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A computational tool able to perform a fast analysis of hybrid rocket engines is presented, describing briefly the mathematical and physical models used. Validation of the code is also shown: 16 different static firing tests available in the open literature are used to compare measured operational parameters such as chamber pressure, thrust, and specific impulse with the code’s output. The purpose of the program is to perform rapid evaluation and assessment on a possible first design of hybrid rockets, without relying on computationally expensive simulations or onerous experimental tests. The validated program considers as benchmark and study case the design of a liquid-oxygen/paraffin hybrid rocket engine to be used as the upper stage of a small launcher derived from VEGA building blocks. A full-factorial parametric analysis is performed for both pressure-fed and pump-fed systems to find a configuration that delivers the equivalent total impulse of a VEGA-like launcher third and fourth stage as a first evaluation. This parametric analysis is also useful to highlight how the oxidizer injection system, the fuel grain design, and the nozzle features affect the performance of the rocket.
Paolo Maria Zolla; Mario Tindaro Migliorino; Daniele Bianchi; Francesco Nasuti; Rocco Carmine Pellegrini; Enrico Cavallini. A Computational Tool for the Design of Hybrid Rockets. Aerotecnica Missili & Spazio 2021, 1 -10.
AMA StylePaolo Maria Zolla, Mario Tindaro Migliorino, Daniele Bianchi, Francesco Nasuti, Rocco Carmine Pellegrini, Enrico Cavallini. A Computational Tool for the Design of Hybrid Rockets. Aerotecnica Missili & Spazio. 2021; ():1-10.
Chicago/Turabian StylePaolo Maria Zolla; Mario Tindaro Migliorino; Daniele Bianchi; Francesco Nasuti; Rocco Carmine Pellegrini; Enrico Cavallini. 2021. "A Computational Tool for the Design of Hybrid Rockets." Aerotecnica Missili & Spazio , no. : 1-10.
Hybrid rockets are considered a promising future propulsion alternative for specific applications to solid or liquid rockets. In order to raise their technology readiness level, it is important to perform predictive numerical simulations of their internal ballistics. The objective of this work is to describe and validate a numerical approach based on Reynolds-averaged Navier–Stokes simulations with sub-models for fluid–surface interaction, radiation, chemistry, and turbulence. Particular attention is given to scale effects by considering two different paraffin–oxygen hybrid rocket engines and a simplified grain evolution approach from the initial to the final port diameter. Moreover, a mild sensitivity of the computed regression rate to paraffin’s melting temperature, surface radiation emissivity, and Schmidt numbers is observed. Results highlight the increasing importance of radiation effects at larger scales and pressures. A numerical rebuilding of regression rate and pressure is obtained with simulations at the time-space-averaged port diameter, producing a reasonable agreement with the available experimental data, but a noticeable improvement is obtained by considering the grain evolution in time.
Mario Migliorino; Daniele Bianchi; Francesco Nasuti. Numerical Simulations of the Internal Ballistics of Paraffin–Oxygen Hybrid Rockets at Different Scales. Aerospace 2021, 8, 213 .
AMA StyleMario Migliorino, Daniele Bianchi, Francesco Nasuti. Numerical Simulations of the Internal Ballistics of Paraffin–Oxygen Hybrid Rockets at Different Scales. Aerospace. 2021; 8 (8):213.
Chicago/Turabian StyleMario Migliorino; Daniele Bianchi; Francesco Nasuti. 2021. "Numerical Simulations of the Internal Ballistics of Paraffin–Oxygen Hybrid Rockets at Different Scales." Aerospace 8, no. 8: 213.
Ground testing of ablative materials aims at providing critical data on the material behavior under hypersonic reentry conditions. This is normally done in plasma wind tunnel facilities. However, non-negligible technical challenges are faced in order to duplicate the real flight conditions, such as inducing the recession of space-relevant ablative materials, which requires sufficiently high inflow total enthalpies, and/or reproducing the actual hypersonic flow velocity, which requires sufficiently high inflow Mach numbers. Often, ground facilities which are providing one requirement are lacking the other one and vice-versa. A possible solution is to use low-temperature ablators in continuous hypersonic blow-down tunnels, where aerodynamic and ablative tests with considerable shape change effects may be performed under reasonably low total temperature conditions and with affordable test durations. These substances are readily available, and they sublimate or ablate in a fashion that can be described fairly accurately by theory. This work has the objective to numerically characterize the shape change of such materials in hypersonic conditions, concurrently providing a validation against literature data and from a dedicated experimental ground test campaign. The numerical procedure relies on ad-hoc mesh generation/evolution strategies taking into account the material shape change, and is based on subsequent steady-state Computational Fluid Dynamics (CFD) computations coupled with a customizable gas-surface interaction wall boundary condition. Preliminary numerical simulations helped the design of the experiments to be carried out in the von Karman Institute (VKI) H-3 hypersonic wind tunnel, in particular for the identification of capsule geometry and size in order to maximize the shape change caused by ablation. Subsequently, camphor is identified as the most suitable low-temperature ablator to be used in the experimental campaign after a thorough analysis of its surface reaction thermodynamics and kinetics. Results from the CFD approach are first compared with a literature experimental test case and then with those of the previously designed experiments, featuring a camphor sub-scale capsule, underlying advantages and limits of the numerical procedure adopted. The obtained numerical and experimental results underline how it is possible to obtain a relevant shape change for relatively small exposure times by using low-temperature ablators in continuous hypersonic blow-down wind tunnels. Hence, results from this work can be used to support the design and sizing of the actual heat shield and the analysis of the capsule’s aerodynamics and stability, accounting for shape change effects, by establishing an appropriate similitude between in-flight and on-ground conditions.
Daniele Bianchi; Mario Tindaro Migliorino; Marco Rotondi; Alessandro Turchi. Numerical Analysis and Wind Tunnel Validation of Low-Temperature Ablators undergoing Shape Change. International Journal of Heat and Mass Transfer 2021, 177, 121430 .
AMA StyleDaniele Bianchi, Mario Tindaro Migliorino, Marco Rotondi, Alessandro Turchi. Numerical Analysis and Wind Tunnel Validation of Low-Temperature Ablators undergoing Shape Change. International Journal of Heat and Mass Transfer. 2021; 177 ():121430.
Chicago/Turabian StyleDaniele Bianchi; Mario Tindaro Migliorino; Marco Rotondi; Alessandro Turchi. 2021. "Numerical Analysis and Wind Tunnel Validation of Low-Temperature Ablators undergoing Shape Change." International Journal of Heat and Mass Transfer 177, no. : 121430.
Numerical analysis of hybrid rocket internal ballistics is carried out with a Reynolds-averaged Navier–Stokes solver integrated with a customized gas–surface interaction wall boundary condition and coupled with a radiation code based on the discrete transfer method. The fuel grain wall boundary condition is based on species, mass, and energy conservation equations coupled with thermal radiation exchange and finite-rate kinetics for fuel pyrolysis modeling. Fuel pyrolysis is governed by the convective and radiative heat flux reaching the surface and by the energy required for the propellant grain to heat up and pyrolyze. Attention is focused here on a set of static firings performed with a lab-scale GOX/HDPE motor working at relatively low oxidizer mass fluxes. A sensitivity analysis was carried out on the literature pyrolysis models for HDPE, to evaluate the possible role of the uncertainty of such models on the actual prediction of the regression rate. A reasonable agreement between the measured and computed averaged regression rate and chamber pressure was obtained, with a noticeable improvement with respect to solutions without including radiative energy exchange.
Daniele Bianchi; Giuseppe Leccese; Francesco Nasuti; Marcello Onofri; Carmine Carmicino. Modeling of High Density Polyethylene Regression Rate in the Simulation of Hybrid Rocket Flowfields. Aerospace 2019, 6, 88 .
AMA StyleDaniele Bianchi, Giuseppe Leccese, Francesco Nasuti, Marcello Onofri, Carmine Carmicino. Modeling of High Density Polyethylene Regression Rate in the Simulation of Hybrid Rocket Flowfields. Aerospace. 2019; 6 (8):88.
Chicago/Turabian StyleDaniele Bianchi; Giuseppe Leccese; Francesco Nasuti; Marcello Onofri; Carmine Carmicino. 2019. "Modeling of High Density Polyethylene Regression Rate in the Simulation of Hybrid Rocket Flowfields." Aerospace 6, no. 8: 88.