A negative pressure zone formed on the sidewall about 15 meters from the outlet. The aeration density at the sidewall was about 1.3%.

• 在侧墙有少量掺气；掺气浓度在1.；3%25左右；掺气的主要原因是侧墙冲击点处产生的立轴漩滚对空气的卷吸作用。