多学者从提高声呐设备的探测能力及隐蔽性方面做了深入的研究。降低声呐部位的自噪声是提高声呐工作性能的关键,通过对自噪声影响因素的特性分析,可提出有利的降低自噪声的方法,从而提高声呐的工作性能。声呐腔自噪声的研究主要是对水动力噪声、螺旋桨噪声和机械噪声等噪声分量的研究。水动力噪声是舰船在10节航速以上时的主要自噪声分量；螺旋桨噪声是舰船在水下的主要噪声源,它对声呐自噪声强度的影响,随着航速的5-6次方增大；舰船机械设备的振动噪声,在低频低航速时是声呐腔自噪声的重要分量。本文的主要工作是结合声呐腔的结构特点和自噪声预报理论,建立声呐腔机械自噪声传播特性研究模型,利用模态分析法对腔体内的机械噪声分量进行预测分析,通过定性的模拟计算,归纳机械噪声对声呐自噪声影响的原因。首先,建立了考虑流固耦合作用的声呐腔的理论分析模型,利用模态法对声呐腔内声场进行理论分析。建立了含弹性边界流固耦合的方程和不含吸声边界的流固耦合模态方程时模态方程,并求得了弹性边界受到外部激励时的声场声压分布解。其次,以弹性薄板模拟受机械振动影响的声呐上平台壁面,矩形腔模拟声呐腔。外部激励作用在弹性平板上,机械噪声通过弹性平板的振动传递到声呐腔内的声呐基阵处。以此模型应用MATLAB软件对矩形腔内的噪声进行算例分析,通过改变系统的参数,如内部阻尼、腔体尺寸及材质、透声窗尺寸等,研究声呐腔内声场的变化规律。为了验算理论模型的正确性,应用LMS Virtual.lab声学软件对矩形腔模型进行有限元分析。最后,为了寻找降低声呐腔内自噪声的方法,提出了夹芯板矩形腔模型。对夹芯板结构进行运动微分方程的建立及求解。经MATLAB仿真分析表明,相同厚度的夹芯板比同厚度的矩形薄板降噪效果好,并且正方形的矩形夹芯板降噪效果优于长方形的；当板为长方形时,随着板的尺寸的变大,其降噪效果变好。夹芯板的阻尼和夹芯层的损耗因子对板的减噪量也产生影响,提高阻尼和增大损耗因子可以降低腔内噪声在共振点附近的突变。本文的研究为寻找声呐腔内机械自噪声的降低方法提供参考依据,具有重要的应用价值。
[Abstract]:Sonar is a kind of equipment for detecting, locating, tracking, navigating and communicating targets in water. It plays an important role in the ship, improve the sonar detection ability and the ship's own concealment, can effectively avoid the occurrence of dangerous accidents, enhance the ship's survivability in the sea water. Many scholars at home and abroad have done in-depth research on improving the detection ability and concealment of sonar equipment. Reducing the self-noise in the sonar position is the key to improve the sonar performance. By analyzing the characteristics of the factors affecting the self-noise, a favorable method of reducing the self-noise can be put forward to improve the working performance of sonar. The research of sonar cavity self-noise is mainly about hydrodynamic noise, propeller noise and mechanical noise. The hydrodynamic noise is the main self-noise component of the ship when the speed is above 10 knots, the propeller noise is the main noise source of the ship underwater, and the influence of hydrodynamic noise on the sonar self-noise intensity increases with the increase of the speed of the ship to the 5-6th power. The vibration noise of ship mechanical equipment is an important component of sonar cavity self-noise at low speed and low speed. The main work of this paper is to establish a study model of the self-noise propagation characteristics of sonar cavity machinery based on the structural characteristics of sonar cavity and the theory of self-noise prediction, and to use modal analysis method to predict and analyze the components of mechanical noise in the cavity. Through qualitative simulation, the causes of the influence of mechanical noise on sonar self-noise are summarized. Firstly, the theoretical analysis model of sonar cavity considering fluid-solid coupling is established, and the sound field in sonar cavity is theoretically analyzed by modal method. The equations of fluid-solid coupling with elastic boundary and the modal equation of fluid-solid coupling without sound absorbing boundary are established. The acoustic pressure distribution of sound field is obtained when the elastic boundary is subjected to external excitation. Secondly, elastic thin plates are used to simulate sonar surface on platform wall and rectangular cavity to simulate sonar cavity affected by mechanical vibration. The external excitation acts on the elastic plate and the mechanical noise is transmitted through the vibration of the elastic plate to the sonar array in the sonar cavity. In this model, MATLAB software is used to analyze the noise in rectangular cavity. By changing the parameters of the system, such as internal damping, cavity size and material, window size, etc., the variation of sound field in sonar cavity is studied. In order to verify the correctness of the theoretical model, the finite element analysis of rectangular cavity model is carried out by using LMS Virtual.lab acoustic software. Finally, in order to find a method to reduce the self-noise in sonar cavity, a rectangular cavity model of sandwich panel is proposed. The differential equations of motion for sandwich panels are established and solved. The MATLAB simulation results show that the noise reduction effect of the same thickness sandwich plate is better than that of the rectangular thin plate with the same thickness, and the noise reduction effect of the square rectangular sandwich plate is better than that of the rectangular sandwich plate. When the plate is rectangular, the noise reduction effect becomes better as the size of the plate becomes larger. The damping of sandwich panel and the loss factor of sandwich layer also affect the noise reduction of the plate. Increasing damping and loss factor can reduce the abrupt change of the noise in the cavity near the common vibration point. The research in this paper provides a reference for finding the method of reducing the mechanical self-noise in sonar cavity and has important application value.
【学位授予单位】：山东大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U666.7
本文编号：2328574
[Abstract]:Sonar is a kind of equipment for detecting, locating, tracking, navigating and communicating targets in water. It plays an important role in the ship, improve the sonar detection ability and the ship's own concealment, can effectively avoid the occurrence of dangerous accidents, enhance the ship's survivability in the sea water. Many scholars at home and abroad have done in-depth research on improving the detection ability and concealment of sonar equipment. Reducing the self-noise in the sonar position is the key to improve the sonar performance. By analyzing the characteristics of the factors affecting the self-noise, a favorable method of reducing the self-noise can be put forward to improve the working performance of sonar. The research of sonar cavity self-noise is mainly about hydrodynamic noise, propeller noise and mechanical noise. The hydrodynamic noise is the main self-noise component of the ship when the speed is above 10 knots, the propeller noise is the main noise source of the ship underwater, and the influence of hydrodynamic noise on the sonar self-noise intensity increases with the increase of the speed of the ship to the 5-6th power. The vibration noise of ship mechanical equipment is an important component of sonar cavity self-noise at low speed and low speed. The main work of this paper is to establish a study model of the self-noise propagation characteristics of sonar cavity machinery based on the structural characteristics of sonar cavity and the theory of self-noise prediction, and to use modal analysis method to predict and analyze the components of mechanical noise in the cavity. Through qualitative simulation, the causes of the influence of mechanical noise on sonar self-noise are summarized. Firstly, the theoretical analysis model of sonar cavity considering fluid-solid coupling is established, and the sound field in sonar cavity is theoretically analyzed by modal method. The equations of fluid-solid coupling with elastic boundary and the modal equation of fluid-solid coupling without sound absorbing boundary are established. The acoustic pressure distribution of sound field is obtained when the elastic boundary is subjected to external excitation. Secondly, elastic thin plates are used to simulate sonar surface on platform wall and rectangular cavity to simulate sonar cavity affected by mechanical vibration. The external excitation acts on the elastic plate and the mechanical noise is transmitted through the vibration of the elastic plate to the sonar array in the sonar cavity. In this model, MATLAB software is used to analyze the noise in rectangular cavity. By changing the parameters of the system, such as internal damping, cavity size and material, window size, etc., the variation of sound field in sonar cavity is studied. In order to verify the correctness of the theoretical model, the finite element analysis of rectangular cavity model is carried out by using LMS Virtual.lab acoustic software. Finally, in order to find a method to reduce the self-noise in sonar cavity, a rectangular cavity model of sandwich panel is proposed. The differential equations of motion for sandwich panels are established and solved. The MATLAB simulation results show that the noise reduction effect of the same thickness sandwich plate is better than that of the rectangular thin plate with the same thickness, and the noise reduction effect of the square rectangular sandwich plate is better than that of the rectangular sandwich plate. When the plate is rectangular, the noise reduction effect becomes better as the size of the plate becomes larger. The damping of sandwich panel and the loss factor of sandwich layer also affect the noise reduction of the plate. Increasing damping and loss factor can reduce the abrupt change of the noise in the cavity near the common vibration point. The research in this paper provides a reference for finding the method of reducing the mechanical self-noise in sonar cavity and has important application value.
【学位授予单位】：山东大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U666.7
【引证文献】
相关会议论文 前1条
1 张均平;;潜艇声呐部位自噪声预报方法研究[A];第十届船舶水下噪声学术讨论会论文集[C];2005年
，本文编号：2328574
本文链接：https://www.wllwen.com/kejilunwen/chuanbolw/2328574.html
