Jacob H. Douma
the side walls of the block. But the velocity was so high that negative pressures occurred
which caused low pressures and cavitation on the side walls. A hydraulic model was
constructed and tests verified the occurrence of negative pressures on the sides of the
blocks. Rounding the upstream corners of the blocks eliminated the negative pressures.
The prototype blocks were reconstructed and are now operating without any cavitation
erosion.
Well, that's an excellent example of the whole process of testing and modeling.
A:
Right. Many large dams do not have high enough velocities to cause cavitation erosion,
and some haven't had enough high flows to experience cavitation erosion yet.
It takes a little while for these ideas to develop and have everybody understand them.
Hydraulic engineers can understand it a little more readily because they have the fluid
dynamics background which concrete engineers do not have.
What were some of the major projects that you were involved with in that first period,
when you were in that Structures Branch?
A:
Oh, let's see. Structures Branch, 1946.
Pine
Fort Randall, Garrison, and Oahe Dams
Did you get involved in the Pick-Sloan Plan--the big
dams up on the
Missouri?
A:
Yes. I was involved with Fort Randall, Garrison, and Oahe dams. Also, the Pine Flat
Dam, which was designed by the Sacramento District. It was a high gravity dam with two
tiers of x
outlet sluices controlled by slide gates that slid down on the upstream
end to close or open the sluices.
It was questionable whether the slide gates could be operated part open under very high
heads. To check this question, the gates were operated part open for various heads, as the
reservoir filled. The maximum operating head was determined for acceptable gate
vibration and low pressures that would not cause cavitation erosion.
That was very successful. It showed that slide gates can operate part open. They won't
vibrate too much or cause cavitation erosion, provided the head isn't too high. We found
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