Effect of fuel variables on carbon formation in turbojet-engine combustors Page: 4 of 18
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REPORT 1352---NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS
TABLE IIL--COMPOSITIONS OF ADDITIVE BLENDS
Materials of known composition
-Propyl nitrate .------. --------- 4.12.8.27 0.5,1 . 3-193
Amyl nitate. _ 4. 32,8 68 o0.5, L 0 53-19
Isooctyl nitrate - 4. 52, 9. 08 0. ,1.0 63-193
n-Buty1nitrate._ Technal grade.... 30.9 3.7 55-89
Amnyl nitrite 29.4 Weightercent 28.1 2.76 65-89
nsoamyl nlrte,
70.6 weight-percent
n-amyl nitrite.
2-Nltropropane. Technical grade_._- 30.9 3.5 55-89
NItrobeanoL.._ Technical grade-.- 30.9 4.2 55-89
ter-Butdlhydro- 0 Weght-percent 30. 9 3.1 55-89
peroxide. solution in trt-
butyl alcohol
Diethyl ether.--- Pure grade...----.. 30.9 2-5 55-89
D -zlo ta- 30 Weight-percent ..-.-.-. 050 0 0.0, 53-193
declfn. t- e04,0 05
Cadmium naph- 10 Weight-percent -------. 0.2 53-193
thenate. cadmium.
Lead naphthe- 37 Weight-percent 0.0025, 0.005 52-105
nate. lead. 0 01,0.10
S 0.0025, 0.005 49-221
Tetraethyl lead.. 64 Weight-percent .. 0 00145, 49-224
lead. as0.
Commercial additives =
A_--- - Lead, copper___-- 1.0 0.106. 53-193
0. 50, 1.0 0. 0531, 0.102 63-193
L0 0.1062 54-41
B...-- ------- Copper, cal lum...... tO 0.0982 53-193
0o---_..-- Chromium.--....... - 0.91 0.1000 63-193
D_,_........... Calcium, sodiu......-- 0.25 0.0299 53-193
.25 .0299 51-41
E-----......... Cobalt alt"_..... 06 0.1096 53-193
F- -.... ..---- Lead, cobalt......... LO 0. 0970 53-193
0.05,0.10,0.21 49-162
G..---.-----.... Calcium-- ------..- 0.50,L0 0.048,0.0975 53-193
.. ---. ---...... Leat------ ---..... . . 2.50 0.2 3 53-193
L.......- ..-- ..- Lead ...----------- 2.50 0.266 53-193
J.-..._...,, Lead ._ ----. _,-- 2.50 0.259 53-193
t Composition is result of qualitative spectroscoplo analyses.
III that are of known composition were chosen to represent
a variety of oxygen-bearing organic materials, including four
alkyl nitrates, an alkyl nitrite, two nitro-compounds, a
peroxide, an ether, and a variety of organo-metallic com-
pounds of iron, cadmium, or lead. Two different compounds
of lead were tested, lead naphthenate and tetraethyl lead.
The commercial additives listed in table III varied in their
intended application. They included diesel fuel additives,
gasoline additives, and oil furnace cleaners. None were
developed specifically for turbojet combustor application,
but all were intended to remove or retard carbon and soot
formation resulting from the combustion of low-grade fuels.
In most cases these additives contained only a small concen-
tration of an active ingredient in a fuel-soluble carrier.
They were examined spectroscopically to determine their
principal elemental constituents.
The additive concentrations investigated (table III) were
based on published and unpublished test data obtained from
other laboratories and on recommendations by the manu-
facturers of the additives. In several cases a number ofi'i
FIGURE 1.--Liner and dome of J33 single combustor used in carbon-
deposition investigation.
additive concentrations were investigated; in many cases
the quantity of additive available limited the number of tests
conducted. Since the experiments were made over a period
of years, several different base fuels were employed. The
base fuels were chosen for their high carbon-forming pro-
penaity.
APPARATUS AND PROCEDURE
SINGLE COMBUSTORS
Installation.-The single-combustor tests were conducted
with the J33 liner and dome assembly shown in figure 1.
The liner and dome from a production engine were welded
together to assure consistent alinement of parts in each test.
The facility in figure 2(a) was used for tests at low inlet air
pressure and temperature, and that in figure 2(b) for the
higher inlet air pressure and temperature. The combustor
liner and dome were installed in a housing similar to the J33
combustor housing, except that circular inlet and bxhaust
transition sections were used. Airflow rate and air pressure
in the combustor were controlled by remotely operated
valves in the combustor inlet and outlet ducting. Water-
spray nozzles in the exhaust ducts cooled the gases prior to
their passage through the exhaust control valves.
The desired combustor-inlet air temperature was obtained
by using either electric preheaters (fig. 2(a)) or a gasoline-
fired heat exchanger (fig. 2(b)). The gasoline-fired heat
exchanger consisted of a series of coiled Inconel tubes, con-
nected in parallel, through which the high-pressure air
flowed. The tubes were heated externally, in crossflow, by
combustion gases from an auxiliary turbojet combustor.
Airflow and fuel-flow rates to the combustor were measured
by means of square-edged orifice plates (installed according
to ASME specifications) and calibrated rotameters, re-
spectively.
(a) Low-pressure facility. (b) High-pressure facility.
FIGURm 2.-Single-combustor installation and auxiliary equipment,312
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Jonash, Edmund R.; Wear, Jerrold D. & Cook, William P. Effect of fuel variables on carbon formation in turbojet-engine combustors, report, October 23, 1957; (https://digital.library.unt.edu/ark:/67531/metadc60768/m1/4/: accessed April 23, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.