Teresa Donateo, Antonio Ficarella and Claudia Lucia De Pascalis
The purpose of this study is to investigate the optimization of design and energy management in a parallel hybrid-electric powertrain to replace the conventional engine of an…
Abstract
Purpose
The purpose of this study is to investigate the optimization of design and energy management in a parallel hybrid-electric powertrain to replace the conventional engine of an existing tactical unmanned aerial vehicle (UAV) equipped with a Wankel engine with a pre-defined flight mission. The proposed powertrain can work in four different operating modes: electric, thermal, power-assist and charging.
Design/methodology/approach
The power request at propeller axis of each flight segment is used as input for an in-house model that calculates the overall fuel consumption throughout the mission (Mfuel) and the maximum payload weight (Wpay) by means of an average-point analysis. These outputs depend on the energy management strategy that is expressed by the power-split ratio between engine and electric phase (Uphase) of each mission phase, according to which the components of the hybrid system are sized. The in-house model is integrated into an optimization framework to find the optimal set of Uphase and battery size that minimizes Mfuel and maximizes Wpay.
Findings
It was found a 3.24% saving of the fuel mass burned throughout the mission (or, alternative an improvement of endurance by 4.3%) with about the same maximum-payload mass (+0.2%) of the original configuration, or a smaller fuel saving with +11% more payload. The fuel saving of 3.24% corresponds to −3.25% in total emissions of CO2 and a 2.34% reduction of the cost-per-mission.
Practical implications
This study demonstrates that environmental advantages, even if limited, can be already obtained from optimal design and management of the hybrid power system with today technologies while waiting for further benefits from the introduction of advanced technologies for batteries and electric machines.
Originality/value
The main novelties are the design of the powertrain on the basis of the energy management and the application of scalability and hybridization to Wankel engines.
Details
Keywords
Teresa Donateo, Antonio Ficarella and Luigi Spedicato
This paper addressed some critical issues in the development of hybrid electric powertrains for aircraft and propose a design methodology based on multi-objective optimization…
Abstract
Purpose
This paper addressed some critical issues in the development of hybrid electric powertrains for aircraft and propose a design methodology based on multi-objective optimization algorithms and mission-based simulations.
Design/methodology/approach
Scalable models were used for the main components of the powertrain, namely, the (two stroke diesel) engine, the (lithium) batteries and the (permanent magnet) motor. The optimization was performed with the NSGA-II genetic algorithm coupled with an in-house MATLAB tool. The input parameters were the size of engine, the hybridization degree and the specification of the battery (typology, nominal capacity, bus voltage, etc.). The outputs were electric endurance, additional volume, performance parameters and fuel consumption over a specified mission.
Findings
Electric endurance was below 30 min in the two test cases (unmanned aerial vehicles [UAVs]) but, thanks to the recharging of the batteries on-board, the total electric time was higher. Fuel consumption was very high for the largest UAV, while an improvement of 11 per cent with respect to a conventional configuration was obtained for the smallest one.
Research limitations/implications
The research used a simplified approach for flight mechanics. Some components were not sized in the proposed test cases.
Practical implications
The results of the test cases stressed the importance of improving energy density and power density of the electric path.
Social implications
The proposed methodology is aimed at minimizing the environmental impact of aircraft.
Originality/value
The proposed methodology was obtained from the automotive field with several original contributions to account for the aircraft application.
Details
Keywords
Teresa Donateo and Roberto Totaro
The purpose of this paper is to analyze real-world flight data of a piston engine training aircraft collected from an internet-based radar service, along with wind data provided…
Abstract
Purpose
The purpose of this paper is to analyze real-world flight data of a piston engine training aircraft collected from an internet-based radar service, along with wind data provided by a weather forecast model, and to use such data to design a hybrid electric power system.
Design/methodology/approach
The modeling strategy starts from the power demand imposed by a real-world wind-corrected flight profile, where speed and altitude are provided as functions of time, and goes through the calculation of the efficiency of the powertrain components when they meet such demand. Each component of the power system and, in particular, the engine and the propeller, is simulated as a black box with an efficiency depending on the actual working conditions. In the case of hybrid electric power system, the battery charging and discharging processes are simulated with the Shepherd model.
Findings
The variability of power demand and fuel consumption for a training aircraft is analyzed by applying the proposed methodology to the Piper PA-28-180 Cherokee, a very popular aircraft used for flight training, air taxi and personal use. The potentiality of hybridization is assessed by analyzing the usage of the engine over more than 90 flights. A tentative sizing of a hybrid electric power system is also proposed. It guarantees a fuel saving of about 5%.
Originality/value
The scientific contribution and the novelty of the investigation are related to the modeling methodology, which takes into account real-world flight conditions, and the application of hybridization to a training aircraft.