Cusati, Vincenzo (2020) Design activities for innovative turboprop aircraft with minimum economic and environmental impact. [Tesi di dottorato]


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Item Type: Tesi di dottorato
Resource language: English
Title: Design activities for innovative turboprop aircraft with minimum economic and environmental impact
Date: 13 March 2020
Number of Pages: 190
Institution: Università degli Studi di Napoli Federico II
Department: Ingegneria Industriale
Dottorato: Ingegneria industriale
Ciclo di dottorato: 32
Coordinatore del Corso di dottorato:
Nicolosi, FabrizioUNSPECIFIED
Date: 13 March 2020
Number of Pages: 190
Keywords: Aerodynamics, Propulsive Effects, Costs
Settori scientifico-disciplinari del MIUR: Area 09 - Ingegneria industriale e dell'informazione > ING-IND/03 - Meccanica del volo
Date Deposited: 02 Apr 2020 09:06
Last Modified: 28 Oct 2021 12:27

Collection description

The research work concerns the design activities for innovative turboprop aircraft with rear engines installation with minimum economic and environmental impact. The configuration has been conceived to transport 130 passengers. As well as classical aircraft design aspects such as aerodynamics, the work is focused also on other multidisciplinary and significant aspect for the certification such as costs. The interest in turboprop aircraft stems from two main reasons: i) their reduced pollutant emissions with respect to jet ii) economic advantages in terms of operating costs and reduced fuel consumption (for short-medium range mission). In the next 20 years regional air traffic is expected to triple at an average yearly rate of 6%, generating a market demand of about 9000 new regional aircraft (with a market value of about e360 billion, averaging e18 billion per year). A detailed market analysis has revealed that the 100 to 149 seat aircraft segment will witness a major fleet transformation with the entry-into-service of new clean-sheet aircraft designs. The turboprop configuration with rear engines could address both the new market requirements of a higher passenger capacity and one of the most relevant European Community challenge concerning the pollutant emissions reduction by means of laminar wing technologies and the nextgeneration propulsion system. However, the turboprop configuration considered in this Ph.D thesis provides for three-lifting surfaces. It was expected that this kind of configuration involves several interference effects among the three-lifting surfaces vii which have to be investigated to assure the configuration feasibility, in particular in terms of longitudinal stability. Thus, the general questions behind the research could be expressed as follow: is it feasible an innovative turboprop three-lifting surface configuration with rear engine installation? How competitive would it be on the aircraft regional market? Obviously, this two questions are strictly related. Concerning the first question, the longitudinal stability of a such innovative configuration is one of the main aspects which must be deepened to ensure the feasibility. It has been already stated that the rear engine installation can lead to a cleaner wing with possibilities to achieve laminar flow extension. Furthermore, a wing without engine nacelles and free of propeller interference effects will be characterized by more efficient high-lift systems resulting in a potential increment in maximum lift coefficient positively affecting ground performances. However, the rear engine installation leads also to Center of Gravity (CG) excursion problems which can also affect aircraft performance. In order to reduce this excursion, the innovative configuration includes a third lifting surface, a canard, positioned ahead of the wing. Nevertheless, the presence of the canard entails several wake interference effects among the aircraft components which have a detrimental effect on longitudinal stability. A great part of the work is dedicated to the study of all of aerodynamic interference effects. In particular, both numerical and experimental investigations have been performed with the aim to detail how the combined downwash coming from both canard and wing lifting surfaces and their wakes affect the horizontal tailplane lifting capabilities and consequently the longitudinal stability. Moreover, since the engines are installed on the tailplane, the investigations include also the propulsive effects (both direct and indirect) in order to enhance the reliability of the tailplane aerodynamic behaviour prediction in a such innovative configuration. High fidelity RANS calculations were performed by means of commercial software STAR-CCM+, on the grid computing infrastructure provided by the University of Naples Federico II, SCoPE, to simulate lots of configurations in a short amount of time. The experimental tests campaign has been performed in the main wind tunnel facility of the Department of Industrial viii Engineering (DII) that is a subsonic, closed circuit tunnel, with a tempered rectangular cross section. As concern the second question, the innovative turboprop is supposed to be competitive with respect to short-medium haul regional jets, in particular with respect to the following aspects: increase the passengers number, SFC and emissions reduction, longer design missions, improve cabin comfort, reduce environmental noise, improve the aerodynamic efficiency. All these aspects could contribute to the success of the configuration on the aviation market. To quantify the possible economic advantageous of the innovative configuration, the Direct Operating Cost (DOC) was chosen as metric. A brief review of the most widely used state-of-the-art methods for aircraft cost estimation has been discussed. Once the costs estimation methodologies have defined, the Cost Estimating Relationships (CER), able to establish cost estimates for operating costs, have been implemented in the software JPAD (Java-based library). The software has been exploited to performed the evaluation of economic impact of the innovative turboprop configuration and to compare this configuration with respect to a possible competitor, a regional jet similar to Airbus A220-300. The issues faced during different project loops and the solutions adopted constitute the true heart of the research, adding an important dowel towards the feasibility of a such innovative turboprop configuration.


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