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

>wA

- .

uoma-

RI.

u

z

[

.-..,:,..

>;..,o+

uvzLu

0c“

-1

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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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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.

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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

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ier t red from tideration

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cmetryble ri

r5pa

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1engthem tiipath lenqth. s amp 1then the bas in

ise~ .

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ORS above. Aoply ng eaua-

= :2.9 ma/L

2. The basic eauation developed to predict the resulting dissolved gasconcentrations is:

●

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ETL 1110-2-239 .S5 Sep 78

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-- ---.

SECTION THRU OVERFLOW WEIR ‘“~ ‘SCALE IN FEET