Enrico Cestino | Politecnico di Torino (original) (raw)
Papers by Enrico Cestino
Structural and Multidisciplinary Optimization
Aerospace
CubeSats usually adopt aluminum alloys for primary structures, and a number of studies exist on C... more CubeSats usually adopt aluminum alloys for primary structures, and a number of studies exist on Carbon Fiber Reinforced Plastic (CFRP) primary structures. The internal volume of a spacecraft is usually occupied by battery arrays, reducing the volume available to the payload. In this paper, a CFRP structural/battery array configuration has been designed in order to integrate the electrical power system with the spacecraft bus primary structure. The configuration has been designed according to the modular design philosophy introduced in the AraMiS project. The structure fits on an external face of a 1U CubeSat. Its external side houses two solar cells and the opposite side houses power system circuitry. An innovative cellular structure concept has been adopted and a set of commercial LiPo batteries has been embedded between two CFRP panels and spaced out with CFRP ribs. Compatibility with launch mechanical loads and vibrations has been shown with a finite element analysis. The results...
Aerospace
In the last ten years, different concepts of electric vertical take-off and landing aircrafts (eV... more In the last ten years, different concepts of electric vertical take-off and landing aircrafts (eVTOLs) have been tested. This article addresses the problem of the choice of the best configuration. VTOLs built since the fifties are presented and their advantages, disadvantages, and problems are discussed. Three representative eVTOLs, one for each main configuration, are compared on five main parameters and three reference missions. The parameters are disk loading, total hover time, cruise speed, practical range, and flight time. The performance of the eVTOLs on the urban, extra-urban, and long-range mission is evaluated computing the time and energy required. The results show that the best configuration depends on the mission. The multirotor is more efficient in hover. The vectored thrust jet is more efficient in cruise and has a higher range. The lift + cruise is a compromise.
SAE Technical Paper Series
Aerospace Science and Technology, 2006
Research is being carried out at the Turin Polytechnic University with the aim of designing a HAV... more Research is being carried out at the Turin Polytechnic University with the aim of designing a HAVE/UAV (High Altitude Very-long Endurance/Unmanned Air Vehicle). The vehicle should be able to climb to an altitude of 17-20 km by taking advantage of direct sun radiation and maintaining a level flight; during the night, a fuel cells energy storage system would be used. A computer program has been developed to carry out a parametric study for the platform design. The solar radiation change over one year, altitude, masses and efficiencies of the solar and fuel cells, as well as the aerodynamic performances have all been taken into account. The parametric studies have shown how the efficiency of the fuel and solar cells and mass have the most influence on the platform dimensions. High modulus CFRP has been used in designing the structure in order to minimize the airframe weight. A Blended Wing Body (BWB) configuration of Solar HALE Aircraft Multi Payload & Operation (SHAMPO) with 8 brushless electric motors has been developed, as a result of the parametric study. The BWB solution, compared with conventional designs, seems to provide the best compromise between performance, availability of surfaces for solar-cells, and volume for multi-payload purposes. Several profiles and wing plans have been analyzed using the CFD software Xfoil and Vsaero. The airfoil coordinates at the root and along the wing span as well as the wing planform were optimised to achieve the best efficiency. A FEM analysis was carried out using the Msc/Patran/Nastran code to predict the static and dynamic behaviour of the UAV structure.
Sae International Journal of Aerospace, Sep 17, 2013
2012 Electrical Systems For Aircraft Railway and Ship Propulsion, 2012
ABSTRACT An all-electric General Aviation airplane was realized within the ENFICA-FC program (ENv... more ABSTRACT An all-electric General Aviation airplane was realized within the ENFICA-FC program (ENvironmentally Friendly Inter City Aircraft powered by Fuel Cells - EC funded project coordinated by Prof. Giulio Romeo). The electric-motor-driven two-seat airplane powered by fuel cells was developed and validated by flight-test in May 2010. The airplane represents the first and unique airplane flying in the world. Six test flights were successfully carried out by POLITO. The all-electrical power system was successfully tested during the experimental flights. Take-off and climbing was obtained at power of 35 kW. Level flight was attained at 150 km/h by mean of only a fuel cell power setting. 2.5 hours of effective flight were obtained during flight tests for a total path of 237 km. A new speed world record of 135 km/h and an endurance of 39 min. was established during flights conducted for the FAI Sporting Code Category C (airplane). The excellent results obtained by the flight tests can be considered as a further step in the European and World Aeronautics Science in introducing a completely clean energy (ZERO CO2 EMISSION). At the same time, more theoretical type studies have been carried out in designing an aircraft powered by hydrogen for 10-20 passengers in the regional and intercity sector”. The airplane works on hydrogen, taking advantage of the “fuel cell” technology at present available, to create an aircraft that is able to connect cities through flights while totally eliminating the environmental impact.
Research is being carried out with the aim of designinga Very -Long Endurance Solar Po wered Auto... more Research is being carried out with the aim of designinga Very -Long Endurance Solar Po wered Autonomous Stratospheric UA V. Th is UA V could play the role of a pseudo satellite and could offer the advantage of allowing a more detailed land vision due to its relative closeness to land (17-20 km) at a much lower cost than a real satellite. Two different configurationsare under investigation in order to decide on the best solution that will co mpletely satisfy the a priori imposed constraints. In recent years, the aeronautical co mmun ity has increasingly focused on the design of solar powered platforms and zero emission airplanes; a coupled system (solar array and hydrogen fuel cells) can be used to supply energy throughout the entire day in order to ensure the continuous flight for several months. As known, a fuel cell system requires at least a couple of external tanks for fuel storage. Hydrogen and oxygen are stored using a pressure vessel installed inside the wing. In this way, the stored gases are subjected not only to pressure loads but also to in-flight loads that can abruptly change the optimu m layout required to satisfy regulation requirements. A parametric analysis has been performed to define the optimu m layout and the number of tanks necessary to supply the required power. In addition a genetic algorith m has been used to optimize the laminate layup in order to reduce the weight of the tank and ensure that it can resist without at failing catastrophically.
Several researches are being carried out at the Politecnico di Torino with the aim of designing a... more Several researches are being carried out at the Politecnico di Torino with the aim of designing a high altitude very-long endurance/unmanned air vehicle (HAVE/UAV). Being able to fly in the stratosphere (15-20 km) and with an endurance of about 4 months offers an advan- tage and possibility that is presently not available with conventional aircraft or satellites. A computer program
The Aeronautical Journal, 2004
Nowadays there is a growing request for Very Long Endurance Solar-Powered Autonomous Aircraft (VE... more Nowadays there is a growing request for Very Long Endurance Solar-Powered Autonomous Aircraft (VESPAA) flying at stratospheric altitudes of 17-25 km because they can act as artificial satellites - with the advantage of being much cheaper, closer to the ground, and being able to perform missions that offer greater flexibility. A long experience has been acquired by the Polytechnic of Turin, Department of Mechanical and Aerospace Eng. (POLITO/DIMEAS, Scientific Responsible Prof. G. Romeo) in Design of Solar powered UAV as High Altitude Very long Endurance Platform positioned in the stratosphere and with an endurance of more than six months. Two different configurations are under investigation in order to understand the best solution that completely fulfill the a priori imposed constraints. The main goal is to obtain a structure as light as possible that ensures the capability to resist at loads evaluated from the flight envelope without catastrophic failures. A Genetic Algorithm has been developed to optimize composite laminates subjected to mechanical, thermal and hygroscopic loads. A set of penalty function has been defined in order to guarantee deformations less than the allowable limit and to avoid local or global buckling. A Progressive Ply Failure Analysis code has been developed in order to evaluate the Last Ply Failure Loads of composite laminates. Since, in agreement with international regulations, the structure must be able to resist at ultimate loads without failures for at least three seconds, Genetic Algorithm and PPFA have been coupled in order to optimize the lay-up of each panel that ensure the minimum wing box weight, a proper safety margin from FPF to LPF and respects of the penalty function. In particular, no failure are allowed at limit load while, at ultimate load, each panel must stay under LPF level.
J Aerosp Eng, 2010
The application of fuel-cell technology to aircraft propulsion and/or energy supply is becoming o... more The application of fuel-cell technology to aircraft propulsion and/or energy supply is becoming of great interest for undoubted advantages in terms of pollution emissions and noise, features particularly important for commuter airplanes that usually take off and land from and in urban areas. The conversion of conventional aircraft into more/all-electric one tends to be based on the installation of such innovative systems. A better understanding of problems related to fuel cells applied to aeronautics is sought by the European Commission funded project environmentally friendly intercity aircraft powered by fuel cells ͑ENFICA-FC͒. The main objective of the ENFICA-FC project is to develop and to validate the use of a fuel-cell based power system for propulsion of an all-electric aircraft. The fuel-cell system will be installed in a light sport aircraft ͑Rapid 200͒ that will be flown and performance tested as a proof of functionality and future applicability. Specific aspects have to be investigated in the onboard installation of the innovative system and new design indications have to be pointed out in order to fulfill the conversion. One of the key items under investigation is the simulation of existing cooling system and the evaluation of motor and fuel-cell temperature; the temperature has to be maintained within the limits established by manufacturers of critical systems during all likely operating conditions as indicated by aeronautic regulations for general aviation. The computational problem addressed in this paper is the numerical computational fluid dynamics ͑CFD͒ simulation of the existing air-cooling system that satisfies air request for cooling and venting. An engineering model has been developed and it is used to support air inlet and outlet design. The flow is reasonably approximated by a potential flow plus boundary layer; hence, total upstream pressure losses are neglected except for those within the thin boundary layer. Pressure recovery of incoming cooling air and pressure coefficient distribution have been studied by using VSAERO panel code, and the optimal position of cooling and venting intakes is defined according to aerodynamic results. Propeller effects are included by referring to an optimal propeller specifically designed for the ENFICA-FC project. Propeller slip-stream wake is modeled by an actuator disk plus a swirl membrane and used to study the problem of motor, electronic, and fuel cells' cooling during takeoff.
Journal of Aerospace Engineering, Jul 1, 2012
The application of fuel cell (FC) technology to aircraft propulsion and/or energy supply is becom... more The application of fuel cell (FC) technology to aircraft propulsion and/or energy supply is becoming of great interest for undoubted advantages in terms of pollution emissions and noise reduction. A better understanding of problems related to fuel cells applied to aeronautics is sought by the European Commission (EC) funded project Environmentally Friendly Inter-City Aircraft Powered by Fuel Cells (ENFICA-FC). The main objective of the ENFICA-FC project was to develop and validate the use of a fuel cell-based power system for the propulsion of more-electric/all-electric aircraft. The fuel cell system was installed in the light sport aircraft Rapid 200, which was flight and performance tested. One of the key items under investigation is the simulation of the cooling system and the evaluation of fuel cell temperature. The polymer electrolyte membrane fuel cell (PEMFC) is considered to be the best candidate for the fuel cell vehicle because it has high power density, solid membrane electrolyte, and as it operates at low temperatures, it has a fast start-up. However, to generate a reliable and efficient power response and to prevent membrane degradation or damage with hydrogen and oxygen depletion, a sophisticated control technique becomes vitally important. In particular, as the ionic conduction of the polymeric membrane is a function of its degree of humidification, the stack temperature has to be carefully controlled to avoid phenomena of water evaporation, causing an increase of ohmic drop and a decrease of stack performances. The output voltage and hence the power of the fuel cell system is affected considerably by the change of the stack temperature. A simplified fluid-dynamic model has been developed and validated by computational fluid dynamics (CFD) analysis and it is used to compute the air flow to the fuel cell heat-exchanger inlet. Propeller effects are included referring to an optimal propeller specifically designed for the ENFICA-FC project. A mathematical model of the fuel cell system dynamics coupled with the fluid-dynamic model was studied in detail and experimentally validated during two flight tests of the Rapid 200-FC.
Composite Structures, Apr 1, 2008
Some main activities have been developed as part of the HELINET research project which was financ... more Some main activities have been developed as part of the HELINET research project which was financed in January 2000, by the European Commission, (Fifth Framework Program in the IST action), to develop a European project in the field of stratospheric platforms. From the aeronautical point of view the following items were studied: (1) the design of an autonomous high altitude long-endurance unmanned air vehicle (HALE-UAV) platform capable of remaining aloft for very long periods of time (between 6 and 9 months) using a solar-powered and fuel cell system and to gain a complete understanding of the feasibility of a near-term aerodynamic HALE concept, in particular as far as stratospheric platforms are concerned (mainly dependent on high efficiency and reliability of solar cells, fuel cells and electric motors), (2) an evaluation of the production and service costs and an assessment of the safety and regulatory aspects of the platform, and (3) the manufacturing of a scale-sized technological demonstrator and the execution of static tests on it up to the ultimate load. The first HELIPLAT Ò (HELIos PLATform) configuration was worked out, on the basis of a preliminary parametric study. The platform was a twin-boom tail type monoplane with eight brushless motors, a long horizontal stabilizer and two rudders. A scaled-prototype was designed to demonstrate the feasibility of this configuration and to perform some structural static and dynamic tests on it. The main CFRP structures were manufactured by CASA (Spain): the principal wing and horizontal tail tubular spars, booms, vertical tail spars and some reinforced ribs. These parts were delivered to the Aerospace Engineering Dept. (DIASP) at the Politecnico di Torino (POLITO) and assembled using special joints while some other necessary parts were manufactured by POLITO-DIASP. A parallel activity was performed to define the structural test configurations and structural test frame. The manufacturing activities and the development of the structural test system is described in the first part of the paper. Static and dynamic experimental tests were performed in two phases (2003 and 2004) on the prototype and the results of the static tests are presented in this paper and compared with numerical and theoretical computations.
ABSTRACT Several researches are being carried out at the Politecnico di Torino with the aim of de... more ABSTRACT Several researches are being carried out at the Politecnico di Torino with the aim of designing a high altitude very-long endurance/unmanned air vehicle (HAVE/UAV). Being able to fly in the stratosphere (15--20 km) and with an endurance of about 4 months offers an advantage and possibility that is presently not available with conventional aircraft or satellites. A computer program has been developed to design the platform. The change in solar radiation over a period of a year, the altitude, masses, and efficiencies of the solar and fuel cells, as well as the aerodynamic, structural, flight mechanics, and aeroelastic performances have all been taken into account. Extensive use has been made of high modulus graphite/epoxy when designing the structure in order to minimize the airframe weight, but also to guarantee the required stiffness and aeroelastic performance. A blended wing body (BWB) configuration has been selected for solar HAVE aircraft multi payload and operation (SHAMPO) with eight brushless electric motors, as the result of a preliminary design. The BWB solution has been designed according to the conventional procedures and airworthiness regulations. It seems to be the best compromise between performance, available surfaces for solar cells and volume for multi-payload purposes, compared to conventional design. Several profiles and wing plans have been analysed and optimized to achieve the best efficiency using the Xfoil and Vsaero computational fluid dynamics (CFD) software. A finite-element method and a classical theoretical analysis was carried out using the Msc/Patran/ Nastran code to predict the static and aeroelastic behaviour of the SHAMPO. Aeroelastic analysis has been performed starting with a classical linear flutter analysis and considering an undeformed equilibrium condition. Classical linear flutter speed show as the airworthiness requirements has been achieved in the case of SHAMPO configuration. A preliminary non-linear aeroelastic model is introduced in the design process in order to deal with specific phenomena correlated with high static structural deflections occurring during standard flight conditions. Important flutter speed reduction (i.e. up to 42 per cent in special cases) are possible including such kind of phenomena.
ABSTRACT Fuel cells could become the main power source for small general aviation aircraft or cou... more ABSTRACT Fuel cells could become the main power source for small general aviation aircraft or could replace APU and internal sub-systems on larger aircraft, to obtain all-electric or more-electric air vehicles. There are several potential advantages of using such a power source, that range from environmental and economic issues to performance and operability aspects. A preliminary design is reported. Also, the paper contains a description of testing activities related to experimental flights of an all-electric general aviation aircraft fueled by hydrogen. Great importance has been given to the testing phase of the prototype and examples of each testing stage are shown ranging from the single components to the final test flights. During the 6 experimental flights a rotation speed of 84 km/h was obtained in 184 m of taxi at power of 35 kW. Level flight was attained at 135 km/h and endurance of 39 min by mean of only a fuel cell power setting (speed world record for the FAI Sporting Code Category C – airplane).
SAE Technical Paper Series, 2015
Structural and Multidisciplinary Optimization
Aerospace
CubeSats usually adopt aluminum alloys for primary structures, and a number of studies exist on C... more CubeSats usually adopt aluminum alloys for primary structures, and a number of studies exist on Carbon Fiber Reinforced Plastic (CFRP) primary structures. The internal volume of a spacecraft is usually occupied by battery arrays, reducing the volume available to the payload. In this paper, a CFRP structural/battery array configuration has been designed in order to integrate the electrical power system with the spacecraft bus primary structure. The configuration has been designed according to the modular design philosophy introduced in the AraMiS project. The structure fits on an external face of a 1U CubeSat. Its external side houses two solar cells and the opposite side houses power system circuitry. An innovative cellular structure concept has been adopted and a set of commercial LiPo batteries has been embedded between two CFRP panels and spaced out with CFRP ribs. Compatibility with launch mechanical loads and vibrations has been shown with a finite element analysis. The results...
Aerospace
In the last ten years, different concepts of electric vertical take-off and landing aircrafts (eV... more In the last ten years, different concepts of electric vertical take-off and landing aircrafts (eVTOLs) have been tested. This article addresses the problem of the choice of the best configuration. VTOLs built since the fifties are presented and their advantages, disadvantages, and problems are discussed. Three representative eVTOLs, one for each main configuration, are compared on five main parameters and three reference missions. The parameters are disk loading, total hover time, cruise speed, practical range, and flight time. The performance of the eVTOLs on the urban, extra-urban, and long-range mission is evaluated computing the time and energy required. The results show that the best configuration depends on the mission. The multirotor is more efficient in hover. The vectored thrust jet is more efficient in cruise and has a higher range. The lift + cruise is a compromise.
SAE Technical Paper Series
Aerospace Science and Technology, 2006
Research is being carried out at the Turin Polytechnic University with the aim of designing a HAV... more Research is being carried out at the Turin Polytechnic University with the aim of designing a HAVE/UAV (High Altitude Very-long Endurance/Unmanned Air Vehicle). The vehicle should be able to climb to an altitude of 17-20 km by taking advantage of direct sun radiation and maintaining a level flight; during the night, a fuel cells energy storage system would be used. A computer program has been developed to carry out a parametric study for the platform design. The solar radiation change over one year, altitude, masses and efficiencies of the solar and fuel cells, as well as the aerodynamic performances have all been taken into account. The parametric studies have shown how the efficiency of the fuel and solar cells and mass have the most influence on the platform dimensions. High modulus CFRP has been used in designing the structure in order to minimize the airframe weight. A Blended Wing Body (BWB) configuration of Solar HALE Aircraft Multi Payload & Operation (SHAMPO) with 8 brushless electric motors has been developed, as a result of the parametric study. The BWB solution, compared with conventional designs, seems to provide the best compromise between performance, availability of surfaces for solar-cells, and volume for multi-payload purposes. Several profiles and wing plans have been analyzed using the CFD software Xfoil and Vsaero. The airfoil coordinates at the root and along the wing span as well as the wing planform were optimised to achieve the best efficiency. A FEM analysis was carried out using the Msc/Patran/Nastran code to predict the static and dynamic behaviour of the UAV structure.
Sae International Journal of Aerospace, Sep 17, 2013
2012 Electrical Systems For Aircraft Railway and Ship Propulsion, 2012
ABSTRACT An all-electric General Aviation airplane was realized within the ENFICA-FC program (ENv... more ABSTRACT An all-electric General Aviation airplane was realized within the ENFICA-FC program (ENvironmentally Friendly Inter City Aircraft powered by Fuel Cells - EC funded project coordinated by Prof. Giulio Romeo). The electric-motor-driven two-seat airplane powered by fuel cells was developed and validated by flight-test in May 2010. The airplane represents the first and unique airplane flying in the world. Six test flights were successfully carried out by POLITO. The all-electrical power system was successfully tested during the experimental flights. Take-off and climbing was obtained at power of 35 kW. Level flight was attained at 150 km/h by mean of only a fuel cell power setting. 2.5 hours of effective flight were obtained during flight tests for a total path of 237 km. A new speed world record of 135 km/h and an endurance of 39 min. was established during flights conducted for the FAI Sporting Code Category C (airplane). The excellent results obtained by the flight tests can be considered as a further step in the European and World Aeronautics Science in introducing a completely clean energy (ZERO CO2 EMISSION). At the same time, more theoretical type studies have been carried out in designing an aircraft powered by hydrogen for 10-20 passengers in the regional and intercity sector”. The airplane works on hydrogen, taking advantage of the “fuel cell” technology at present available, to create an aircraft that is able to connect cities through flights while totally eliminating the environmental impact.
Research is being carried out with the aim of designinga Very -Long Endurance Solar Po wered Auto... more Research is being carried out with the aim of designinga Very -Long Endurance Solar Po wered Autonomous Stratospheric UA V. Th is UA V could play the role of a pseudo satellite and could offer the advantage of allowing a more detailed land vision due to its relative closeness to land (17-20 km) at a much lower cost than a real satellite. Two different configurationsare under investigation in order to decide on the best solution that will co mpletely satisfy the a priori imposed constraints. In recent years, the aeronautical co mmun ity has increasingly focused on the design of solar powered platforms and zero emission airplanes; a coupled system (solar array and hydrogen fuel cells) can be used to supply energy throughout the entire day in order to ensure the continuous flight for several months. As known, a fuel cell system requires at least a couple of external tanks for fuel storage. Hydrogen and oxygen are stored using a pressure vessel installed inside the wing. In this way, the stored gases are subjected not only to pressure loads but also to in-flight loads that can abruptly change the optimu m layout required to satisfy regulation requirements. A parametric analysis has been performed to define the optimu m layout and the number of tanks necessary to supply the required power. In addition a genetic algorith m has been used to optimize the laminate layup in order to reduce the weight of the tank and ensure that it can resist without at failing catastrophically.
Several researches are being carried out at the Politecnico di Torino with the aim of designing a... more Several researches are being carried out at the Politecnico di Torino with the aim of designing a high altitude very-long endurance/unmanned air vehicle (HAVE/UAV). Being able to fly in the stratosphere (15-20 km) and with an endurance of about 4 months offers an advan- tage and possibility that is presently not available with conventional aircraft or satellites. A computer program
The Aeronautical Journal, 2004
Nowadays there is a growing request for Very Long Endurance Solar-Powered Autonomous Aircraft (VE... more Nowadays there is a growing request for Very Long Endurance Solar-Powered Autonomous Aircraft (VESPAA) flying at stratospheric altitudes of 17-25 km because they can act as artificial satellites - with the advantage of being much cheaper, closer to the ground, and being able to perform missions that offer greater flexibility. A long experience has been acquired by the Polytechnic of Turin, Department of Mechanical and Aerospace Eng. (POLITO/DIMEAS, Scientific Responsible Prof. G. Romeo) in Design of Solar powered UAV as High Altitude Very long Endurance Platform positioned in the stratosphere and with an endurance of more than six months. Two different configurations are under investigation in order to understand the best solution that completely fulfill the a priori imposed constraints. The main goal is to obtain a structure as light as possible that ensures the capability to resist at loads evaluated from the flight envelope without catastrophic failures. A Genetic Algorithm has been developed to optimize composite laminates subjected to mechanical, thermal and hygroscopic loads. A set of penalty function has been defined in order to guarantee deformations less than the allowable limit and to avoid local or global buckling. A Progressive Ply Failure Analysis code has been developed in order to evaluate the Last Ply Failure Loads of composite laminates. Since, in agreement with international regulations, the structure must be able to resist at ultimate loads without failures for at least three seconds, Genetic Algorithm and PPFA have been coupled in order to optimize the lay-up of each panel that ensure the minimum wing box weight, a proper safety margin from FPF to LPF and respects of the penalty function. In particular, no failure are allowed at limit load while, at ultimate load, each panel must stay under LPF level.
J Aerosp Eng, 2010
The application of fuel-cell technology to aircraft propulsion and/or energy supply is becoming o... more The application of fuel-cell technology to aircraft propulsion and/or energy supply is becoming of great interest for undoubted advantages in terms of pollution emissions and noise, features particularly important for commuter airplanes that usually take off and land from and in urban areas. The conversion of conventional aircraft into more/all-electric one tends to be based on the installation of such innovative systems. A better understanding of problems related to fuel cells applied to aeronautics is sought by the European Commission funded project environmentally friendly intercity aircraft powered by fuel cells ͑ENFICA-FC͒. The main objective of the ENFICA-FC project is to develop and to validate the use of a fuel-cell based power system for propulsion of an all-electric aircraft. The fuel-cell system will be installed in a light sport aircraft ͑Rapid 200͒ that will be flown and performance tested as a proof of functionality and future applicability. Specific aspects have to be investigated in the onboard installation of the innovative system and new design indications have to be pointed out in order to fulfill the conversion. One of the key items under investigation is the simulation of existing cooling system and the evaluation of motor and fuel-cell temperature; the temperature has to be maintained within the limits established by manufacturers of critical systems during all likely operating conditions as indicated by aeronautic regulations for general aviation. The computational problem addressed in this paper is the numerical computational fluid dynamics ͑CFD͒ simulation of the existing air-cooling system that satisfies air request for cooling and venting. An engineering model has been developed and it is used to support air inlet and outlet design. The flow is reasonably approximated by a potential flow plus boundary layer; hence, total upstream pressure losses are neglected except for those within the thin boundary layer. Pressure recovery of incoming cooling air and pressure coefficient distribution have been studied by using VSAERO panel code, and the optimal position of cooling and venting intakes is defined according to aerodynamic results. Propeller effects are included by referring to an optimal propeller specifically designed for the ENFICA-FC project. Propeller slip-stream wake is modeled by an actuator disk plus a swirl membrane and used to study the problem of motor, electronic, and fuel cells' cooling during takeoff.
Journal of Aerospace Engineering, Jul 1, 2012
The application of fuel cell (FC) technology to aircraft propulsion and/or energy supply is becom... more The application of fuel cell (FC) technology to aircraft propulsion and/or energy supply is becoming of great interest for undoubted advantages in terms of pollution emissions and noise reduction. A better understanding of problems related to fuel cells applied to aeronautics is sought by the European Commission (EC) funded project Environmentally Friendly Inter-City Aircraft Powered by Fuel Cells (ENFICA-FC). The main objective of the ENFICA-FC project was to develop and validate the use of a fuel cell-based power system for the propulsion of more-electric/all-electric aircraft. The fuel cell system was installed in the light sport aircraft Rapid 200, which was flight and performance tested. One of the key items under investigation is the simulation of the cooling system and the evaluation of fuel cell temperature. The polymer electrolyte membrane fuel cell (PEMFC) is considered to be the best candidate for the fuel cell vehicle because it has high power density, solid membrane electrolyte, and as it operates at low temperatures, it has a fast start-up. However, to generate a reliable and efficient power response and to prevent membrane degradation or damage with hydrogen and oxygen depletion, a sophisticated control technique becomes vitally important. In particular, as the ionic conduction of the polymeric membrane is a function of its degree of humidification, the stack temperature has to be carefully controlled to avoid phenomena of water evaporation, causing an increase of ohmic drop and a decrease of stack performances. The output voltage and hence the power of the fuel cell system is affected considerably by the change of the stack temperature. A simplified fluid-dynamic model has been developed and validated by computational fluid dynamics (CFD) analysis and it is used to compute the air flow to the fuel cell heat-exchanger inlet. Propeller effects are included referring to an optimal propeller specifically designed for the ENFICA-FC project. A mathematical model of the fuel cell system dynamics coupled with the fluid-dynamic model was studied in detail and experimentally validated during two flight tests of the Rapid 200-FC.
Composite Structures, Apr 1, 2008
Some main activities have been developed as part of the HELINET research project which was financ... more Some main activities have been developed as part of the HELINET research project which was financed in January 2000, by the European Commission, (Fifth Framework Program in the IST action), to develop a European project in the field of stratospheric platforms. From the aeronautical point of view the following items were studied: (1) the design of an autonomous high altitude long-endurance unmanned air vehicle (HALE-UAV) platform capable of remaining aloft for very long periods of time (between 6 and 9 months) using a solar-powered and fuel cell system and to gain a complete understanding of the feasibility of a near-term aerodynamic HALE concept, in particular as far as stratospheric platforms are concerned (mainly dependent on high efficiency and reliability of solar cells, fuel cells and electric motors), (2) an evaluation of the production and service costs and an assessment of the safety and regulatory aspects of the platform, and (3) the manufacturing of a scale-sized technological demonstrator and the execution of static tests on it up to the ultimate load. The first HELIPLAT Ò (HELIos PLATform) configuration was worked out, on the basis of a preliminary parametric study. The platform was a twin-boom tail type monoplane with eight brushless motors, a long horizontal stabilizer and two rudders. A scaled-prototype was designed to demonstrate the feasibility of this configuration and to perform some structural static and dynamic tests on it. The main CFRP structures were manufactured by CASA (Spain): the principal wing and horizontal tail tubular spars, booms, vertical tail spars and some reinforced ribs. These parts were delivered to the Aerospace Engineering Dept. (DIASP) at the Politecnico di Torino (POLITO) and assembled using special joints while some other necessary parts were manufactured by POLITO-DIASP. A parallel activity was performed to define the structural test configurations and structural test frame. The manufacturing activities and the development of the structural test system is described in the first part of the paper. Static and dynamic experimental tests were performed in two phases (2003 and 2004) on the prototype and the results of the static tests are presented in this paper and compared with numerical and theoretical computations.
ABSTRACT Several researches are being carried out at the Politecnico di Torino with the aim of de... more ABSTRACT Several researches are being carried out at the Politecnico di Torino with the aim of designing a high altitude very-long endurance/unmanned air vehicle (HAVE/UAV). Being able to fly in the stratosphere (15--20 km) and with an endurance of about 4 months offers an advantage and possibility that is presently not available with conventional aircraft or satellites. A computer program has been developed to design the platform. The change in solar radiation over a period of a year, the altitude, masses, and efficiencies of the solar and fuel cells, as well as the aerodynamic, structural, flight mechanics, and aeroelastic performances have all been taken into account. Extensive use has been made of high modulus graphite/epoxy when designing the structure in order to minimize the airframe weight, but also to guarantee the required stiffness and aeroelastic performance. A blended wing body (BWB) configuration has been selected for solar HAVE aircraft multi payload and operation (SHAMPO) with eight brushless electric motors, as the result of a preliminary design. The BWB solution has been designed according to the conventional procedures and airworthiness regulations. It seems to be the best compromise between performance, available surfaces for solar cells and volume for multi-payload purposes, compared to conventional design. Several profiles and wing plans have been analysed and optimized to achieve the best efficiency using the Xfoil and Vsaero computational fluid dynamics (CFD) software. A finite-element method and a classical theoretical analysis was carried out using the Msc/Patran/ Nastran code to predict the static and aeroelastic behaviour of the SHAMPO. Aeroelastic analysis has been performed starting with a classical linear flutter analysis and considering an undeformed equilibrium condition. Classical linear flutter speed show as the airworthiness requirements has been achieved in the case of SHAMPO configuration. A preliminary non-linear aeroelastic model is introduced in the design process in order to deal with specific phenomena correlated with high static structural deflections occurring during standard flight conditions. Important flutter speed reduction (i.e. up to 42 per cent in special cases) are possible including such kind of phenomena.
ABSTRACT Fuel cells could become the main power source for small general aviation aircraft or cou... more ABSTRACT Fuel cells could become the main power source for small general aviation aircraft or could replace APU and internal sub-systems on larger aircraft, to obtain all-electric or more-electric air vehicles. There are several potential advantages of using such a power source, that range from environmental and economic issues to performance and operability aspects. A preliminary design is reported. Also, the paper contains a description of testing activities related to experimental flights of an all-electric general aviation aircraft fueled by hydrogen. Great importance has been given to the testing phase of the prototype and examples of each testing stage are shown ranging from the single components to the final test flights. During the 6 experimental flights a rotation speed of 84 km/h was obtained in 184 m of taxi at power of 35 kW. Level flight was attained at 135 km/h and endurance of 39 min by mean of only a fuel cell power setting (speed world record for the FAI Sporting Code Category C – airplane).
SAE Technical Paper Series, 2015