一种智能化的流速仪率定系统

介绍了一种对流速仪传感器－旋浆的自动率定系统，该系统以８０Ｃ３１为ＣＰＵ，控制异步电机和流速仪，完成对旋浆主要参数的率定。     

ADP与传统流速仪封冻期流量测验比测精度分析

在黑龙江干流卡伦山水文站进行封冻期流量的比测分析时,采用了声学多普勒剖面流速仪进行实测,并与机械旋浆式流速仪的实测资料进行比对分析,目的是通过声学多普勒测流技术与机械旋浆式流速仪测量技术进行对比,验证声学多普勒剖面流速仪冰期流量测验的精度,取代机械旋浆式流速仪进行封冻期流量测验。     

PC机实时水位、流速检测系统

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。     

省水利科研所研制成功直读多能小流速仪达到国内先进水平

为了实现水工模型测试技术的现代化,省水利科研所最近研制成功了用于测量水工模型流速的直读多能小流速仪,达到了国内先进水平。本仪器采用了中规模集成电路,配以电阻式或光电式微型旋浆传感器后,即能根据传感器特性进行计数和运算。直接在荧光屏上显示出水流的平均流速和即时流速。本仪器的最大特点是,在电阻式流速仪中采用文氏振荡器,既作为载波振荡器,又作为     

模型试验流速测量仪器的分析研究

分析研究了用于模型试验的流速测量传感器和相关仪器,重点介绍了旋浆流速仪、电磁流速仪和超声波流速仪。     

论我国转子式流速仪技术改进与管理创新

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。     

旋桨式流速仪的常见故障及日常维护

为了提升流速仪维修工作的水平及流速仪的可靠性和精确性,采用文献研究法和案例分析法为本研究提供一些理论基础。研究得知:旋浆式流速仪的日常维护应从仪器维修和故障清洗两方面入手,处理好当前旋浆式流速仪的常见故障和日常维护,能够在一定程度上提升流速仪的整体工作水平,进而促进我国水文监测事业的发展。     

河工模型跟踪式数字流速流向仪的设计与研制

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。     

中华人民共和国国家标准 旋桨式流速仪(报批稿)

本标准参照采用国际标准化组织ISO2537—1985《明渠水流测量旋杯和旋桨式流速仪》。 1 主题内容与适用范围本标准规定了旋桨式流速仪的组成结构、技术要求、检定、试验方法、检验规则和标志、包装、运输、贮存等。本标准适用于江河、湖泊、水库、渠道等水文测验用的旋桨式流速仪(以下简称流速仪)。 2 引用标准     

雷达在测流中的应用

一、前言在水文测验中常用旋杯式流速仪或旋浆流速仪来测量水流流速。最近虽出现了超声波流速仪,但上述仪器都要同水流直接接触,因此在特大洪水时,测流工作极为困难,以至经常测不到较高流速资料,甚至还危及人身安全,有时只好藉助投放浮标来近似地测量河段表面流速。而雷达测流则在一定程度上能克服上述弊病,尤其对天然河流高速水流、桥墩附近的急     

An integral calculation approach for numerical simulation of cavitating flow around a marine propeller behind the ship hull

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.     

NUMERICAL PREDICTION OF PROPELLER EXCITED ACOUSTIC RESPONSE OF SUBMARINE STRUCTURE BASED ON CFD,FEM AND BEM

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.     

船舶螺旋桨低频噪声研究

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     

高负荷螺旋桨水动力性能试验研究

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.     

采用径向回流平衡孔的低比速离心泵压力脉动特性

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。     

A PRACTICAL METHOD TO PREDICT FLUCTUATING PRESURE INDUCED BY A PROPELLER OPERATING IN WAKE FIELD AND ITS VALIDATION

1.INTRODUCTIONThepredictionoffluctuatingpressurecausedbyapropellerisanimportantsubjectforevaluatingvibrationperformanceduringshipdesignstage.Inthispaper,apracticalmethodandaprogramareintroducedanddescribedinthreeparts.Inthefirstpart,aquasi--steadypropellerliftinglinetechniqueplusliftingsurfaceandviscouscorrectionsisusedtodeterminekinematicsparameters.Thecurvedflowofthewakeisconsideredasanequivalentaddedcambertobladesection.Inthesecondpart,cavityextentonbladeatdifferentangularpositionshasb…     

Numerical simulation of hull/propeller interaction of submarine in submergence and near surface conditions简

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.     

EFFECT OF A PROPELLER AND GAS DIFFUSION ON BUBBLE NUCLEI DISTRIBUTION IN A LIQUID

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.     

PREDICTION OF UNSTEADY CAVITATION OF PROPELLER USING SURFACE-PANEL METHOD

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.     

船舶螺旋桨周围粘流场数值预报与流场分析

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