Research And Application For River Model Similarity Theory And Automatic Measuring And Controlling Technique

By means of wide investigation, instruments development, a series of model experiments and relative theory analysis, following results are obtained in river model time scale distortion ratio, model roughening, inflow and outflow controlling methods and equipment, new water level and velocity measuring technique, model automatic measuring and controlling system:(1) With the aid of configuration software, a large scale river model automatic measuring and controlling system is developed, realizing river model automatically controlling and basic hydraulic parameters automatically measuring.(2) A series of experiments on time scale distortion are made with real river model, inflow and outflow boundary condition, and continuous simulation. By means of analysis of the experimental data on model water level, water-surface gradient, cross velocity, outflow discharge process and the sediment transportation capacity, the main physical reasons for the above hydraulic parameters deviations caused by time scale distortion are illustrated: response delay of model channel storage capacity and rate of water level with time. For mild channel, it is shown that dynamic term and resistance term deviations caused by the distortion influence model water flow movement more seriously than inertia term do. It is suggested that the time distortion ratio should becontrolled in river model design(In this model, m1=2~3 is suitable).(3) Hydraulic resistance coefficient formulas are derived according to a great number of flume experiments and relative theory analysis.(4) Mathematic models are derived for digital weirs and electromagnetic flow meter inflow controlling systems. For which, dynamic characteristics, controlling errors, applicable limits are compared.(5) New type difference tail-gates and their combinations are developed, which can decrease tail water level oscillation in tipping tail-gate controlling system. Mathematic models are also obtained for the mentioned controlling systems, stability of which is analyzed.(6) New type water gauge and infrared modulated propeller type micro current meter are developed, and collective acquisition of distributed velocities is realized.The results of hydraulic resistance and automatic measuring and controlling system presented by this paper have been applied to practical engineering hydraulic model research, forming a characteristics system.