Numerical and Experimental Investigation of Unidirectional Vortex Injection in Hybrid Rocket Engines

Bellomo, Nicolas; Barato, Francesco; Faenza, Martina; Lazzarin, Marta; Bettella, Alberto; Pavarin, Daniele

doi:10.2514/1.b34506

Cited by 53 publications

(23 citation statements)

References 20 publications

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“…Integrating Eqs. (10) and (11) within the liquid layer and solid layer thicknesses, respectively, and considering the surface energy balance at the melt-layer/solid interface, the steady-state conduction term ' q ss cond can be expressed as: where c l and c s indicate the Figure 1 Para©n wax properties as a function of carbon number: (a) melting enthalpy [3]; (b) critical values [26,27]; and (c) normal boiling (1) and melting (2) temperatures [26,27] melt-layer and solid fuel heat capacities, respectively. The terms -h melt and T m represent the para©n wax melting enthalpy and melting temperature, respectively.…”

Section: Liquefying Fuels (Para©n Wax)mentioning

confidence: 99%

Modeling of gas–surface interface for paraffin-based hybrid rocket fuels in computational fluid dynamics simulations

Bianchi

Nasuti

Delfini

2019

Progress in Propulsion Physics – Volume 11

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Numerical simulations of the flowfield in a hybrid rocket engine are carried out with a multispecies chemically reacting Reynolds-averaged Navier–Stokes (RANS) solver which includes detailed gas–surface interaction (GSI) modeling based on surface mass and energy balances. The oxidizer is gaseous oxygen which is homogeneously fed into single-port cylindrical grains. The modeling of GSI already developed and validated for pyrolyzing fuels such as hydroxyl-terminated polybutadiene (HTPB), is extended to the case of liquefying fuels, such as paraffin wax. A simplified two-step global reaction mechanism is considered for the gas-phase chemistry to model the combustion process inside the chamber. Numerical simulations performed at different gas/melt-layer interface temperatures and oxygen mass fluxes show a considerable increase of fuel regression rate, in the range of 3 up to 5 times, for the liquefying fuel with respect to the pyrolyzing one. Results show that the regression rate enhancement is significant only when the gas/melt-layer interface of the liquefying fuel is close to the melting temperature. At increasing gas/melt-layer interface temperatures, the regression rate decreases following an inverse power law and gets close to that of a pyrolyzing fuel for the same operating conditions. Finally, regression rate behavior at varying oxygen mass flux of liquefying fuels is not substantially altered from that of pyrolyzing fuels as the oxidizer flux exponent remains rather constant.

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Section: Liquefying Fuels (Para©n Wax)mentioning

confidence: 99%

Modeling of gas–surface interface for paraffin-based hybrid rocket fuels in computational fluid dynamics simulations

Bianchi

Nasuti

Delfini

2019

Progress in Propulsion Physics – Volume 11

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“…Pressure-fed systems are more interesting in the context of CISAS activities in the past and the near future. CISAS has been testing hybrid rocket motors since 2007 in pressure regulated and self-press mode mainly using N 2 O as oxidizer and paraffin as fuel 19,20,21 . Paraffin-based hybrid rockets have a great potential for small launcher applications.…”

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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“…Table 3. Reaction rates constants for reactions (9) and (10) Reaction rate A n E a /R, K k f1 [12] 4.9486 x 10 9 0.0 15200 k f2 [33] 2.2400 x 10 6 0.0 5032.7 k b2 [33] 1.1000 x 10 13 -0.97 39456.5…”

Section: Iib Gas Phase Reactionsmentioning

confidence: 99%

Numerical Analysis of Port Diameter Effect on Hybrid Rocket Fuel Regression Rate with Axial Injection

Bianchi¹,

Nasuti

Carmicino

2015

51st AIAA/SAE/ASEE Joint Propulsion Conference

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Numerical simulations of the flowfield in a hybrid rocket motor are carried out with a Reynolds averaged Navier-Stokes solver including detailed gas surface interaction modeling based on surface mass and energy balances. Results are compared with several test data obtained from two dedicated test campaigns conducted with static firings of a laboratoryscaled hybrid rocket in which gaseous oxygen is fed into axisymmetric hydroxyl-terminated polybutadiene cylindrical grains through an axial conical subsonic nozzle. A first numerical rebuilding of all of the firing tests has been performed to validate the model, highlighting its prediction capabilities and modeling limits. Despite the several geometrical simplifications, which allowed relatively modest grid sizes to be used and efficient parametrical analysis to be performed, the presented CFD approach is fairly able to capture the main features of the motor internal ballistics both in terms of average chamber pressure and regression rate trends with oxidizer mass flux and port diameter. Computed flowfields showed the establishment of a significant recirculation region at the motor head end, which promotes propellant mixing, and raises the fuel regression rate. Numerical simulations, supported by the experimental results, demonstrated the main role played by the characteristics of this particular injection configuration in determining the fuel regression rate spatial distribution and trend, and clarified the mechanism for which the port diameter has a direct influence on the fuel regression. Nomenclaturē m = time-averaged mass flow rate, kg/ṡ ω i = species source term in control surface, kg/m 2 · ṡ m = mass blowing rate per unit area, kg/m 2 · ṡ q = heat flux, W/m 2 r = regression rate, m/ṡ w i = species source term in control volume, kg/m 3 · s η = inward (from solid to gas) coordinate normal to surface ρ = density, kg/m 3 D im = effective diffusion coefficient, m 2 /s h = enthalpy, J/kg k = thermal conductivity, W/m · K M = molecular weight of the species, kg/kmole N = number of species p = pressure, N/m 2 T = temperature, K v = velocity component normal to surface, m/s y = mass fraction y + = dimensionless wall distance Subscripts f = fuel i = species s = solid material w = wall Superscripts = average in time and spacê = average in space

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Numerical and Experimental Investigation of Unidirectional Vortex Injection in Hybrid Rocket Engines

Cited by 53 publications

References 20 publications

Modeling of gas–surface interface for paraffin-based hybrid rocket fuels in computational fluid dynamics simulations

Modeling of gas–surface interface for paraffin-based hybrid rocket fuels in computational fluid dynamics simulations

Numerical Investigation of Hybrid Rocket Combustion Chamber Transient Behavior

Numerical Analysis of Port Diameter Effect on Hybrid Rocket Fuel Regression Rate with Axial Injection

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