發(fā)布時間：2018-08-03 06:41

【摘要】：水下航行器在現(xiàn)代國防事業(yè)中起到了巨大的作用，而其振動與噪聲水平是決定當(dāng)代水下航行器生命力和隱蔽性攻擊能力的最重要的參數(shù)之一。水下航行器主要由軸系與殼體兩子系統(tǒng)相互耦合而組成，其振動噪聲主要來源于三大方面：機(jī)械振動噪聲、流噪聲以及螺旋槳運(yùn)動引起的振動噪聲。其中螺旋槳運(yùn)動引起的噪聲是航行器在多數(shù)時間是最主要的振動和噪聲源，準(zhǔn)確評估并設(shè)法降低系統(tǒng)這一原因的振動噪聲是實(shí)現(xiàn)水下航行器設(shè)計與改進(jìn)的重要環(huán)節(jié)。螺旋槳運(yùn)動引起的系統(tǒng)振動包括兩部分，分別是螺旋槳直接振動和螺旋槳間接振動，其中引起螺旋槳間接振動有兩種主要原因，一是由螺旋槳多方向非定常激勵引起的軸系振動經(jīng)各支撐軸承傳遞到殼體導(dǎo)致，一是由螺旋槳轉(zhuǎn)動引起軸系與艉軸承之間的摩擦振動傳遞到殼體導(dǎo)致。 針對螺旋槳非定常力激起系統(tǒng)振動及聲輻射，論文從軸承支撐角度分析了軸系與殼體接觸面的特點(diǎn)及其簡化模型，在軸承彈簧阻尼模型的基礎(chǔ)上分別建了軸系子系統(tǒng)、空氣中軸系-殼體耦合系統(tǒng)和流體中軸系-殼體耦合系統(tǒng)有限元模型，對三種模型進(jìn)行了固有模態(tài)分析，以及縱向、橫向激勵下系統(tǒng)振動特性分析，并深入研究了三種模型之振動特性變化規(guī)律，指出縱向振動是系統(tǒng)振動研究的主要方向；推力軸承基座結(jié)構(gòu)對縱向振動傳遞有著重要影響。除此之外，論文還從表面聲壓、輻射聲壓、聲輻射功率及聲輻射效率等方面探究系統(tǒng)的基本聲輻射特性，研究了其與系統(tǒng)振動特性的關(guān)系，指出了系統(tǒng)縱向振動引起的聲輻射對系統(tǒng)總體聲輻射的重要作用。 以往的研究都認(rèn)為螺旋槳非定常激勵是系統(tǒng)主要外激勵，然而實(shí)際系統(tǒng)中由于艉軸承與軸系摩擦引起的振動與噪聲對系統(tǒng)特性同樣有影響。對于軸系與艉軸承摩擦振動，文章首先分析了水潤滑橡膠艉軸承的摩擦特性，并利用模態(tài)減縮研究了艉軸承摩擦激勵產(chǎn)生的自激振蕩及粘-滑現(xiàn)象。結(jié)果表明，摩擦振蕩的產(chǎn)生是由系統(tǒng)縱向振動-橫向振動-摩擦振動相互耦合而導(dǎo)致的自振失穩(wěn)的結(jié)果；模態(tài)阻尼、軸系轉(zhuǎn)速、支撐剛度等諸多因素都可以影響摩擦振蕩的形成。此外，文章針對軸系完全對中和軸系有不對中的兩種不同工況，分別討論了摩擦振動的特點(diǎn)，并將摩擦振動與螺旋槳非定常激勵對整體振動的影響程度進(jìn)行了分析，得出系統(tǒng)在軸系對中條件不良時，摩擦振動是不可忽略的振動源的結(jié)論。 基于振動及噪聲特性的分析，文章提出了改變軸承剛度及阻尼參數(shù)、添加縱向加強(qiáng)筋、改變推力軸承基座結(jié)構(gòu)、添加縱向隔振器、艉部下移等方案控制系統(tǒng)振動，，討論了每種措施的效果與可行性。對比結(jié)果表明，若要求對結(jié)構(gòu)改動較小，通過添加縱向隔振器及添加一根加強(qiáng)筋等方式能夠起到一定的減振效果；若從設(shè)計階段改進(jìn)，應(yīng)用對稱式主推力軸承基座支撐，不僅可以減小系統(tǒng)在縱向及橫向激勵下的振動響應(yīng)，還可以減小系統(tǒng)的縱-橫耦合程度。本文有關(guān)結(jié)構(gòu)優(yōu)化分析的研究對工程設(shè)計具有一定的借鑒意義。
[Abstract]:Underwater vehicle plays a great role in modern national defense, and its vibration and noise level is one of the most important parameters to determine the vitality of the contemporary underwater vehicle and the ability of concealed attack. The underwater vehicle is mainly composed of the coupling of the shafting and the shell two subsystems, and its vibration and noise are mainly derived from three aspects. Mechanical vibration noise, flow noise and the vibration noise caused by the propeller motion. The noise caused by the propeller motion is the most important vibration and noise source of the aircraft in most of the time. It is an important link to realize the design and improvement of the underwater navigator by accurate assessment and reduction of the vibration and noise of the system. The vibration caused by the motion consists of two parts, which are the direct vibration of the propeller and the indirect vibration of the propeller, in which there are two main reasons for the indirect vibration of the propeller. One is that the shaft vibration caused by the unsteady excitation of the propeller is transmitted to the shell by the bearing of the propeller, and the other is the shaft and the stern shaft caused by the rotation of the propeller. The friction vibration between the bearings is transmitted to the shell.
Aiming at the unsteady force of the propeller to arouse the vibration and sound radiation of the system, the characteristics and simplified model of the contact surface of the shafting and the shell are analyzed from the bearing support angle. On the basis of the bearing spring damping model, the shafting subsystem, the axle housing coupling system in the air and the finite element model of the shaft shell coupling system in the fluid are built respectively. The inherent modal analysis of the three models and the analysis of the vibration characteristics of the system under the longitudinal and transverse excitation are carried out, and the variation of the vibration characteristics of the three models is deeply studied. It is pointed out that the longitudinal vibration is the main direction of the study of the system vibration, and the thrust bearing base structure has an important influence on the longitudinal vibration transmission. The basic sound radiation characteristics of the system are investigated from the surface acoustic pressure, the radiation pressure, the sound radiation power and the sound radiation efficiency. The relationship between the system and the vibration characteristics of the system is studied. The important role of the sound radiation caused by the longitudinal vibration of the system to the overall sound radiation of the system is pointed out.
The previous research holds that the unsteady propeller excitation is the main external excitation of the system. However, the vibration and noise caused by the friction between the stern bearing and the shaft system have the same influence on the system characteristics. The self excited oscillation and stick slip phenomenon of the stern bearing friction excitation are studied. The results show that the generation of the friction oscillation is the result of the self vibration instability caused by the coupling between the longitudinal vibration of the system - the transverse vibration and the friction vibration of the system; and the modal damping, the shaft speed, the support stiffness and so on can affect the formation of the friction oscillation. In this paper, the characteristics of friction vibration are discussed respectively for the two different working conditions of the shaft system with the neutral axis. The influence degree of the friction vibration and the propeller unsteady excitation on the whole vibration is analyzed. The conclusion is that the friction vibration is an unnegligible source of vibration when the system is poor in the shaft system.
Based on the analysis of the vibration and noise characteristics, the effect and feasibility of the control system are discussed, including the change of the bearing stiffness and damping parameters, the addition of the longitudinal reinforcement, the change of the thrust bearing base structure, the addition of the longitudinal vibration isolator, the stern shift and so on. In the design phase, the vibration response of the system can be reduced and the longitudinal and transverse coupling of the system can be reduced. The study of analysis has certain reference significance for engineering design.
【學(xué)位授予單位】：上海交通大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TJ6;TB123

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