LIA: Y-: " t• FTD LIBRARYL~ .i L~4!~ ASEP 12 1969

FTD-HT- 23-290-68

DETERMINATION OF THE EFFECT OF ATMOSPHERIC HUMIDITYON THE CHARACTERISTICS OF A TURBOFAN ENGINE

by

B. D. Fishbeyn and N. V. Pervystin

DEC •'& IS•

"Distribution of this document isunlimited. It may be releasedto the Clearinghouse, Departmentof Commerce, for sale to thegeneral public.

3.eprt4&*d bv

NATIONAL TECHNICALINFORMATION SERVICE

SpI n *IIl ld VI 221II

FTD-HT- 23 -290-65

EDITED TRANSLATION

DETERMINATION OF THE EFFECT OF ASMOSPHERIC HIUMDITY

ON THE CHARACTERISTICS OF A TURBOFAN ENGINE

By: B. D. Fishbeyn and N. V. , Ayshin

English pages: 11

Source: Izvestiya Vysshikh Uchebnykh Zavedeniy.Aviatsionnaya Tekhnika (News of Institutionsof Higher Learning. Aeronautical Engineering).No. 2, 1967, pp. 1±2-iI8.

Translated by: I. Heenan/TDBRS-3

THIS TrhANSLATIGN IS A RENDITION OF THE ORIGI.NAL FOREIGN TEXT WITHOUT ANY ANALYTICAL OREDITORIAL COMMENT. STATEMENTS OR THEORIES PREPARED BY:ADVOCATED OR IMPLIED ARE THOSE OF THE SOURCEAND DO NOT NECESAR'LY REFLECT THE POSITI"N TRANSLATION DIVISIONOR OPINION OF THE FOREIGN TECHNOLOGY 01- FOREIGN TECHNOLOGY DIVISIONVISION. WP.AF9. OHIO.

FTD-HT- 23-29o-bb Date 19

xB

DEERMINATION OF THE EFFECT OF ATMOSPHERIC HUMIDITY

ON THE CHARACTERISTICS OF A TURBOFAN ENGINE.

B. D. Fishbeyn and N. V. Pervyshin

Des ignations

R - engine thrust,

CR - speeific fuel consumption,

n - number of rotor revolutions,GT - fuel consumption,GB - air consumption,

P - pressure,T - temperature,

Gv - amount cf air vapor in humid air,G - amount of air involved in cooling the turbine,Bcool

Rr, RB -- gas ,onstants of combustion products and dry air,

i -- heat content,

Hu - net calorific value of fuel,

nz - combustion efficiency,

Lu - coefficient of peripleral speed,

u - peripheral speed,acr - critical speed of sound,

Cp -heat capacity at constant pressure,

k -- adiabatic index,

,• FTD-HT..23- 290-66

WI pop""

( ý' 7i-gas dynamic function,Xd - moisture content (absolute humidity),

cp - relative humidity.

Ratios of the values for corresponding parameters at a different

humidity to their values at = 0 are indicated by a bar overhead.

Indices

i - engine inlet,* paramete.rs of retE.rded flow,

0 - parameters reduced to conditions of standard atmosphere,

k - parameters behind the compressor.,

r, T - parameters in front of and behind the turbine,

s - parameters of the saturating vapors at a given TH,

hum - humid air (gas),

H - ambient mediu-m.

i. Introduction

The effect of atmospheric humidity on the basic parameters of

Jet engines has- been discussed in literature.

It has been established that in the summer and autumn in the USSR

and during the entire year in the tropics this effect can be quite -•

noticeabfe; therefore, it should be taken intir consideration when

analyzing the characteristics of specific units and the engine as .

whole.

.Basad on data from reference [1], we can assume that the adiabatic

S-efficiency of the comnpressor and the turbine remains virtually the

.same; the force lines on the compressor characteristict plotted in

dimensionless form,. are not displaced.

FTD-iiT-23.-290--938 C2

----------

Engine parameters change only from variations in the properties of

the working substance, namely, its gas constant and adiabatic index.

It usually requires a large amount of calculation and a longperiod of time to take the effect of humidity into account.

The method of calculation presented below for turbofan engines

"makes it possible to reduce considerably the time required while stillpreserving the accuracy necessary for practical use.

A diagram of the engine is shown in Fig. 1.

2. Basic allowances and relationships.

The following assumptions should be made when calculating theeffect of humidity on the prameters of turbofan engines:

i) identical temperature for humid and dry air at engine inlet

T = idem,2) identical coefficient of peripheral speed,3) identical geometry of gas-air tract,

4) self-similarity of all examined regimes of engine operation

based on the Reynolds number.

In accordance with this, the following is valid when the engine

operates in humid air:

reduced number of rotor revolutions-u

reduced air consumption -

(G' 1/: i 0. C+ I "

I ~ A.44~*+I) ()m R.1/,, t" 3, " -2'r-

SFTD-HIT-23-290-68 3

When k varies within the range i. 4 1.32, which corresponds

to T11 - 288 - 3230 K and 9 = 0.0 - 1.0, the ratio q(X)hu, - with1.0wt

sufficient accuracy (errors does not exceed approximately 0.1 - 0.15%). -

Then

"",. V' '. (2)o, ,.

where

k m)k-,.k )

I a . I- I I~ •

Fig .

AA

Flg .. I I 9

asolutc- moisture content -- 4t

Fig.of d on t & d Ti is pres o- A in Fig. 2),

h 1e:!.t -a p i!'c ty O f r h'e -.7i x tu r e - -:

Tu ,ts- 8

"A.

"" -. +-()

gas constant of the mixture -

I R, ,dR -V-W

adiabatic index for the mixture -

k: -- ".----a m -. (6) •

When calculating the processes of compression and expansion,

heat capacity and adiabatic indices are taken for the mean temperatures

of these proceeses.

Fuel consumption through the combustion chamber is found from the

heat-balance equation I

r r

l+d V

S(% - ,,o•, .+ 2 -; • : •'

.... ,--:I -

where CT• P are the average heat capacities of the vapor athere av• pvt

conztarn, tressure, taken at. temperatures TK* P . must

Siece turbine performance curves are uz,,ally plotted for

,:o:iu'.; n products in dry air, when using' them In this case, we must

,.•nslder .the presence of water vapor:

I:

i.',~;,-o

rT (8)m3-u

*q QIMaj~(a. + + ,a ().

here

where 1.0 for the possib_- range k = f (qD, Tf).

Compression and expansion are calculated with the well known "•

equations used in the theory of gas turbine engines (5].

The position of points, showing the joint operation of engine :!

units, on their performance curves is found by the method of successive

approximations while satisfying the equation of continuity in all

sections of the gas-air tract and fulfilling an energy balance.

In other respects, the calculation methodology which takes into

account air humidity does not differ from the usual methods applied

in the theory of gas-turbine engines.

When designing two-contour engines with displacement of the flows

of the internal and cxtirnal contours, we assume that static pressure

in the sections at the mixing chamber inlet is identical for both

contours. Parameters at the end of the mixing chamber'are found fromthe equations of gas flow in a cylindrical tube.

Based on this method we can determine The effect of humidity in

a wide ambient teinpetature ran•ge under various control programs.

FTD-I T-2 -29C -26i8 -

I?

LI

The resualts of calculations bAsed on the effect of humidity on

the parameters of an engine with flow displacement, conducted at

TH 288 - ,33°K and T - 0 - 1.0 for engine operations from 0.4

nominal to take-off performance, have shown that when the following is

"observed at engine inletT•* -- dem , X _ , I - dem

we can represent the variations in the basic parameters in the form of

generalized relationships which are valid throughout the examined

range of TH and q:

fci-g I+a,.d+b,.d',ýT I + +aj-d + bl-W, ,"~~. 1- + a,.d + b,.dI,,(O

I 4.+a4 4 d+b64 -dI (10)fr. I + 1j-d+ bs*dI,

where d absolute humidity. These relationships (10) are represented

in Figs. 3 and 4.

A

T-1to* - . .

zig. 3.V

For a turbofan engine with a full displacement and the degree ofit:; two-contour characteristic - 1.0, the following values for

coefficients a and b are obtained:

...-- 0,6.0•28, 1.0,4882, a03-=--0.3352, 7,-0.2607, A; -- 0,0845,O, 62 0.3828, b3 0.4011. b- -

CLrIO~

Fig. 4.

Thus, when studying the effect of humidity on engine parameters,

it is not necessary to perform numerous and time-consuming calculations.

The method suggested was used in the evaluation of the effect ofhumidity on parameters of turbofan engines with 0 - 4"degrees, of a two-

contour nature, flow displacemeiit, and a separate exhaust in the ranige*gas temperatures in front of the turbine Tr 900 - 14000 abs.

The calculations showed that the numerical values indicated for

coefficients a and b allow the computation of relative parameters withrespect to (10) with an error no greater thani 0.5% for the entirerange of TrI and degrees of the two-contours characteristics for the

* designs of turbofan engines studied.

To achieve the greatest accuracy in determintn.1g relative parameters,we ehould correct the values for coefficients a -ad b in equations -

(0) (Figs. 3 and 4.). For this it is necessary to perform two or*three calculations with different values for absolute humnidity d and

use the derived relationships:

T. f.(d.

FTD-IT-2,3-290-68 8

S7"W. Wý

Generalized rela-k;onships of the type (10) make it possible toplot the throttle characteristics for any q) and TH, based on availableengine throttle characteristics calculated for dry-air operation,and then to study the quantitative effect of humidity under anyprinciple of engine control in the e;xamined conditiono.

As a result of such a stud'?, gr-aphs are plotted showing theeffect of humidity on thrust, specific fuel consumption, and otherparameters, as presented in Figs. 5 and 6.

494

-I-A

Fig. 6.

The graphs in Figt.0 3ad~aeue nth olwn anr

genT 1 adq.The n withh thiido Figs. 3 and 41 are sed on thefolwnmaer

obtained value of d, IT U , Gp nop are determined and

multiplied by the value of the corresponding parameters taken from the

FTD-H!T2325 S9rJ.689

throttle performance curve cf the engine and 3tandard conditions. The

stratification of the throttle performance curve (for example, for

engine thrust) due to the effect of humidity is shown in Fig. 7. 2

We should emphasize that this method and the generalized

relationships (10) can be recommended-for the study of the humidity

effect on parameters of any gas-turbine engine.

10.0

~*1~1i

_. .Cl /i* I•

* " -F g ' "

S3. Conclusions .•

1. General"ied relationships are derived for T o, GB I noa -,ý0fo T' Bo _-

"" f(d), which make it possible to evaluate easily the effect of

humidity on the basic parameters of a turbofan engine.

2. This method can be recommended for use in the study of. any

type of gas-turbine Jet engine.

FTD-HT-23-290-68 10•

References

S"1. Gaygerov, V. I. Vliyaniye svoystv rabochego tela na kharak-..- teristiki tsentrobezhnogo kompressora i gazpvpu turbiny (The effect*. of the properties of the operating medium on The performance curve

of a centrifugal compressor and a gas turbine). M, 1957.

2. Litvin, A. M. Tekhnicheskaya termodina-mika. M.igosenergoizdat. (Technical thermodynamics). 1947.

3. Tablitsy termodinamicheskikh svoystobg gazob. M.gosenergoizdat (Thermodynamics property tables for gnsses). 1953.

4. M;±khaylovskiy, S. A. Termodinamicheskive raschetv Protsessovparogazovykh" smesey M., Tekhizdat (Thermodynamics calculations onprocesses of vapor-gas mixtures). 19b2.(Jet 5. Stechkin, B. S. et ai. Teoriya reaktivnykh dvigateley

engine theory). Ch. 1. Oborongiz, 1958.

Received21 January 1966

F-T2"ii

IoI

FTD-HT-23-29o-68 i