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Pini, M. (author), Giuffré, A. (author), Cappiello, A. (author), Majer, M. (author), Bunschoten, E.C. (author)Modeling non-ideal compressible flows in the context of computational fluid-dynamics (CFD) requires the calculation of thermodynamic state properties at each step of the iterative solution process. To this purpose, the use of a built-in fundamental equation of state (EoS) in entropic form, i.e., s= s(e, ρ), can be particularly cost-effective,...book chapter 2023
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Tosto, F. (author), Wheeler, Andrew (author), Pini, M. (author)In this work, we investigate the sources of dissipation in adiabatic boundary layers of non-ideal compressible fluid flows. Direct numerical simulations of transitional, zero-pressure gradient boundary layers are performed with an in-house solver considering two fluids characterized by different complexity of the fluid molecules, namely air...book chapter 2023
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Fuentes Monjas, B. (author), Head, A.J. (author), de Servi, C.M. (author), Pini, M. (author)This work assessed the accuracy of the SU2 flow solver in predicting the isentropic expansion of Siloxane MM through the converging-diverging nozzle test section of the Organic Rankine Cycle Hybrid Integrated Device (ORCHID) [9]. The expansion is modeled using compressible Euler equations, and assuming adiabatic flow, while the fluid...book chapter 2023
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Giuffré, A. (author), Pini, M. (author)Non-ideal compressible flows exhibit physical behaviors that are quantitatively and qualitatively different than those of a perfect or ideal gas. As such, the classical gas dynamic relationships that can be found on fluid-mechanics textbooks cannot be directly applied to characterize this type of flows. NiceProp is a tool for interactively...journal article 2022
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Agromayor, Roberto (author), Anand, N. (author), Pini, M. (author), O. Nord, Lars (author)Currently, most of the adjoint-based design systems documented in the open literature assume that the fluid behaves as an ideal gas, are restricted to the optimization of a single row of blades, or are not suited to impose geometric constraints. In response to these limitations, this paper presents a gradient-based shape optimization framework...journal article 2022
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Tosto, F. (author), Giuffré, A. (author), Colonna, Piero (author), Pini, M. (author)In this work we examine the flow deviation and its relationship to critical choking, i.e., choking of the meridional component of velocity, in transonic turbine cascades operating with non-ideal compressible flows. To this purpose, a generalized expression of the corrected flow per unit area as a function of both the thermodynamic state and...journal article 2022
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Giuffré, A. (author), Colonna, Piero (author), Pini, M. (author)The impact of size and working fluid on the efficiency, operating range, and axial thrust on bearings is examined for high-speed, oil-free centrifugal compressors. First, the development and validation of a reduced-order model based on scaling principles is documented. Then, the validated compressor model is used to generate design maps for...journal article 2022
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Giuffré, A. (author), Colonna, Piero (author), Pini, M. (author)The environmental control system (ECS) is the largest auxiliary power consumer, i.e, around 75% of non-propulsive power, among the aircraft subsystems. The adoption of a novel ECS architecture, based on an electrically-driven vapor compression cycle system, can enable a twofold increase of coefficient of performance (COP), as compared to the...conference paper 2022
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Scaccabarozzi, R. (author), Martelli, Emanuele (author), Pini, M. (author), de Servi, C.M. (author), Chiesa, Paolo (author), Gatti, Manuele (author)This paper documents a thermo-fluid-dynamic mean-line model for the preliminary design of multistage axial turbines with blade cooling applicable to supercritical CO<sub>2</sub> turbines. Given the working fluid and coolant inlet thermodynamic conditions, blade geometry, number of stages and load criterion, the model computes the stage-by...journal article 2022
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Tosto, F. (author), Lettieri, C. (author), Pini, M. (author), Colonna, Piero (author)Paradigmatic compressible one-dimensional flows provide insights regarding the loss mechanisms of fluid machinery components typical of power and propulsion systems, like turbomachines and heat exchangers. Their performance also depends on the working fluid, thus, on both molecular complexity and thermodynamic state. Four typical flow...journal article 2021
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Sanghera, B.S. (author), Anand, N. (author), Souverein, Louis (author), Penin,, Loıc (author), Pini, M. (author)Axial turbine stages for gas generator cycle type rocket engines typically employ highly-loaded supersonic stator vanes. Consequently, the flow pattern downstream of the vanes is characterized by shock waves which induce high-frequency excitation on the subsequent rotor. For this reason, the optimal design of the stator is crucial in the context...conference paper 2021
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Rubino, A. (author), Colonna, Piero (author), Pini, M. (author)The lack of established optimal design guidelines for turbomachinery operating in the nonideal flow regime (e.g., organic Rankine cycle turbines, CO<sub>2</sub> compressors, compressors for refrigeration systems) demands for effective and efficient automated design methods. Past research work focused on gradient-free methods applied to...journal article 2021
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- Pini, M. (author), de Servi, C.M. (author), Spinelli, Andrea (author), Di Mare, Francesca (author), Guardone, Alberto (author) contribution to periodical 2021
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Leverone, F.K. (author), Cervone, A. (author), Pini, M. (author), Gill, E.K.A. (author)Small satellites with increased capabilities in terms of power and propulsion are being demanded for future missions. This paper addresses an alternative bi-modal solution which consists of a solar thermal propulsion system coupled with a micro-Organic Rankine Cycle system, to co-generate thrust and electrical power. Current literature on bi...journal article 2021
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Agromayor, Roberto (author), Anand, N. (author), Müller, Jens Dominik (author), Pini, M. (author), Nord, Lars O. (author)Turbomachinery design is increasingly carried out by means of automated workflows based on high-fidelity physical models and optimization algorithms. The parametrization of the blade geometry is an essential aspect of such workflows because it defines the design space in which an optimal solution can be found. Currently, parametrization...journal article 2021
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Giuffré, A. (author), Pini, M. (author)The impact of non-ideal compressible flows on the fluid-dynamic design of axial turbine stages is examined. First, the classical similarity equation (CSE) is revised and extended to account for the effect of flow non-ideality. Then, the influence of the most relevant design parameters is investigated through the application of a dimensionless...journal article 2021
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Beltrame, F. (author), Head, A.J. (author), de Servi, C.M. (author), Pini, M. (author), Schrijer, F.F.J. (author), Colonna, Piero (author)This paper reports one of the initial NICFD experiments in the nozzle test section of the ORCHID aimed at providing accurate data for the validation of flow solvers, albeit, at this stage of the research, the focus is limited to inviscid phenomena. Notably, a series of schlieren photographs displaying Mach waves in the supersonic flow of the...conference paper 2021
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Tosto, F. (author), Giuffré, A. (author), Colonna, Piero (author), Pini, M. (author)In this work we examine the behavior of non-ideal compressible swirling flows. Based on a first-principle analysis, we derive a generalized expression of the corrected flow per unit area as function of the isentropic exponent, characteristic Mach numbers, and swirl parameter. The calculated trends of the corrected flow with respect to these...book chapter 2021
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Rubino, A. (author), Vitale, S. (author), Colonna, Piero (author), Pini, M. (author)The possibility of taking into account unsteady flow effects if performing turbomachinery shape optimization is attractive to accurately address inherently time dependent design problems. The harmonic balance method is an efficient solution for computational fluid dynamics problems of turbomachinery characterized by quasi-periodic flows. If...journal article 2020
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Leverone, F.K. (author), Pini, M. (author), Cervone, A. (author), Gill, E.K.A. (author)Small satellites are receiving increased recognition in the space domain due to their reduced associated launch costs and shorter lead time when compared to larger satellites. However, this advantage is often at the expense of mission capabilities, such as available electrical power and propulsion. A possible solution is to shift from the...journal article 2020