THE FLOW OF WATER IN WOOD-STAVE PIPE. 
63 
the loss of head due to such change is negligible, the change in velocity 
head alone being appreciable. 
Unless a tapered outlet structure is installed it will be best to 
consider all of the velocity head within the pipe as dissipated in impact 
and eddies due to the sudden enlargement of the sectional area in the 
outlet chamber. That is, for purposes of design recovered velocity 
head should not be counted upon. 
During the season of 1915 the writer endeavored to secure informa- 
tion as to the amount of head lost between the surface of the water 
at the intake and a point 3 diameters down the pipe, charging such 
loss of head to velocity and entry losses jointly. Some of the pipes 
tested were of concrete and some of wood, but this difference did not 
alter the value of the information secured. The latter was meager, 
however, for the reason that designers have been ultraconservative 
in allowing for friction losses of head in the pipe; consequently the 
entrance in most cases is not submerged. The water from the canal 
rushes down the first reaches of pipe and in a very turbulent and air- 
charged condition finally fills the pipe. 
Table 6 shows the results of such tests as could be made. These 
were incident to those made for the determination of friction losses 
in the pipe. 
Table 6. — Tests for loss of head at inlet ofvjood and concrete pipes. 
1 
Test. 
2 
Diam- 
eter. 
3 
Mean 
veloc- 
ity in 
pipe 
per 
second. 
4 
Loss of 
head, 
intake 
to 
gauge 
1. 
5 
Loss of 
head 
per foot 
ofpipe, 
gauge 
1-2. 
6 
Length 
ofpipe, 
3D to 
gauge 
i _ 
7 
Total 
loss 
from 
3D to 
gauge 
8 
Loss 
be- 
tween 
intake 
and 
3D. 
9 
h v = 
veloc- 
ity 
head 
forV, 
col. 3. 
10 
h e = 
entry 
head 
= |h v . 
11 
hv+he. 
1 
Inches. 
8 
8 
12 
12 
60 
60 
54 
54 
Feet. 
3.51 
3.56 
1.60 
1.60 
3.08 
3.03 
4.03 
4.02 
Foot. 
0.039 
.014 
.021 
.047 
.125 
.098 
.498 
.431 
Foot. 
0. 0108 
.0108 
. 00126 
.00146 
.00054 
.00056 
.0015 
.0016 
Feet. 
3.8 
3.8 
7.0 
7.0 
65.0 
65.0 
12.8 
12.8 
Foot. 
0.041 
.041 
.009 
.010 
.035 
.036 
.019 
.021 
Foot. 
-0.002 
- .027 
4- .012 
+ .037 
+ .090 
+ .062 
+ .479 
+ .410 
Foot. 
0.191 
.197 
.040 
.040 
.150 
.144 
.254 
.252 
Foot. 
0. 095 
.097 
.020 
.020 
.075 
.072 
.127 
.126 
Foot. 
0.286 
2 
.294 
3 
.060 
4 
.060 
.225 
6 
.216 
7 
.381 
8 
.378 
It is appreciated that this table is of but little assistance in the 
design of intakes, but it is offered as a start toward the collection of 
information on this subj ect. Except in the case of tests 1 and 2 the 
velocity of approach was indeterminate, due to changes in channel 
section and to eddying conditions. It will have served its purpose 
if it brings out the fact that close computations on entry and velocity 
head losses can be but approximate. 
A hook gauge in a stilling box in the intake gave the water surface 
at that point, while the elevation of the top of the equivalent water 
column (see p. 22) at gauge No. 1, deducted from the elevation of 
