Blended Wing Body Research Articles

Conceptual design of Wau Bulan UAV

This paper presents conceptual design of an UAV that using “Wau Bulan” shape as its planform. Wau Bulan is a one type of Malaysia’s kite. Wau bulan kite has wing and tail part. Wau Bulan wing is a lens shape wing with aspect ratio 3.48. Tail part shape likes crescent moon. Tail part area is 46.23% of wing area. Wau Bulan UAV was designed to perform surveillance mission. Initial weight sizing and performance sizing was done to assure the reasonable value of aerodynamics and propulsion parameter. Joined wing and blended wing body technology concepts were used to aim the requirement parameters that defined during initial sizing process. The aerodynamics characteristic was analyzed using experimental method. Experimental results show that wau bulan planform aerodynamics characteristics fulfill designed parameter that chosen during initial sizing.

Influences of distributed propulsion system parameters on aerodynamic characteristics of a BLI-BWB UAV

Focusing on the aerodynamic characteristics of the blended wing body (BWB) aircraft with boundary layer ingestion(BLI) distributed propulsion system; the influences of propulsion system parameters under the condition of cruise and takeoff are studied. Firstly, based on the momentum source method (MSM), the NASA ducted propeller model is simulated, which verifies the reliability of the numerical method in this paper. Then, by using the method of structural grid and S-A turbulence model to solve the Reynolds averaged Navier-Stokes (RANS) equation, the aerodynamic characteristics of the BLI UAV model with D80 ducted fan in cruise state are numerically calculated. It is proved that the advantage of the BLI distributed propulsion system is superior in increasing lift. And the aerodynamic characteristics of the BLI UAV with different propulsion system parameters are compared. At last, the aerodynamic effect of ducted fan thrust on the BLI UAV is carried out. The results show that, due to the suction function of the BLI distributed propulsion system, the air flow velocity near the BWB fuselage is effectively accelerated, and the flow along the spanwise is restrained, which improves the lift coefficient about 16% and lift-to-drag ratio about 10%. Under the condition of equal thrust, the D80 ducted fan brings larger load of the propeller, which makes the static pressure at the inlet and outlet smaller. Compared with D150 ducted fan, the lift-to-drag ratio is increased by 15%. When aircraft takes off, increasing the thrust of the ducted fan can reduce the possibility of flow separation on the upper surface of the fuselage, which is conducive to the safety.

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.

Conceptual design of a novel Unmanned Ground Effect Vehicle

In this work, a methodology for the conceptual design of a combined Box-wing and Blended-Wing-Body unmanned aerial platform, which exploits the ground effect, is presented. Ground Effect Vehicles (GEVs) are aircrafts or aerial vehicles capable of flying very close to the surface of water areas, being a promising alternative to ships and seaplanes operating in closed seas. In order to exploit the air cushion that is formed underneath, GEVs have low Aspect Ratio wings. Thus, the Blended-Wing-Body (BWB) layout configuration is an appealing choice due to the large available body surface. On the other hand, a tailless vehicle having the BWB layout is facing challenging stability issues, especially in a turbulent and highly volatile environment as the one close to the sea level. Therefore, the addition of the Box wing configuration, namely a continuous-surface nonplanar wing formation with no wing tips, is deemed beneficiary as a way to overcome the stability challenges and eliminate the wingtip vortices. The combination of these two prominent platforms leads to improved aerodynamic performance and eventually, a reduced fuel consumption. The design methodology starts by the estimation of the most important design parameters, such as aspect ratio, sweep angle, and taper ratio, which are continuously refined in an iterative computational framework during the conceptual design phase. In an initial approach, the flight scenario with no ground effect interference is studied, with the use of both analytical calculations and computational fluid dynamics simulations. The results from the conceptual design phase indicate that the UGEV configuration has a considerable potential as an alternative to ships or seaplanes, based on its ability to carry larger payload than seaplanes and deliver it faster than ships.

Cooling system design for the internal combustion engine of a BWB UAV prototype

The current study presents an analytical design methodology for a compact thermal management system (cooling system) of a high-power density internal combustion rotary engine. The engine is installed on a fixed wing, tactical Blended-Wing-Body (BWB) Unmanned Aerial Vehicle (UAV) prototype that has been developed for the aerial delivery of cargo and lifesaving supplies. The design methodology is based mainly on a low-fidelity thermodynamic model and on high-fidelity Computational Fluid Dynamics (CFD) analyses. The results are validated against wind tunnel experiments for the cooling system of the engine. The overall methodology is divided into two distinct segments, the design of the heat exchanger (HEX) and the sizing of the cold-air inlet ducts. The low-fidelity thermodynamic model is based on 0D and 1D textbook methods and well-established formulae from the existing literature. The thermodynamic model is used for the calculation of the geometrical characteristics of the HEX. The high-fidelity CFD modeling is employed to yield a more detailed investigation of the flow field around the HEX and provide information about whether the airflow velocity requirements, for the 0D and 1D model, are met. Additionally, the detailed CFD computations assist the design of high-efficiency inlet ducts, in order to secure optimal airflow through the HEX and around the engine compartment. Using the proposed methodology, a functional HEX experimental prototype is designed and manufactured, as a proof of concept, in order to be thoroughly examined on a test rig in laboratory conditions. Multiple experiments are conducted in a variety of inlet temperatures and airflow velocities, for the validation and fine-tuning of the overall proposed design methodology. The study concludes with the final HEX design, as well as an analysis of its integration aspects on the tactical BWB UAV prototype.

Albatross and Falcon inspired Bionic UAV: An Aerodynamic Analysis

The drone industry yearns for enhanced aerodynamic performance. In order to achieve this feat, researchers and engineers are trying to mimic the natural flyers due to their aerodynamic optimality. One such flyer, the Albatross is an inspiration for many marine drones due to its planform and aerodynamic efficiency. The wing of the plan form is designed and simulated to study its properties. The Bell-Shaped Lift Distribution is incorporated for higher efficiency and elimination of the total downwash produced in case of an Elliptical Lift Distribution. A blended wing body inspired by the Falcon is used for smoother airflow interactions. Furthermore, a tilt-rotor design provides an efficient combination of hovering and cruising modes of flight. Design choices and changes are discussed and tested to obtain an efficient tilt-rotor UAV inspired by the Albatross.

Optimization of wing structure using carbon fibre on a combined shell blended wing body

Composite materials have many advantages in macro materials and nanomaterials. The strength of composite material is fully based on the orientation of ply. This research deals with the pressurized inner wing. Such design of the wing and fuselage remains a significant challenge for Flying Wing aircraft. Since the inner wing is nearly rectangular, it is relatively inefficient to resist the pressure loads by bending that consequently brings weight penalty. The wing structure was evaluated by using carbon fibre material at different orientations on fabric. To reduce this weight penalty of the wing, the internal multi-shell structure was combined to form a boxed multi bubble section configuration. The novel section was modelled and the structural properties were evaluated.

CFD-aided optimization of a tactical Blended-Wing-Body UAV platform using the Taguchi method

The current study presents the layout optimization of a tactical, fixed-wing UAV, during the early stages of the preliminary design. The reference platform is a Blended-Wing-Body (BWB) configuration, whose mission is the aerial delivery of cargo and lifesaving supplies. The optimization is conducted by means of Computational Fluid Dynamics (CFD) using the Taguchi experimental design method. The aspect ratio, taper ratio and sweep angle are defined as the key design parameters. An L9 orthogonal array is used to investigate the effect of those parameters on the maximum velocity, the takeoff runway and the gross takeoff weight, which serve as the performance criteria. The combinations that maximize the top speed, minimize the takeoff runway and the gross takeoff weight are extracted. Furthermore, an Analysis of Variance (ANOVA) is carried out to assess the contribution of each design variable to the performance criteria.

A study on the hydrodynamic performance of manta ray biomimetic glider under unconstrained six-DOF motion.

A manta ray biomimetic glider is designed and studied with both laboratory experiments and numerical simulations with a new dynamic update method called the motion-based zonal mesh update method (MBZMU method) to reveal its hydrodynamic performance. Regarding the experimental study, an ejection gliding experiment is conducted for qualitative verification, and a hydrostatic free-fall experiment is conducted to quantitatively verify the reliability of the corresponding numerical simulation. Regarding the numerical simulation, to reduce the trend of nose-up movement and to obtain a long lasting and stable gliding motion, a series of cases with the center of mass offset forward by different distances and different initial angles of attack have been calculated. The results show that the glider will show the optimal gliding performance when the center of mass is 20mm in front of the center of geometry and the initial attack angle range lies between A0 = -5° to A0 = -2.5° at the same time. The optimal gliding distance can reach six times its body length under these circumstances. Furthermore, the stability of the glider is explained from the perspective of Blended-Wing-Body (BWB) configuration.

Research on analytical scaling method and scale effects for subscale flight test of blended wing body civil aircraft

Although a subscale flight test (SFT) is an essential step in the practical application of a blended wing body (BWB) civil aircraft, research on similarity scaling methods and the scale effects during a BWB SFT is still lacking. Therefore, this paper presents an analytical scaling method based on the standard atmospheric model and full-scale flight envelope for analysing the scale factor and flight altitude during the SFT of a BWB aircraft that uses the NPU-300 concept under different similarity conditions. The relations between the size of the subscale test vehicle (STV) and the similarity conditions are summarised, and the corresponding test scope is given. The results showed that under the premise of Froude number similarity, the minimum STV sizes were 51.54% and 75.19% of the full-scale aircraft to simulate Reynolds and Mach numbers, respectively. Extending the test altitude helped to relax the size requirements and broaden the test scope. Furthermore, a quantitative computational fluid dynamics (CFD) study of the scale effects and an analysis of the STV mass requirements were conducted for both high-speed and low-speed BWB SFTs. For the high-speed case, the scale effects mainly influenced the viscosity, surface velocity, and shock wave characteristics. The wing loading was the core parameter for the high-speed STV mass design. A 30% scaled STV with constant wing loading could control the lift–drag ratio loss to within 2.0. For the low-speed case, the scale effects changed the aerodynamic performance by reducing the boundary layer anti-separation ability and control surface efficiency. These coupling effects showed that the scale factor should be at least 50% to obtain the full-scale stall characteristics. The research on the analytical scaling method and scale effects reported in this paper can provide an approach and basis for BWB SFT design and data correction.

Disturbance and Uncertainty Suppression Control for a Saucer-Shaped Unmanned Aerial Vehicle Based on Extended State Observer

For saucer-shaped unmanned aerial vehicles with blended wing bodies (BWBs), un-modelled coupling effect uncertainty and external disturbance missing the matching conditions have always been the concerns. To solve this flight control problem, this research has proposed a composite backstepping controller incorporated with a finite-time convergent differentiator and a nonlinear extended state observer (ESO). More specifically, the differentiator is employed to obtain the derivatives of the virtual control laws in finite-time and therefore eliminate the inherent “explosion of term” problem in backstepping. By the effective real-time estimation of ESO without the peaking value problem, the total effect of internal uncertainties and external disturbances is compensated in the control law design, which can dispense with parameter identification and model approximation. Furthermore, based on Lyapunov theory, it is proved rigorously that all the signals of the resulting closed-loop systems are bounded. In the final part of this paper, simulation results are presented to validate the effectiveness of the proposed control scheme.

Design and experimental validation of a specialized pressure-measuring rake for blended wing body aircraft’s unconventional inner flow channel

The internal drag of the unconventional inner flow channel of blended wing body aircraft must be measured accurately to correct the air intake effect of the blended wing body flow-through model in wind tunnel tests. In this study, the pressure distribution of the inner flow channel under the interaction of internal and external flows was obtained through numerical simulation. A specialized pressure-measuring rake was designed based on the numerical results, and a validation test was conducted in a 2.4 m × 2.4 m transonic wind tunnel. Compared with the flow in traditional inlets/nozzles, the flow in the unconventional inner channel in the current research is asymmetric, the distortion index is higher, and the internal drag is more sensitive to flow changes. The wind tunnel test results have a good correlation with the numerical results, and the repeatability of the test results is satisfactory, indicating that the measurement accuracy and precision of the pressure-measuring rake are acceptable. The design method of the specialized rake is feasible, and it can be used to guide the measurement of complex flow in unconventional inner flow channels of blended wing body aircraft.

Multi-Fidelity Design Optimization of a Long-Range Blended Wing Body Aircraft with New Airframe Technologies

The German Cluster of Excellence SE²A (Sustainable and Energy Efficient Aviation) is established in order to investigate the influence of game-changing technologies on the energy efficiency of future transport aircraft. In this paper, the preliminary investigation of the four game-changing technologies active flow control, active load alleviation, boundary layer ingestion, and novel materials and structure concepts on the performance of a long-range Blended Wing Body (BWB) aircraft is presented. The BWB that was equipped with the mentioned technologies was designed and optimized using the multi-fidelity aircraft design code SUAVE with a connection to the Computational Fluid Dynamics (CFD) code SU2. The conceptual design of the BWB aircraft is performed within the SUAVE framework, where the influence of the new technologies is investigated. In the second step, the initially designed BWB aircraft is improved by an aerodynamic shape optimization while using the SU2 CFD code. In the third step, the performance of the optimized aircraft is evaluated again using the SUAVE code. The results showed more than 60% reduction in the aircraft fuel burn when compared to the Boeing 777.

Shape Optimization of Blended-Wing-Body Underwater Gliders Based on Free-Form Deformation

Currently developed underwater gliders can be roughly divided into the two types:traditional configuration and unconventional configuration. As a type of underwater gliders with unconventional configuration, a blended-wing-body (BWB) underwater glider has better fluid dynamic performances because of its unique shape. However, it is difficult to design the shape of the BWB underwater glider that has excellent hydrodynamic performances. Therefore, it is of great significance to optimize its shape, which this paper carries out by using the free-form deformation (FFD). The complete and automatic shape optimization framework is established by jointly using FFD parameterization method, CFD solver, optimization algorithm and mesh deformation method. The framework is used to optimize the shape of a BWB underwater glider. The average drag coefficient of the BWB underwater glider during its sinking and floating in one working period is used as the objective function to optimize its shape, with the volume constraints considered. The optimization results show that the gliding performance of the BWB underwater glider is remarkably enhanced.

Conceptual Design, Flying, and Handling Qualities Assessment of a Blended Wing Body (BWB) Aircraft by Using an Engineering Flight Simulator

The Blended Wing Body (BWB) configuration is considered to have the potential of providing significant advantages when compared to conventional aircraft designs. At the same time, numerous studies have reported that technical challenges exist in many areas of its design, including stability and control. This study aims to create a novel BWB design to test its flying and handling qualities using an engineering flight simulator and as such, to identify potential design solutions which will enhance its controllability and manoeuvrability characteristics. This aircraft is aimed toward the commercial sector with a range of 3000 nautical miles, carrying 200 passengers. The BWB design was flight tested at an engineering flight simulator to first determine its static stability through a standard commercial mission profile, and then to determine its dynamic stability characteristics through standard dynamic modes. Its flying qualities suggested its stability with a static margin of 8.652% of the mean aerodynamic chord (MAC) and consistent response from the pilot input. In addition, the aircraft achieved a maximum lift-to-drag ratio of 28.1; a maximum range of 4,581 nautical miles; zero-lift drag of 0.005; while meeting all the requirements of the dynamic modes.

Assessment of the BWB aircraft for military transport

PurposeThe growth in air mobility, rising fuel prices and ambitious targets in emission reduction are some of the driving factors behind research towards more efficient aircraft. The purpose of this paper is to assess the application of a blended wing body (BWB) aircraft configuration with turbo-electric distributed propulsion in the military sector and to highlight the potential benefits that could be achieved for long-range and heavy payload applications.Design/methodology/approachMission performance has been simulated using a point-mass approach and an engine performance code (TURBOMATCH) for the propulsion system. Payload-range charts were created to compare the performance of a BWB aircraft with various different fuels against the existing Boeing 777-200LR as a baseline.FindingsWhen using kerosene, an increase in payload of 42 per cent was achieved but the use of liquefied natural gas enabled a 50 per cent payload increase over a design range of 7,500 NM. When liquid hydrogen (LH2) is used, the range may be limited to about 3,000 NM by the volume available for this low-density fuel, but the payload at this range could be increased by 137 per cent to 127,000 kg.Originality/valueThe results presented to estimate the extent to which the efficiency of military operations could be improved by making fewer trips to transport high-density and irregular cargo items and indicate how well the proposed alternatives would compare with present military aircraft. There are no existing NATO aircraft with such extended payload and range capacities. This paper, therefore, explores the potential of BWB aircraft with turbo-electric distributed propulsion as effective military transports.

Aerodynamics Analysis on the Effect of Canard Aspect Ratio on Blended Wing Body Aircraft using CFD Simulation

Blended Wing Body Aircraft (BWB) is an unconventional aircraft that combined the conventional and flying wing aircraft’s design. The unique design of the BWB offers a high fuel efficiency, low noise, and large payload volume for the size of aircraft. However, the BWB is unstable due to the absence of the its vertical stabilizer. A possible solution to improve this problem is using a horizontal control surface, the canard. For this purpose, the numerical simulation using NUMECA Computational Fluid Dynamic (CFD) software were conducted to obtain the aerodynamics forces subjected on this aircraft. The lift coefficient (CL), drag coefficient (CD) and moment coefficient (CM) are analysed at Mach number 0.1. The study is specifically to discuss the effect of canard setting angle ™ of BWB from ™ = -10° to 10° in that particular of aspect ratio (AR 2, 4, 6 and 8) towards aerodynamics parameters, CL, CD, and CM.

Influence of Spanwise Load Distribution on Blended-Wing–Body Performance at Transonic Speed

The influence of spanwise load distributions on the overall performance of a blended-wing–body (BWB) model at transonic speed is investigated to understand the tradeoffs between aerodynamic efficiency and wing structure weight. The overall performance improvement is measured by the net weight saving relative to the maximum takeoff weight (). A BWB model based on the reference shape of the Boeing second-generation BWB model is taken as the baseline model. Taking the elliptic and triangular spanwise loading as the two extreme distributions, models with varying spanwise loadings have been designed. High-fidelity Reynolds-averaged Navier–Stokes solutions coupled with an inverse design optimization code considering static aeroelasticity is used in the inverse design process. For the BWB models, shifting the spanwise load from the elliptic design toward the triangular design shows a significant reduction in wing root bending moment compared with the traditional civil transports, thus resulting in significant structural weight savings. A wing root bending moment relief of 19% is obtained for the averaged elliptic–triangular design relative to the elliptic design, whereas the loss in aerodynamic efficiency is only 4.4%. The combined effects result in a net weight saving between 0.63 and 1.86% of .

A prototype for rapid generation of cabin layout of blended wing body aircraft

A prototype for rapid generation of cabin layout of blended wing body aircraft

Three-Dimensional Aerodynamic/Stealth Optimization Based on Adjoint Sensitivity Analysis for Scattering Problem

A radar cross section (RCS) gradient calculation approach based on the discrete adjoint equation of Maxwell integral equation is proposed. The adjoint method can obtain the gradients of all design variables by a single solution of the scattering problem if electric field integral equation is adopted, and by one solution of the scattering problem and one adjoint problem if magnetic field integral equation or combined field integral equation is adopted. Multilevel fast multipole method (MLFMA) is employed in the solution of the scattering and adjoint problem. The accuracy and reliability of the adjoint approach are verified with a double-ogive model. Optimizations considering aerodynamic, stealth, and aerodynamic/stealth performance of a blended-wing–body aircraft with a gradient-based optimizer are conducted. Stealth optimization results indicate that a small leading-edge radius and curvature on the forepart are beneficial to RCS reduction. Aerodynamic performance of aerodynamic optimized model and aero/stealth optimization result are comparable, but stealth performance of aero/stealth optimized result is inferior to stealth optimization. Conflictions between small leading edge and drag reduction are not very prominent based on the current study, whereas curvature is harmful to aerodynamic performance.