Improvements to the Marketability of Hybrid Propulsion Technologies

Kearney, Darren; Joiner, Keith F.; Gnau, Michael; Casemore, Mark

doi:10.2514/6.2007-6144

Cited by 23 publications

(16 citation statements)

References 7 publications

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“…Moreover the will for simplicity characteristic of the hybrid concept favors the choice of the much simpler pressure fed solution. However, it is worth noting that both AMROC and Lockheed Martin began large scale development considering pressure fed rockets while shifting to pump fed in the following 4,5,6,7,8,9 . The same trend has been seen in the liquid field where the "Big dumb booster" concept has been proposed several times 10,11 to decrease cost/complexity but has never reached operation (up to now).…”

Section: Introductionmentioning

confidence: 99%

Numerical Investigation of Hybrid Rocket Combustion Chamber Transient Behavior

Barato

Faenza

Pavarin

et al. 2013

49th AIAA/ASME/SAE/ASEE Joint Propulsion Conference

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Paraffin-based hybrid rockets offer a great potential towards a green, safer, cheaper and more reliable access to space. As for liquids, the pressurization system has a fundamental impact on hybrid rocket motor performances. In particular, unlike liquid rockets, the oxidizer to fuel ratio cannot be directly controlled in a hybrid motor but it is dependent on the complex coupling between oxidizer mass flow (linked to pressurization) and chamber behavior (fuel regression). Pressure-fed circular port hybrid rockets are attractive for their perceived simplicity. In this paper several solutions for the pressurization system of paraffin-based hybrid rocket motors are investigated. A numerical model has been developed in order to determine the main performance parameters of the hybrid motor with time. For this purposes the prediction of oxidizer and fuel mass flows, tank and chamber pressures, thrust and residual gas in the tank is obtained through the modeling of the principal subsystem's behavior. The lumped parameter code is composed by three sub-model linked together: the combustion chamber, the oxidizer tank and the pressurant tank. In the first part of the paper several solutions are investigated like the blowdown mode, the pressure regulated mode, the use of a cavitating venturi, the use of single and multiple orifices, the use of a digital valve, the heating of the pressurant and finally the eventual combustion of the pressurant. For every technique the main aspects/issues are highlighted. In the second part an equivalent model for self-pressurization is presented. It is shown that if proper designed, self-pressurization is a simple, lightweight and high performing solution. However, because of its temperature sensitivity, for optimal performance a good thermal control is required. Nomenclatureregression rate law coefficients A = area D = diameter c v,p = specific heats (at constant volume, pressure) e = specific energy E = energy = throat erosion rate g = gravitational acceleration G = mass flux h = specific enthalpy = mass flow m = rocket mass M = mass L = length = regression rate O/F = oxidizer to fuel ratio c* = characteristic velocity 1 Ph.D. student, University of Padua, CISAS G. Colombo, francesco.barato@studenti.unipd.it, Student Member Joint Propulsion Conferences 2 = expansion ratio = density T = thrust, temperature V = volume V a = valve position p = pressure = heat flow = heat transfer coefficient R = gas constant = ratio of specific heats = efficiency = time constant x = vapor mass fraction s = specific entropy S = entropy v = velocity = tank mass factor subscripts a = ambient c = combustion chamber cv = cavitating venturi ev = evaporated i = initial, interface inj = injection f = final, frontal l = liquid n = nozzle prop = propellant ox = oxidizer fuel = fuel vap = vapor p = port pt = pressurant tank press = presurant s = exit t = tank, throat v = vapor, valve or orifice w = wall

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Section: Introductionmentioning

confidence: 99%

Numerical Investigation of Hybrid Rocket Combustion Chamber Transient Behavior

Barato

Faenza

Pavarin

et al. 2013

49th AIAA/ASME/SAE/ASEE Joint Propulsion Conference

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“…In conventional hybrid combustion using polymeric solid fuel, the low-fuel regression rate is due in part to the decrease of the heat amount from the flame zone to the fuel surface in which the radial blowing of gasified fuel from the solid fuel surface blocks the incoming heat flux [1]. A lot of methods, e.g., the addition of the energetic materials to the fuel or oxidizer, use of fuels with low effective heat of gasification, swirling oxidizer flow, insertion of mechanical devices to increase the turbulent intensity, and increase of the fuel burning surface using a multiport grain have all been proposed for overcoming this intrinsic limit on the regression rate [2][3][4][5][6][7][8]. However, none of these methods is free from shortcomings.…”

mentioning

confidence: 99%

Evaluation of Paraffin–Polyethylene Blends as Novel Solid Fuel for Hybrid Rockets

Kim

Moon

Kim

et al. 2015

Journal of Propulsion and Power

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A novel paraffin-based blends fuel prepared from pure paraffin wax of the alkane family with polyethylene of the alkene family is proposed and tested in a slab motor to visualize the droplet entrainment mechanism followed by a hybrid rocket motor test to analyze its combustion characteristics. The mechanical strength of the proposed blended fuel is investigated by increasing the polyethylene weight percent. The overall regression rate of 5 wt % of polyethylene with 95 wt % of pure paraffin is found to be 3.9 factors higher than that of a pure polyethylene. Improved combustion efficiency under the condition of a similar oxidizer mass flow rate range is achieved with respect to pure paraffin fuel in which performance gain is comparable to that of the SP-1a fuel of Stanford University. Spectrum analysis of the chamber pressure shows no critical instability mode for the range of this study. The blend fuel is found to be comparatively effective for the hybrid rocket fuel in terms of mechanical strength, combustion efficiency, combustion instability, and combustion performance. Nomenclature A f = cross-sectional area of final chamber, m 2 A i = cross-sectional area of initial chamber, m 2 A pf = cross-sectional area of final grain port, m 2 A pi = cross-sectional area of initial grain port, m 2 A t = exhaust nozzle throat area, m 2 a = regression rate coefficient c exp = experimental characteristic velocity, m∕s c theo = theoretical characteristic velocity, m∕s D pf = diameter of final grain port, m D pi = diameter of initial grain port, m G o = time-space-averaged oxidizer mass flux, kg∕m 2 -s H f = height of final slab fuel grain, m H i = height of initial slab fuel grain, m L f = fuel grain length, m _ m ent = entrained mass flux from fuel surface, kg∕m 2 -s _ m o = time-averaged oxidizer mass flow rate, g∕s n = oxidizer mass flux exponent P c = chamber pressure, MPa _ r = time-space-averaged fuel regression rate, mm∕s t b = burning time, s W f = fuel grain width, m α = dynamic pressure exponent β = thickness exponent γ = viscosity exponent η c = efficiency of characteristic velocity μ l = liquid layer viscosity, Pa-s π = surface tension exponent ρ f = fuel grain density, kg∕m 3 σ = surface tension, N∕m

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“…The rocket length L includes the oxidizer tank length. The reduction of the port area makes the ratio L/D worse if the oxidizer tank and grain have the same diameter [30]. On the contrary, if the diameter of the oxidizer tank may be larger that grain diameter, both L is reduced and D augmented thus improving the ratio L/D.…”

Section: Low Fuel Regression Rate Effects In Classical Hresmentioning

confidence: 99%

Approaches to Low Fuel Regression Rate in Hybrid Rocket Engines

Pastrone

2012

International Journal of Aerospace Engineering

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Hybrid rocket engines are promising propulsion systems which present appealing features such as safety, low cost, and environmental friendliness. On the other hand, certain issues hamper the development hoped for. The present paper discusses approaches addressing improvements to one of the most important among these issues: low fuel regression rate. To highlight the consequence of such an issue and to better understand the concepts proposed, fundamentals are summarized. Two approaches are presented (multiport grain and high mixture ratio) which aim at reducing negative effects without enhancing regression rate. Furthermore, fuel material changes and nonconventional geometries of grain and/or injector are presented as methods to increase fuel regression rate. Although most of these approaches are still at the laboratory or concept scale, many of them are promising.

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Improvements to the Marketability of Hybrid Propulsion Technologies

Cited by 23 publications

References 7 publications

Numerical Investigation of Hybrid Rocket Combustion Chamber Transient Behavior

Numerical Investigation of Hybrid Rocket Combustion Chamber Transient Behavior

Evaluation of Paraffin–Polyethylene Blends as Novel Solid Fuel for Hybrid Rockets

Approaches to Low Fuel Regression Rate in Hybrid Rocket Engines

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