Laboratory investigation of icing in the carburetor and supercharger inlet elbow of an aircraft engine 5: effect of injection of water-fuel mixtures and water-ethanol-fuel mixtures on the icing characteristics Page: 4 of 12
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NACA MR No. fL28
The procedure and equipment used in these tests are described
in detail in reference 2. In addition, internal-ooolant flows and
temperaturesu were recorded at frequent. intervals. Condition were
established and stabilized at the beginning of each run before the
injection of the internal-coolant aid fuel mxrtures.
The following conditions were held constant during each run: .
Svbgine speed, rpm. . . . . . . . . . . . . . . . . . . . . . 3000
Internal-coolant temperature, Of . . . . . . . . . . . . ,. 40
Carburetor top-deck pressure, inches of mercury absolute . .. . 83
An air flow of approximately 10,703 pounda per hour and a fuel-air
ratio aof 0.08 were established at the beginning of each run.
The following table presents the range of variables used in
Coolant Carburetor- Relative Coolant ratio
air temper- humidity
Water-fuel 0-60 59-100 0-0.81
Water-ethanol - fuel -20-60 58-100 0.20-0.80
RESULTS AND DISCUSSION
Observation through windows in the supercharger inlet elbow and
through the transparent section above the carburetor showed that all
the ice formed in the inlet elbow. Ice formations were first observed
on the center rib below the carburetor. During runs at very severe
icing conditions, ice would continue to form around the impeller
entrance, the injection nozzle, and in the inlet elbow below the
nozzle. Sometimes ice formed on the rotatin hub of the impeller.
Because these runs were made at full throttle, no throttle icing was
encountered and, -as no free water in exceess of saturation was injected
above the carburetor, no impact icing occurred.
Results of icing tests with water-fuel injection and with water-
ethanol - fuel injection are presented in tables I and II, respectively.
The criterion of serious icing has been chosen as a 2-percent reduction
in air flow (reference 1). When water-fuel injection was used, serious
ioing was encountered at carburetor-air (dry-bulb) temperatures below
400 7 and at all relative humidities investigated in these tests. When
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Renner, Clark E. Laboratory investigation of icing in the carburetor and supercharger inlet elbow of an aircraft engine 5: effect of injection of water-fuel mixtures and water-ethanol-fuel mixtures on the icing characteristics, report, December 1945; (digital.library.unt.edu/ark:/67531/metadc61810/m1/4/: accessed November 16, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.