Blended Wing Body Configuration Research Articles

Mission-Driven Inverse Design of Blended Wing Body Aircraft with Machine Learning

The intent of this work was to investigate the feasibility of developing machine learning models for calculating values of airplane configuration design variables when provided time-series, mission-informed performance data. Shallow artificial neural networks were developed, trained, and tested using data pertaining to the blended wing body (BWB) class of aerospace vehicles. Configuration design parameters were varied using a Latin-hypercube sampling scheme. These data were used by a parametric-based BWB configuration generator to create unique BWBs. Performance for each configuration was obtained via a performance estimation tool. Training and testing of neural networks was conducted using a K-fold cross-validation scheme. A random forest approach was used to determine the values of predicted configuration design variables when evaluating neural network accuracy across a blended wing body vehicle survey. The results demonstrated the viability of leveraging neural networks in mission-dependent, inverse design of blended wing bodies. In particular, feed-forward, shallow neural network architectures yielded significantly better predictive accuracy than cascade-forward architectures. Furthermore, for both architectures, increasing the number of neurons in the hidden layer increased the prediction accuracy of configuration design variables by at least 80%.

Blended Wing Body Configuration for Hydrogen-Powered Aviation

Hydrogen aircraft have the potential to achieve more significant climate impact reductions at a lower cost than aircraft powered by biofuels or other drop-in sustainable aviation fuels. Nevertheless, even as a liquid, hydrogen requires four times more volume than kerosene to store the same energy. Companies and researchers have suggested that the blended wing body configuration is well-suited to hydrogen because it can efficiently store large fuel tanks. However, nobody has quantified this claim, at least publicly. We address this gap by comparing optimized kerosene and hydrogen versions of blended wing body and tube and wing aircraft. Our models predict that, with ambitious hydrogen tank technology assumptions, a hydrogen blended wing body has a 3.8% energy penalty compared to a kerosene blended wing body. In contrast, the energy penalty for a tube and wing is 5.1%. These results suggest that the blended wing body configuration is slightly better suited to hydrogen than a tube and wing. However, the conclusion breaks down under less optimistic scenarios where lightweight conformal liquid hydrogen tanks are unavailable. Nonetheless, the energy penalties of switching the two configurations to hydrogen have a similar order of magnitude. Any kerosene blended wing body fuel burn benefit over a tube and wing also applies to hydrogen versions. As a result, kerosene blended wing body technology developments, such as maturing the structural design of the noncircular pressurized passenger cabin, remain valuable for future hydrogen-powered aircraft.

Towards More Efficient Electric Propulsion UAV Systems Using Boundary Layer Ingestion

The implementation of distributed propulsion and boundary layer ingestion for unmanned aerial vehicles represents various challenges for the design of embedded ducts in blended wing body configurations. This work explores the conceptual design and evaluation of DP configurations with BLI. The aerodynamic integration of each configuration is evaluated following a proposed framework, including simulation analysis. Power saving coefficient and propulsive efficiency were compared against a baseline podded case. The results show the optimal propulsion configuration for the BWB UAV obtaining 3.95% of power benefit and propulsive efficiency (ηp>80%). Indeed, the aerodynamic integration effects for the proposed design maintain the BWB’s aerodynamic efficiency, which will contribute to longer endurance and better performance.

Design Investigation of Potential Long-Range Hydrogen Combustion Blended Wing Body Aircraft with Future Technologies

Present work investigates the potential of a long-range commercial blended wing body configuration powered by hydrogen combustion engines with future airframe and propulsion technologies. Future technologies include advanced materials, load alleviation techniques, boundary layer ingestion, and ultra-high bypass ratio engines. The hydrogen combustion configuration was compared to the configuration powered by kerosene with respect to geometric properties, performance characteristics, energy demand, equivalent CO2 emissions, and Direct Operating Costs. In addition, technology sensitivity studies were performed to assess the potential influence of each technology on the configuration. A multi-fidelity sizing methodology using low- and mid-fidelity methods for rapid configuration sizing was created to assess the configuration and perform robust analyses and multi-disciplinary optimizations. To assess potential uncertainties of the fidelity of aerodynamic analysis tools, high-fidelity aerodynamic analysis and optimization framework MACH-Aero was used for additional verification. Comparison of hydrogen and kerosene blended wing body aircraft showed a potential reduction of equivalent CO2 emission by 15% and 81% for blue and green hydrogen compared to the kerosene blended wing body and by 44% and 88% with respect to a conventional B777-300ER aircraft. Advancements in future technologies also significantly affect the geometric layout of aircraft. Boundary layer ingestion and ultra-high bypass ratio engines demonstrated the highest potential for fuel reduction, although both technologies conflict with each other. However, operating costs of hydrogen aircraft could establish a significant problem if pessimistic and base hydrogen price scenarios are achieved for blue and green hydrogen respectively. Finally, configurational problems featured by classical blended wing body aircraft are magnified for the hydrogen case due to the significant volume requirements to store hydrogen fuel.

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.

Experimental and computational investigation of the vortical structures generated from a blended-wing-body UAV model

The current study presents a combination of experimental and computational investigations of a scaled-down Blended Wing Body (BWB) Unmanned Aerial Vehicle (UAV) model. The BWB model features highly swept wings. The experiments are conducted in a subsonic windtunnel in the Laboratory of Fluid Mechanics and Turbomachinery, in the Aristotle University of Thessaloniki. More specifically, surface oil flow visualization and Laser-Doppler Anemometry (LDA) are employed to investigate the vortical structures emanating from the leading edge and the wingtips of the model and provide the corresponding velocity and vorticity profiles. Using the windtunnel measurement data as a reference point, both steady-state and transient computational fluid dynamics (CFD) analyses are also conducted. The flow around the BWB scaled-down model is modeled by adopting four turbulence models, three of them based on the concept of the eddy-viscosity and one, on the Reynolds-stress transport equation modeling. The modeling results are compared to the experimental measurements, emphasizing on the streamwise and spanwise velocity profiles, axial vorticity profiles and separation patterns. The results of this study provide insight on the vortical phenomena dominating the flowfield over and around BWB configurations and conclusions concerning the tradeoffs between accuracy and computational efficiency are drawn.

Flow Field Investigation of a Blended Wing Body in Low Speeds

With the advancement in the modern transport system, it has become imperative to achieve larger aircraft volume at minimum cost wherein aerodynamics plays a major role. The present work aims to investigate the flow over a typical blended wing body (BWB) configuration at different angles of attack adopting experimental and computational techniques. Experiments consisted of the force measurements and oil flow visualizations at a free stream velocity of around 19 m/s. Computations were made using the commercially available software ANSYS 18.1. Results indicated that the use of a Blended Wing Body Configuration resulted in improved aerodynamic characteristics in comparison to other wing configurations such as Delta/ Double delta wings. Surface flow visualization carried out over the BWB configuration indicated the reason behind increased lift coefficients. Reasonable agreement of experiments and computations was observed.

Design, Computational Aerodynamic, Aerostructural, and Control Stability Investigations of VTOL-Configured Hybrid Blended Wing Body-Based Unmanned Aerial Vehicle for Intruder Inspections

Unmanned aerial vehicles (UAVs) are gaining in popularity and sophistication in today’s modern world. UAVs are now available in a wide range of configurations. A UAV’s many applications include aerial photography and videography and target tracking. The upward-pointing propellers of some modern fixed-wing UAVs make it possible for them to take off and land vertically. Surveillance and intruder inspections are two areas where the blended wing body (BWB) configuration shines. This is because its weight is spread uniformly throughout the body, its radar signal is weaker than that of alternative configurations, and there is a relatively small amount of interference with its movement. With common design factors in mind, like vertical takeoff and landing, aerodynamic drag, and fundamental wing stability, the optimal BWB plan form for surveillance is designed. CATIA is used to finish the conceptual design of the BWB-based UAV. A fluid-structure interaction (FSI) study is carried out after the model has been examined in ANSYS Fluent. The UAV’s responsiveness is improved through simulation in the MATLAB environment after a proportional-integral-derivative-type altitude controller was developed. The results demonstrate that providing the UAV with an altitude instruction enhances its performance. Given the flexibility of the suggested BWB UAV’s design, we have decided to limit its maximum forward speed to 75 m/s and its maximum rate of vertical ascension to 50 m/s. Rapid BWB UAVs like the one seen here are quite helpful in dangerous situations.

A Fast Aerodynamic Model for Aircraft Multidisciplinary Design and Optimization Process

A multidisciplinary design analysis and optimization process is developed at ONERA for the design of tube and wing and blended wing–body aircraft configurations. This process is composed of different disciplinary modules (geometry, propulsion, aerodynamics, structure, handling qualities and flight mission), and the overall process considers different fidelity levels for these modules at each step of the design process. This article describes the low-fidelity aerodynamic module used during the preliminary design optimization process. Analytical formulations retained for lift and drag components are presented in the first part. Then, the performances estimated by the aerodynamic module on some reference configurations are compared with both numerical and experimental data, showing a quite good agreement for both tube and wing and blended wing–body configurations not only for global performance but also for individual drag components.

Numerical Analysis of Porpoising Stability Limit of a Blended-Wing–Body Aircraft During Ditching

The ditching processes of a blended-wing–body (BWB) aircraft under different initial speeds and pitch angles are simulated by numerically solving the unsteady Reynolds-averaged Navier–Stokes equations and the realizable turbulence model using the finite volume method. The volume-of-fluid model is adopted to capture the water–air interface. The six-degree-of-freedom model is employed to couple fluid dynamics and aircraft rigid-body kinematics. The global moving mesh is used to deal with the relative motion between the aircraft and the water. It is found that the plane composed of initial speed and pitch angle can be divided into two regions by a stability limit line, that is, the porpoising motion region (the aircraft takes coupled oscillatory motion between heaving and pitching) with large initial speeds and pitch angles and the stable motion region with low initial speeds and pitch angles. When the initial speed is large, the aircraft’s pitch-up moment peak and heaving amplitude are enhanced. Hence the aircraft carries out the porpoising motion. For the large initial pitch angle, the water entry depth of the aircraft increases and the waterline moves forward, which produces a more significant pitch-up moment peak and overload peak. As a result, the aircraft conducts the porpoising motion. The porpoising stability of the BWB configuration is obviously worse than the conventional and flying wing configurations. When the BWB aircraft ditches on water, the pilots should reduce the initial speed and pitch angle as much as possible to avoid the dangerous porpoising motion.

Investigation on the flow mechanism of nacelle airframe interaction for podded blended wing body transport

For the flow interaction between the podded engine and the airframe of blended wing body configuration(BWB), taking the 300 seats class BWB civil transport NPU-BWB-300 designed by Northwestern Polytechnical University as the research object, the influence of the podded engines on the BWB airframe at typical high and low speed conditions were investigated by CFD method, and the airframe-nacelle interference mechanism was revealed. The results indicate that the podded engines mainly affect the high speed performance of BWB, but have little effect on the low speed performance. The flow interaction between the airframe and the nacelle at high speed condition is serious when podded the engines, which leads to strong shock wave and flow separation. The flow mechanism of the above-mentioned interaction is as follows: firstly, the large supersonic region and shock wave on the nacelle external surface interferes with airframe surface flow seriously, which induces shock wave and flow separation; secondly, a convergent-divergent channel is formed between the airframe and the nacelle, resulting in the "throat" effect, which produces shock wave and flow separation.

Low Speed Aerodynamic Analysis of the N2A Hybrid Wing–Body

Reduction of atmospheric emissions is currently a mandatory requirement for aircraft manufacturers. Several studies performed on Blended Wing–Body configurations showed a promising capability of reducing fuel consumption by increasing, at the same time, passengers’ transport capabilities. Although several aerodynamic studies are available at transonic speeds, low-speed evaluations of aerodynamic performances of Blended Wing Body aircrafts are less investigated. In this framework, the present paper deals with the aerodynamic performance of the N2A aircraft prototype at low-Mach number conditions. Aircraft longitudinal aerodynamics is addressed at M∞=0.2 with steady state three-dimensional RANS simulations carried out at two Reynolds numbers equal to 6.60×106 and 1.27×108, respectively. The former refers to an experimental test campaign performed at NASA Langley 14-by-22 foot subsonic tunnel, while the latter is related to free-flight conditions close to an approach and landing phase. Flowfield simulations are performed using the Computational Fluid Dynamic code FLUENT and the SU2 open-source code, currently adopted for research applications. Numerical solutions are validated by using available experimental data with reference to lift, drag, pitching moment and drag polar estimations. Pre-stall and post-stall aerodynamic behaviour through mean flow-field visualization along with the comparison of pressure distributions at several AoAs is addressed. Furthermore, the effect of convective discretization on a numerical solution for SU2 is discussed. Results indicate a good agreement with available experimental predictions. The present study aims to bridge existing computations at a Eulerian low-Mach number, with RANS computations and constitutes a further test-case for SU2 code with respect to a full aircraft configuration.

Aerodynamic characteristics research of a distributed propulsion blended-wing-body aircraft

According to the development and research background of the next generation civil aircraft, the aerodynamic characteristics and stall mechanism of a specified distributed propulsion (DP) blended-wing-body (BWB) aircraft are analyzed and studied by combining the numerical simulation and the wind tunnel tests. Firstly, the DP BWB configuration and the numerical simulation methods are introduced. Secondly, the aerodynamic performance of the DP BWB aircraft between with and without the DP induced effects into consideration are compared and analyzed by using the numerical simulation. Finally, the stall mechanism is sorted out based on the wind tunnel flow-field visualization, and at the same time, the numerical simulation method is also validated. The results show that the span-wise flow along the leading edge (LE) of the plane platform for DP installation is the main factor to induce stall at high angle of attack (AOA), while the middle fuselage can still provide enough lift to maintain flight at high angle of attack, and the DP system has an obvious combination effect on the flow on the wing, which maybe is an effective way to control and improve the BWB stall characteristics at high AOA.

Aerodynamic Design, Analysis and Validation of a Small Blended-Wing-Body Unmanned Aerial Vehicle

This paper describes the aerodynamic design and assessment of a blended-wing–body (BWB) configuration under the distributed electric propulsion (DEP) installation constraints. The aerodynamic design rationale and process is described, as well as how the DEP system is considered and simplified in the optimization design process. Both the BWB configuration and the DEP induced effects are numerically simulated and analyzed using the Reynolds Averaged Navier–Stokes (RANS) computational fluid dynamics (CFD) flow solvers. To further demonstrate the feasibility and reliability of the design approach, the wind tunnel tests of a scaled model of the designed BWB configuration are carried out, and both the aerodynamic characteristics and the BWB surface flow are measured and analyzed. The results indicate the reliability and feasibility of the optimization design method introduced in this paper.

Aero-structural numerical analysis of a blended wing body unmanned aerial vehicle using a jute-based composite material

Research and development of biocomposites for Unmanned Aerial Vehicle (UAV) structures have become relevant throughout the last decade, due to their cost and lightweight accompanied with good mechanical properties. Moreover, Blended Wing Body configurations (BWB) have aroused special interest, because of their aerodynamic efficiency, manufacturing simplicity and increased fuel economy. In this context, the present study investigates the strength distribution in a semi-monocoque structure of a blended wing body UAV using a composite material based on pre-load jute fibers. For this aim, a three-dimensional numerical simulation with a unidirectional fluid–solid coupling is implemented in a steady analysis at cruise conditions. The air pressure distribution is calculated using computational fluids dynamics (CFD), which then incorporates the aerodynamic loads within the structural module and using finite element method (FEM) determines the static stress distribution and deformation. The properties and manufacturing characteristics of jute-based composite material used in the numerical analysis were incorporated in the analysis and the numerical model was validated against experimental data. Based on the comparison between the structure built by pre-load jute fibers-based composite material and EPO foam, the results show that the proposed material reduces the deformation in 65% and performs better mechanically.

Gradient based empirical cumulative distribution function approximation for robust aerodynamic design

A robust optimization approach based on the use of the conditional value at risk function is presented, together with an application to a robust transonic aerodynamic design problem of the central section of a Blended Wing-Body configuration. The conditional value at risk is estimated using an approach based on the empirical cumulative probability distribution function. The quantities of interest of the risk function are the aerodynamic characteristics of the airfoil, namely lift, drag, and pitching moment coefficients, computed solving the Reynolds-averaged Navier-Stokes equations with the open-source fluid-dynamic solver SU2. Conditional value at risk computation is costly, so techniques and methods for the reduction of the computational cost are introduced. In particular, the empirical cumulative distribution function is approximated with a first-order series expansion using efficiently calculated gradients from SU2 discrete adjoint solver.

Quasi-3D Aerodynamic Analysis Method for Blended-Wing-Body UAV Configurations

The current study presents a low-fidelity, quasi-3D aerodynamic analysis method for Blended-Wing-Body (BWB) Unmanned Aerial Vehicle (UAV) configurations. A tactical BWB UAV experimental prototype is used as a reference platform. The method utilizes 2D panel method analyses and theoretical aerodynamic calculations to rapidly compute lift and pitching moment coefficients. The philosophy and the underlying theoretical and semi-empirical equations of the proposed method are extensively described. Corrections related to control surfaces deflection and ground effect are also suggested, so that the BWB pitching stability and trimming calculations can be supported. The method is validated against low-fidelity 3D aerodynamic analysis methods and high-fidelity, Computational Fluid Dynamics (CFD) results for various BWB configurations. The validation procedures show that the proposed method is considerably more accurate than existing low-fidelity ones, can provide predictions for both lift and pitching moment coefficients and requires far less computational resources and time when compared to CFD modeling. Hence, it can serve as a valuable aerodynamics and stability analysis tool for BWB UAV configurations.

Assessment on critical technologies for conceptual design of blended-wing-body civil aircraft

Civil aviation faces great challenges because of its robust projected future growth and potential adverse environmental effects. The classical Tube-And-Wing (TAW) configuration following the Cayley’s design principles has been optimized to the architecture’s limit, which can hardly satisfy the further requirements on green aviation. By past decades’ investigations the Blended-Wing-Body (BWB) concept has emerged as a potential solution, which can simultaneously fulfill metrics of noise, emission and fuel burn. The purpose of the present work is to analyze the developments of critical technologies for BWB conceptual design from a historical perspective of technology progress. It was found that the high aerodynamic efficiency of BWB aircraft can be well scaled by the mean aerodynamic chord and wetted aspect ratio, and should be realized with the trade-offs among stability and control and low-speed performance. The structure concepts of non-cylinder pressurized cabin are of high risks on weight prediction and weight penalty. A static stability criterion is recommended and further clear and adequate criteria are required by the evaluations of flying and handling qualities. The difficulties of propulsion and airframe integration are analyzed. The energy to revenue work ratios of well-developed BWB configurations are compared, which are 31.5% and 40% better than that of TAW, using state-of-art engine technology and future engine technology, respectively. Finally, further study aspects are advocated.

Trailing edge geometry effect on the aerodynamics of low-speed BWB aerial vehicles

The influence of different planform parameters on the aerodynamic performance of large-scale subsonic and transonic Blended Wing Body (BWB) aircraft have gained comprehensive research in the recent years, however, it is not the case for small-size low subsonic speed Unmanned Aerial Vehicles (UAVs). The present work numerically investigates aerodynamics governing four different trailing edge geometries characterizing BWB configurations in standard flight conditions at angles of attack from -4o to 22o to provide generic information that can be essential for making well-informed decisions during BWB UAV conceptual design phase. Simulation results are discussed and comparatively analyzed with useful implications for formulation of proper mission profile specific to every BWB configuration.

Low Speed Wind Tunnel Test of a Blended Wing Body Configuration

Low Speed Wind Tunnel Test of a Blended Wing Body Configuration