Browsing by Subject "Rocket"
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Item End-effects regime study in full-scale and laboratory scale setups(2015-12) Rojo, Raymondo Mendivil, III; Goldstein, David Benjamin, doctor of aeronautics; Tinney, Charles Edmund, 1975-; Ruf, JosephFull-scale launch data from a cluster of three rocket engines employing a Thrust Optimized Parabolic contour nozzle and hot gas was compared with a laboratory-scale representation. The laboratory setups comprised of both three-nozzle and four-nozzle cluster aerodynamically scaled for use with cold gas. The evolving free-shock separated and restricted separated shock flow states seen in the full-scale was reproduced in the laboratory as well as an end-effects regime prior to flowing full. Acoustic pressure waveforms recorded on the base of both vehicles and behind the rocket clusters are analyzed using various statistical metrics as well as time-frequency analysis, along with the influence staggered starts have on these waveforms. Wall pressure data captured near the lip of these nozzles were compared with the acoustics and analyzed for evidence of nozzle interaction. During the end-effects regime, the nozzles produced high intensity loads and steepened waveforms given by raises the overall sound pressure level, and in both the skewness and kurtosis values of the acoustic pressure time derivative. The finding reveals a 3 dB reduction in end-effect regime loads when a stagger was introduce. However, the effects of stagger had neglible influence on the skewness and kurtosis of the acoustic pressure time derivative as they rose to the same levels, thereby demonstrating the intermittence and impulsiveness of the acoustic waveforms that form during rocket engine startup.Item Experimental Techniques for the Study of Liquid Monopropellant Combustion(2012-07-16) Warren, WilliamPropellants based on hydroxylammonium nitrate (HAN) have shown promise as a hydrazine replacement because of their comparably low toxicity, low vapor pressure, high specific impulse and high density. Herein, the recent history of advanced monopropellant research is explored, and new experimental techniques are presented to investigate the combustion behavior of a potential hydrazine replacement propellant. Nitromethane, a widely available monopropellant with a recent resurgence in research, is utilized in the current study as a proof of concept for the newly designed equipment and as a step towards investigating more-advanced, HAN-based monopropellants. A strand bomb facility capable of supporting testing at up to 340 atm was employed, and experiments were performed between 28 atm and 130 atm. Burning rate data for nitromethane are calculated from experiments and a power correlation is established as r(mm/s) = 0.33[P(MPa)]^1.02. A comparison with available literature reveals this correlation to be very much in agreement to other studies of nitromethane. Other physical characteristics of nitromethane combustion are presented. Updates to the facility and new methods to examine the combustion of liquid propellant are described in detail. Special focus is given to procedures and safety information.Item Hybrid Rocket Burning Rate Enhancement by Nano-Scale Additives in HTPB Fuel Grains(2014-12-10) Thomas, James CLow regression rates in hybrid rockets limit their use and capability, but additive aluminum nano-particles represent a possible solution to this problem. In this thesis, aluminum nano-particles were characterized and added to hybrid motor grains to assess their effects on the combustion behavior of hybrid rocket fuel grains. Procedures for the fabrication of 6-inch-long motors with combustion port diameters of 1 cm and 2.54 cm (1 inch) were developed for formulations with and without additive particles. The implementation of commercial aluminum particles at a mass loading of 5% as a burning rate enhancer was assessed on a lab-scale burner. Traditional temporally and spatially averaged techniques were applied to determine the regression rates of plain and aluminized HTPB motors burning in gaseous oxygen. Resistance-based regression sensors were embedded in motor grains and used to determine instantaneous and averaged burning rates. The resistive-based sensors exhibited good accuracy and unique capabilities not achievable with other regression measurement techniques, but still have limitations. The addition of commercial nano-aluminum, with a diameter of 100 nm, to hybrid motors increased the motor surface regression rate for oxidizer mass fluxes in the range of 0-15 g/cm2-s. Future testing will focus on the evaluation of motors containing novel aluminum particles manufactured in situ with the HTPB at a mass loading of 5%, which are expected to perform better than similar commercially aluminized motors.