Browsing by Author "Broca, Olivier"
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Item Open Access Application of model based systems engineering for the conceptual design of a hybrid-electric Atr 42-500: from system architecting to system simulation(American Society of Mechanical Engineers, 2021-01-11) Cappuzzo, Federico; Broca, Olivier; Vouros, Stavros; Roumeliotis, Ioannis; Scullion, CalumThe progress in aerospace technology over the recent years led to the development of more sophisticated and integrated systems. To cope with this complexity, the aerospace industry is seeing a progressive trend towards adopting Model-Based Systems Engineering (MBSE) in various stages of the product development cycle. The ability to capture emerging behavior, mitigation of risk and improved communication among different stakeholders are some key benefits that MBSE provides over traditional methods for complex systems and processes. This paper attempts to bridge the gap between system architecting and system simulation activities by proposing a methodology to facilitate seamless flow of information between the two development aspects. This methodology was applied to the development of a parallel hybrid-electric version of the ATR 42–500. The use case was designed for a regional mission of 400 nautical miles with the ability to meet regulation requirement of carrying enough reserves for landing at an alternate airport. An integrated systems model, consisting of gas turbine engine, electric powertrain, and flight dynamics, was developed with Simcenter Amesim to analyze the dynamics performance of the aircraft throughout the whole mission. The key metrics evaluated were fuel consumption, take-off weight and the Energy Specific Air Range (ESAR) of the aircraft. As environmental regulations are becoming more stringent, pollutant and noise emissions were considered in the study. The most promising hybrid configurations are recognized, the potential benefits are quantified highlighting the strong potential of System Architecting and System Simulation to provide valuable insights early in the development cycle, reducing the time and cost of product development.Item Open Access Assessment of engine operability and overall performance for parallel hybrid electric propulsion systems for a single-aisle aircraft(American Society of Mechanical Engineers, 2022-01-04) Kang, Sangkeun; Roumeliotis, Ioannis; Zhang, Jinning; Broca, Olivier; Pachidis, VassiliosThis paper aims to assess the gas turbine operability and overall hybrid electric propulsion system (HEPS) performance for a parallel configuration applied to a 150 passenger single-aisle aircraft. Two arrangements are considered: one where the low-pressure (LP) shaft is boosted and one where the high-pressure (HP) shaft is boosted. For identifying limits in the hybridization strategy, steady-state and transient operation are considered, and the hybridization effect on compressor operability is determined. Having established the electric power on-take limits with respect to gas turbine operation, the systems performance at aircraft level is quantified for the relevant cases. Different power management strategies (PMS) are applied for the two arrangements and for different power degrees of hybridization. The results indicate that despite the fact that pollutant emission and fuel consumption may improve for hybrid propulsion, this comes at the cost of reduced payload and operability margins. Boosting the LP shaft may give the highest engine performance benefits but with a significant weight penalty, while the LP compressor system operability is negatively affected. On the other hand, boosting the HP shaft provides lower engine performance benefits but with smaller weight penalty and with less operability concerns.Item Open Access Assessment of thermo-electric power plants for rotorcraft application(ASME, 2019-10-01) Roumeliotis, Ioannis; Mourouzidis, Christos; Zafferetti, Mirko; Deniz, Unlu; Broca, Olivier; Pachidis, VassiliosThis paper assesses a parallel electric hybrid propulsion system utilizing simple and recuperated cycle gas turbine configurations. An adapted engine model capable to reproduce a turboshaft engine steady state and transient operation is built in Simcenter Amesim and used as a baseline for a recuperated engine. The transient operation of the recuperated engine is assessed for different values of heat exchanger effectiveness, quantifying the engine lag and the surge margin reduction which are results of the heat exchanger addition. An oil and gas mission of a twin engine medium helicopter has been used for assessing the parallel hybrid configuration. The thermo-electric system brings a certain level of flexibility allowing for better engine utilization, thus firstly a hybrid configuration based on simple cycle gas turbine scaled down from the baseline engine is assessed in terms of performance and weight. Following the recuperated engine thermo-electric power plant is assessed and the performance enhancement is compared against the simple cycle conventional and hybrid configurations. The results indicate that a recuperated gas turbine based thermo - electric power plant may provide significant fuel economy despite the increased weight. At the same time the electric power train can be used to compensate for the reduced specific power and potentially for the throttle response change due to the heat exchanger addition.Item Open Access Dynamic simulation of a rotorcraft hybrid engine in Simcenter Amesim(European Rotorcraft Forum, 2018-09-30) Roumeliotis, Ioannis; Nikolaidis, Theoklis; Pachidis, Vassilios; Broca, Olivier; Unlu, DenizThis paper assesses a series hybrid propulsion system utilizing a recuperated gas turbine configuration. An adapted engine model capable to reproduce a turboshaft engine steady state and transient operation is built and used as a baseline for a recuperated engine. The recuperated engine presents a specific fuel consumption improvement of more than 15% at maximum continuous rating at the expense of surge margin which is reduced. An Oil and Gas (OAG) mission of a Twin Engine Medium helicopter has been used for assessing the hybrid configuration. The thermo-electric system brings a certain level of flexibility allowing for the recuperated engine to operate for high take-off weight cases. If envisioned 2025 technology is considered the fuel benefit of the series hybrid recuperated configuration for the OAG mission is in the range of 5%. The integrated system models (gas turbine, electric and heat exchanger systems) are built in Simcenter Amesim, a system modelling platform allowing for both steady state and dynamic simulation.Item Open Access Integrated systems simulation for assessing fuel thermal management capabilities for hybrid-electric rotorcraft(American Society of Mechanical Engineers, 2021-01-11) Roumeliotis, Ioannis; Castro, Lorenzo; Jafari, Soheil; Pachidis, Vassilios; De Riberolles, Louis; Broca, Olivier; Unlu, DenizFuture aircraft and rotorcraft propulsion systems should be able to meet ambitious targets and severe limitations set by governments and organizations. These targets cannot be achieved through marginal improvements in turbine technology or vehicle design. Hybrid-electric propulsion is being widely considered as a revolutionary concept to further improve the environmental impact of air travel. One of the most important challenges and barriers in the development phase of hybrid-electric propulsion systems is the Thermal Management System (TMS) design, sizing and optimization for addressing the increased thermal loads due to the electric power train. The aim of this paper is to establish an integrated simulation framework including the vehicle, the propulsion system and the fuel-oil system (FOS) for assessing the cooling capability of the FOS for the more electric era of rotorcrafts. The framework consists of a helicopter model, propulsion system models, both conventional and hybrid-electric, and a FOS model. The test case is a twin-engine medium (TEM) helicopter flying a representative Passenger Air Transport (PAT) mission. The conventional power plant heat loads are calculated and the cooling capacity of the FOS is quantified for different operating conditions. Having established the baseline, three different Power Management Strategies (PMS) are considered and the integrated simulation framework is utilized for evaluating FOS temperatures. The results highlight the limitations of existing rotorcraft FOS to cope with the high values of thermal loads associated with hybridization for the cases examined. Hence, new ideas and embodiments should be identified and assessed. The case of exploiting the fuel tank as a heat sink is investigated and the results indicate that recirculating fuel to the fuel tank can enhance the cooling capacity of conventional FOS.Item Open Access Performance and emission assessment of thermo-electric power plant for rotorcraft propulsion(American Society of Mechanical Engineers, 2021-01-11) Roumeliotis, Ioannis; Arena, Francesco; Liu, Yize; Vouros, Stavros; Pachidis, Vassilios; Broca, Olivier; Toure, Djiby; Unlu, DenizThis paper assesses a gas turbine based parallel rotorcraft hybrid electric propulsion system in terms of overall performance and emissions. Three different electric power train technology levels and three different power management strategies are considered for identifying the potential benefits of hybridization in relation to technology advancements and quantifying the effect of PMS. For this analysis, a Passenger Air Transport of a twin-engine medium helicopter is used. The propulsion systems mission simulation and emissions calculation are performed in Simcenter Amesim. The assessment framework integrates a thermal power-plant model, an electric power plant model for the hybrid electric cases, a helicopter simulation model and suitable pollutant emissions calculation correlations. For establishing NOx emission correlations that can be used for turboshaft engine calculations, a systematic evaluation of different correlations available in the literature is performed. The correlations are compared for different operating points against a calibrated stirred reactor model. The suitable correlations are utilized in the framework. The propulsion system is sized according to the technology levels and power management strategy considered, updating the helicopter Take-Off Weight for each case. The results indicate that there is potential for efficiency betterment and CO2 emissions reduction. The benefits strongly depend on the power management strategy and energy and power density of the electric power train. For current technology level and for the cases examined herein no benefits in terms of overall performance and emissions accrue. If future technology level is considered, hybridization may offer benefits in terms of performance to the expense of NOx emissions for the case that the power train is used for boosting and the gas turbine is scaled down. Power splitting may offer block fuel, turbine life and NOx benefits to the expense of overall energy performance.