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Combustion of solid fuel slabs with gaseous oxygen in a hybrid motor analogUsing a high-pressure, two-dimensional hybrid motor, an experimental investigation was conducted on fundamental processes involved in hybrid rocket combustion. HTPB (Hydroxyl-terminated- Polybutadiene) fuel cross linked with diisocyanate was burned with GOX under various operating conditions. Large amplitude pressure oscillations were encountered in earlier test runs. After identifying the source of instability and decoupling the GOX feed line system and combustion chamber, the pressure oscillations were drastically reduced from +/- 20% of the localized mean pressure to an acceptable range of +/- 1.5%. Embedded fine-wire thermocouples indicated that the surface temperature of the burning fuel was around 1000 K depending upon axial locations and operating conditions. Also, except near the leading-edge region, the subsurface thermal wave profiles in the upstream locations arc thicker than those in the downstream locations since the solid-fuel regression rate, in general, increases with distance along the fuel slab. The recovered solid fuel slabs in the laminar portion of the boundary layer exhibited smooth surfaces, indicating the existence of a liquid melt layer on the burning fuel surface in the upstream region. After the transition section, which displayed distinct transverse striations, the surface roughness pattern became quite random and very pronounced in the downstream turbulent boundary-layer region. Both real time X-ray radiography and ultrasonic pulse-echo techniques were used to determine the instantaneous web thicknesses and instantaneous solid-fuel regression rates over certain portions of the fuel slabs. Globally averaged and axially dependent but time-averaged regression rates were also obtained and presented. Several tests were conducted using, simultaneously, one translucent fuel slab and one fuel slab processed with carbon black powder. The addition of carbon black did not affect the measured regression rates or surface temperatures in comparison to the translucent fuel slabs.
Document ID
19960023633
Acquisition Source
Marshall Space Flight Center
Document Type
Conference Paper
Authors
Chiaverini, Martin J.
(Pennsylvania State Univ. University Park, PA United States)
Harting, George C.
(Pennsylvania State Univ. University Park, PA United States)
Lu, Yeu-Cherng
(Pennsylvania State Univ. University Park, PA United States)
Kuo, Kenneth K.
(Pennsylvania State Univ. University Park, PA United States)
Serin, Nadir
(Pennsylvania State Univ. University Park, PA United States)
Johnson, David K.
(Pennsylvania State Univ. University Park, PA United States)
Date Acquired
August 17, 2013
Publication Date
October 1, 1995
Publication Information
Publication: 32nd JANNAF Combustion Subcommittee Meeting
Subject Category
Inorganic And Physical Chemistry
Accession Number
96N26325
Funding Number(s)
CONTRACT_GRANT: NAS8-39945
Distribution Limits
Public
Copyright
Other

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