下游水位对水平旋转内消能泄洪洞水力特性的影响

通过试验研究与分析，发现下游水位对水平旋转内消能泄洪洞的各种水力特性均有较大的影响，且均与环流内空腔压强P0的变化有关。随下游水位的变化，洞内可能出现不同的流态区。在一定的下游水位范围内，泄流量具有最大值。通气孔的通风是由于两种完全不同的机理所致：在相对下游水位等于1左右，通风量变化急剧且具有最大值。空腔直径随下游水位的降低而增大，并趋向于常数，随下游水位上升而减小并趋向于零。在较高的上游水位时，壁面压强随下游水位的上升呈幂指数增大或线性增大；在相对下游水位等于1左右，不同的上游水位时消能率几乎为常数，但在相对下游水位大于1后，下游水位的增大会导致消能率较大的衰减。

Effect of downstream water level on horizontal rotary flowin internal energy dissipation tunnel

The effects of downstream water level on cavity pressure, flow regime, discharge capacity, ventilation and wall pressure of horizontal rotary flow in internal energy dissipation tunnel are studied experimentally. It is found that all these effects are significantly and closely related to the variation of cavity pressure. Following the variation of downstream water level the flow regime in the tunnel will change. The discharge capacity of the tunnel may reach maximum at certain range of downstream water level. When the relative downstream water level is equal to 1.0 the discharge of ventilation airflow reaches maximum and energy dissipation rate maintains constant in spite of the increasing of reservoir water level. The cavity diameter increases with the reduction of downstream water level and tends to constant. The increase of downstream water level results in the increase of tunnel wall pressure.