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DEPARTMENT OF THE ARMYU.S. Army Corps of Engineers
CECW- Washington, DC 20314-1000 ETL 1110-2-239
Technical LetterNo. 1110-2-239 15 September 1978
Engineering and DesignNITROGEN SUPERSATURATION
Distribution Restriction Statement
Approved for public release; distribution is unlimited.
Report Documentation Page
Report Date 15 Sep 1978
Report Type N/A
Dates Covered (from... to) -
Title and Subtitle Engineering and Design: Nitrogen Supersaturation
Contract Number
Grant Number
Program Element Number
Author(s) Project Number
Task Number
Work Unit Number
Performing Organization Name(s) and Address(es) Department of the Army U.S. Army Corps of EngineersWashington, DC 20314-1000
Performing Organization Report Number
Sponsoring/Monitoring Agency Name(s) and Address(es)
Sponsor/Monitor’s Acronym(s)
Sponsor/Monitor’s Report Number(s)
Distribution/Availability Statement Approved for public release, distribution unlimited
Supplementary Notes
Abstract
Subject Terms
Report Classification unclassified
Classification of this page unclassified
Classification of Abstract unclassified
Limitation of Abstract UU
Number of Pages 32
DEPARTMENT OF THE ARMYOffice of the Chief of Engineers
DAEN-CWE-HD Washington, DC 20314
Engineer TechnicalLetter Nc. lliO-2-239
ETL 1110-2-229
1. purpose. The purpose of tlnis letter is to prov-ide guidancefor ‘luation and identification of those projects withhydraulic structures having the potential to produce nitrogens’~persacuration.
projects.
3. References.
z. ER 1130-2-334
b. E~ ~5_2_ll
4. SibliouraDhv.
a. ER 1110-2-1402
b. EM 1110-2-1602
c. E14 1110-2-1603
5. Discussion.
a. I;itroqen supersaturationn and associated fish. incrtalitvdue to gas cu~ble disease has occurred at Corps of Engineers -projects on the Columbia River in the North Pacific Division(NPD) and more recently at the Harry S. Truman project in theMissouri River Division. Nitrogen su~ersaturatior. can resultat any hydraulic structure from entrained air introduced byt:?e s~illway-stilling basin action. As the flow is subjectedto hydrostatic ~ressure in the stilling ‘~asir.ra :ortior. ofthe ent~ei~~d a~r is driven into solution before La has theopportunity to rise to the sur~ace and escape into tne a:~Q-sphere. 3.potential problem situation will exist if -’p~.lecharacteristics of the flow within or downstream of the
ETL 1110-2-23915 Sep 79
. .ETL 1110-2-239
Sep 78
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uoma-
RI.
u
z
[
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>;..,o+
uvzLu
0c“
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4
3
.ETL 1110-2-23915 Sep 7a
0
ETL 1110-2-23915 Sep 78
appropriate portions of Survey-Feasibil ity Repcrts, Desigr.fiemoranda, Detailed Prcject Reports, etc.
Chief, Engineering DivisionDirectorate of Civil k~orks
.
5
ETL 1110-2-23915 Sep 78
.,,.,.
3 //1 ./’ ,.!
l:, .16X, x
!.
~
The water parce? indicated in cross-section by the snaced area mcves
through the stilling basin, decelerating and increasing in heignt. It
extends laterally the full effective width, u of tilestil~ing Sasin as
illustrated in Figure 3 of the main report.
16 For that length of spillway that is in operaticnat a given time, the discharge is uniform along the
Waken from: “A Nitrogen Gas (N2) Model for the Lower ColurfiiaRiver,“Final Report,Water Resources Engineers, Inc., under cont=act toUS Army Corps of Engineers, North PacificDivision, January 1971
~. 1110-2-23915 Sep 78
crest(this is equivalent to assming that theproperties of the Mter parcel are constant slangany line parallel tfYthe spillway cre5t).
ETL 1110-2-23915 Sep 78
=+: total surface area of the air bubblescontained in the water parcel,
,“
U7 = effective saturation concentration ofdissolved nitrogen in the water parcei, and
c = actual concentration of dissolved nitrogenin the water parcel.
\
With these assumptions, we can now define the parameters {Y,A, and c--sin equation A-2 as functions of the locatlon cf the water parcel In t;ne
stilling basin.
Assumption 6 allows us to write the mass /.<as the product o:
the concentration C and the v~lume of the water parcel ,
(A-3)
where u is the effective width of the stilling basin, i.e., u = (number
of gates open) x (width per gate).
The saturation concentration of a gas such as Nz or Oz thdt is
only slightly soluble in water is governed by Henry’s Law which states
that the equilibrium or saturation concentration of the gas in solution
is directly proportional to the pressure existing at the gas-liquid
interface. In the water parcel the pressure P at an elevation z above
the stilling basin floor is
where PO is the atmospheric (or barometric) pressure, and the Q parameters
are the densities of the roller and main flow as shown in Figure A-1.
Hence, the saturation concentration at any elevation z in the parcel Is
given as:
~L 1110-2-239L5 Sep 78
ETL 1110-2-23915 Sep 78
(A-8)
,n = number of moles of ai~ in the bubble,
Q=.. universal gas constant,m=& absolute temperature, and~= the total pressure in the bubble.
In eciuationA-8, R can be replaced by rib/28.9where 28.9 is the molecular
weight of air. The diameter d.~ and the zrea L. ot a spnere are given b!f::
.
Now, combining equations A-8 and A-9, the following expression results
for the surface area .4Lof an air bubble with mass r.h:
lhus, if the total air mass-entrained per unit vclume 07 water at.~fiis
~{,, the total air bubble surface areas A’, per unit volume of waterwis
f;und from the bubble size distribution and equation A-10 as
or-
(A-11)
(A-?2)
e
ETL LILO-2-23915 Sep 78
. .
~T~ 1110.2.239
15 Sep 78
.
.We can now write rate expression ~ in terms of the location in the
stilling basin by using the relat;;nship
where v is the velocity of the parcel and q is the discnarge per unit
width of the stillinq basin. In addition, we define a system parameter
X, whicn we will call the encrairtimenzcoeffi;cian:, as
Substituting equation A-18 and ,4-19into A-17 gives the expression for
the concentration change in the water parcel as
The solution is obtained as fo?;ows. 1Eva uate the pressure terns at>~3
the mid~o~nt 0$ the stilling basin ~ = — to obtain2
*
(A-19)
(A-zo)
EZL Ll10-2-239LS Sep 78
I
I
“..
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.4 ●
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.4.”.
o
/13
%. b.=aE a & ‘oare mpirically detsmtied frcm ab~med data. They-u
arz shown below:
YODEL CO~TICI=~S
?ROJ“&T ~ a
Little Goose 1.00 0.09LO~er ~on~ental 1.00 0.09Ice Harbor Loo 0.30XLAlary 1.00 1.00John Day 1.00 o.~o
The Dalles 0.50 0.803onneville 1.00 1.90
Al Developed by %ater 3esources E~ineers, Iac. for
7 “5-.+ ,
in 1971.
LOWER MONUMENTAL ~oca CLs3EU EL *53,
-.,
.
‘\.
... * ~-—. ._. _ .- ___ ._.— — .-. _ ._.
.. . . . ..-— ‘“”
LoWER GRANITE
i
McNARYCcu cA.%b\
- --- =.
15 Sep 78 . -. ..- .—-—.-_.... -..-—.-—.LITTLE GOOSE
m-u.,r
(,
.‘.
JOHN DAY
./. . ‘
.--— .—— —— —— - ..-—. — -—-—- -———— ----—
.
.. ETL 1110-2-239”
15 Sep 78
PREDICTION OF DISSOLVED G+AT HYDRAL~IC STRUCTURES&l
?/ ~n~by Perry L. Johnsor~Danny L. King~/
~/ Reprinted with the permission of the authors&/ Hydraulic Engineer, Bureau of Reclamation, Denver, Colorado
~/ Chief, Hydraulics Branch, Bureau of Reclamation, Denver, Colorado
Inclosure 2
ETL 1110-2-23915 Sep78., . .
As a basis for development of the analysis, the following data were collected”;
2.
3.
;..:,-;
ETL 1110-2-23915 Sep 78
produce questionable ~esiJ]ts. The vertical dimension of :5,5jet (thickness cf
Jet that the bubble would rise Ehrough) is never constant. The time, :, b~sed
on bubble rise time, t~, was evaludted by dividing the calculated vertical
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ETL 1110-2-23915 Sep 78 . -
ETL 1110-2-2391S Sep 78
7
ETL 1110-2-239,,15 Sep78. .
Since the flow is not horizontal the flo’w depth must be di’~ided by the cosineof the anqle of penetration to obtain the vertical dimension of the jet.
-.,-.
ETL 111 0-2 -23915 Sep 78
head, Hvinterval(evaluatthe consis lessbased on
aath len
, to the appropriused is based on
a,te flo~+basin re
path lenqth,tention time
X, is Hv, the bas
/ix. If then f Cw path
‘)se
is~
1? the smathe flow
ier t red from tideration
in Gee bub
Ow
cmetryble ri
r5pa
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1engthem tiipath lenqth. s amp 1then the bas in
ise~ .
sothe bas in +,.95
,;
‘ae
8+3.3+3.5=:~ . ..0 ft (4.6 m)
ionIs
n
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u e.
8- K s
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c(t) 27.4
s s then the on ~hLll e.
is
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disso? we ccmcute:
C7.
ncenf14---is
r‘5 . ,.
3
v!. = 0.1
ORS above. Aoply ng eaua-
= :2.9 ma/L
2. The basic eauation developed to predict the resulting dissolved gasconcentrations is:
●
.
11
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ETL 1110-2-239 .S5 Sep 78
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7
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SECTION THRU OVERFLOW WEIR ‘“~ ‘SCALE IN FEET