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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.
We have investigated supercritical-p (p > 1192 psi (8.22 MPa)) methanol at pressures up to 1645 psi (11.3 MPa) flowing through a heated tube at flow rates of 4–7 lb/h (1.8–3.2 kg/h). Tube heated lengths have been varied from 4 to 6 in (10 to 15 cm), internal diameters from 0.027 to 0.069 in (0.069 to 0.175 cm), and heat inputs between zero and 800 W. Fluid temperature at the tube inlet remained subcritical (T < 464 °F (513 K)); outlet temperatures were transcritical or supercritical. Two phenomena were observed: system-wide bulk-mode oscillations and localized acoustic modes. In this study, predictive efforts are undertaken to characterize system-wide bulk-mode oscillations. The parameter space has been nondimensionalized, yielding four dimensionless variables. Stability criteria based on these dimensionless groups have been established for two separate test articles and fluids; both criteria suggest that the heat required for the onset of oscillations is proportional to the mass flow rate times the mean pressure and inversely proportional to the fuel density.
Steven A. Hunt; Mario Tindaro Migliorino; Carlo Scalo; Stephen D. Heister. Onset Criteria for Bulk-Mode Thermoacoustic Instabilities in Supercritical Hydrocarbon Fuels. Journal of Fluids Engineering 2021, 143, 1 .
AMA StyleSteven A. Hunt, Mario Tindaro Migliorino, Carlo Scalo, Stephen D. Heister. Onset Criteria for Bulk-Mode Thermoacoustic Instabilities in Supercritical Hydrocarbon Fuels. Journal of Fluids Engineering. 2021; 143 (4):1.
Chicago/Turabian StyleSteven A. Hunt; Mario Tindaro Migliorino; Carlo Scalo; Stephen D. Heister. 2021. "Onset Criteria for Bulk-Mode Thermoacoustic Instabilities in Supercritical Hydrocarbon Fuels." Journal of Fluids Engineering 143, no. 4: 1.
We have investigated one-dimensional compression waves, produced by heat addition in quiescent and uniform initial conditions, in six different supercritical fluids, each taken in four states ranging from compressible pseudo-liquid fluid to ideal gas. Navier–Stokes simulations of a canonical semi-infinite domain flow problem, spanning five orders of magnitude of heating rate, are also carried out to support the theoretical analysis. Depending on the intensity of the Gaussian-shaped energy source, linear waves or shock waves due to nonlinear wave steepening are observed. A new reference heating rate parameter allows to collapse in the linear regime the whole dataset, together with the existing experimental data, thanks to its absorption of real-fluid effects. Moreover, the scaling strategy illustrates a clear separation between linear and nonlinear regimes for all fluids and conditions, offering motivation for the derivation of a unified fully predictive model for shock intensity. The latter is performed by extending the validity of previously obtained theoretical results in the nonlinear regime to supercritical fluids. Finally, thermal to mechanical power conversion efficiencies are shown to be proportional, in the linear regime, to the fluid’s Grüneisen parameter, which is the highest for compressible pseudo-liquid fluids, and maximum in the nonlinear regime for ideal gases.
M. T. Migliorino; C. Scalo. Heat-induced planar shock waves in supercritical fluids. Shock Waves 2019, 30, 153 -167.
AMA StyleM. T. Migliorino, C. Scalo. Heat-induced planar shock waves in supercritical fluids. Shock Waves. 2019; 30 (2):153-167.
Chicago/Turabian StyleM. T. Migliorino; C. Scalo. 2019. "Heat-induced planar shock waves in supercritical fluids." Shock Waves 30, no. 2: 153-167.
We have performed high-order compressible Navier–Stokes simulations of a thermoacoustically unstable resonator employing $\text{CO}_{2}$ in transcritical conditions. The parameter space spans the range of base pressures $p_{0}=1.01-1.5\,p_{cr}$ and temperature differences $\unicode[STIX]{x0394}T=T_{hot}-T_{cold}$ up to 200 K, with thermodynamic and transport properties obtained from the Peng–Robinson equation of state and Chung’s model. The set-up is a classic standing-wave thermoacoustic resonator, which has been optimized resulting in a minimum temperature difference required to sustain the instability of 23 K. Strong real-fluid effects in the thermoacoustic response in the linear regime are observed: (i) the thermoviscous functions need to depend on the complex eigenvalue (and not just the angular frequency) for linear theory to accurately predict the growth rate observed in the Navier–Stokes simulations, due to a high growth-rate-to-frequency ratio; (ii) the growth rate and frequency vary in a non-monotonic fashion with respect to $p_{0}$ and $\unicode[STIX]{x0394}T$ ; (iii) the pressure eigenmode amplitude tends to flatten out, and the pressure–velocity phase difference smoothly transitions from $\unicode[STIX]{x03C0}/2$ to $-\unicode[STIX]{x03C0}/2$ at the average pressure node location; and (iv) the sharp change in base acoustic impedance at transcritical conditions introduces a discontinuity in the eigenmodes’ spatial derivative. The energy budgets illustrate, for a given $\unicode[STIX]{x0394}T$ , the increase of the acoustic power produced, but also of the heat input required, for thermodynamic conditions approaching the critical point. Finally, intense mass transport events at transcritical conditions are shown to entail thermodynamic and convective nonlinearities, which do not, however, govern the limit cycle physics, dominated instead by nonlinear minor losses.
Mario Tindaro Migliorino; Carlo Scalo. Real-fluid effects on standing-wave thermoacoustic instability. Journal of Fluid Mechanics 2019, 883, 1 .
AMA StyleMario Tindaro Migliorino, Carlo Scalo. Real-fluid effects on standing-wave thermoacoustic instability. Journal of Fluid Mechanics. 2019; 883 ():1.
Chicago/Turabian StyleMario Tindaro Migliorino; Carlo Scalo. 2019. "Real-fluid effects on standing-wave thermoacoustic instability." Journal of Fluid Mechanics 883, no. : 1.
Dayle Alexander; Mario Tindaro Migliorino; Stephen Heister; Carlo Scalo. Numerical and Experimental Analysis of a Transcritical Thermoacoustic Prototype. 2018 Fluid Dynamics Conference 2018, 1 .
AMA StyleDayle Alexander, Mario Tindaro Migliorino, Stephen Heister, Carlo Scalo. Numerical and Experimental Analysis of a Transcritical Thermoacoustic Prototype. 2018 Fluid Dynamics Conference. 2018; ():1.
Chicago/Turabian StyleDayle Alexander; Mario Tindaro Migliorino; Stephen Heister; Carlo Scalo. 2018. "Numerical and Experimental Analysis of a Transcritical Thermoacoustic Prototype." 2018 Fluid Dynamics Conference , no. : 1.
Mario Tindaro Migliorino; Jean-Baptiste Chapelier; Carlo Scalo; Guido Lodato. Assessment of spurious numerical oscillations in high-order spectral difference solvers for supercritical flows. 2018 Fluid Dynamics Conference 2018, 1 .
AMA StyleMario Tindaro Migliorino, Jean-Baptiste Chapelier, Carlo Scalo, Guido Lodato. Assessment of spurious numerical oscillations in high-order spectral difference solvers for supercritical flows. 2018 Fluid Dynamics Conference. 2018; ():1.
Chicago/Turabian StyleMario Tindaro Migliorino; Jean-Baptiste Chapelier; Carlo Scalo; Guido Lodato. 2018. "Assessment of spurious numerical oscillations in high-order spectral difference solvers for supercritical flows." 2018 Fluid Dynamics Conference , no. : 1.
Mario Tindaro Migliorino; Prateek Gupta; Carlo Scalo. Real fluid effects on thermoacoustic standing-wave resonance in supercritical CO2. 8th AIAA Theoretical Fluid Mechanics Conference 2017, 1 .
AMA StyleMario Tindaro Migliorino, Prateek Gupta, Carlo Scalo. Real fluid effects on thermoacoustic standing-wave resonance in supercritical CO2. 8th AIAA Theoretical Fluid Mechanics Conference. 2017; ():1.
Chicago/Turabian StyleMario Tindaro Migliorino; Prateek Gupta; Carlo Scalo. 2017. "Real fluid effects on thermoacoustic standing-wave resonance in supercritical CO2." 8th AIAA Theoretical Fluid Mechanics Conference , no. : 1.