6 research outputs found
Proračun normalne sile i momenta propinjanja kombinacije tijelo-krilo
U ovom je diplomskom radu pokušano doci do rezultata za normalnu silu i moment propinjanja kombinacije tijelo-krilo spajanjem dvije razlicite numericke metode; Weissinger metode za krilo i metode izvora i dipola za tijelo. Razvijena metoda nazvana je vrtlog-izvordipol, ili skraceno VID. Metodom se na temelju ispunjavanja rubnih uvjeta o nepropusnosti površine odreduju intenziteti _ vrtloga kojima se simulira postojanje krila, te izvora i dipola koji simuliraju pristnost tijela u struji zraka. Pomocu tako definiranog strujanja može se odrediti lokalna brzina optjecanja na površini kombinacije a zatim i raspored tlaka iz Bernoullijeve jednadžbe. Koeficijent normalne sile i momenta propinjanja odreduje se na osnovi rasporeda koeficijenta tlaka po površini kombinacije. Proracun je napisan u programu Matlab a daje rezultate za odredeni napadni kut. Program je testiran na modelu samog krila i modelu samog tijela a rješenja su usporedena sa onima iz Weisinger metode i izvor – dipol metode za tijelo. Rezultat normalne sile i momenta propinjanja zadane kombinacije usporeden je sa rezultatima numerickih metoda za istu kombinaciju sa jedne AIAA radionice
Aircraft performance monitoring from flight data
Poznavanje stvarnih performansi zrakoplova bitno je za učinkovitu eksploataciju i pravovremeno održavanje. Performanse su određene fizikalnim karakteristikama zrakoplova. U Priručniku za letenje opisane su teorijske performanse određene od proizvođača nakon proizvodnje zrakoplova i testiranja u letu. Komercijalni zrakoplovi su tijekom svog operativnog ciklusa uglavnom izloženi predviđenim uvjetima eksploatacije. Unatoč predviđenim uvjetima eksploatacije i redovnom održavanju, starenje materijala i velika opterećenja na strukturu zrakoplova kod leta visokim podzvučnim Machovim brojem, mogu dovesti do promjene temeljnih fizikalnih faktora koji određuju performanse. Zbog toga se stvarne performanse zrakoplova nerijetko razlikuju od teorijskih. Zračni prijevoznici prate stanje zrakoplova i njegove stvarne performanse tijekom korištenja. U ovom radu prikazan je pregled dosadašnjih metoda praćenja performansi i mogućnosti istraživanja na području određivanja fizikalnih parametara zrakoplova u eksploataciji prema podacima iz leta.To ensure timely maintenance and efficient aircraft operations, it is necessary to know and keep track of aircraft’s actual performance. Flight performance is determined by aircraft\u27s physical characteristics. Theoretical aircraft performance, obtained after manufacturing and flight testing, are described in flight manual. Transport aircraft in operation is usually exposed to standard operational conditions. Despite the standard operational conditions and regular aircraft maintenance, structure aging and high dynamic loads due to high subsonic Mach number could lead to changes of main physical factors that determine flight performance. For this reason actual aircraft performance often differs from theoretical. Commercial airlines monitor true performance of aircraft in operation. This paper presents an overview of existing performance monitoring methods as well as first indications for new research possibilities regarding physical characteristics determination for aircraft in operation using flight data
Estimation of Aerodynamic Coefficients in a Small Subsonic Wind Tunnel
To apply the experimental data measured in a wind tunnel for a scaled aircraft to a free-flying model, conditions of dynamical similarity must be met or scaling procedures introduced. The scaling methods should correct the wind tunnel data regarding model support, wall interference, and lower Reynolds number. To include the necessary corrections, the current scaling techniques use computational fluid dynamics (CFD) in combination with measurements in cryogenic wind tunnels. There are a few methods that enable preliminary calculations of typical corrections considering specific measurement conditions and volume limitation of test section. The purpose of this paper is to present one possible approach to estimating corrections due to sting interference and difference in Reynolds number between the real airplane in cruise regime and its 1:100 model in the small wind tunnel AT-1. The analysis gives results for correction of axial and normal force coefficients. The results of this analysis indicate that the Reynolds number effects and the problem of installation of internal force balance are quite large. Therefore, the wind tunnel AT-1 has limited usage for aerodynamic coefficient determination of transport airplanes, like Dash 8 Q400 analyzed in this paper
Proračun normalne sile i momenta propinjanja kombinacije tijelo-krilo
U ovom je diplomskom radu pokušano doci do rezultata za normalnu silu i moment propinjanja kombinacije tijelo-krilo spajanjem dvije razlicite numericke metode; Weissinger metode za krilo i metode izvora i dipola za tijelo. Razvijena metoda nazvana je vrtlog-izvordipol, ili skraceno VID. Metodom se na temelju ispunjavanja rubnih uvjeta o nepropusnosti površine odreduju intenziteti _ vrtloga kojima se simulira postojanje krila, te izvora i dipola koji simuliraju pristnost tijela u struji zraka. Pomocu tako definiranog strujanja može se odrediti lokalna brzina optjecanja na površini kombinacije a zatim i raspored tlaka iz Bernoullijeve jednadžbe. Koeficijent normalne sile i momenta propinjanja odreduje se na osnovi rasporeda koeficijenta tlaka po površini kombinacije. Proracun je napisan u programu Matlab a daje rezultate za odredeni napadni kut. Program je testiran na modelu samog krila i modelu samog tijela a rješenja su usporedena sa onima iz Weisinger metode i izvor – dipol metode za tijelo. Rezultat normalne sile i momenta propinjanja zadane kombinacije usporeden je sa rezultatima numerickih metoda za istu kombinaciju sa jedne AIAA radionice
Fuel Burn Method Assessment Using Automatic Dependent Surveillance–Broadcast and European Reanalysis Data: Limited Flight Sample Analysis
Fuel burn during the actual route flown is an important indicator of aircraft operational efficiency. This study aims to assess and systematically evaluate the method for fuel consumed during flights using data from the automatic dependent surveillance–broadcast (ADS-B), European reanalysis (ERA5) meteorological dataset, and BADA 3 performance. A literature background and comprehensive methodology are provided for fuel estimation using track data. The airborne part of the trajectory was used to estimate the total trip fuel consumed during several flights of a commercial airliner. The calculated fuel burn is compared with measured fuel consumption from the flight data recorder (FDR). The results show that fuel consumption for the entire airborne part of the trajectory can be estimated with an average error of 1.2% and with a standard deviation of 1.3%. Detailed results of fuel burn for individual flight phases, from the initial climb to the approach, are also presented. In addition, this paper also discusses the sources of errors and the potential applications of the method for network operations and environmental monitoring
Predicting the Remaining Useful Life of Light Aircraft Structural Parts: An Expert System Approach
This paper introduces an expert system approach for predicting the remaining useful life (RUL) of light aircraft structural components by analyzing operational and maintenance records. The expert system consists of four modules: knowledge acquisition, knowledge base, inference, and explanation. The knowledge acquisition module retrieves data from mandatory records, such as aircraft logbooks and mass and balance sheets. The knowledge base stores specific remaining useful lives (SRULs) for different load profiles that are determined using numerical strength analysis. The inference module utilizes the Palmgren-Miner rule to estimate the accumulated fatigue damage of the structural component based on the input data and the knowledge base. Lastly, the explanation module links the accumulated damage to the maintenance program and suggests the appropriate maintenance action. The Cessna 172R main landing gear leg is utilized as a case study, demonstrating the variance of RUL depending on the operating conditions. The objective of this approach is to enhance light aircraft maintenance decision making and advance operational safety