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Assessing alternative fuels for helicopter operation / A. Alexiou in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 134 N° 11 (Novembre 2012) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 134 N° 11 (Novembre 2012) . - 10 p. Titre : Assessing alternative fuels for helicopter operation Type de document : texte imprimé Auteurs : A. Alexiou, Auteur ; A. Tsalavoutas, Auteur ; B. Pons, Auteur Année de publication : 2012 Article en page(s) : 10 p. Note générale : gas turbines Langues : Anglais (eng) Mots-clés : aviation  fuel;  refining  technology;  transport/utility  helicopter Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : At present, nearly 100% of aviation fuel is derived from petroleum using conventional and well known refining technology. However, the fluctuations of the fuel price and the vulnerability of crude oil sources have increased the interest of the aviation industry in alternate energy sources. The motivation of this interest is actually twofold: firstly, alternative fuels will help to stabilize price fluctuations by relieving the worldwide demand for conventional fuel. Secondly, alternative fuels could provide environmental benefits including a substantial reduction of emitted CO2 over the fuel life cycle. Thus, the ideal alternative fuel will fulfill both requirements: relieve the demand for fuels derived from crude oil and significantly reduce CO2 emissions. In the present paper, the effects of various alternative fuels on the operation of a medium transport/utility helicopter are investigated using performance models of the helicopter and its associated turboshaft engine. These models are developed in an object-oriented simulation environment that allows a direct mechanical connection to be established between them in order to create an integrated model. Considering the case of a typical mission for the specific helicopter/engine combination, a comparative evaluation of conventional and alternative fuels is then carried out and performance results are presented at both engine and helicopter levels. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000134000011 [...] [article] Assessing alternative fuels for helicopter operation [texte imprimé] / A. Alexiou, Auteur ; A. Tsalavoutas, Auteur ; B. Pons, Auteur . - 2012 . - 10 p. gas turbines Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 134 N° 11 (Novembre 2012) . - 10 p. Mots-clés : aviation  fuel;  refining  technology;  transport/utility  helicopter Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : At present, nearly 100% of aviation fuel is derived from petroleum using conventional and well known refining technology. However, the fluctuations of the fuel price and the vulnerability of crude oil sources have increased the interest of the aviation industry in alternate energy sources. The motivation of this interest is actually twofold: firstly, alternative fuels will help to stabilize price fluctuations by relieving the worldwide demand for conventional fuel. Secondly, alternative fuels could provide environmental benefits including a substantial reduction of emitted CO2 over the fuel life cycle. Thus, the ideal alternative fuel will fulfill both requirements: relieve the demand for fuels derived from crude oil and significantly reduce CO2 emissions. In the present paper, the effects of various alternative fuels on the operation of a medium transport/utility helicopter are investigated using performance models of the helicopter and its associated turboshaft engine. These models are developed in an object-oriented simulation environment that allows a direct mechanical connection to be established between them in order to create an integrated model. Considering the case of a typical mission for the specific helicopter/engine combination, a comparative evaluation of conventional and alternative fuels is then carried out and performance results are presented at both engine and helicopter levels. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000134000011 [...]

Modeling contra-rotating turbomachinery components for engine performance simulations / A. Alexiou in Transactions of the ASME . Journal of engineering for gas turbines and power, Vol. 134 N° 11 (Novembre 2012) 

Public ISBD [article]  in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 134 N° 11 (Novembre 2012) . - 10 p. Titre : Modeling contra-rotating turbomachinery components for engine performance simulations : the geared turbofan with contra-rotating core case Type de document : texte imprimé Auteurs : A. Alexiou, Auteur ; I. Roumeliotis, Auteur ; N. Aretakis, Auteur Année de publication : 2012 Article en page(s) : 10 p. Note générale : gas turbines Langues : Anglais (eng) Mots-clés : modeling  contra-rotating  turbomachinery  components;  suitably;  aero-engine  core  concepts Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : This paper presents a method of modeling contra-rotating turbomachinery components for engine performance simulations. The first step is to generate the performance characteristics of such components. In this study, suitably modified one-dimensional mean line codes are used. The characteristics are then converted to three-dimensional tables (maps). Compared to conventional turbomachinery component maps, the speed ratio between the two shafts is included as an additional map parameter and the torque ratio as an additional table. Dedicated component models are then developed that use these maps to simulate design and off-design operation at the component and engine levels. Using this approach, a performance model of a geared turbofan with a contra-rotating core (CRC) is created. This configuration was investigated in the context of the European program “NEW Aero-Engine Core Concepts” (NEWAC). The core consists of a seven-stage compressor and a two-stage turbine without interstage stators and with successive rotors running in the opposite direction through the introduction of a rotating outer spool. Such a configuration results in a reduced parts count, length, weight, and cost of the entire high pressure (HP) system. Additionally, the core efficiency is improved due to reduced cooling air flow requirements. The model is then coupled to an aircraft performance model and a typical mission is carried out. The results are compared against those of a similar configuration employing a conventional core and identical design point performance. For the given aircraft-mission combination and assuming a 10% engine weight saving when using the CRC arrangement over the conventional one, a total fuel burn reduction of 1.1% is predicted. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000134000011 [...] [article] Modeling contra-rotating turbomachinery components for engine performance simulations : the geared turbofan with contra-rotating core case [texte imprimé] / A. Alexiou, Auteur ; I. Roumeliotis, Auteur ; N. Aretakis, Auteur . - 2012 . - 10 p. gas turbines Langues : Anglais (eng) in Transactions of the ASME . Journal of engineering for gas turbines and power > Vol. 134 N° 11 (Novembre 2012) . - 10 p. Mots-clés : modeling  contra-rotating  turbomachinery  components;  suitably;  aero-engine  core  concepts Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : This paper presents a method of modeling contra-rotating turbomachinery components for engine performance simulations. The first step is to generate the performance characteristics of such components. In this study, suitably modified one-dimensional mean line codes are used. The characteristics are then converted to three-dimensional tables (maps). Compared to conventional turbomachinery component maps, the speed ratio between the two shafts is included as an additional map parameter and the torque ratio as an additional table. Dedicated component models are then developed that use these maps to simulate design and off-design operation at the component and engine levels. Using this approach, a performance model of a geared turbofan with a contra-rotating core (CRC) is created. This configuration was investigated in the context of the European program “NEW Aero-Engine Core Concepts” (NEWAC). The core consists of a seven-stage compressor and a two-stage turbine without interstage stators and with successive rotors running in the opposite direction through the introduction of a rotating outer spool. Such a configuration results in a reduced parts count, length, weight, and cost of the entire high pressure (HP) system. Additionally, the core efficiency is improved due to reduced cooling air flow requirements. The model is then coupled to an aircraft performance model and a typical mission is carried out. The results are compared against those of a similar configuration employing a conventional core and identical design point performance. For the given aircraft-mission combination and assuming a 10% engine weight saving when using the CRC arrangement over the conventional one, a total fuel burn reduction of 1.1% is predicted. DEWEY : 620.1 ISSN : 0742-4795 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JETPEZ000134000011 [...]