Studies on propulsion and on-board systems matching in agile project distributed collaborative MDO environment applying for advanced regional and medium haul jet

The article deals with the evaluation of the influences of the electrification of the aircraft On-Board Systems on Propulsion System performance. In particular, four system architectures have been proposed, each one with a different level of electrification. The influences have been also analysed at aircraft level including a regional and a medium haul reference aircraft. The analysis is carried out using the distributed and collaborative MDAO environment developed in the framework of the AGILE research project. At the end, different behaviours have been observed for the two reference aircraft indicating a different trend in systems matching

Battery lifetime of electric vehicles by novel rainflow-counting algorithm with temperature and C-rate dynamics: Effects of fast charging, user habits, vehicle-to-grid and climate zones

The adoption of electric vehicles is expected to soon widespread to cope with energy transition needs; however, concerns on battery lifetime arise, especially related to charging behaviors, vehicle usage habits, vehicle-to -grid and weather conditions. In fact, lifetime battery modeling is a challenging dynamic to characterize, as it involves complex chemical processes related to charging, discharging and temperature dynamics over long time spans that are often difficult to dominate, given the large uncertainties. Having a fatigue-like behavior, the battery aging has sometimes been modeled using rainflow-counting algorithms, yet traditional modeling is not holistic and approximations are used, especially when considering temperature or current dynamics. Based on experimental data, this paper aims at developing a holistic battery degradation model based on rainflow-counting algorithm to properly account for all major determinants of capacity loss, namely cycling usage, calendar lifetime, dynamic temperature and battery current. The approach is coupled with a physical-electro-thermal modeling of the vehicle system, developed in Modelica language, to accurately simulate the intertwined thermal and electrical behavior of the system subject to different usage charging behaviors, including slow and fast charging, as well as vehicle-to-grid application. The proposed case study shows the expected lifetime of electric vehicles to be comparable with of traditional cars (10-20y) and that the proposed temperature -dependent battery modeling enables reducing estimation errors up to 27%. A sensitivity on different climate zones has been considered and results suggest that cool climates can increase life expectancy by 30% with respect to hot climates in typical Italian contexts

A model-based rams estimation methodology for innovative aircraft on-board systems supporting mdo applications

The reduction of aircraft operating costs is one of the most important objectives addressed by aeronautical manufactures and research centers in the last decades. In order to reach this objective, one of the current ways is to develop innovative on-board system architectures, which can bring to lower fuel and maintenance costs. The development and optimization of these new aircraft on-board systems can be addressed through a Multidisciplinary Design Optimization (MDO) approach, which involves different disciplines. One relevant discipline in this MDO problem is Reliability, Availability, Maintainability and Safety (RAMS), which allows the assessment of the reliability and safety of aircraft systems. Indeed the development of innovative systems cannot comply with only performance requirements, but also with reliability and safety constraints. Therefore, the RAMS discipline plays an important role in the development of innovative on-board systems. In the last years, different RAMS models and methods have been defined, considering both conventional and innovative architectures. However, most of them rely on a document-based approach, which makes difficult and time consuming the use of information gained through their analysis to improve system architectures. On the contrary, a model-based approach would make easier and more accessible the study of systems reliability and safety, as explained in several studies. Model Based Systems Engineering (MBSE) is an emerging approach that is mainly used for the design of complex systems. However, only a few studies propose this approach for the evaluation of system safety and reliability. The aim of this paper is therefore to propose a MBSE approach for model-based RAMS evaluations. The paper demonstrates that RAMS models can be developed to quickly and more effectively assess the reliability and safety of conventional and innovative on-board system architectures. In addition, further activities for the integration of the model-based RAMS methodology within MDO processes are described in the paper

ASSESSMENT OF NEW TECHNOLOGIES IN A MULTI-DISCIPLINARY DESIGN ANALYSIS AND OPTIMIZATION ENVIRONMENT INCLUDING RAMS AND COST DISCIPLINES

The aim of the present paper is to assess the effect of new technologies on the whole aircraft product including its costs, reliability and maintainability characteristics. Several studies have been conducted dealing with the preliminary evaluation of Reliability, Availability, Maintainability and Safety (RAMS) of conventional aircraft. They provide a very effective method to preliminary estimate RAMS characteristics but their employment is not completely suitable for the analysis of unconventional configurations adopting new technologies. This paper aims at evaluating how the aircraft costs and RAMS characteristics are affected by new structures material, natural laminar flow wing technology and unconventional actuator system (electro-hydrostatic actuators), hence an update of the state of the art models is needed. This evaluation is performed by means of a setup and execution of a Multidisciplinary Design Analysis and Optimization (MDAO) workflow. The MDAO environment includes the aircraft conceptual design, aircraft performance, structure design, engine design, on-board systems design, RAMS and maintenance cost modules. The RAMS module is used to obtain the failure rates and maintenance effort (in terms of maintenance man hour per flight hour) at subsystem level. The cost module is based on a new maintenance cost model able to estimate the operating cost of the different aircraft variants. The selected new technologies are applied to a regional jet developed within the framework of AGILE research project. For each technology, a different variant of this aircraft is analyzed. Results show that some important saves are reached both in terms of maintenance and fuel cost when new technologies are applied

Fluid-flow pressure measurements and thermo-fluid characterization of a single loop two-phase passive heat transfer device

Abstract A Novel Single Loop Pulsating Heat Pipe (SLPHP), with an inner diameter of 2 mm, filled up with two working fluids (Ethanol and FC-72, Filling Ratio of 60%), is tested in Bottom Heated mode varying the heating power and the orientation. The static confinement diameter for Ethanol and FC-72, respectively 3.4 mm and 1.7mm, is above and slightly under the inner diameter of the tube. This is important for a better understanding of the working principle of the device very close to the limit between the Loop Thermosyphon and Pulsating Heat Pipe working modes. With respect to previous SLPHP experiments found in the literature, such device is designed with two transparent inserts mounted between the evaporator and the condenser allowing direct fluid flow visualization. Two highly accurate pressure transducers permit local pressure measurements just at the edges of one of the transparent inserts. Additionally, three heating elements are controlled independently, so as to vary the heating distribution at the evaporator. It is found that peculiar heating distributions promote the slug/plug flow motion in a preferential direction, increasing the device overall performance. Pressure measurements point out that the pressure drop between the evaporator and the condenser are related to the flow pattern. Furthermore, at high heat inputs, the flow regimes recorded for the two fluids are very similar, stressing that, when the dynamic effects start to play a major role in the system, the device classification between Loop Thermosyphon and Pulsating Heat Pipe is not that sharp anymore

Environmental & flight control system architecture optimization from a family concept design perspective

One method an Original Equipment Manufacturer (OEM) can apply to reduce development and manufacturing costs is family concept design: each product family member is designed for a different design point, but a significant amount of components is shared among the family members. In this case, a trade-off exists between member performance and commonality. In the design of complex systems, often many different architectures are possible, and the design space is too large to explore exhaustively. In this work, we present an application of a new architecture optimization method to the design of a family of passenger transport jets, with a focus on the sizing of the Environmental Control System (ECS) and Flight Control System (FCS). The architecture design space is modeled using the Architecture Design Space Graph (ADSG), a novel method for constructing model-based system architecture optimization problems. Decisions are extracted and the multi-objective optimization problem is automatically formulated. Objectives used are commonality, representing acquisition costs, and fuel burn, representing a part of operation costs. These metrics are evaluated using a cross-organizational collaborative multidisciplinary analysis toolchain, and the resulting Multidisciplinary Design Optimization (MDO) problem is solved using a multi-objective evolutionary optimization algorithm. The results show that the trade-off between commonality and fuel burn is only present above a certain commonality level