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 of wood and concrete pipes. 



1 



Test. 



3 



Diam- 

 eter. 



3 



Mean 

 veloc- 

 ity in 



pipe 



per 

 second. 



4 



Loss of 

 head, 

 intake 



to 

 gauge 



5 



Loss of 

 head 

 per foot 

 of pipe, 

 gauge 

 1-2. 



6 



Length 

 ofpipe, 

 3D to 

 gauge 

 1. 



7 



Total 

 loss 

 from 

 3D to 

 gauge 



8 



Loss 



be- 

 tween 

 intake 



and 



3D. 



9 



hv= 

 veloc- 

 ity 

 head 

 forV, 

 col. 3. 



10 



h.= 

 entry 

 head 

 = ihv. 



11 



hv+h.. 



1 



Indies. 

 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 

 + .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 



5 



.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 



