Combustion Visualization of Paraffin-Based Hybrid Rocket Fuel at Elevated Pressures

Jens, Elizabeth T.; Chandler, Ashley; Cantwell, Brian; Hubbard, Gill; Mechentel, Flora S.

doi:10.2514/6.2014-3848

Cited by 14 publications

(3 citation statements)

References 11 publications

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“…For HTPB no droplet entrainment was measured and the flame seemed brighter and thicker than for paraffin. Experiments with this setup have been continued by Jens et al (Jens et al, 2014a(Jens et al, , 2014b. They reported unsteady blowing events of paraffin droplets with the tests at higher pressure, slightly above the critical pressure of their paraffin samples.…”

Section: Optical Investigations Of Hybrid Rocket Combustionmentioning

confidence: 91%

Evaluation techniques for optical analysis of hybrid rocket propulsion

Petrarolo

Kobald

2016

JFST

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This article summarizes recent results of data evaluation techniques obtained with optical investigations on the combustion behavior of hybrid rocket fuels. Tests are performed in a 2D slab burner configuration with windows on two sides. Liquefying paraffin-based fuels are tested in combination with gaseous oxygen (GOX). High speed videos of combustion tests are recorded in order to investigate the combustion phenomena of this kind of fuels. Hybrid combustion of liquefying fuels is dominated by transient flow dynamics like Kelvin-Helmholtz instability and vortex shedding, also due to the characteristic turbulent diffusion flame. In order to better evaluate these flow phenomena, characteristic frequencies and wavelengths of the main structures of the flow field and of the combustion flame appearing in the video data have to be found. In this work, a spatial and temporal analysis of these structures is carried out by using two different techniques, applied within an automated video evaluation routine. First of all, the Proper Orthogonal Decomposition (POD) technique is used. Its results deliver linearly uncorrelated variables, which are the principal components of the flow field. This method enables to recognize the main structures of the flow field and the combustion flame appearing in the video data. Secondly, the Independent Component Analysis (ICA) technique is applied to the same data. It is able to search for statistically independent, or as independent as possible, structures hidden in the data. It increases the independence to higher statistical orders with respect to POD. The basis functions found with the ICA are expected to describe the essential structure of the data and to resemble some physical processes involved in the combustion. With both methods it is possible to compute spatial and temporal coefficients, which can be later analyzed by applying a Power Spectral Density (PSD) in order to obtain the excited frequencies and wavelengths during the combustion. Finally, the results of the two methods are compared in order to better understand and interpret them. The results collected so far and the comparison of both techniques show that their application is consistent and useful for the automated evaluation of combustion data. Petrarolo and Kobald, Journal of Fluid Science and Technology, Vol.11, No.4 (2016) fuel grains for high thrust applications. The multiport design increases the residual mass of unburnt fuel and thereby decreases the delivered specific impulse. Instabilities are also more likely with this type of design.Liquefying hybrid rocket fuels were only found recently. Cryogenic solid n-pentane showed regression rates 5-10 times higher than polymeric hybrid fuels (Carrick and Larson, 1995, Larson et al., 1996, DeRose et al., 1997.Paraffin-based fuels, tested at Stanford University, show a 3-5 times higher regression rate at similar mass fluxes compared to polymers , Karabeyoglu, 1998. This is achieved by a different combustion mechanism. Paraffin fuels form a liquid layer on the...

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Section: Optical Investigations Of Hybrid Rocket Combustionmentioning

confidence: 91%

Evaluation techniques for optical analysis of hybrid rocket propulsion

Petrarolo

Kobald

2016

JFST

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“…The current feed system is also different from the 2012 apparatus, details are provided in Ref. 10. The oxidizer mass flow rate for each test is determined from differential pressure transducer measurements across a venturi along with upstream temperature and static pressure measurements.…”

Section: Methodsmentioning

confidence: 99%

Schlieren Imaging of the Combustion of Classical and High Regression Rate Hybrid Rocket Fuels

Jens¹,

Narsai²,

Cantwell³

et al. 2014

50th AIAA/ASME/SAE/ASEE Joint Propulsion Conference

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This paper explores turbulent boundary layer development within a hybrid rocket motor. Schlieren images of the combustion of typical hybrid motor fuels with gaseous oxygen in a slab-burning configuration are presented. The recently upgraded Stanford Combustion Visualization Facility was used to conduct atmospheric pressure tests investigating the combustion of classical fuels such as Hydroxyl-Terminated PolyButadiene (HTPB), High Density PolyEtheylene (HDPE) and polymethyl methacrylate (PMMA) as well as liquefying high regression rate fuels, specifically neat paraffin with blackener. High speed color and schlieren videos were recorded for each test. No drastic change in boundary thickness growth was observed for the different fuels in the range of mass fluxes studied.

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“…The main valve for oxygen has been measured to open in under a third of a second, and close in about one second. As done previously, 19 the flow within the feed system is choked through an orifice and the flow rate is measured using a venturi. Figure 12 shows the P&ID diagram utilized for the experiments.…”

Section: E Feed Systemmentioning

confidence: 99%

Indirect Heat Flux Measurements at the Nozzle Throat of a Hybrid Rocket Motor

Narsai¹,

Momanyi²,

Venkataraman³

et al. 2015

51st AIAA/SAE/ASEE Joint Propulsion Conference

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Nozzle erosion in hybrid rocket motors is an unsolved problem that poses a hurdle to small-scale and long-burning hybrid rocket motor development. In studying nozzle erosion, it is immediately realized that heat transfer and heat flux into the nozzle material play a significant role in the throat regression phenomena. Furthermore, heat flux measurements at the throat could aid in the validation of CFD models currently being developed by other researchers. The purpose of this paper is to measure and analyze the inner surface heat flux experienced at the nozzle throat of a hybrid rocket motor.

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Combustion Visualization of Paraffin-Based Hybrid Rocket Fuel at Elevated Pressures

Cited by 14 publications

References 11 publications

Evaluation techniques for optical analysis of hybrid rocket propulsion

Evaluation techniques for optical analysis of hybrid rocket propulsion

Schlieren Imaging of the Combustion of Classical and High Regression Rate Hybrid Rocket Fuels

Indirect Heat Flux Measurements at the Nozzle Throat of a Hybrid Rocket Motor

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