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1

Optimisation of a Nacelle Electro-Thermal Ice Protection System for Icing Wind Tunnel Testing

Gallia Mariachiara, Carnemolla Alessandro, Premazzi Marco, Guardone Alberto

Transactions on Aerospace Research

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2023

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Nr 1 (270)

32--44

EN

Aircraft are equipped with ice protection systems (IPS), to avoid, delay or remove ice accretion. Two widely used technologies are the thermo-pneumatic IPS and the electro-thermal IPS (ETIPS). Thermopneumatic IPS requires air extraction from the engine negatively affecting its performances. Moreover, in the context of green aviation, aircraft manufacturers are moving towards hybrid or fully electric aircraft requiring all electric on-board systems. In this work, an ETIPS has been designed and optimised to replace the nacelle pneumatic-thermal system. The aim is to minimise the power consumption while assuring limited or null ice formation and that the surface temperature remains between acceptable bounds to avoid material degradation. The design parameters were the length and heat flux of each heater. Runback ice formations and surface temperature were assessed by means of the in-house developed PoliMIce framework. The optimisation was performed using a genetic algorithm, and the constraints were handled through a linear penalty method. The optimal configuration required 33% less power with respect to the previously installed thermo-pneumatic IPS. Furthermore, engine performance is not affected in the case of the ETIPS. This energy saving resulted in an estimated reduction of specific fuel consumption of 3%, when operating the IPS in anti-icing mode.

2

Thermal performance analysis of manned airships in a thermally variable environment

Shi Hong, Liu Meinan, Chen Jiamin, Zou Yitao

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2022

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Vol. 70, nr 5

art. no. e143105

EN

The safety and reliability of the manned airship depend to a considerable extent on its thermal performance. In this paper, heat balance equations are developed and solved in the C++ programming language. The temperature variation of the enclosure, gasbag, and nacelles of the manned airship is investigated. In addition, the effects of season, latitude, and orientation on the thermal performance of the manned airship and the airship nacelle are investigated. The results show that: (1) The average temperature difference of the nacelle surface at the same time is 25 K, while the maximum temperature difference in the nacelle is 29 K during the day, (2) the temperature distribution in the nacelle is similar in spring and autumn, with maximum temperature between 306 K and 309 K. The maximum temperature in the nacelle is between 300 K and 303 K in winter while the maximum temperature in the nacelles is between 309 K and 315 K in summer, (3) as the flight position of the manned airship changes from 20°N to 60°N, the average nacelle temperature varies slightly by about 1 K. However, as the latitude increases, the high- temperature region shifts from the bottom of the nacelle to the side of the nacelle, and (4) the temperature distribution of the upper envelope of the airship varies considerably with orientation. However, the average temperature of the nacelle is less impacted by orientation. These results are useful for understanding the thermal performance of manned airships.

3

Aerodynamic effect of turbo prop engine slipstream on aircraft tail assembly vibration

Zalewski W., Stalewski W.

Journal of KONES

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2017

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Vol. 24, No. 4

363--367

EN

The article presents a computational analysis of the effect of the turboprop engine slipstream on generation of aerodynamic forces induced vibrations of aircraft tail assembly (empennage). Working propellers exhaust system, engine nacelle, and wing-engine nacelle flow interference phenomenon can cause strong non-stationary disturbances behind the wing of the aircraft. These disturbances, propagating in the direction of the aircraft tail assembly, may be an important factor influencing the operation of the airplane flow control system and the source of aerodynamic forces generating vibrations of the entire plane structure. The article presents an example of analysis of this phenomenon for a light passenger-transport aircraft using advanced numerical models for simulation of the flow around the aircraft. In the computational model, Navier-Stokes flow equations were solved by finite volume method with the K-Omega SST turbulence model to calculate the turbulent kinetic energy distribution in the flow slipstream behind the airplane propulsion unit. The Ansys Fluent commercial solver was used to run analyses. To perform the simulation, high quality, dedicated conformal computational mesh, consisting of hexahedral and tetrahedral elements was prepared to evaluate the propagation of the flow disturbances with limited numerical dispersion effect. Mesh generation was conducted using Ansys ICEM CFD and Mesher software. Unsteady aerodynamic forces for horizontal and vertical tail-planes of the airplane were computed during simulations. Fourier analysis of the driven forces was performed, which resulted in finding the dominating vibration frequencies generated by the flow field around the tail assembly. The visualization of the flow field and the regions of the strong disturbances were presented. Results can be exploited in the pre-design process of aerodynamic configuration of multi-engine aircrafts.

4

Wpływ obecności gondoli na kształt łopat wirnika turbiny wiatrowej o poziomej osi obrotu

Woźniak A.

Materiały Budowlane

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2014

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nr 5

38--40

PL

Dobrze znane metody konstrukcji łopatek turbin wiatrowych o poziomej osi obrotu oparte są na napływie jednorodnym [1], natomiast prawdziwe turbiny wiatrowe pracują w niejednorodnym strumieniu. Przyczyną tej niejednorodności może być obecność gondoli wiatraka. Celem artykułu jest przedstawienie wpływu obecności gondoli na kształt łopatek wirnika turbiny wiatrowej, tj. kształt cięciwy i kąta skręcenia.Opisanametoda łączy twierdzenie Betza o minimalnej mocy indukowanej śmigła z modyfikowaną teorią opływu ciała smukłego oraz zasadą zachowania pędu i momentu pędu w przypadku elementu łopaty wirnika.

EN

Well established methods of wind turbine blades aerodynamic design are founded on assumption of uniform inflow. Real wind turbine works in non-uniform stream affected by vertical velocity gradient, nacelle. It seems that the effect for small turbine will be strong. The purpose of the present paper is investigation of nacelle on shape of the blade i.e. radial chord and twist distribution in so-called reverse (design) problem for HAWT. In the paper a sample calculations of the rotor geometry for given conditions has been presented. It was shown that the presence of nacelle has an appreciable influence on twist and chord distribution in the inner portion of the rotor disk.