This paper introduces the concept of a thermal management system (TMS) with integrated on-board power generation capabilities for a Mach 8 hypersonic aircraft powered by liquid hydrogen (LH2). This ...work, developed within the EU-funded STRATOFLY Project, aims to demonstrate an opportunity for facing the challenges of hypersonic flight for civil applications, mainly dealing with thermal and environmental control, as well as propellant distribution and on-board power generation, adopting a highly integrated plant characterized by a multi-functional architecture. The TMS concept described in this paper makes benefit of the connection between the propellant storage and distribution subsystems of the aircraft to exploit hydrogen vapors and liquid flow as the means to drive a thermodynamic cycle able, on one hand, to ensure engine feed and thermal control of the cabin environment, while providing, on the other hand, the necessary power for other on-board systems and utilities, especially during the operation of high-speed propulsion plants, which cannot host traditional generators. The system layout, inspired by concepts studied within precursor EU-funded projects, is detailed and modified in order to suggest an operable solution that can be installed on-board the reference aircraft, with focus on those interfaces impacting its performance requirements and integration features as part of the overall systems architecture of the plane. Analysis and modeling of the system is performed, and the main results in terms of performance along the reference mission profile are discussed.
This paper discloses the architecture and related performance of an environment control system designed to be integrated within a complex multi-functional thermal and energy management system that ...manages the heat loads and generation of electric power in a hypersonic vehicle by benefitting from the presence of cryogenic liquid hydrogen onboard. A bleed-less architecture implementing an open-loop cycle with a boot-strap sub-freezing air cycle machine is suggested. Hydrogen boil-off reveals to be a viable cold source for the heat exchangers of the system as well as for the convective insulation layer designed around the cabin walls. Including a 2 mm boil-off convective layer into the cabin cross-section proves to be far more effective than a more traditional air convective layer of approximately 60 mm. The application to STRATOFLY MR3, a Mach 8 waverider cruiser using liquid hydrogen as propellant, confirmed that presence of cryogenic tanks provides up to a 70% reduction in heat fluxes entering the cabin generated outside of it but inside the vehicle, by the propulsive system and other onboard systems. The effectiveness of the architecture was confirmed for all Mach numbers (from 0.3 to 8) and all flight altitudes (from sea level to 35 km).
Based on recent research activities, the cost of the propellant may represent up to the 90% of the Direct Operating Cost for a hypersonic vehicle. Therefore, it can be considered the most relevant ...cost item of the overall Life Cycle Cost. In this context, the paper focuses on the estimation of the cost of liquid hydrogen, one of the most promising fuels for high-speed applications, considering its specific energy content. In particular, a methodology is here presented to guide engineers through the evaluation of the impact of the LH
2
price on Direct Operating Cost and then onto the overall Life Cycle Cost for a long-haul point-to-point transportation system. Starting from an overview of the current H
2
productive scenarios, future possible technological improvements allowing an increment of the production rate and a reduction of the related socio-economic impact are described. Then, a detailed cost-estimation model is presented for the so-called “green” hydrogen. Eventually, the developed cost model is applied to the LAPCAT A2 and LAPCAT MR2.4 vehicles and mission concepts, demonstrating that in a future scenario (2050) the LH
2
cost can be lowered down to 2 €/kg. With this fuel price, the share of fuel cost onto Direct Operating Cost can be reduced down to 70%.
Recent studies have revealed that control surface deflection can cause a reduction in the aerodynamic efficiency of a hypersonic aircraft of up to 30%. In fact, the characterization of the Flight ...Control System is essential for the estimation of the consistent aerodynamic characteristics of the vehicle in different phases, considering the contribution of control surfaces to stability and trim. In terms of the sizing process, traditional methodologies have been demonstrated to be no longer applicable to estimations of the actuation power required for the control surfaces of a high-speed aircraft, due to their peculiar working conditions and to the characteristics of the flow to which they are exposed. In turn, numerical simulation approaches based on computational fluid dynamics or panel methods may require considerable time resources, which do not fit with the needs of the quick and reliable estimates that are typical of the early design phases. Therefore, this paper is aimed at describing a methodology to show how to anticipate the Flight Control System design for high-speed vehicles at the conceptual design stage, properly considering the interactions at vehicle level and predicting the behavior of the system throughout an entire mission. It is also a core part of the work to provide designers with an example of how neglecting the effect of trim drag can be detrimental to a reliable estimation of overall aircraft performance. The analysis, mainly focused on the longitudinal plane of the vehicle, is presented step-by-step on a specific case study, namely the STRATOFLY MR3 vehicle, a Mach 8 waverider concept for civil antipodal flights. The application of the methodology, conceived as an initial step towards an iterative Flight Control System design process, also shows that the most power-demanding phases are take-off, low supersonic acceleration, and approach, where peaks of over 130 kW are reached, while an average of 20 kW is sufficient to support deflections in a hypersonic cruise.
The design of integrated and highly efficient solutions for thermal management is a key capability for different aerospace products, ranging from civil aircraft using hydrogen on board to ...miniaturized satellites. In particular, this paper discloses a novel numerical tool for the design and thermal performance assessment of heat pipes. To achieve this goal, a numerical Ansys Parametric Design Language code is set up to verify the effective subtractive heat flux guaranteed by the selected heat pipe arrangement. The methodology and related tool show their ability to provide good thermal performance estimates for different heat pipe designs and operating conditions. Specifically, the paper reports two very different test cases: (1) solid metal heat pipes to cool down the crotch leading-edge area of the air intake of a Mach 8 civil passenger aircraft, and (2) a copper-water heat pipe to cool down a Printed Circuit Board of a generic small LEO satellite. The successful application of the methodology and numerical code confirms the achievement of the ambitious goal of developing in-house tools to support heat pipe thermal performance prediction for the entire aerospace domain.
This paper presents an innovative methodology and tool developed by Politecnico di Torino and the European Space Agency (ESA) to support life cycle cost (LCC) estimation for high-speed transportation ...systems. This ad hoc built-in tool aims at supporting engineers in cost estimations during conceptual and preliminary design phases. This includes the evaluation of research, development, test and evaluation costs (RDTE costs), production costs as well as direct and indirect operating costs (DOC and IOC). Eventually, the results of the LCC evaluation for two different high-speed transport vehicles is provided and discussed.
Managing the lifecycle of the elements of a complex and safety-critical system, from conceptual design to support in operation, is still a relevant challenge in the industrial domain. Starting from ...research and engineering activities, up to production and delivery, the need of maintaining the trace of dependence, changes, and possible updates regarding the final product is a crucial aspect for success. Particularly, conceptual and preliminary design activities are affected by a high level of uncertainty and a certain degree of project instability, usually caused by the need to explore alternative solutions and variants. Different tasks are performed concerning the identification of system requirements, functional and physical behavior using model-based design (MBD), and model-based systems engineering, which, generally, are subjected to extensive trade studies aimed at identifying the best solution. In this context, this paper presents how model-based digital twin and threads concepts will likely change the way in which the MBD process is managed, overcoming the issues associated with federated IT infrastructures and with tools integration. Notably, lifecycle and nonlifecycle related interoperability aspects are described, with particular focus on the exploitation of standards for lifecycle collaboration and heterogeneous simulation. The design of an ice protection system for a regional aircraft is selected as case study, starting from the work performed by the authors within the EC-funded research project CRYSTAL.
Assessing the economic viability of new high-speed systems concepts since the early design phases is crucial for the success of future hypersonic vehicles including cruisers, reusable access-to-space ...and re-entry systems. Besides literature reports few parametric cost models for high-speed vehicles, all of them makes exclusively use of mass as parameter and none of the models moves beyond the vehicle level. This paper describes a new parametric cost estimation model which moves beyond the state-of-the-art methodologies (1) by integrating vehicle design and operational parameters (in addition to the mass) as cost drivers for the prediction of the vehicle life-cycle cost, (2) by introducing prediction margins accounting for the uncertainties on the data-driven correlations, (3) by providing a first estimate of the costs of every on-board subsystem, including combined cycle engines and multi-functional subsystems, (4) by increasing the granularity of the analysis up to technology level, thus providing a valuable support to Technology Roadmaping activities. The parametric cost estimation model has been refined and exploited in the context of the Horizon 2020 STRATOFLY project, where the technological, operational, environmental, and economic viability of a Mach 8 waverider concept have been investigated.
•Innovative RDTE&PROD cost estimation methodology for civil high-speed vehicle.•New parametric equations using vehicle design and operational parameters as drivers.•Costs predictions at subsystems level including complex multi-functional subsystems.•Cost estimation as valuable support to technology roadmapping activities.•Technology Readiness Level as new cost driver for the RDTE cost of vehicles.
Embedded propulsion systems will allow future hypersonic aircraft to reach amazing levels of performance. However, their peculiar small-radius air-intake leading edges pose serious challenges from ...the aerothermodynamic, design, integration, and manufacturing standpoints. This paper discloses the methodology developed in the framework of the H2020 STRATOFLY project and specifically tailored to support the conceptual and preliminary design phases of future high-speed transportation systems. The methodology implements an incremental approach which includes multi-fidelity design, modelling and simulation techniques. The specific application to the MR3, a Mach 8 waverider configuration with an embedded dorsal mounted propulsive subsystem, is reported. Different alternative solutions have been thoroughly analysed, including five liquid metals as fluids (Mercury, Caesium, Potassium, Sodium and Lithium) and relative wick and case materials (Steel, Titanium, Nickel, Inconel® and Tungsten) and three leading-edges materials (CMC, Tungsten with low emissivity painting and Tungsten with high emissivity painting). The analysis of the heat transfer limits (the capillary, entrainment, viscosity, chocking and boiling limits) carried out for all five fluids and relative compatible materials, together with a more accurate FEM analysis, suggest the adoption of a Nickel–Potassium liquid metal heat pipe completely integrated in a platelet air-intake leading edge made of CMC material. Ultimately, the effectiveness of the adopted solution throughout all mission phases has been verified with a detailed numerical model, built upon an electrical analogy.
•Liquid Metals Heat-Pipe solution for hypersonic air-intake leading edge.•Integrated design methodology with multi-fidelity modelling & simulation techniques.•Application to the STRATOFLY MR3 Mach 8 waverider concept.•Nickel–Potassium liquid metal heat pipe in a CMC platelet air-intake leading edge.•Verification of the effectiveness of the solution throughout all mission phases.
