CFD Simulation of a Hybrid Rocket Motor with Liquid Injection

Lazzarin, Marta; Faenza, Martina; Barato, Francesco; Bellomo, Nicolas; Colombo, Cisas G.; Pavarin, Daniele; Grosse, Matthias

doi:10.2514/6.2011-5537

Cited by 20 publications

(13 citation statements)

References 5 publications

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“…Commercial codes are not developed and validated for hybrid rockets fluid dynamics simulation; anyway, the numerical/physical models already provided can be used in this kind of applications. Previous works at CISAS 3,4 showed that commercial codes applied to hybrid combustion give reasonable results. Commercial codes are usually robust, easy to use, and off-the-shelf.…”

Section: The Spartan Programmentioning

confidence: 86%

Numerical Investigation of Hybrid Motors for the EU FP7 SPARTAN Program

Lazzarin¹,

Bellomo²,

Faenza³

et al. 2012

48th AIAA/ASME/SAE/ASEE Joint Propulsion Conference &Amp;amp; Exhibit

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The SPARTAN (SPAce exploration Research for Throttleable Advanced eNgine) project is targeted at the development of a soft-lander demonstrator for Mars landing, based on throttleable hybrid rocket engine propulsion technology. Within the project, CISAS "G. Colombo" is in charge of the development of a new advanced CFD code for the hybrid rocket motor unsteady simulation, of other CFD simulations conducted with commercial software to investigate the fluid dynamics of the rockets developed by NAMMO, and of ground fire tests to be conducted at lab-scale. Thus, for the CFD simulations, an Open Source code (OpenFOAM) and a commercial code (Ansys CFX) have been used. The flow field has been investigated in its different aspects, to understand the physics behind the processes of injection and combustion. The main approximations applied to this study when analyzing the flow with commercial codes are steady state analysis and fixed chemistry in the combustion chamber. Both vortex and axial injection have been simulated by means of the CFD: an axial injector has been used for the CISAS lab-scale rocket motor and a vortex injector for the test cases reproducing NAMMO's configurations. Regarding vortex injection, the results highlight that it improves the turbulent mixing between the reactants and pushes the flame near the wall, enhancing the heat flux transmitted and thus the regression rate, thanks to its strong helical flow and centrifugal effects. Further efforts have been oriented to take into consideration regression rate dependency on the wall heat flux: besides injecting a fixed and pre-established fuel mass flow, the latter has been coupled to heat exchange. This study is in a preliminary phase, but the first results show that CFD regression rate as a function of the oxidizer mass flux follows the same trend as predicted by:, with a and n experimentally estimated by NAMMO. Concerning OpenFOAM numerical solver, it provides a transient solution of the flow field, but uses corresponding boundary conditions compared to commercial software, in order to allow a full comparison of the steady state results obtained. The study performed with OpenFOAM is a work in progress. The starting point has been a comparison with the results obtained using commercial CFD, to validate the open source solver and boundary conditions. This comparison has showed that OpenFOAM can predict the experimental results as well as commercial software does. At the moment, a feasibility study is being conducted in order to develop a custom and flexible boundary condition, able to calculate regression rate as a function of the wall heat flux independently on the specific oxidizer/fuel combination. Other studies are also necessary to limit the computational time required by this open source tool.

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Section: The Spartan Programmentioning

confidence: 86%

Numerical Investigation of Hybrid Motors for the EU FP7 SPARTAN Program

Lazzarin¹,

Bellomo²,

Faenza³

et al. 2012

48th AIAA/ASME/SAE/ASEE Joint Propulsion Conference &Amp;amp; Exhibit

Self Cite

View full text Add to dashboard Cite

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“…In the axial injection simulation, the area from which the oxidizer enters the combustion chamber is the whole circumference that generates the cylinder. This has been observed to be a better choice than injection from single channels, comparing the solutions with a simulation with liquid injection and vaporization [16]. In fact, in the axial case the gas flow resulting from droplets evaporation has already a more uniform advancing front at a much lower velocity than the injection one.…”

Section: A Simulation Setupmentioning

confidence: 89%

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

Bellomo

Barato

Faenza

et al. 2013

Journal of Propulsion and Power

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A study on vortex injection in hybrid rocket engines with nitrous oxide and paraffin has been performed. The investigation followed two paths: first, the flowfield was simulated with a commercial computational fluid dynamics code; then, burn tests were performed on a laboratory-scale rocket. The computational fluid dynamics analysis had the dual purpose to help the design of the laboratory motor and to understand the physics underlying the vortex flow coupled with the combustion process compared with axial injection. Vortex injection produces a more diffuse flame in the combustion chamber and improves the mixing process of the reactants, both aspects concurring to increase the c efficiency. A helical streamline develops downstream of the injection region, and the pitch is highly influenced by combustion, which straightens the flow due to the acceleration in the axial direction imposed by the temperature rise. Experimental tests with similar geometry have been performed. Measured performance shows an increase in regression rate up to 51% and a c efficiency that rises from less than 80% with axial injection up to more than 90% with vortex injection. Moreover, a reduction of the instabilities in the chamber pressure has been measured. Nomenclature A t= nozzle throat area a = multiplication coefficient for regression rate G ox = mass flux in combustion chamber L g = grain length M f = mass of burned fuel M m = molar mass _ m tot = mean total mass flow n = exponential coefficient for regression rate O∕F = oxidizer to fuel mass ratio p, pc = pressure, mean chamber pressure R u = universal gas constant r = radial coordinate T = temperature t = time u r , u z , u θ = radial, tangential, and axial velocity z = axial coordinate μ = dynamic viscosity ρ f = density of fuel ρ = density ϕ i , ϕ e , ϕ m = initial, final, and mean diameter of the grain ω = vortex angular velocity

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“…The development of a sophisticated model, in which heat transfer tank and water surface, the dissolution of gases be analyzed theoretically for example by a complex CFD simulation not feasible in the given framework of this work. propellant mass for a hybrid propellant 16 The use of such a diaphragm to reach a high level of turbulence in the grain section demonstrated to enhance combustion efficiency and fuel regression rate [27] [34] [35].…”

Section: F Determination Of Propellant Massmentioning

confidence: 99%

“…The use of such a diaphragm to reach a high level of turbulence in the grain section downstream was [27] [34] [35].…”

Section: Determination Of Propellant Massmentioning

confidence: 99%

Use of Hybrid Rocket Technology for Submarine Emergency Deballasting

Grosse¹,

Bettella²

2011

47th AIAA/ASME/SAE/ASEE Joint Propulsion Conference &Amp;amp; Exhibit

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One of the most effective measures for a rapid return of military submarines to the surface in case of life threatening, hazardous or potentially catastrophic failures is the emergency blowing of the forward main ballast tanks. This can be achieved with various systems. Gas generator based modular emergency blow systems show several advantages compared to designs, which use highly compressed air in terms of specific gas work, mass flow and gas storage density. Operational gas generators for emergency blowing use either a liquid hydrazine monopropellant or a solid propellant consisting of GAP and strontium nitrate for gas generation. An alternative hybrid propellant gas generator is proposed to avoid safety issues, which both operational gas generators types possess. Also the relative free selection of the blow gas composition motivates the use of a hybrid propellant combination. A mass model for a hybrid gas generator is developed using design elements of the hydrazine gas generator and applied to a number of different hybrid propellant combinations. The hybrid propellant mass is determined by use of the assumption that the volume reduction due to heat losses, water condensation and gas dissolution in the ballast tank can be compared for a blow gas that is generated from a solid or a hybrid propellant. The effectiveness of the modeled hybrid gas generator is assessed amongst others by blow system mass, system volume and required gas generator quantity. Comparing these preliminary results to the operational solid and liquid propellant gas generator shows that even a nonoptimized hybrid propellant gas generator system is very probably competitive in terms of mass and volume. Nomenclaturea = regression rate constant p t = tank pressure ADN = ammonium dinitramide R = universal gas constant c* = characteristic velocity r ɺ = fuel regression rate GAP = glycidyl azide polymer T c = combustion temperature G ox = oxidizer mass flux T gas = gas temperature HAN = hydroxylammonium nitrate V ba = ballast tank volume HAP = hydroxylammonium perchlorate V gas = gas volume ∆H f = molar enthalpy of formation v gas = specific gas volume HTPB = hydroxyl-term. polybutadiene V i = initial volume IRFNA = inhibited red fuming nitric acid W gas = gas work M = molar mass w gas = specific gas work 2 m c = combusted mass α = mass flux exponent m cool = water coolant mass Φ = average O/F (oxidizer-to-fuel) ratio m gas = gas mass ρ f = final density m i = initial mass ρ fu = fuel density m pro = propellant mass ρ i = initial density p a = ambient pressure η blow = blowing efficiency p ba = pressure in ballast tank η c* = combustion efficiency p c = chamber pressure gas = gas p f = final pressure exp = experimental p i = initial pressure th = theoretical

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CFD Simulation of a Hybrid Rocket Motor with Liquid Injection

Cited by 20 publications

References 5 publications

Numerical Investigation of Hybrid Motors for the EU FP7 SPARTAN Program

Numerical Investigation of Hybrid Motors for the EU FP7 SPARTAN Program

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

Use of Hybrid Rocket Technology for Submarine Emergency Deballasting

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