Commercial Transport Aircraft Research Articles

Performance analysis of electrical environmental control and ice protection systems in a commercial transport aircraft

PurposeThis paper aims to assess the impact of electrifying the environmental control system (ECS) and ice protection system (IPS), the primary pneumatic system consumers in a conventional commercial transport aircraft, on aircraft weight, range, and fuel consumption.Design/methodology/approachThe case study was carried out on Airbus A321-200 aircraft. Design, modelling and analysis processes were carried out on Pacelab SysArc software. Conventional and electrical ECS and IPS architectures were modelled and analysed considering different temperature profiles.FindingsThe simulation results have shown that the aircraft model with ±270 VDC ECS and IPS architecture is lighter, has a more extended range and has less relative fuel consumption. In addition, the simulation results showed that the maximum range and relative fuel economy of all three aircraft models increased slightly as the temperature increased.Practical implicationsConsidering the findings in this paper, it is seen that the electrification of the conventional pneumatic system in aircraft has positive contributions in terms of weight, power consumption and fuel consumption.Social implicationsThe positive contributions in terms of weight, power consumption and fuel consumption in aircraft will be direct environmental and economic contributions.Originality/valueApart from the conventional ECS and IPS of the aircraft, two electrical architectures, 230 VAC and ±270 VDC, were modelled and analysed. To see the effects of the three models created in different temperature profiles, analyses were done for cold day, ISA standard day and hot day temperature profiles.

Powered Low-Speed Experimental Aerodynamic Investigation of an Over-Wing-Mounted Nacelle Configuration

Over-wing integration of ultrahigh bypass turbofan engines can be a solution for next-generation commercial transport aircraft since it eliminates the ground clearance issue and it has the potential to reduce ground noise due to acoustic shielding. Moreover, a unique characteristic of this installation type is the powered lift benefit at low-speed flight conditions. This paper aims to experimentally investigate the effect of the engine power setting on the low-speed aerodynamic performance of an over-wing-mounted nacelle configuration comprising a conventional tube-and-wing layout. Thus, low-speed wind tunnel tests were performed for a half-span powered scale model of the aforementioned configuration. The effect of the engine power setting on the wing lift and spanwise pressure distributions was investigated. The experiments were carried out for angles of attack varying from 0 to 6° and inlet mass flow ratios up to 2.4. The results were used to validate computational fluid dynamics simulations conducted for the same wind tunnel conditions. It has been shown that a significant powered lift benefit can be achieved for the studied configuration, without a penalty in the net propulsive force and that the lift increases linearly with the inlet mass flow ratio. Furthermore, it was observed that the engine power setting largely influences the pressure distributions along the wing, especially at the spanwise sections closer to the nacelle. The low-momentum zone created upstream of the engine at high power settings reduces the pressure at the wing’s upper surface, which is the main factor responsible for the increased lift. By taking advantage of such behavior, drag can potentially be reduced at takeoff and climb due to a lower flap setting required for the same lift.

A Rapid Surrogate Model for Estimating Aviation Noise Impact across Various Departure Profiles and Operating Conditions

Aviation noise remains a key barrier to the sustainable growth of commercial aviation. The advent of emerging technologies, such as urban air mobility, and the renewed interest in commercial supersonic transport aircraft, has only further raised concerns over the resultant community noise exposure. The foundation of any noise mitigation effort is the ability to accurately model noise metrics over a wide range of scenarios. Aviation noise is influenced by a wide variety of factors, including aircraft type, payload weight, thrust settings, airport elevation, ambient weather, and flight trajectory. Traditional noise modeling paradigms rely on physics-based and empirical calculations, which are computationally expensive. Attempts at speeding up the computations with alternate models could deliver on speed or accuracy, but not both. Recent research has indicated that model order reduction techniques hold promise for transforming and greatly reducing the number of quantities that need to be modeled. Paired with surrogate modeling techniques, a rapid and accurate noise model can be generated. The research presented in this manuscript expands on the model order reduction method and develops a rapid noise surrogate model, which can account for the piloting actions, the ambient temperature, and airport elevation. The presented results indicate that the method works well with minimal error for most modeling scenarios. The results also outline avenues for improvement, such as using a different class of surrogate models or modeling additional training cases. The model developed in this research has numerous applications for multi-query applications, such as parametric trade-off analyses and optimization studies. With the inclusion of airport and aircraft parameters, the model enables the development of frameworks that optimize piloting actions for noise mitigation on the ground.

Aerodynamic Investigation of Blended Wing Body Configuration


 A blended wing body (BWB) configuration is an unconventional aircraft design in which the wing and fuselage are blended to form an aircraft. This design concept has inherent higher aerodynamic efficiency, environmental benefits and capacities. These advantages make the BWB configuration a feasible concept for commercial transport aircraft. In the present work, a 3-D BWB model is designed in SolidWorks and fabricated using a 3D printer. The numerical and experimental analyses are carried out with this BWB geometry. Aerodynamic characteristics and flow features obtained from the open-source CFD software OpenFOAM have been studied, analyzed, and compared with the wind tunnel results. Experimental and computational data compare well and the present BWB can operate at a high angle of attack. The coefficient of lift (CL) increases with AoA up to 45º. The CL starts decreasing beyond this AoA, and the present BWB geometry stalls at around AoA = 45º. The coefficient of drag (CD) increases with the increase in AoA due to the spreading of the separated region over the geometry. Lift/Drag (L/D) variation with AoA is also studied to find the optimum flight configuration of the present BWB geometry. Sectional pressure distribution at different spanwise locations, velocity contours, pathlines, surface limiting streamlines and tuft flow visualization are also presented to investigate the flow. The studies investigate the aerodynamics, flow field and optimal flight configuration for cruising a BWB geometry.

A Wide-Scanning Array Antenna of Connected Vertical Bowtie Elements Structurally Integrated Within an Aircraft Fuselage

A low-profile, wide-scanning phased-array antenna of vertical bowtie elements fully integrated with a structurally efficient radome and ribs of an aircraft fuselage is proposed in this paper. The array is designed to simultaneously fulfil the electrical requirements of an airborne antenna sensor and the mechanical requirements of a load-carrying aircraft fuselage. The array antenna is capable of steering the beam up to ±80° in the azimuth plane over a 20% bandwidth (2.4 GHz to 3 GHz) with the active reflection coefficient (Γ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><i>act</i></sub> ) below –10 dB in an infinite array environment. Experimental results of a 16×16 element array demonstrator agree well with the simulation results. The 16×16 array antenna is capable of steering the beam up to ±60° and ±75° with the bandwidth of 20% and 10%, respectively at Γ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><i>act</i></sub> ≤ –10 dB. The array antenna also achieved good stiffness and performed well in the vibration loads of commercial transport aircraft.

Analysis of a new standing passenger seat design for commercial transport aircraft

In order to have profitable flight operations, many airlines have used high-density passenger cabin design and arrangement. By doing this, more passengers can be accommodated inside the cabin per flight, hence reducing the overall flight costs per passenger. With conventional aircraft seats, the seat pitch is progressively reduced over the years to accommodate additional passengers into the cabin and this has created high flight comfort issues among the passengers. Reduced seat pitch also means that available legroom at each seat becomes smaller, which leads to discomfort due to inadequate space for many passengers in their sitting positions. For short-haul flights, the standing passenger cabin concept has been explored and proposed to help resolve this issue. Since passengers will require less legroom space in their standing positions, it is possible to have reduced seat pitch (hence more passengers) and acceptable comfort. A proposed standing passenger seat design is studied in this work to establish and support its suitability to be used in the standing passenger cabin concept. Finite element analysis is conducted to demonstrate its ability to fulfill the strength requirements imposed by the aviation authority. Furthermore, several design improvements have also been made to minimize its weight while still satisfying the strength requirements. The final standing passenger seat design has been shown to have adequate structural strength to cope with the requisite 9-g loading and a mass of about 11.7 kg which is lower than most conventional aircraft seats. All in all, this indicates that the proposed standing seat design has a good potential to be applied for air transportation and further supports the future implementation of the standing cabin concept. The final design from this study can be further refined in future studies to improve its characteristics.

Potential Impacts on Ozone and Climate From a Proposed Fleet of Supersonic Aircraft

AbstractThere has been renewed interest in developing commercial supersonic transport aircraft due to the increased overall demands by the public for air travel, the aspiration for more intercontinental travel, and the desire for shorter flight times. Various companies and academic institutions have been actively considering the designs of such supersonic aircraft. As these new designs are developed, the environmental impact on ozone and climate of these fleets need to be explored. This study examines one such proposed commercial supersonic fleet of 55‐seater that is projected to fly at Mach 2.2, corresponding to cruise altitudes of 17–20 km, and which would burn 122.32 Tg of fuel and emit 1.78 Tg of NOx each year. Our analyses indicate this proposed fleet would cause a 0.74% reduction in global column ozone (∼2 Dobson Units), which is mainly attributed to the large amounts of nitrogen oxides released in the atmosphere from the supersonic aircraft. The maximum ozone loss occurs at the tropics in the fall season, with a reduction of −1.4% in the total column ozone regionally. The stratospheric‐adjusted radiative forcing on climate from this fleet was derived based on changes in atmospheric concentrations of ozone (59.5 mW/m2), water vapor (10.1 mW/m2), black carbon (−3.9 mW/m2) and sulfate aerosols (−20.3 mW/m2), resulting in a net non‐CO2, non‐contrail forcing of 45.4 mW/m2, indicating an overall warming effect.

Drag Decomposition Using Partial-Pressure Fields: Ventus-3 and NASA Common Research Model

The development of partial-pressure field (PPF) theory (Schmitz, S “Drag Decomposition Using Partial-Pressure Fields in the Compressible Navier–Stokes Equations,” AIAA Journal, Vol. 57, No. 5, 2019, pp. 2030–2038) and the application of the concept to conditions relevant to commercial transport aircraft, operating in both the subsonic and transonic regimes (Hart, P. L., and Schmitz, S., “Drag Decomposition using Partial-Pressure Fields: ONERA M6 Wing,” AIAA Journal, Vol. 60, No. 5, 2022 pp. 2941–2951), have shown promise as complements to classical far-field methods. In the present work, a further comprehensive analysis of drag decomposition methods is applied to wing and aircraft configurations. First, the Ventus-3 sailplane wing case demonstrates the ability of PPFs to successfully deconstruct drag on industry-relevant cases including transition modeling and winglets. A quantitative comparison to classical aerodynamic theory and far-field methods supports PPF theory and provides additional insight to viscous–inviscid interaction by means of a viscous interactional aerodynamics term in PPF theory. Second, the NASA Common Research Model is simulated in transonic flow to showcase drag decomposition of full aircraft configurations where PPF applications are used to provide further insight into wave drag sources acting on the aircraft in comparison to classical far-field decomposition methods.

Impact of Design Constraints on Noise and Emissions of Derivative Supersonic Engines

The propulsion systems used in commercial supersonic transport (SST) aircraft, such as the Concorde, have used repurposed engines or derivative engines based on cores from existing donor engines rather than purpose-designed clean-sheet engines. A similar approach is currently being adopted in the development of new SSTs. Turbomachinery components and cooling mass flow rates in derivative engines are sized by the design cycle of the donor engine and constrain the design of the derivative engine cycle. Here, we identify the constraints imposed by the donor engines and quantify their impact on the specific fuel consumption (SFC), certification noise, and (oxides of nitrogen) emissions index [EI()] relative to purpose-designed clean-sheet engines. We design and optimize a clean-sheet and derivative engine for a notional 55 metric ton SST proposed by NASA. A clean-sheet engine optimized for SFC results in an approximately 4.5% reduction in SFC, an approximately 2.5-fold increase in EI(), and a 1.2 EPNdB increase in certification noise relative to the derivative engine. Applying a constraint on EI() to the clean-sheet engine results in an approximately 0.5% reduction in SFC relative to the derivative engine. The work provides a quantitative comparison of clean-sheet purpose-built engines and derivative engines from an environmental perspective that can inform policy makers as they develop updated environmental standards for civil supersonic aircraft.

Airfoil Morphed Leading-Edge Design for High-Lift Applications Using Genetic Algorithm

A genetic algorithm was developed for the optimal design of morphing airfoil leading-edge shapes to maximize airfoil , while retaining a constant leading-edge arc length. Using a candidate slotted, natural laminar flow airfoil, an inviscid–viscous flow simulation program suite was used to evaluate a randomized population of airfoils during the design process at low-speed, high-lift flight conditions of a representative single-aisle commercial transport aircraft. The use of a continuous morphing strategy to perform treatment of the leading-edge geometry in high-lift scenarios, as opposed to leading-edge flap or slat elements, is envisaged as a means to mitigate surface discontinuities and retain laminar flow qualities of future airfoil sections in cruise conditions. By using different definitions of the objective cost function, multiple morphed airfoil designs were found through the genetic algorithm to create a library of possible designs aimed to purposefully alleviate the leading-edge stall tendencies of the baseline airfoil. Three morphed designs were validated through experimentation in a low-speed, open-return wind tunnel. Resulting data were used to verify that the leading-edge separation property of the baseline airfoil during stall was effectively alleviated with use of the morphed leading-edge geometries.

Thermal Management System Optimization for a Parallel Hybrid Aircraft Considering Mission Fuel Burn

Electrified aircraft propulsion enables new aircraft designs with fewer emissions. One challenge of electrified architectures is handling the electrical components’ waste heat. This is because batteries and other electrical components are sensitive to high temperatures and accumulate heat within their structure. In this work, we investigate using a thermoacoustic refrigerator to cool the battery of a parallel hybrid single-aisle commercial transport aircraft. This thermoacoustic refrigeration system is powered by waste heat from the turbofan engine core, whereas a conventional refrigerator consumes electricity from the battery or shaft power offtakes. Compared to a conventional vapor cycle refrigerator, the thermoacoustic refrigeration system results in greater mission fuel burn because of pressure losses attributable to the extraction of heat from the turbofan to drive the thermoacoustic refrigerator. Heat exchangers with very low pressure losses may render the thermoacoustic refrigeration system beneficial compared to conventional refrigeration in certain use cases, such as low-altitude missions.

Performance analysis of electrical flight control actuation system in a commercial transport aircraft

PurposeIn more than 100 years of aviation, significant progress has been made in flight control systems. The aircrafts that have entered service for the past ten years tend towards power-by-wire flight control with electrical actuators. The purpose of this study is to analyse the effects of electrical actuation on power consumption, weight and fuel consumption on a commercial transport aircraft.Design/methodology/approachThe Airbus A321-200 aircraft was chosen as a case study for analysing the effects of electrical actuation on the flight control actuation system (FCAS) architecture, and Pacelab SysArc software was used for design, modelling and analysis. As alternatives to the existing system, hybrid and all-electric models are built to a set of design guidelines with certain limitations.FindingsCompared to the existing FCAS architecture model, 80 kg weight savings in the hybrid FCAS architecture model and 171 kg weight savings in the all-electric FCAS architecture model were observed. In terms of fuel consumption, it has been observed that there is 0.25% fuel savings in the hybrid FCAS architecture model, and 0.48% fuel savings in the all-electric FCAS architecture model compared to the existing FCAS architecture model at 3200 NM.Practical implicationsIn line with the data obtained from this study, it is predicted that electrical actuation is more preferable in aircraft, considering its positive effects on weight and fuel consumption.Originality/valueIn this study, three different models were created: the existing FCAS architecture of a commercial transport aircraft, the hybrid FCAS architecture and the all-electric FCAS architecture. Hybrid and all-electric models are built according to a set of design guidelines, with certain limitations. Then, similar flight missions consisting of the same flight conditions are defined to analyse the effects of power consumption, weight, and fuel consumption comparatively.

Drag Decomposition Using Partial-Pressure Fields: ONERA M6 Wing

Drag decomposition has classically been undertaken using a far-field approach both from a wind-tunnel testing and computational fluid dynamics standpoint. It has been suggested by Schmitz (“Drag Decomposition Using Partial-Pressure Fields in the Compressible Navier-Stokes Equations,” AIAA Journal, Vol. 57, No. 5, 2019, pp. 2030–2038) that a decomposition of static pressure into partial pressure fields can allow one to decompose a computational fluids dynamics solution in the near field. This paper covers the implementation process of partial pressure fields on the ONERA M6 wing at conditions relevant to commercial transport aircraft. Relations between partial pressure field decomposition, the classical far-field theory, and physical drag sources are discussed. It is demonstrated that the near-field partial pressure field decomposition is equivalent to classical far-field analysis. In transonic flow, a new method to compute wave drag using a combination of both partial pressure fields and the far-field method is demonstrated.

Applying Machine Learning to Enhance Runway Safety Through Runway Excursion Risk Mitigation

Risk of runway excursion caused by pilots continuing an unstable approach to landing has been identified by aviation accident investigators as a primary contributing factor in airline landing accidents. The purpose of this research was to develop and test predictive models for unstable approach risk misperception in the National Airspace System using machine learning. The research applied machine learning algorithms to flight recorder data gathered from a fleet of commercial transport aircraft and made available by NASA. Once evidence of unstable approaches was identified and extracted from the flight recorder data, a determination was made whether a rejected landing or continuance to landing was made. Federal Aviation Administration unstable approach criteria were used in the identification of unstable approaches based on flight data variables evaluated at 500 feet above the ground on approach to landing. Six machine learning algorithms were used, including logistic regression, decision tree, gradient boosting, random forest, and support vector machine. The results indicated that the decision tree with three branches produced the best predictive model. This model was able to predict the pilot error of continuing an unstable approach to landing with an accuracy of 98%. Glideslope deviation, selected airspeed, localizer deviation, and flaps not extended were the most important influential predictors of pilot error leading to an unstable approach.

Anti-icing hot air jet heat transfer augmentation employing inner channels

Many approaches exist today that employ hot-air from aircraft compressor bleed for anti-icing critical aircraft surfaces. This paper introduces and numerically analyzes the novel application of an inner or etched channel to augment heat transfer from a hot-air jet impinging on a curved surface representing the inner surface of an aircraft wing’s leading edge or slat. The study shows that proper positioning, geometry, and flow characteristics of a channel along the inner surface of the leading edge can significantly enhance heat transfer, boost the anti-icing system performance, and greatly enhance flight safety during critical icing weather conditions. Commercially available CFD software, ANSYS Fluent is used to model and analyze the effect of different geometric and flow parameters typical of those found in small to medium category commercial transport aircraft to help determine the optimum arrangement. These parameters include: (1) jet nozzle height-to-slot diameter ratios from 4 to 8, (2) channel width-to-slot diameter ratios from 0.4 to 1.8, and (3) inner-channel inlet location angles from 10° to 60°. Each configuration resulting from a combination of the above parameters was simulated at Reynolds numbers based on jet-slot diameter of 30,000, 60,000, and 90,000. Empirical relations based on available experimental data are used to validate the results. The main findings of the study reveal that the jet height-to-slot diameter ratio of 6, inner channel height-to-slot diameter ratios of 1.8, and inner-channel inlet angular locations of 10° combination resulted in the highest heat transfer at all Reynolds number as well as higher at increased Reynold numbers.

Relating air quality and other factors to comfort and health related symptoms reported by passengers and crew on commercial transport aircraft (ASHRAE RP-1262)

Passenger and flight crew concerns over the negative impact of the aircraft cabin environment on health and comfort have lingered for years. During flight, passengers and crew can experience reduced atmospheric pressure, low relative humidity, and potential air quality degradation, which could lead to adverse health complaints. The goal of this project was to investigate the potential link between perceived health symptoms and discomfort and aircraft cabin environmental conditions and human factors. Passengers and crew completed validated health and comfort surveys on 130 domestic and international flights across varied aircraft, durations, and seasons. Environmental conditions and airborne levels of contaminants were measured during 80 of these flights. Extremes in cabin temperature or degraded air quality parameters led to higher rates of passenger discomfort. Odds ratios were higher for several adverse health symptoms for certain aircraft types and durations, while ventilation rates were positively correlated with discomfort and adverse health symptoms. Median levels of CO, CO2, and ozone were below established exposure limits. Results from this study help further our knowledge of aircraft comfort and can help airlines and industry agencies determine the most critical impacts on health and comfort to better inform standards to improve passenger and crew experiences.

Numerical Investigation of Aeroelastic Deformation Effect on the NASA Common Research Model

The risk of the aeroelastic deformation of the wings to the flight safety has become increasingly prominent for commercial transport aircraft due to the requirements for lightweight structure. In this work, Reynolds averaged Navier-Stokes (RANS) method coupled with transfinite interpolation were employed to investigate the influence of static elastic deformation of wing on aerodynamic characteristics of NASA CRM. Both bend and twist distributions were scaled in numerical simulations based on dynamic pressure, which was shown to be reasonable by the compassions between the calculations and measurements. The numerical results show premature flow separation in the middle and outboard of the wing for original configuration. Furthermore, the flow separation was supressed by the upward bending of the wing and negative twist in the leading edge, and the aerodynamic characteristics of the aircraft were improved by the aeroelastic deformation.

Design of a slotted, natural-laminar-flow airfoil for commercial transport applications

Slotted, natural-laminar-flow (SNLF) airfoils are a novel aerodynamic concept that enable significant performance improvements over conventional, single-element NLF airfoils. The S207, SNLF airfoil has been designed using requirements derived from a transonic, truss-braced wing commercial aircraft configuration. The airfoil is designed for a cruise Reynolds number of 13.2×106 and it exhibits a drag divergence Mach number exceeding 0.71. At these conditions, low drag is predicted to occur between lift coefficients of 0.40 and 0.79. The S207 airfoil exhibits a range-based figure of merit nearly triple that of a turbulent airfoil representative of modern commercial transport aircraft. Slotted configurations also have benefits for low-speed, high-lift conditions representative of approach. The S207 airfoil exhibits a low-speed, maximum lift coefficient in excess of 2.1, and is limited by compressibility effects around the leading edge. Incorporation of this airfoil onto a transonic, truss-braced wing configuration shows strong potential for meeting mid- and far-term goals for reducing aircraft fuel/energy consumption.

Post-stall flight dynamics of commercial transport aircraft configuration: A nonlinear bifurcation analysis and validation

Loss-of-control has become the largest fatal accident category for worldwide commercial jet accidents, and any initiative aimed at preventing such events requires an understanding of the fundamental aircraft behavior, especially the flight dynamics at post-stall region at which loss-of-control usually occurred. A series of low-speed static and dynamic wind tunnel tests of the Common Research Model over a large angle of attack/sideslip envelope was conducted and a non-linear aerodynamic model was developed. The bifurcation analysis, complemented by time-history simulation was used to understand the post-stall flight dynamics and the numerical analysis results were preliminary validated by wind tunnel virtual flight test. Several representative post-stall behaviors for the transport aircraft have been identified, including departure, periodic oscillation, post-stall gyration and steep spiral, etc. Furthermore, the predicted periodic oscillation in pitch motion has been perfectly duplicated in wind tunnel virtual flight test. The approach used in this work shows a promising way to uncover the flight dynamics of transport aircraft at extreme and loss-of-control flight conditions, as well as to apply to nonlinear unsteady aerodynamics modeling and validation, flight accident investigation, advanced flight control law design or studying initiative for loss-of-control prevention or mitigation.

Fuel consumption optimisation using structural equation modelling and genetic algorithm approach: The case of commercial aviation

The main aim of this study is to develop a model for minimising fuel consumption in civil aviation. Structural equation modelling (SEM) is utilised for this purpose and the model is developed in terms of various factors that influence fuel consumption in civil aviation. Total 249 questionnaires were sent out to aviation experts to identify the decision variables of strongly correlated dimensions. The results of SEM show four key underlying factors that have a positive effect on both fuel consumption and fuel optimisation. These factors are aircraft design and technology, aviation infrastructure and operation management, socioeconomic measures and the use of alternative fuels. Fuel consumption of commercial transport aircraft was reduced using a genetic algorithm. The results of this study reinforce that fuel consumption optimisation could have a distinctive effect on competitive benefit and structural performance commercial aviation.