Blended Wing Body Research Articles

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.

Conceptual design of Blended Wing Body for Future Air Transportation

Blended wing body is a fixed wing aircraft which are smoothly blended together with no clear dividing line and no distinct wings also be given a wide Aerofoil shaped body. The future transportation is of aircrafts will incline towards the aerodynamically efficient and capable of carrying large number of passengers over long range and environmental benefits is the main paradigm in the design of aircraft BWB has a high lift to drag ratio which increases the CL max and velocity of the airplane with high load factor and high economy compared with traditional aircraft. Evacuation pressure or the cabin pressurization is the major issues in most of the designs with the minimum aerodynamic lift coefficient and drag coefficient. On the other side of the trend is towards the increasing cruise speed. High speed flow is connected with overcoming of intensive drag rise accruing due to existence of intensive shock, closing local area of supersonic flow. Increase of flight Mach number is possible only by using flow control methods and through affecting the shock increases of aspect ratio leads to increase of lift coefficient corresponding to maximal lift to drag. High bypass ratio engines have smaller fuel consumption and lower noise level but have negative effect on flow around airframe including take-off and landing phases. The necessity of solving problem of intensive aerodynamic heating of surface element of flight vehicles and by ensuring of their stability and controllability and also by need of implementing of high-volume tanks for hydrogen fuel and super high bypass ratio engines.

Design optimization-under-uncertainty of a forward swept wing unmanned aerial vehicle using SAMURAI

In this paper the design optimization-under-uncertainty of a forward swept wing (FSW) blended wing body (BWB) unmanned aerial vehicle (UAV) is examined. Conventional BWBs are often tailless, which leads to a backward swept wing to ensure longitudinal static stability. This in turn can induce flow separation at the tip, leading to a loss of lift, controllability and the appearance of a nose-up pitching moment. A possible solution to this problem is a conceptual redesign by introducing a forward swept wing, which is inherently free of tip-stall, but needs a careful design in order to be controllable. However, fixed wing UAVs are often produced by means of direct injection expanded foam moulding, which is characterized by not negligible production tolerances. This lead to a reliability-based robust design optimization problem, for which a novel framework is employed: SAMURAI. Firstly, the method accounts for computational cost by means of surrogate modelling, an analytical treatment of the problem and an asynchronous updating scheme that balances design space exploration and objective exploitation. Secondly, the method treats the problem as a multi-objective problem, which leads to a Pareto front of robust and reliable designs. The result is a novel series of UAV designs that are inherently free of tip stall, perform robustly and meet the stability requirements with the target reliability obtained with a computationally feasible budget.

Integration of the Athena Vortex Lattice Aerodynamic Analysis Software into the Multivariate Design Synthesis of Blended Wing Body Aircraft

Integration of the Athena Vortex Lattice Aerodynamic Analysis Software into the Multivariate Design Synthesis of Blended Wing Body Aircraft

Verification of an Optimized Shape of Blended-Wing-Body Configuration using Artificial Neural Network

In the current year’s alternative aircraft shapes, such as Blended - Wing- Body (BWB) aircraft, are considered and explored to create more effective aircraft shapes, specifically for more proficient and very huge transportation and eco-friendlier. In addition to the elimination of the tail for this specific type of aircraft and a significant reduction in equivalent weight, drag force, and radar cross-section, the available space for mounting equipment within has been improved and the operational reach has additionally been increased. Irrespective of all these stated advantages, instability is the undesirable outcome of eliminating the tail. Reviewing this deficiency involves designing a tandem of control surfaces and reflexed wing sections and utilizing a complex PC control system. Hence, several researchers have attempted to address the challenges raised by the aerodynamic shape optimization of BWBs, as well as the need to satisfy design specifications. In this paper, an experimental method was initially accepted to optimize the shape of a baseline design of a BWB. The shape was further allowed to be optimized using a Genetic Algorithm (GA). To strengthen the outcome of the optimized shape Artificial Neural Network (ANN) was used for different angles of attack ranging from -5o to 20o and airspeed ranging from 50 m/s to 700 m/s. A feed-forward back prop network with two layers of perceptron was deployed to achieve the goal of aerodynamic efficiency already set by both the experiment and CFD simulation. The goals of ANN and GA matched with a minor variation of 2% in their output results.

Effects of wing twist on lift and drag characteristics of blended wing body aircraft

Blended Wing Body is a revolutionary concept offering phenomenal performance advantages over conventional aircraft. There are various aerodynamic features that are added to the wing in order to adjust the lift distribution and wing twist is one of them. This paper presents a progressive study to examine the effects of twist angles on the aerodynamic characteristics of a Blended Wing Body (BWB) aircraft. CFD analysis is carried out on seven BWB models having wing twists ranging from +3° to -3°. Each model is analyzed at four different Mach numbers. The coefficient of drag (Cd) and coefficient of lift (Cl) is determined and plotted against the twist angle to obtain a trend. The Cl/Cd ratio is also calculated to observe the overall aerodynamic performance of the BWB.

Sustainable Technology on Aircraft Design: A Review

Next-generation air transportation is a key to influence the environment, safety, and the economy. Several programs strive to create emerging innovation towards sustainability, system integrity, and alternative fuels to guarantee a reduction of its environmental effect as greenhouse gas. Nowadays, the aerospace industry is looking forward to aviation sustainable developments across the globe. Few initiatives through a novel configuration of aircraft is established like Blended Wing Body, Flying V aircraft, Box wing Aircraft, and Double bubble Aircraft to enhance the cargo and passenger volume occupancy and cut-off the fuel burn percent. With the use of disruptive technologies, researchers are progressing the revolutionary airframe for transportation. A systematic overview and comprehensive survey of passenger-based aircraft are investigated. The objective study is to examine fuel burn and its impact on the environment by types of aircraft. In-depth literature review studies on four pillar strategies used to design an efficient airplane. In addition, this paper also serves on advancement in evolutionary technologies used in jet transport aircraft. Reflecting the benefits and challenges of different aircraft designs technologies were also highlighted. This paper highlights the future implications and managerial insights for future aircraft designers.

Design of Elevons Wings and Performance Investigation for A Blended Wing Body UAV

To study a hybrid VTOL- Blended wing body design for its wings and elevons and perform CFD simulations with the wings. The steps for designing wing configuration and Elevon positioning involve different variables giving rise to a large number of design possibilities for a control surface. In the current study methods, have been proposed for the selection of optimized wing configuration and elevons positioning and validated with simulations model. Meta-heuristic methods like genetic algorithms are used for arriving at favorable solutions and Matlab coding is written for the initial draft of wing geometry, selected geometries are iterated in XFLR5 for stability and control, and later validated with simulations around the fluid domain. Elevons are control surfaces generally installed in tailless aircraft at the wing’s trailing edge. It applies to roll and pitching force to wings as it combines the functionality of both pitching and rolling control. Design space was mathematically plotted and solved using MATLAB to decide elevons, wing configuration, and their positions. Initial selection of wing geometry, aoa, and structural design for maneuverability and stability for the enhanced aerodynamic performance of BWB UAV. In this presented paper drag coefficient of the designed BWB UAV comes out to be precisely around 0.02216 using computational modeling. Variation curve of Lift and drag coefficient with aspect ratio and angle of attack. Post-processing results of pressure forces and velocity profile on Wings accurately validate the proposed method of control surface optimization. Designed BWB UAV has increased lift to drag ratio, reduced weight of airframe which improves performance. The Design phase is highly iterative, Through this research paper, an attempt has been made to develop a methodology for selection and investigation of control surfaces against requirements that makes BWB UAV more helpful for practical use and increasing the lift and endurance efficiency of the hybrid VTOL- Blended wing body aircraft.

Stability characteristics and airworthiness requirements of blended wing body aircraft with podded engines

Blended-Wing-Body (BWB) aircraft have a relatively short fuselage and no horizontal tail, and they usually adopt podded engines and a V tail instead of a vertical tail. Generally, BWB aircraft have decreased longitudinal and directional static stability and damping. In this paper, the three-axis static and dynamic stability characteristics of an example BWB aircraft with podded engines are studied. According to the differences in flight characteristics of BWB aircraft and conventional aircraft, the different airworthiness requirements for BWB aircraft are analyzed: first, based on current airworthiness regulations and transport aircraft flying quality specification, the relaxation requirement of longitudinal static stability for BWB aircraft is studied; second, the influences of podded engines on longitudinal trim, attitude and trajectory responses and maximum directional control power requirement of BWB aircraft are analyzed; third, the changes in the proportional relationships between the takeoff characteristic speeds of the example BWB aircraft are analyzed. In view of these variations in directional control power requirement and relationships between takeoff characteristic speeds, new recommendations for airworthiness evaluation are proposed for BWB aircraft. The conclusions of this paper are helpful references for configuration design, flight control law design and airworthiness evaluation of BWB aircraft.

Numerical analysis of the porpoising motion of a blended wing body aircraft during ditching

The ditching performance of a BWB aircraft is studied using the numerical method. The unsteady Reynolds-Averaged Navier-Stokes equations and the Realizable k−ε turbulence model are solved by the finite volume method, the implicit 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, and the global moving mesh is used to deal with the relative motion between the aircraft and the water. The accuracy of the present numerical method is validated by the high-speed ditching experiment of a 3D flat plate. The porpoising motion of the BWB aircraft during ditching is discovered for the first time, and this motion is independent of the initial pitch angle, i.e., the amplitude and period of the motion and load curves are coincident for different initial angles. The porpoising motion is determined by a couple of hydrodynamic and aerodynamic loads, and the total load peak is mainly caused by the former. The hydrodynamic load is mainly from the staggered positive-negative pressure stripe on the aircraft belly. The variation in aerodynamic load is mainly induced by the compression work in the dynamic ground effect.

Observer-based incremental backstepping sliding-mode fault-tolerant control for blended-wing-body aircrafts

This paper presents an adaptive incremental nonlinear backstepping sliding-mode (INBSM) controller, for fault tolerant tracking control of a blended wing body (BWB) aircraft with unknown disturbances and actuator faults. The INBSM controller is based on a nonlinear dynamics model of the BWB aircraft. In addition, a radial basis function neural network disturbance observer (RBF-NNDO) is proposed to enhance the disturbance attenuation ability. A fault estimator is suggested to improve actuator fault tolerant control level. The closed-loop control system of the BWB aircraft is proved to be globally asymptotically stable using Lyapunov theory. Simulations of the combined NNDO-INBSM controller are presented and compared with both the INBSM design and an adaptive fuzzy controller. The results demonstrate an improved capability of the NNDO-INBSM control for the BWB aircraft to execute realistic attitude tracking missions, even in the presence of center of gravity movement, unknown disturbances, model uncertainties and actuator faults.

Investigation on improving longitudinal static stability of a blended wing body aircraft

Investigation on improving longitudinal static stability of a blended wing body aircraft

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.

Noise shielding surrogate models using dynamic artificial neural networks

The optimal design methodologies in aeronautics are known to be constrained by the computational burden required by direct simulations. Due to this reason, the development of efficient metamodelling techniques represents nowadays an imperative need for the designers. In fact, surrogate models has been demonstrated to significantly reduce the number of high-fidelity evaluations, thus alleviating the computing effort. Over the last years, the aeronautical designers community has switched from a design approach predominantly based on direct simulations to an extensive use of metamodels. Recently, to further improve the efficiency, several dynamic approaches based on parameters self-tuning have been developed to support the metamodel construction. This work deals with the use of surrogate models based on Artificial Neural Network for the noise shielding of unconventional aircraft configurations. Here, the insertion loss field of the a Blended Wing Body is reproduced by means of advanced machine learning techniques. The relevant framework is the calculation of the noise emitted by innovative aircraft configurations by means of suitable corrections of existing well-assessed noise prediction tools. The self-tuning algorithm has demonstrated to be accurate and efficient, and the observed performance discloses the possibility to implement numerical strategies for the reliable and robust unconventional aircraft optimal design

Theoretical model proposal on direct calculation of wetted area and maximum lift-to-drag ratio

PurposeAs measuring flight performance by experimental methods requires a lot of effort and cost, theoretical models can bring new perspectives to aircraft design. This paper aims to propose a model on the direct calculation of wetted area and L/Dmax.Design/methodology/approachModel is based on idea that the wetted area is proportional to aircraft gross weight to the power of 2/3 (Wg2/3). Aerodynamic underpinning of this method is based on the square–cube law and the claim that parasitic drag is related to the Swet/Swing. The equation proposed by Raymer was used to find the L/Dmax estimate based on the calculated wetted area. The accuracy of the theoretical approach was measured by comparing the L/Dmax values found in the reference literature and the L/Dmax values predicted by the theoretical approach.FindingsProposed theoretical L/Dmax estimate matches with the actual L/Dmax data in different types of aircraft. Among the conventional tube-wing design, only the sailplanes have a very low Swet/Swing. The Swet/Swing of flying wings, blended wing bodies (BWBs) and large delta wings are lower than conventional tube-wing design. Lower relative wetted area (Swet/Swing) is the key design criterion in high L/Dmax targeted designs.Originality/valueThe proposed model could be used in wing sizing according to the targeted L/Dmax value in aircraft design. The approach can be used to estimate the effect of varying gross weight on L/Dmax. In addition, the model contributes to the L/Dmax estimation of unusual designs, such as variable-sweep wing, large delta wings, flying wings and BWBs. This study is valuable in that it reveals that L/Dmax value can be predicted only with aspect ratio, gross weight (Wg) and wing area (Swing) data.

Predicting Maximum Lift Coefficient for Compound Wings Using Lifting Line Theory

In the context of conceptual design there are low-fidelity lifting line models capable of predicting the maximum lift coefficient of trapezoidal twisted wings. However, more complex geometries like that of the blended-wing–body (BWB) require the introduction of additional geometrical hypotheses. This paper introduces a compound-wing lifting line model that predicts the maximum lift coefficient of geometries like the BWB. Such a model would decrease computation times at early design stages for the BWB. The proposed model is calibrated using Reynolds-Averaged Navier–Stokes (RANS) simulations of a regional BWB geometry near stall with three different twist distributions at low-speed conditions. Application of the calibrated compound wing model on the regional BWB geometry allows to quickly find an optimal twist distribution for this specific configuration: a semiconstant twist distribution on a fraction of the outer wing.

A Study of 3D Printed Box Structure

Unmanned Aerial Vehicles (UAV) are commonly used for surveillance and aerial mapping. Balsa wood construction is common for small UAV. However, for larger UAV size, balsa construction can be too fragile. 3D printing based airframe can help in producing accurate profile contour needed in a wing design, particularly on Blended Wing Body (BWB) design. Nowadays, 3D printing machines are not expensive and easily available. Flight Technology and Test Centre (FTTC) RIG, Universiti Teknologi MARA (UiTM) has been developing and building small BWB UAV made of 3D printing. At the moment, the strength and stiffness of the wing box structure has not been properly investigated. The general target of this research is to understand the static mechanical behavior of a small wing box suitable for UAV manufactured by 3D printing. A simple wing box that can be produced on in-house 3D printer was produced. Standard tensile test was conducted to the PLA (Polylactic Acid) printed material. Finite element simulation of the wing box was performed, and static test experiment was conducted. Stresses and displacements were obtained and analyzed.

Polynomial-Chaos–Kriging with Gradient Information for Surrogate Modeling in Aerodynamic Design

This paper proposes a variant of gradient-enhanced surrogate model based on polynomial-chaos–kriging (PCK) to assist aerodynamic design exploration. The main aim is to improve the accuracy of kriging when gradient information is available via the adjoint method. In contrast to the standard gradient-enhanced kriging (GEK), the gradient information is used to enrich both the trend function and the stochastic part, using the polynomial-chaos expansion (PCE) as the trend function. The optimal polynomial terms are selected by scanning through various polynomial orders in which the coefficients are calculated by means of the generalized least squares or the least angle regression algorithm. The performance of the gradient-enhanced PCK (GEPCK) was compared with GEK, gradient-enhanced PCE (GEPCE), and their nongradient counterparts on a set of analytical and a suite of aerodynamic problems consisting of aerodynamic design exploration of a blended-wing–body configuration, an inviscid transonic flow over an airfoil, and a low-fidelity aerostructural wing design. The results show notable improvements obtained by GEPCK in terms of performance and robustness compared with other gradient-enhanced surrogate models. Based on these results, it can be concluded that enhancing the trend part with gradient is highly beneficial in improving the accuracy of the kriging surrogate model.

Disturbance Observer Enhanced Neural Network LPV Control for a Blended-Wing-Body Large Aircraft

The problem of trajectory tracking control for a blended-wing-body (BWB) large aircraft with model parameter uncertainties and unknown disturbances is considered. A linear parameter-varying (LPV) model is derived from the nonlinear dynamics of the BWB aircraft from which a robust linear parameter-varying controller is designed to track a desired trajectory. Using a single quadratic Lyapunov function (SQLF) and an infinite number of linear matrix inequalities to be evaluated at all vertices, a pair of positive definite symmetric matrix solutions are determined via Lyapunov stability theory and linear matrix inequality technique. Furthermore, a disturbance-observer is designed to process the unknown disturbances. Considering the plant exists some model errors except for disturbances, a radial basis function neural network approximation is embedded into the SQLF LPV controller to improve tracking performances, and a composite disturbance-observer based neural network single quadratic Lyapunov function (NNSQLF) controller can realize desired trajectory tracking of the linear parameter-varying system through regulating performance weighting functions. The closed-loop system of trajectory tracking control is proved to be asymptotically stable by using Lyapunov theory. Simulation results of forward flight speed and altitude tracking control of the BWB aircraft show that the proposed disturbance-observer based NNSQLF control can robustly stabilize the LPV system and precisely track the desired trajectory by comparing with conventional SQLF control and parameter-dependent Lyapunov function control, even in unknown exterior disturbances and model uncertainties.

Virtual flight test techniques to predict a blended-wing-body aircraft in-flight departure characteristics

As one of the promising configurations of the next generation of commercial aircraft, research on departure characteristics of the Blended-Wing-Body (BWB) is of great signification to safe flight limits. A three-degree-of-freedom (3-DOF) virtual flight test in a wind tunnel has been implemented for a candidate configuration to predict the departure characteristics. The support mechanism, the test model and the control law of the virtual flight test are introduced. In order to show the relationship between virtual flight test and actual flight test, the similarity criterion is also given. In open loop, the model has mild oscillations in the longitudinal and lateral directions, which are stable in closed-loop. The effect of flight control has been verified in virtual flight and actual subscale flight test. The analysis of system identification results indicate that the model has a good response to the excitation signal, and the response is in reasonable agreement with the flight test. Finally, the virtual flight departure test results are compared with the flight test. It shows that there is a good correspondence between the angle of attack and the elevator deflection at departure. This gives promising evidence of the practicability of virtual flight testing to predict departure of a BWB.