【作者】 曹贻鹏；

【导师】 张文平；

【作者基本信息】 哈尔滨工程大学 ， 轮机工程， 2008， 博士

【摘要】 目前,关于水下结构的减振降噪研究多集中在机械噪声、螺旋桨自噪声和水动力噪声领域,对螺旋桨脉动力经由推进轴系、轴承支撑传递到壳体结构,激励壳体结构振动并向外界流场辐射噪声问题的研究较少,因此,对上述问题进行研究,将有助于进一步降低水下结构的辐射噪声。本文对螺旋桨一轴系与结构耦合作用引起的结构振动与辐射噪声问题开展研究,研究其规律特性,提出减振降噪方法,设计实验模型,验证分析方法及所提出的控制措施的有效性。分述如下:建立带有推进轴系的水下壳体结构计算模型,使用有限元/直接边界元方法对螺旋桨横向、纵向脉动激励引起的壳体结构辐射噪声规律特性进行分析。横向激励作用下结构主要体现为弯曲振动,辐射声压沿结构的长度方向分布,纵向激励作用下结构辐射声压分布在结构的首尾,且横向、纵向脉动激励下结构辐射声功率传函量级相当,都需采取方法进行控制。对螺旋桨纵向力引起的水下结构辐射噪声进行控制。分析弹性基础和推力轴承刚度对激振力传递特性及结构辐射声功率的影响,在此基础上,从纵向力在系统内的传递途径入手,改变推力轴承支撑样式、在轴段上安装纵向减振器及动力吸振器以降低结构的辐射噪声。分析螺旋桨横向力引起的水下结构辐射噪声的振动声辐射规律及控制方法。建立适应轴孔较长情况的轴承支撑模型,讨论尾轴后、前轴承支撑及推力轴承轴承刚度、轴承跨距对结构辐射噪声的影响。研究释放轴承支撑自由度、安装碳纤维轴段、在轴与轴承之间、推进轴系内中空部分填充阻尼材料、在尾轴后、前轴承位置安装动力吸振器等方法降低结构的辐射噪声。从能量传递角度分析轴系-结构耦合振动问题,鉴于结构复杂,使用基于有限元的功率流方法求解系统输入功率,经过各轴承支撑传递到壳体结构上的功率,以及结构内、外壳体的能量分布。分析激振力、力矩及层间流场对结构能量分布特性及传递特性的影响,同时从能量传递的角度对本文所采取的振动控制方法进行论述。设计轴系-壳体结构耦合振动试验台架,此台架可以测量经由螺旋桨传递到壳体结构的横向、纵向激振力以及轴系、壳体的振动响应。对此结构进行试验模态分析和受迫振动分析,验证计算方法的正确性,同时得到轴系与壳体结构的耦合振动规律。在此基础上,选用文中提出的横向、纵向激励控制方法,设计相应试验结构,对各控制方法的控制效果进行试验评估,验证控制方法的有效性。更多还原

【Abstract】 The analysis of underwater structure vibration and noise control is received more attention now. There are many literatures study the calculation methods and control methods for structure vibration and radiated noise. These analyses about underwater structure vibration and noise control focus on mechanical appliance noise, propeller noise and fluid dynamical noise. The problem that propeller exciting force transfers from shafting, the bearing supporting to structure, causing structure radiated noise is less studied now. By such problem solved, the underwater structure noise will be more decreased.The underwater structure vibration and noise caused by propeller exciting force are studied in this paper. The characteristic of structure radiated noise is studied. The methods of structure vibration and noise control are calculated. The experiment model is designed. The calculation methods and the validity of vibration control methods are examed.The calculating model of underwater structure with shafting is built. The vibration and radiated noise characteristics of underwater structure caused by longitudinal and lateral propeller force are analysised by FEM/DBEM in this paper. The flexural vibration of structure is mainly excited by lateral propeller force and the radiated pressure mainly distributes alone the length of structure. The distribution of radiated pressure is mainly in the axial direction of structure when structure excited by longitudinal propeller force. The amplitudes of response function of structure radiated sound power caused by longitudinal and lateral propeller force have same level, which prove that methods should be adopted to decrease the structure vibration and noise caused by both longitudinal and lateral propeller force.The methods that can reduce the radiated noise of underwater structure caused by longitudinal propeller force are studied in this paper. The effect of flexural base on the characteristic of transfer force and radiated sound power of structure is analysised. The different structure of thrust bearing supporting, the vibration isolator and dynamic vibration absorber are used to reduce the radiated noise of underwater structure.The methods that can reduce the radiated noise of underwater structure caused by lateral propeller force are studied in this paper. The calculating model that can simulate long axis hole is made. The effects of different stiffness of rear bearing, front bearing, thrust bearing and the distance of bearing on underwater structure radiated noise are studied. The releasing DOF of bearing supporting, installing the carbon fibre shafting, filling damping material and installing dynamic vibration absorber are used to reduce the radiated noise of underwater structure.The coupled shafting and structure vibration is studied by power flow method. Because of analysis model is complex, the finite element method is adopted to calculate the system input power, the transfer power at each bearing supporting and the energy distribution of structure. The effect of exciting force, exciting moment and inner fluid on chatacteristic of energy transfer and distribution is analysised. The effect of each vibration control method is studied by power flow method.The coupled shafting and structure experiment model is designed, which can measure the longitudinal, lateral exciting force at bearing supporting and the vibration reaponse on shafting and structure. The experiment modal analysis and forced vibration analysis is carried. The correctness of simulation method is examed and the characteristic of structure vibration is got. The devices of vibration control are designed and the validity of such methods on vibration control is validated.更多还原