ADCP流速及流量测量原理

现代海洋测绘PPTby陈志高ADCP流速及流量测量原理2声学多普勒流速剖面仪•Acoustic•Doppler•Current•Profiler起源：1980s四大海洋观测仪器之一：海洋湖泊河口3ADCP是用于采集流速大小和方向的声学设备流速剖面视为不同水层(Bin)或深度单元（BepthCell）的流速基本概念4•Acoustic•Doppler•Current•Profiler基本概念5声波发射•ADCP的换能器以固定频率向水体和水底分别发射一个短脉冲和长脉冲声波•声脉冲由于水里颗粒物存在反射并被换能器接收6声波发射1cm1cm1mmEuphasiidCopepodPteropod7声波发射•ADCP收到悬浮颗粒物反射回来的声波由于悬浮颗粒物的相对速度而产生频移•这就是多普勒效应8多普勒效应•Acoustic•Doppler•Current•Profiler9多普勒频移TRAINAPPROACHES--HigherPitchTRAINRECEDES--LowerPitch10相对速度•悬浮颗粒物与换能器有相对运动才存在“多普勒效应”•如果悬浮颗粒物运动垂直于（90度）换能器则没有“多普勒效应”•知道了悬浮颗粒物与换能器发声方向的角度就可以通过“多普勒”频移推算出悬浮颗粒物的运动速度11相对速度Time0Time1Time18Waves10Waves9WavesTime1AcousticBeamScattersADCPTransducerA8WavesMeasured12流速测量•Acoustic•Doppler•Current•Profiler13流速测量•ADCP通常具有3个以上换能器，同时发射和接受3个波束以上的声信号，获得3个以上的相对速度•信号按波束独立处理并转换成波束向相对速度•利用波速间的角度，将波束向（波束坐标）的相对速度转换为水平和垂向速度（地球坐标）14坐标关系和速度转换波束坐标系：V1、V2、V3、V4123411002sin2sin11002sin2sin11114cos4cos4cos4cos111122sin22sin22sin22sinVUVVVWVe仪器坐标系：U、V、W、e15地球坐标系：如果存在安装误差或罗经误差坐标关系和速度转换16流速剖面•Acoustic•Doppler•Current•Profiler17传统流速仪法起点桩水面f0D1f2f3fnfn-1d1D2d2d3D3f1D4A1A2A3V1V2V3V4流速测量流量测量VKnCV—流速（m/s）n—旋桨回转率，n=N/T(1/s)K—水力螺距（m）C为仪器常数（m/s）流速面积法实时多垂线多水深单元效率高量程大传统流速仪ADCP水深单元流速剖面19ADCP测流回顾•Acoustic–以固定频率发射声波脉冲.•Doppler–接受反射回来有“多普勒”频移的声波，通过频移计算波束向的相对速度•Current–应用4波速向相对速度、波速间夹角、姿态数据（首向heading,纵摇pitch,横摇roll）•Profiler–测量不同层次（depthcell）的流速20走航式ADCP流速测量ShortPulseLongPulseBottomBeamdoesnotcompletelyilluminatebottomatonetime.Beamilluminatesbottomcompletelyatonetime(A)(B)Water-trackBottom-track21盲区上盲区下盲区实测区岸边区岸边距岸边距微断面水深单元上下盲区：*09.5()buzzu左右盲区：mVV为流速系数：0.67~0.75Distance=3mDepth0.20.20.1流量测量QENSEMBLE=1.5m3/sSQ=1.5m3/sDistance=9mDepth流量测量0.20.20.10.30.30.30.20.3QENSEMBLE=4.2m3/sSQ=5.7m3/sDistance=15mDepth流量测量0.20.20.10.30.30.30.20.30.40.40.50.40.50.40.30.30.20.30.5QENSEMBLE=12.3m3/sSQ=18m3/sDistance=21mDepth流量测量0.20.20.10.30.30.30.20.30.40.40.50.40.50.40.30.30.20.30.50.60.70.60.60.60.50.50.40.40.30.30.2QENSEMBLE=17.1m3/sSQ=35.1m3/sDistance=27mDepth流量测量0.20.20.10.30.30.30.20.30.40.40.50.40.50.40.30.30.20.30.50.60.70.60.60.60.50.50.40.40.30.30.20.80.80.80.80.70.70.50.50.40.40.30.30.2QENSEMBLE=21.6m3/sSQ=56.7m3/sDistance=33mDepth流量测量0.20.20.10.30.30.30.20.30.40.40.50.40.50.40.30.30.20.30.50.60.70.60.60.60.50.50.40.40.30.30.20.80.80.80.80.70.70.50.50.40.40.30.30.21.01.01.00.91.00.90.70.70.50.50.40.40.20.2QENSEMBLE=28.2m3/sSQ=84.9m3/sDistance=39mDepth流量测量0.20.20.10.30.30.30.20.30.40.40.50.40.50.40.30.30.20.30.50.60.70.60.60.60.50.50.40.40.30.30.20.80.80.80.80.70.70.50.50.40.40.30.30.21.01.01.00.91.00.90.70.70.50.50.40.40.20.21.01.01.00.91.00.90.70.70.50.50.40.40.20.2QENSEMBLE=28.2m3/sSQ=113.1m3/sDistance=45mDepth流量测量0.20.20.10.30.30.30.20.30.40.40.50.40.50.40.30.30.20.30.50.60.70.60.60.60.50.50.40.40.30.30.20.80.80.80.80.70.70.50.50.40.40.30.30.21.01.01.00.91.00.90.70.70.50.50.40.40.20.21.01.01.00.91.00.90.70.70.50.50.40.40.20.20.90.80.80.60.50.40.20.80.80.70.50.4QENSEMBLE=23.1m3/sSQ=136.2m3/sDistance=51m流量测量0.20.20.10.30.30.30.20.30.40.40.50.40.50.40.30.30.20.30.50.60.70.60.60.60.50.50.40.40.30.30.20.80.80.80.80.70.70.50.50.40.40.30.30.21.01.01.00.91.00.90.70.70.50.50.40.40.20.21.01.01.00.91.00.90.70.70.50.50.40.40.20.20.90.80.80.60.50.40.20.80.80.70.50.40.70.70.60.40.30.60.40.30.2QENSEMBLE=13.2m3/sSQ=149.4m3/sDistance=57m流量测量0.20.20.10.30.30.30.20.30.40.40.50.40.50.40.30.30.20.30.50.60.70.60.60.60.50.50.40.40.30.30.20.80.80.80.80.70.70.50.50.40.40.30.30.21.01.01.00.91.00.90.70.70.50.50.40.40.20.21.01.01.00.91.00.90.70.70.50.50.40.40.20.20.90.80.80.60.50.40.20.80.80.70.50.40.70.70.60.40.30.60.40.30.20.40.30.20.20.1QENSEMBLE=3.6m3/sSQ=153m3/s32思考题（1）ADCP一般安装在运动载体上，怎样获得绝对流速？（2）怎样计算流量？