Experimental investigations of water intake/outlet towers (shafts)

Conclusions

• 1. In a pump regime the discharge openingsoperate full section at a height h≤(0.2–0.3)d_c; separation of the flow from the sill of the openings occurs at larger values of h. For tower diameter D_tw=2d_c the height of the throughgoing flow increases slightly at the exit with increase of the the height of the discharge openings to h<0.6d_c and for D_tw≥3d_c it decreases. When h≥0.6d_c the height of the throughgoing flow is constant and at the exits is about (0.55–0.6)h for D_tw=4d_c, (0.27–0.35)h for D_tw=3d_c, and (0.18–0.22)h for D_tw=4d_c.

  During operation of the discharge openings full section ($\bar h$ ≤ 0.3), an increase of the tower diameter is accompanied by an increase of nonuniformity of the distribution of velocities over the height of the openings; the opposite picture is observed with the occurrence of separation of the flow from the sill, i.e., for$\bar h$ > 0.3.

• 2. In the pump operating regime for a height of the openings h≥(0.5–0.6)d_c, the intakes/outlets with an outside diameter of the discharge openings D_tw=2d_c have smaller values of the resistance coefficients (by 0.02–0.06) than for D_tw≥3d_c, and for h<(0.5–0.6)d_c intakes/outlets with a tower diameter D_tw≥4d_c are preferable with respect to head losses.

• 3. In a turbine regime without trash racks, smaller head losses are observed in intakes/outlets with D_tw≥3d_c; a decrease of the tower diameter to D_tw=2d_c leads to a considerable increase of the head loss coefficient: by 0.05–0.18 in the range of heights of the openings h=(0.6–0.3)d_c; the presence of trash racks of the same height leads to an increase of the resistance coefficient of the intake/outlet with D_tw=2d_c.

• 4. With consideration that with a change in the outside diameter of the discharge opening, the increase of the head loss coefficient with increase of their height in the pump regime changes in magnitude and signt and also that investments in construction depend on the outside diameter of the discharge openings (tower), the final choice of the size of the intake/outlet can be made only on the basis of a technicoeconomic comparison of variants with the use of the results of the studies presented in this article.