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PC机实时水位、流速检测系统 总被引:2,自引:0,他引:2
本文针对三工模型试验中水位和流速测量需要,开发研制了一套基于PC微机的水位和流速检测系统。该系统配套八路跟踪式编码水位仪、六路光电式和六中睡电阻式旋浆流速传感器,经试用表明该检测系统具有很好的适用性和抗干扰能力,并且用户界面友好,是一种具有推广价值的三工模型试验中必备仪器。 相似文献
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介绍旋浆流速仪旋转轴动态密封装置,旋浆流速仪内摩阻力矩测量设备,检定系数长期稳定的旋浆流速仪及无检定槽就地检修检定方法等科研成果,这些成果对确保水文测验精度,仪器的维护,检修,性能检定,科学管理,以及我国水文测验事业的发展具有现实意义,同时介绍成果在推广中的管理经验,这是对沿用100多年来旋浆流速仪检修,检定的技术改革与管理创新。 相似文献
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为更好地同步测量河工模型含沙水流的流速和流向,设计研制了一种新型跟踪式数字流速流向仪,其由流向自动跟踪装置和旋浆流速检测仪2部分构成。已有的旋浆流速测量仪器已较为成熟可靠,在此设计研制了流向测量仪器,主要采用了步进电机机电一体化与数字电路技术,并采用阻抗式传感器进行信号转换。给出了逻辑电路原理框图,介绍了电路分析、元器件的选用以及仪器的率定方法。率定与应用结果表明,研制的跟踪式数字流速流向仪适用于较大含沙水流的泥沙模型及清水模型,并能够自动跟踪测量流向和流速,为模型试验提供了一种新型的流速流向测量仪器。 相似文献
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《水动力学研究与进展(B辑)》2018,(6)
In this paper, the unsteady cavitating turbulent flow around a marine propeller is simulated based on the unsteady Reynolds averaged Navier-Stokes(URANS) with emphasis on the hull-propeller interaction by an integral calculation approach, which means the propeller and hull are treated as a whole when the cavitating flow is calculated. The whole calculational domain is split to an inner rotating domain containing a propeller and an outer domain containing a hull. And the two split sections are connected together in ANSYS CFX by using the GGI interfaces and the transient rotor stator frame change/mixing model. The alternate rotation model is employed for the advection term in the momentum equations in order to reduce the numerical error. Comparison of predictions with measurements shows that the propeller thrust coefficient can be predicted satisfactorily. The unsteady cavitating flow around the propeller behind the ship hull wake shows quasi-periodic features including cavity inception, growth and shrinking. These features are effectively reproduced in the simulations which compare well to available experimental data. In addition, significant pressure fluctuations on the ship hull surface induced by the unsteady propeller cavitation are compared with experimental data at monitoring points on the hull surface. The predicted amplitudes of the first components corresponding to the first blade passing frequencies match well with the experimental data. The maximum error between the predictions and the experimental data for the pressure pulsations is around 8%, which is acceptable in most engineering applications. 相似文献
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A mesh-less Refined Integral Algorithm (RIA) of Boundary Element Method (BEM) is proposed to accurately solve the Helmholtz Integral Equation (HIE).The convergence behavior and the practicability of the method are validated.Computational Fluid Dynamics (CFD),Finite Element Method (FEM) and RIA are used to predict the propeller excited underwater noise of the submarine hull structure.Firstly the propeller and submarine’s flows are independently validated,then the self propulsion of the "submarine+propeller" system is simulated via CFD and the balanced point of the system is determined as well as the self propulsion factors.Secondly,the transient response of the "submarine+ propeller" system is analyzed at the balanced point,and the propeller thrust and torque excitations are calculated.Thirdly the thrust and the torque excitations of the propeller are loaded on the submarine,respectively,to calculate the acoustic response,and the sound power and the main peak frequencies are obtained.Results show that:(1) the thrust mainly excites the submarine axial mode and the high frequency area appears at the two conical-type ends,while the torque mainly excites the circumferential mode and the high frequency area appears at the broadside of the cylindrical section,but with rather smaller sound power and radiation efficiency than the former,(2) the main sound source appears at BPF and 2BPF and comes from the harmonic propeller excitations.So,the main attention should be paid on the thrust excitation control for the sound reduction of the propeller excited submarine structure. 相似文献
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船舶螺旋桨低频噪声研究 总被引:11,自引:0,他引:11
螺旋桨低频噪声构成了船舶中高速航行时整个辐射噪声中的重要分量。螺旋桨的低频离散谱噪声是由船尾伴流场和叶片的相互作用引起的,而低频宽带噪声是由船尾粘性湍流场和叶片的相互作用产徨的。利用升力面理论和声学方法得到的离散谱噪声的预报公式,对螺旋桨直径、侧斜变化对离散谱噪 声的影响作了数值计算,并得到了工程上有实用意义的结果。在分析螺旋桨低频宽带器材怕成因的基础上得到了理论计算方法,并作为数值计算。整个方法 相似文献
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高负荷螺旋桨水动力性能试验研究 总被引:1,自引:0,他引:1
以某大型集装箱船高负荷螺旋桨为研究对象,分别采用大侧斜、反弯扭叶片和毂帽鳍等技术进行螺旋桨优化设计,以改善螺旋桨的空泡和水动力性能.设计了5型螺旋桨,分别在空泡水筒进行了模拟伴流场中的空泡和激振力试验,并在拖曳水池进行了敞水试验.试验结果表明,采用大侧斜可有效减小螺旋桨诱导船艉激振力;反弯扭叶片螺旋桨空泡性能较好,有较低的螺旋桨诱导船艉激振力水平;桨毂帽鳍可改善毂涡空泡,模型试验状态下可提高推进效率2%左右. 相似文献
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采用Relizable k~ε模型对具有径向回流平衡孔以及传统轴向回流平衡孔和无平衡孔结构的低比速离心泵进行全流场非定常数值模拟,并进行时域分析和频域分析。研究结果表明:平衡孔采用径向回流方式、传统轴向回流方式以及无平衡孔结构这3种方案时,离心泵的叶轮进口、蜗壳出口以及蜗壳隔舌处的流体均随时间呈周期性波动,脉动频率以叶片通过频率为主;具有径向回流平衡孔的低比速离心泵与其他2种结构形式的低比速离心泵相比,能够有效地改善蜗壳隔舌处的压力脉动情况。 相似文献
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1.INTRODUCTIONThepredictionoffluctuatingpressurecausedbyapropellerisanimportantsubjectforevaluatingvibrationperformanceduringshipdesignstage.Inthispaper,apracticalmethodandaprogramareintroducedanddescribedinthreeparts.Inthefirstpart,aquasi--steadypropellerliftinglinetechniqueplusliftingsurfaceandviscouscorrectionsisusedtodeterminekinematicsparameters.Thecurvedflowofthewakeisconsideredasanequivalentaddedcambertobladesection.Inthesecondpart,cavityextentonbladeatdifferentangularpositionshasb… 相似文献
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Hull/propeller interaction is of great importance for powering performance prediction. The features of hull/propeller interaction of a submarine model with a high-skew five blade propeller in submergence and near surface conditions are numerically simulated. The effect of propeller rotation is simulated by the sliding mesh technique. Free surface is captured by the volume of fluid (VOF) method. Computed results including resistance, thrust, torque and self-propulsion factor are compared with experimental data. It shows fairly good agreement. The resistance and wave pattern of the model at different depths of submergence are computed. And the thrust, torque and self-propulsion factor of the model in submergence and near surface condition are compared to analyze the effect of free surface on self-propulsion performance. The results indicate that free surface has more influence on resistance than that on self-propulsion factors. 相似文献
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A multi-bubble dynamics code accounting for gas diffusion in the liquid and through the bubble wall was developed and used to study the modification of a bubble nuclei population dynamics by a propeller.The propeller flow field was obtained using a Reynolds-Averaged Navier-Stokes(RANS) solver and bubble nuclei populations were propagated in this field.The numerical pro-cedure enabled establishment of the possibility of production behind the propeller of relatively large visible bubbles starting from typical ocean nuclei size distributions.The resulting larger bubbles are seen to cluster in the blade wakes and tip vortices.Parametric investigations of the initial nuclei size distribution,the dissolved gas concentration,and the cavitation number were conducted to ide-ntify their effects on bubble entrainment and the resultant void fractions and bubble distribution modifications downstream from the propeller.Imposed synthetic turbulence-like fluctuations unto the average RANS flow field were also used to study the effect avera-ging in the RANS procedure has on the results. 相似文献
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XIONGYing YEJin-ming WANGDe-xun 《水动力学研究与进展(B辑)》2005,17(1):43-49
This paper has predicted the range and volume of unsteady sheet cavitation of a propeller by using the surface panel method. The linearization in cavity thickness is adopted to reduce the computing time and storage space. The iteration scheme between chordwise strips has been used because the range and volume of cavitation are both unknown. The propeller cavitation range determined by the calculation method presented in this paper agrees with the observation results of cavity image at cavitation tunnel very well, and this proves the practicability of the method. 相似文献
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船舶螺旋桨周围粘流场数值预报与流场分析 总被引:8,自引:3,他引:5
本文叙述了通过直接求解雷诺平均应力方程(RANS)来获得船舶螺旋桨粘流场数值解的方法与数值求解步骤,该方法采用非交错网格系统,利用幂函数格式离散动量方程,预报-校正方法求解速度-压力耦合问题,应用Baldwin-Lomax代数湍流模式求解雷诺应力项使方程组封闭,以此来获得螺旋桨粘流场,为了验证数值方法的稳定性和可靠性,文中以DTRC4119桨为算例,对螺旋桨粘流场进行了数值求解,通过对计算结果的分 相似文献