Some functions of water flow through the tilting open channel flume made of acrylates controled by personal computer, which is connected with electromagnetic flow meter and frequency convertor of motor pump, respectively.
The comparisons of constant-value, follow-up and programed controls in stability time lag and features showed as follows.
In constant-value control, the commercial electric source showed the best stability.
But in the follow up and programed control, the faster the change of desired discharge, the bigger the deviation became.
In paticular, in a linear hydrograph as the discharge changed 5 to 20(l/s) in 12 minutes, the average value of control deviation was less than 0.3(l/s). Nextly, in the sine curved hydrograph with 8 to 15(l/s) in average, 2 to 5(l/s) in amplitude and 0.5 to 12.0 minutes in period was examined. And in order to generate the desired sine curved hydrograph, the necessity of the refomation of input sine curve as the functions of the desired one, K(a, (dt)/T,β), and α((dt)/T, β) were recognized, where is a in amplitude, T in period of desired sine curve, and β in the the ratio of the manupulated variable to the control deviation in time dt, where is K in multiplier to a and α in phase for refomation.
Then, the Manning's coefficient of roughness, wave propagations and its reformation with amplified or damped oscillation in this flume were easily estimated and this system showed much convenience to such experiment of steady or unsteady flow.