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Francesco Nasuti - One of the best experts on this subject based on the ideXlab platform.
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pseudo boiling and heat transfer deterioration while heating supercritical liquid Rocket engine propellants
Journal of Supercritical Fluids, 2021Co-Authors: Francesco Nasuti, Marco PizzarelliAbstract:Abstract Heating of liquid propellants used as the coolant in Rocket Engines may lead to undesired phenomena such as pseudo-boiling or heat transfer deterioration under specific conditions. This can be an issue for propellants characterized at the same time by relatively low critical pressure and temperature. Light hydrocarbons, as for instance methane, belong to this family. In the present paper, a critical review is made of the main results obtained by Authors and their coworkers for the present application. Focus is on the correlations and trends inferred by their numerical simulations mainly carried out considering methane as the coolant, perhaps the most challenging one.
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characterization of unsteadiness in an overexpanded planar nozzle
AIAA Journal, 2019Co-Authors: Emanuele Martelli, Francesco Nasuti, Pietro Paolo Ciottoli, L Saccoccio, Mauro Valorani, Matteo BernardiniAbstract:The sea-level startup of Rocket Engines is characterized by the nozzle experiencing a high degree of overexpansion and consequent internal flow separation with a strong unsteady shock-wave/boundary...
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numerical analysis of nozzle material thermochemical erosion in hybrid Rocket Engines
Journal of Propulsion and Power, 2013Co-Authors: Daniele Bianchi, Francesco NasutiAbstract:Ablative materials are commonly used to protect the nozzle metallic housing and to provide the internal contour to expand the exhaust gases in both solid and hybrid Rockets. Because of interaction with hot gas, these materials are chemically eroded during Rocket firing, with a resulting nominal performance reduction. The objective of the present work is to study the erosion behavior of graphite nozzles in hybrid Engines at different operating conditions and compare results with those obtained for solid motors. A main distinctive feature of hybrid engine operating conditions is, in fact, a greater concentration of oxygen-containing combustion products than solid motors. The adopted approach relies on a validated full Navier–Stokes flow solver coupled with a thermochemical ablation model that takes into account heterogeneous chemical reactions at the nozzle surface, rate of diffusion of the species through the boundary layer, ablation species injection in the boundary layer, heat conduction inside the nozzl...
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coupled wall heat conduction and coolant flow analysis for liquid Rocket Engines
Journal of Propulsion and Power, 2013Co-Authors: Marco Pizzarelli, Francesco Nasuti, Marcello OnofriAbstract:Coolant flow modeling in regeneratively cooled Rocket Engines fed with turbo machinery is a challenging task because of the high wall temperature gradient, the high Reynolds number, the high aspect ratio of the channel cross section, and the heat transfer coupling with the hot-gas flow and the solid material. In this study the effect of wall heat conduction on the coolant flow is analyzed by means of coupled computations between a validated Reynolds-averaged Navier–Stokes equations solver for the coolant flowfield and a Fourier’s equation solver for the thermal conduction in the solid material. Computations of supercritical-hydrogen flow in a straight channel with and without coupling with the solid material are performed and compared to understand the role played by the coupling on the coolant flow evolution. Finally, the whole cooling circuit of the space shuttle main engine main combustion chamber is analyzed in detail and discussed for the sake of comparison of results obtained with the present couple...
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analysis of curved cooling channel flow and heat transfer in Rocket Engines
Journal of Propulsion and Power, 2011Co-Authors: Marco Pizzarelli, Francesco Nasuti, Marcello OnofriAbstract:DOI: 10.2514/1.B34163 Coolant-flow modeling in regeneratively cooled Rocket Engines fed with turbomachinery is a challenging task because of the high wall-temperature gradient, the high Reynolds number, the high aspect ratio of the channel cross section,andthecurvedgeometry.Inthepresentstudy,tobettercomprehendtheroleofthethrust-chambershapeof a Rocket engine on the heat exchange, computations of supercritical hydrogen flow in single- and double-curvature channels are carried out. In particular, a parametric numerical analysis of the flow in an asymmetrically heated rectangular channel with a high aspect ratio and various radii of curvature is performed by means of a Reynoldsaveraged Navier–Stokes solver for real fluids, which is validated against experimental data of heated and curvedchannel flow taken from open literature. Results permit the effect of curvature on global heat transfer coefficient, pressure loss, and bulk temperature increase to be quantified.
Marco Pizzarelli - One of the best experts on this subject based on the ideXlab platform.
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pseudo boiling and heat transfer deterioration while heating supercritical liquid Rocket engine propellants
Journal of Supercritical Fluids, 2021Co-Authors: Francesco Nasuti, Marco PizzarelliAbstract:Abstract Heating of liquid propellants used as the coolant in Rocket Engines may lead to undesired phenomena such as pseudo-boiling or heat transfer deterioration under specific conditions. This can be an issue for propellants characterized at the same time by relatively low critical pressure and temperature. Light hydrocarbons, as for instance methane, belong to this family. In the present paper, a critical review is made of the main results obtained by Authors and their coworkers for the present application. Focus is on the correlations and trends inferred by their numerical simulations mainly carried out considering methane as the coolant, perhaps the most challenging one.
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coupled wall heat conduction and coolant flow analysis for liquid Rocket Engines
Journal of Propulsion and Power, 2013Co-Authors: Marco Pizzarelli, Francesco Nasuti, Marcello OnofriAbstract:Coolant flow modeling in regeneratively cooled Rocket Engines fed with turbo machinery is a challenging task because of the high wall temperature gradient, the high Reynolds number, the high aspect ratio of the channel cross section, and the heat transfer coupling with the hot-gas flow and the solid material. In this study the effect of wall heat conduction on the coolant flow is analyzed by means of coupled computations between a validated Reynolds-averaged Navier–Stokes equations solver for the coolant flowfield and a Fourier’s equation solver for the thermal conduction in the solid material. Computations of supercritical-hydrogen flow in a straight channel with and without coupling with the solid material are performed and compared to understand the role played by the coupling on the coolant flow evolution. Finally, the whole cooling circuit of the space shuttle main engine main combustion chamber is analyzed in detail and discussed for the sake of comparison of results obtained with the present couple...
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analysis of curved cooling channel flow and heat transfer in Rocket Engines
Journal of Propulsion and Power, 2011Co-Authors: Marco Pizzarelli, Francesco Nasuti, Marcello OnofriAbstract:DOI: 10.2514/1.B34163 Coolant-flow modeling in regeneratively cooled Rocket Engines fed with turbomachinery is a challenging task because of the high wall-temperature gradient, the high Reynolds number, the high aspect ratio of the channel cross section,andthecurvedgeometry.Inthepresentstudy,tobettercomprehendtheroleofthethrust-chambershapeof a Rocket engine on the heat exchange, computations of supercritical hydrogen flow in single- and double-curvature channels are carried out. In particular, a parametric numerical analysis of the flow in an asymmetrically heated rectangular channel with a high aspect ratio and various radii of curvature is performed by means of a Reynoldsaveraged Navier–Stokes solver for real fluids, which is validated against experimental data of heated and curvedchannel flow taken from open literature. Results permit the effect of curvature on global heat transfer coefficient, pressure loss, and bulk temperature increase to be quantified.
Thomas Sattelmayer - One of the best experts on this subject based on the ideXlab platform.
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interaction of combustion with transverse velocity fluctuations in liquid Rocket Engines
Journal of Propulsion and Power, 2015Co-Authors: Thomas Sattelmayer, Martin Schmid, Moritz SchulzeAbstract:The verification of thermoacoustic stability is one of the most essential steps in the framework of the development of liquid Rocket Engines. In hybrid methods, which allow fast and detailed evaluation of the flame/acoustics interaction, the simulation of wave propagation is separated from the analysis of flame response to acoustic perturbations. This requires a feedback model for the interaction of combustion and acoustics. Transverse modes, which are particularly prone to combustion instabilities due to their low nozzle damping, are dominated by velocity fluctuations in the transverse direction. The interaction of these fluctuations with the combustion process in liquid Rocket Engines is numerically studied in the paper, employing a Rocket engine configuration with hypergolic propellants as an example. It is shown that the fluctuations lead to major changes in the mean flow near the injector as evaporation and mixing are accelerated. Furthermore, the study reveals that the displacement of the flame cent...
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stability behaviour of a cylindrical Rocket engine combustion chamber operated with liquid hydrogen and liquid oxygen
EUCASS, 2013Co-Authors: Stefan Groning, Dmitry Suslov, Michael Oschwald, Thomas SattelmayerAbstract:High frequency combustion instabilities in liquid propellant Rocket Engines are investigated using a subscale Rocket engine with the propellant combination hydrogen/oxygen at representative conditions. It has been demonstrated in previous test runs with this combustion chamber that it shows self-excited high frequency combustion instabilities at specific operating conditions with gaseous hydrogen at a temperature of 115 K. In order to investigate the effect of the hydrogen temperature, this analysis has been expanded to test runs with liquid hydrogen. It is shown that the hydrogen temperature has a significant influence on the acoustic behaviour of the combustion chamber and therefore on the observed instabilities.
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simulation of combustion instabilities in liquid Rocket Engines with acoustic perturbation equations
Journal of Propulsion and Power, 2009Co-Authors: J Pieringer, Thomas Sattelmayer, Felix FasslAbstract:The authors present a new method for predicting combustion instabilities in liquid Rocket Engines. This method is based on the solution of the linearized governing equations for a three-dimensional combustor geometry in the time domain. The aim of this paper is to show the general feasibility of the approach and to explain the general behavior of the model. The computational domain comprises the combustion chamber itself and the convergent part of the nozzle. The heat release is included via a source term in the linearized energy equation. In the example of the European Aestus engine, it is shown that the model is able to predict the different oscillation modes without any preliminary assumptions about them. An analysis of the influence of the nozzle illustrates that its behavior is automatically included in the approach by design. In comparison to the solution of the full Navier―Stokes equations, the method has the advantage of a much lower numerical cost.
Hendrick P - One of the best experts on this subject based on the ideXlab platform.
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Role of precombustion chamber design in feed-system coupled instabilities of hybrid Rockets
'American Institute of Aeronautics and Astronautics (AIAA)', 2020Co-Authors: Lee J, Bertoldi Aedm, Andrianov A, Ra Borges, Veras Cag, Battistini Simone, Morita T, Hendrick PAbstract:Oxidizer feed-system coupled instabilities have been observed in several liquid and hybrid propellant Rocket Engines, although they are not likely to be catastrophic for the latter. However, severe pressure oscillation in hybrid Rocket may result in a significant reduction in the performance of the propulsion system restricting the application of the technology. In this research, feed-system coupled instabilities were studied theoretically and experimentally for hybrid Rocket Engines. Two test campaigns were performed to investigate the effects of the precombustion chamber and oxidizer injector configurations on engine pressure oscillation. Then, an extended mathematical formulation (including the injector pressure drop, the precombustion chamber residence time, the gas residence time, and the combustion time lag) has been proposed. The investigation was based on a transfer function using the stability limit analysis and the root locus method. It has been found that the configuration of the precombustion chamber plays an important role in the nature of the feed-system coupled instabilities, and a correlation was proposed to predict the fundamental frequency based on the oxidizer precombustion chamber residence time. The work has shown that the precombustion chamber length and the oxidizer injection velocity are key parameters that affect the period of the pressure oscillations in hybrid Engines subjected to feed-system coupled instabilities
Bernhard Weigand - One of the best experts on this subject based on the ideXlab platform.
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an efficient multi fluid mixing model for real gas reacting flows in liquid propellant Rocket Engines
Combustion and Flame, 2016Co-Authors: Daniel T. Banuti, Volker Hannemann, Klaus Hannemann, Bernhard WeigandAbstract:Abstract This paper introduces a new model for real gas thermodynamics, with improved accuracy, performance, and robustness compared to state-of-the-art models. It is motivated by the physical insight that in non-premixed flames, as encountered in high pressure liquid propellant Rocket Engines, mixing takes place chiefly in the hot reaction zone among ideal gases. We developed a new model taking advantage of this: When real fluid behavior only occurs in the cryogenic oxygen stream, this is the only place where a real gas equation of state (EOS) is required. All other species and the thermodynamic mixing can be treated as ideal. Real fluid properties of oxygen are stored in a library; the evaluation of the EOS is moved to a preprocessing step. Thus decoupling the EOS from the runtime performance, the method allows the application of accurate high quality EOS or tabulated data without runtime penalty. It provides fast and robust iteration even near the critical point and in the multiphase coexistence region. The model has been validated and successfully applied to the computation of 0D phase change with heat addition, and a supercritical reactive coaxial LOX/GH 2 single injector.
