Effect of Initial Mixture-Temperature on Burning Velocity of Hydrogen-Air Mixtures With Preheating and Simulated Preburning Page: 4 of 24
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NACA TN 4156
vm mass burning rate, g/(cm2)(sec)
Po density of initial mixture, g/cm3
(P equivalence ratio, fraction of stoichiometric fuel-oxygen ratio
The fuel used in this investigation was electrolytic hydrogen,
stated to be 99.8 percent pure by the supplier. Prepurified nitrogen and
tap water were used to prepare the preburned mixtures. Laboratory service
air containing approximately 0.3 volume percent water was used.
Fuel-air ratio and flame temperature (table I) were calculated by
the method and data of reference 3 on the basis of air containing 20.95
mole percent oxygen (ref. 3, p. 19) with the remainder considered to be
A conventional flow system utilizing critical flow orifices (ref. 4)
was used to meter the gases (hydrogen, air, and nitrogen) to the burner.
Water vapor was introduced by bubbling the mixed gases through water
thermostatically controlled to the desired temperature. A manually opera-
ted solenoid permitted rapid shutoff of fuel and flushing of the fuel
line with nitrogen in the event of flashback.
Burner Tubes and Temperature Control
Two brass burner tubes were used. One bad a 3.00-millimeter inside
diameter and was water-jacketed. This tube was used for runs at 2870 and
3170 K. Its length-to-diameter ratio of about 150 ensured laminar flow.
For the runs at higher temperature a 2.31-millimeter-inside-diameter tube
was used that had a length-to-diameter ratio of about 80. This tube was
wrapped with three individually controlled lengths of asbestos-covered
heating wire to permit regulation of the wall and gas temperatures.
A bare-wire iron-constantan thermocouple was used to monitor gas
temperatures axially at three stations between the port and a point about
7 inches down into the burner. The monitored gas temperatures were
maintained within 150 F of one another.
The apparatus just described sufficed for the simple preheating
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Heimel, Sheldon. Effect of Initial Mixture-Temperature on Burning Velocity of Hydrogen-Air Mixtures With Preheating and Simulated Preburning, report, October 1957; (https://digital.library.unt.edu/ark:/67531/metadc56795/m1/4/: accessed April 19, 2019), University of North Texas Libraries, Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.