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Engine performance and surge margins optimization by means of nozzles variability

Zarati, Khaled and Duplaa, Sébastien and Carbonneau, Xavier and Tantot, Nicolas Engine performance and surge margins optimization by means of nozzles variability. (2015) In: 22nd ISABE Conference, 25 October 2015 - 30 October 2015 (Phoenix, United States).

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Abstract

Overall trends for next generation aero-engines are oriented to more efficient architectures to ensure a reduction in fuel consumption and an improvement in expected ranges, emissions levels and operability. Engine manufacturers have investigated different ways to improve engine performance, for instance by using new materials, technologies or integration methods. Engine performance can also be improved though changes in thermodynamic cycle by means of variable cycle devices capable of better adapting it to flight conditions. Due to current design constraints, engines are optimized to best average performance for a specific mission type, yet not for all the operating points encountered throughout the missions. By adding a degree of freedom, the cycle can be further optimized during the entire mission potentially leading to additional fuel savings. This paper presents an analysis of the impact of variable fan and core nozzle areas on the performance of a long range turbofan through a long range mission. By moving the operating points, these devices have a strong effect on engine operations and therefore on the Specific Fuel Consumption. Variations in Specific Fuel Consumption are evaluated as well as compressors surge margins, considered as important performance and operability parameters, throughout the same 14hours long range mission and for range of +/- 15% for the fan nozzle area and +/- 20% for the core nozzle area. This study shows that optimization of the fan nozzle area on each mission point for minimum SFC can lead to fuel savings of up to 20kg (44lb) representing 0.05% of improvement. However, maximizing the surge margin by optimizing the variable fan nozzle permits an increase of up to 7% depending on the considered compressor. On the other hand, optimization of the core nozzle area on each mission point for minimum specific fuel consumption allows a reduction of 127kg (282lb) in fuel consumption, representing an improvement of 0.34% while having different effects on the engine compressors surge margins. Using the core area to maximize the surge margin provides an increase of up to 2% depending on the considered compressor with a side effect on specific fuel consumption. At this stage, the results from this study suggest that the amount of fuel savings obtained through the use of variable fan nozzle and variable core nozzle may not be sufficient to overcome the associated constraints such as added weight and integration aspects. However, a broader optimization approach,involving all the design aspects and parameters could lead to different quantitative conclusions.

Item Type:Conference or Workshop Item (Paper)
Audience (conference):International conference proceedings
Uncontrolled Keywords:
Institution:Université de Toulouse > Institut Supérieur de l'Aéronautique et de l'Espace - ISAE-SUPAERO (FRANCE)
Other partners > SAFRAN (FRANCE)
Laboratory name:
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Deposited By: Xavier CARBONNEAU
Deposited On:03 Sep 2015 12:17

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