Research On Real-time Flow Flux Monitoring Based On High Frequency Acoustic Tomography

Due to geographical,ecological environment and economic value,monitoring of hydrological parameters in shallow sea and estuary areas is of great significance:on the one hand,fresh water is an indispensable resource for people's daily life,while in shallow sea,estuaries and reservoirs are the main sources of fresh water,and the areas near coastal and river are densely populated areas,so hydrological monitoring in those area is particularly important;On the other hand,as a country where the two rivers civilization began,the amount of water inflows into the sea is huge every year.The abundant water resources play an important role in China's shipping,fishery,underwater resource exploration,military and other aspects.Based on the importance of hydrological monitoring,this thesis focuses on the monitoring of estuary flow temperature,current speed and river flux.Sound wave,as a mechanical wave,is the only known wave that can travel far underwater.Sound wave has the physical characteristics of emission,refraction,scattering.It is precisely because of these properties that sound wave will carry some characteristics of medium in the process of medium transmission,that is,to study the transmission time,transmission path,transmission loss and sound energy distribution of sound wave underwater,we can get some hydrological parameters of the water area,such as flow temperature and velocity of water body,then combine water level and underwater terrain,the flux of the river section can be obtained.Aiming at the research content of this thesis,firstly,the existing methods of temperature,current speed and flux measurement are discussed and sorted out,strengths and weaknesses of the existing methods are analyzed,and the inversion of water temperature and velocity in shallow sea and estuary areas by using large-scale ocean acoustic tomography technology is proposed.Secondly,on the basis of theory,model and simulation,high frequency acoustic tomography instrument,using in estuary area flux monitoring,is developed independently.The software adopts the man-machine interface based on LabVIEW software to realize the modulation,transmission,reception,display and preservation of signals;the AWDT remote data transmission software realizes the transmission,calculation inversion,processing of raw data and real-time online release of water temperature,current speed and flux data;and the hardware includes industrial computer,data acquisition card,underwater probe and self-developed filter amplifier board,power amplifier board and GPS synchronous circuit board,etc.We placed the self-developed instrument in Jiangdong Reservoir Area of Beixi of Jiulong River in Fujian Province.The three-dimensional topography of the river is surveyed,then simulated the sound ray according to the terrain,and a long-term acoustic observation station was set up.The real-time on-line monitoring of water temperature,velocity and flux of the river is realized.The comparison of the data obtained with the traditional temperature and flow measuring equipment shows that the on-line monitoring technology of river hydrological parameters based on acoustic tomography is applied to river temperature and flow measurement.The monitoring of flow temperature,current speed and flux has high accuracy and practicability.