Hypersonic Waverider Research Articles

Gradient-enhanced deep Gaussian processes for multifidelity modeling

Multifidelity models integrate data from multiple sources to produce a single approximator for the underlying process. Dense low-fidelity samples are used to reduce interpolation error, while sparse high-fidelity samples are used to compensate for bias or noise in the low-fidelity samples. Deep Gaussian processes (GPs) are attractive for multifidelity modeling as they are non-parametric, robust to overfitting, perform well for small datasets, and, critically, can capture nonlinear and input-dependent relationships between data of different fidelities. Many datasets naturally contain gradient data, most commonly when they are generated by computational models that have adjoint solutions or are built in automatic differentiation frameworks.Principally, this work extends deep GPs to incorporate gradient data. We demonstrate this method on an analytical test problem and two realistic aerospace problems: one focusing on a hypersonic waverider with an inviscid gas dynamics truth model and another focusing on the canonical ONERA M6 wing with a viscous Reynolds-averaged Navier-Stokes truth model.In both examples, the gradient-enhanced deep GP outperforms a gradient-enhanced linear GP model and their non-gradient-enhanced counterparts.

Design and Evaluation of a Hypersonic Waverider Vehicle Using DSMC

This work investigates the aerodynamic performance of a hypersonic waverider designed to operate at Mach 7, focusing on optimizing its design through advanced computational methods. Utilizing the Direct Simulation Monte Carlo (DSMC) method, the three-dimensional flow field around the specifically designed waverider was simulated to understand the shock wave interactions and thermal dynamics at an altitude of 90 km. The computational approach included detailed meshing around the vehicle’s critical leading edges and the use of three-dimensional iso-surfaces of the Q-criterion to map out the shock and vortex structures accurately. Additional simulation results demonstrate that the waverider achieved a lift–drag ratio of 2.18, confirming efficient aerodynamic performance at a zero-degree angle of attack. The study’s findings contribute to the broader understanding of hypersonic flight dynamics, highlighting the importance of precise computational modeling in developing vehicles capable of operating effectively in near-space environments.

Flight control design for a hypersonic waverider configuration: A non-linear model following control approach

AbstractDLR is currently investigating the potential of hypersonic flight systems in the context of different mission scenarios. One configuration type of higher interest for civil and military purposes is the hypersonic glide vehicle (HGV). Such HGVs operate over broad flight envelopes and pose complex flight dynamic characteristics. This article presents DLR’s generic hypersonic glide vehicle 2 (GHVG-2) and proposes an integrated non-linear flight control architecture that is based on the idea of the non-linear dynamic inversion and non-linear model following control methodologies. The proposed control scheme is designed to sufficiently and robustly handle the system dynamics of the over-actuated flight vehicle. The approach is first discussed, and the performance of the suggested control laws is later investigated via simulations of a high-fidelity non-linear flight dynamic model in the nominal case and under the presence of parametric uncertainties. The presented results demonstrate that the proposed NMFC approach provides benefits for the robust control of the regarded hypersonic system.

Artificial neural network-based streamline tracing strategy applied to hypersonic waverider design

Streamline tracing in hypersonic flows is essential for designing a high-performance waverider and intake. Conventionally, the streamline equations are solved after obtaining the velocity field over a basic flow field from simplified flow differential equations or three-dimensional computational fluid dynamics. The hypersonic waverider shape is generated by repeatedly applying the streamline tracing approach along several planes. This approach is computationally expensive for iterative waverider optimization. We provide a novel strategy where an Artificial Neural Network (ANN) is trained to directly predict the streamlines without solving the differential equations. We consider the standard simple cone-derived waverider using Taylor–Maccoll equations for the conical flow field as a template for the study. First, the streamlines from the shock are solved for a wide range of cone angle and Mach number conditions resulting in an extensive database. The streamlines are parameterized by a third-order polynomial, and an ANN is trained to predict the coefficients of the polynomial for arbitrary inputs of Mach number, cone angle, and streamline originating locations. We apply this strategy to design a cone-derived waverider and compare the geometry obtained with the standard conical waverider design method and the simplified waverider design method. The ANN technique is highly accurate, with a difference of 0.68% from the standard method in the coordinates of the waverider. The performance of the three waveriders is compared using Reynolds averaged Navier–Stokes simulations. The ANN-derived waverider does not indicate severe flow spillage at the leading edge. The new ANN-based approach is 20 times faster than the standard method.

Inverse Design of Hypersonic Waveriders with Variable Cross-Section Shock Waves

A new inverse design methodology for a variable cross-section shock waverider (VCSW) is proposed to extend the flexibility of waverider design based on the local-turning osculating cones method. The proposed waverider is designed to ride on the top of a variable cross-section shock wave, whose cross-sectional shape is an ellipse with different eccentricity ratios. The feasibility and effectiveness of this method are verified using inviscid computational fluid dynamics simulations. To investigate the influence of the eccentricity ratio on the shape and aerodynamic performance of waveriders, five VCSW cases with different eccentricity ratio distributions are derived and numerically analyzed in detail. The results demonstrate that the VCSW with an increasing eccentricity ratio along the streamwise direction has a larger volumetric efficiency but a smaller lift-to-drag ratio. There is a contradiction between the volumetric and aerodynamic performances, and the tradeoff should be considered in the design process. In addition, the growth rate of the eccentricity ratio along the streamwise direction is also an important factor to design VCSW, which can be used to improve the performance of hypersonic waverider vehicles.

Simulation of high-temperature flowfield around hypersonic waverider using graphics processor units

Provision of flight safety during hypersonic flight is a challenging scientific and technical problem. Waverider concept is based on matching the wing leading edge of the shock formed off the vehicle forebody. A hypersonic vehicle spends the major part of its cruise flight in high temperature flow. Design and optimization of waverider at hypersonic speeds is a challenging problem because a large number of variants are required to be computed to achieve a larger lift-to-drag ratios. Numerical simulation of the flowfield around a hypersonic waverider is performed using a high-temperature air model and a hybrid architecture based on graphics processing units. The mathematical model and computational algorithm are verified and validated against CFD benchmark problems. The results obtained show flowfield around hypersonic waverider and its aerodynamic quality at different angles of attack. The scalability of the developed model is investigated, and the results of the study of the efficiency of calculating hypersonic fluidflows on graphics processors are presented. The computational times achieved with the perfect and real gas models are compared.

Parametric Study on Lateral–Directional Stability of Hypersonic Waverider

Lateral–directional stability is a critical issue for the design of any kind of aircraft. For the hypersonic waverider, the nonaxisymmetric, flat, and slender geometric feature makes it susceptible to the problem of lateral–directional instability. Therefore, the influence of geometric feature on the lateral–directional static and dynamic stability of hypersonic waverider is studied so as to enable the designer to consider this problem in the preliminary aircraft design stage. A series of power-law waveriders is generated at a given design space of the leading-edge parameters. Then, the variation of the static and dynamic derivatives with the design parameter is obtained by use of a surrogate model. It is found that increasing the dihedral angle of the lower surface can improve both the lateral and directional static stability of the total waverider. Furthermore, the dynamic instability mechanisms are analyzed in detail based on the approximate formulas derived from the linearized small-disturbance equations of motion. Especially, a concept of the Dutch-roll dynamic derivative is proposed, which plays an important part in the damping of the Dutch roll. Finally, it is found that increasing the dihedral angle can also improve the damping of the dynamic modes, including the roll, spiral, and Dutch roll.

Numerical study on aerodynamic performance of waverider with a new bluntness method

Abastrct The waverider is deemed the most promising configuration for hypersonic vehicle with its high lift-to-drag ratio at design conditions. However, considering the serious aero-heating protection, the sharp leading edge must be blunted. The existing traditional bluntness methods including the following two types: “reducing material method” and “adding material method”. Compared to the initial waverider, the volume will be smaller or larger using the traditional methods. With the fixed blunted radius, the volume and aerodynamic performance is determined. In this paper, a new bluntness method which is named “mixing material method” is developed. In this new method, a new parameter is introduced based on the traditional two bluntness methods. Under fixed blunted radius, the volume and aerodynamic performance can be changed within a wide range by adjusting the parameter. When the parameter is 0 and 1, the novel blunted method degenerated into the “reducing material method” and “adding material method” respectively. The influence of new parameter on the aerodynamic characteristics and volume are studied by numerical simulation. Results show that the volume, lift and lift-to-drag ratio increases with the increase of the parameter under the fixed blunt radius, but simultaneously, the drag will also increase. Therefore, considering the different requirements of the air-breathing hypersonic aircrafts for the balance of thrust and drag, lift and weight, a suitable bluntness parameter can be selected to achieve a balance. This research can provide reference for hypersonic waverider vehicle design.

Low speed lateral-directional dynamic stability analysis of a hypersonic waverider using unsteady Reynolds averaged Navier Stokes forced oscillation simulations

Hypersonic waveriders have the potential to significantly reduce travel times on long haul civilian transport routes. The design of hypersonic aircraft is heavily influenced by the aerodynamic efficiency at the cruise Mach number, resulting in less than ideal geometries for subsonic flight. Waverider aerodynamics and stability in the low speed regime is rarely investigated and not well understood, but is crucial for horizontal take-offs and landings. To date, low speed analyses of waverider shapes have been confined to static investigations, with limited work on longitudinal dynamics. No studies outlining the lateral-directional dynamic stability and aerodynamic derivatives has ever been published. This paper presents results for the low speed propelled variant of the Mach 8 HEXAFLY-INT waverider, which was subjected to forced oscillations in roll, yaw and side-to-side translations. This was achieved using unsteady Reynolds Averaged Navier Stokes simulations. Tests were conducted at a speed of 20 m/s, which correlates to a Reynolds number of approximately 1.5×106. The dynamic motion was at a forced frequency of 1 Hz with angle amplitudes of 1 degree. The vehicle was analysed through an angle of attack range from -5 to 15 degrees in 5 degree increments. Results for the nominal centre of gravity location at 44.4% of the vehicle length show values for the dynamic derivatives within expected ranges, apart from the rolling moment due to yaw rate below approximately 2 degrees angle of attack. A similar finding for the dihedral derivative in static tests concluded that the low mounted wing with anhedral results in instabilities at low angles of attack. Investigations conducted at a centre of gravity location of 53.1% of the vehicle length, the aft static stability limit, also showed data within normal ranges. For these cases, the derivative magnitudes were lower, which indicates decreased damping compared to the nominal centre of gravity location. Some significant impact was seen on the roll damping derivative due to lowering the centre of gravity. This is from a combination of non-linear wing side force variance with angle of attack and the reduction of the moment arm, which resulted in less damping. The derivatives generally showed little sensitivity to changes in the oscillation frequency, with frequency rates ranging from 0.5 to 2 Hz tested. Overall, the results from this study highlighted the complex combinations of rate induced forces which contribute to the dynamic behaviour of the aircraft.

Low speed longitudinal dynamic stability analysis of a hypersonic waverider using unsteady Reynolds averaged Navier Stokes forced oscillation simulations

Hypersonic waveriders have the potential to significantly reduce travel times on long haul civilian transport routes. The design of hypersonic aircraft is heavily influenced by the aerodynamic efficiency at the cruise Mach number, resulting in less than ideal geometries for subsonic flight. Waverider aerodynamics and stability in the low speed regime is rarely investigated and not well understood, but is crucial for horizontal take-offs and landings. To date, low speed analyses of waverider shapes is confined to static investigations, with no studies on the dynamic behaviour ever completed. This paper presents results from unsteady Reynolds Averaged Navier Stokes simulations modelling pitching and plunging forced oscillations of the low speed propelled variant of the Mach 8 HEXAFLY-INT waverider. Tests were conducted at a speed of 20 m/s, which correlates to a Reynolds number of approximately 1.5×106. Pitching and plunging oscillations were at 1 Hz with an angle of attack amplitude of 1 degree. The vehicle was analysed through an angle of attack range from -5 to 15 degrees in 5 degree increments. Results for the HEXAFLY-INT aircraft at the nominal centre of gravity location, 44.4% of the vehicle length, show that the vehicle is positively damped for all cases tested. Static derivative predictions extracted from the dynamic data showed strong agreement with existing static CFD and wind tunnel results. Further dynamic investigations conducted at a centre of gravity location of 53.1% of the vehicle length, the aft static stability limit, also showed positive damping. For these cases, the derivative magnitudes were lower, which indicates decreased damping compared to the nominal centre of gravity location. The vehicle was generally not sensitive to changes in driving frequency, with oscillation rates ranging from 0.5 to 2 Hz tested. However, during plunging tests, the pitching moment derivative was seen to change by as much as 22%. This is attributed to changes in the leading edge vortices with AoA rate. The results from this study, along with previous work looking at the static aerodynamics, stability and control authority, show the feasibility of moving to the flight test phase, but the aircraft dynamic stability in the lateral-directional planes must first be investigated.

Low speed lateral-directional aerodynamic and static stability analysis of a hypersonic waverider

Hypersonic waveriders have the potential to significantly reduce travel times on long haul civilian transport routes. The design of hypersonic aircraft is heavily influenced by the aerodynamic efficiency at the cruise Mach number, resulting in less than ideal geometries for subsonic flight. Waverider aerodynamics and stability in the low speed regime is rarely investigated and not well understood, but is crucial for horizontal take-offs and landings. This paper presents a combination of numerical simulation results and experimental data for the low speed propelled variant of the Mach 8 HEXAFLY-INT waverider. Aerodynamic, control and stability testing for lateral-directional cases was conducted in the University of Sydney 4 foot by 3 foot low speed facility. Computational fluid dynamics simulations are compared with wind tunnel tests for angles of attack between -5 and 15 degrees and angles of sideslip between -8 and 8 degrees. Throughout these ranges, aileron and rudder deflections up to 10 degrees are investigated. Results show that the vehicle aerodynamics are dominated by asymmetric wing and fin vortices, resulting in non-linear aerodynamic forces. At a centre of gravity location of 44.4% of the vehicle length the aircraft is stable directionally, but has lateral instability at angles of attack below -2 degrees. This is attributed to the low mounted wings with anhedral. The instability is minor and is not expected to result in an uncontrollable condition. Lowering the centre of gravity by approximately 2 centimetres, or 17% of the local fuselage height, can correct the instability. Lateral-directional dynamic stability was predicted using static derivatives and was found to be stable through the entire AoA range tested, with no dependence on mass moments of inertia. Both aileron and rudder controls are found to provide sufficient control authority, but the aircraft may benefit from increased rudder size. The results from this study, along with previous work on longitudinal stability and performance show the feasibility of moving to the flight test program, but aircraft dynamic stability must first be investigated.

Multiple Osculating Cones’ Waverider Design Method for Ruled Shock Surfaces

The traditional osculating cones’ (OCs’) waverider design method is widely used in hypersonic waverider airframe design. However, it becomes ineffective when the shock strength in each osculating plane varies and the azimuthal pressure gradients appear to be important. To solve this problem, a method called the multiple osculating cones’ (multiple-OCs’) waverider design method has been developed for ruled shock surfaces. The new method discretizes the ruled shock surface into elements that can be derived from multiple locally conical flows. Multiple locally conical flows indicate that neighboring osculating planes have different shock generators. This feature not only provides a practical way to represent the azimuthal pressure gradients but also extends the variety of waverider designs. Waverider test cases at and are performed by the osculating cones with variable shock angles’ (OC-VSAs’) method and the multiple-OCs’ method, respectively. It has been shown that the multiple-OCs’ method is applicable to more generalized shock surfaces. The comparison results reveal that the waverider derived by the multiple-OCs’ method has a better agreement with the computational fluid dynamics solution than the OC-VSAs’ method. Moreover, the new method ensures a more homogeneous inlet captured flowfield on the bottom side of the waverider, which is favorable for hypersonic airframe propulsion integration.

Novel design methodology of integrated waverider with drip-like intake based on planform leading-edge definition method

Based on the planform leading-edge definition method, a novel methodology for designing an inlet-airframe integrated waverider vehicle, has been proposed and the resulting intake owns the superiority of the drip-like shape. In this study, the design of the vehicle contour relies on the axisymmetric basic flowfield and leading-edge planform curves, namely the former is presently generated by a shock wave curve, and the latter produces a drip-like intake, on account of the 3D cowl lip curve. Importantly, defining the leading edge on the horizontal projection plane facilitates to adjust the planform shape of the integrated waverider and the sweep angle of the wing. At last, the new design methodology is proved to be effective to design an integrated hypersonic waverider vehicle. This study provides more options for designing novel inlet-airframe integrated hypersonic vehicles.

Low speed longitudinal aerodynamic, static stability and performance analysis of a hypersonic waverider

Hypersonic waveriders have the potential to significantly reduce travel times on long haul civilian transport routes. The design of hypersonic aircraft is heavily influenced by the aerodynamic efficiency at the cruise Mach number, resulting in less than ideal geometries for subsonic flight. Waverider aerodynamics and stability in the low speed regime is rarely investigated and not well understood, but is crucial for horizontal take-offs and landings. This paper presents a combination of numerical simulation results and experimental data for the low speed variant of the Mach 8 HEXAFLY-INT waverider. Aerodynamic, control and stability testing was conducted in the University of Sydney 4 foot by 3 foot low speed facility, while propulsion testing of the vehicle-integrated electric ducted fan was completed in the 7 foot by 5 foot tunnel. Motor thrust settings were tested for 8 lithium polymer cells connected serially drawing between 5 and 25 amperes. Computational fluid dynamics simulations are compared with wind tunnel tests for angles of attack between −5 and 25 degrees and elevon deflections between −10 and 10 degrees. Results show the aerodynamics is dominated by leading edge flow separation and vortex lift. At a centre of gravity location of 44.4% of the vehicle length, stability is observed up to 22 degrees angle of attack. Past this point, instability occurs due to vortex breakdown. The centre of gravity aft stability limit was found at 53.1% of the vehicle length. Overall, good agreement is seen between simulation and tunnel data, validating the modelling methods used. The low speed demonstrator can achieve trimmed flight from 12 m/s, but is only speed stable above 19 m/s. A cruise speed of 19 m/s is selected and can be attained with approximately −9.2 degrees of elevon and 7.1 degrees AoA for a centre of gravity location of 44.4%. Shifting the centre of gravity aft can reduce the trim angle of attack to below 6 degrees with −4 degrees elevon deflection. Take-off and landing can be achieved at 15 m/s between 9.8 and 12 degrees angle of attack, depending on centre of gravity configuration. A maximum climb rate of 2.1 m/s is predicted at 16.3 m/s based on the power settings tested. Overall, the results show the aircraft satisfies stability and performance requirements in the longitudinal axis.

Mach 5–3.5 Morphing Waverider Accuracy and Aerodynamic Performance Evaluation

This paper investigates a morphing hypersonic waverider concept and determines the morphing surface accuracy and control requirements required to achieve Mach 5 to Mach 3.5 on-design operation. Hypersonic waveriders are of interest in the aerospace community due to their significant aerodynamic performance improvements over conventional vehicles in the hypersonic flight regime, although designed for only a single, specific Mach number. The Naval Research Laboratory (NRL) morphing waverider achieves on-design waverider performance across a range of speeds by maintaining shock attachment through morphing the waverider’s lower stream surface and maintaining a rigid leading edge and top surface. A Q-DEIM sensitivity analysis is performed to define a set of actuator locations on the lower surface, which ensures that the morphing error, defined by the difference between the morphed surface and the desired surface shape, is minimized. This paper demonstrates 5- and 14-control-point cases that reduce 87% and 95% of the morphing error, respectively, for a 2-in.-wide morphing hypersonic waverider designed for wind tunnel testing across Mach numbers ranging from Mach 5 to Mach 3.5. Viscous computational fluid dynamics is used to determine the calculated morphing-error effect on the resulting aerodynamics. The results demonstrate that the 14- and 5-control-point cases achieve 97% and 95% of the performance benefits relative to the on-design waverider stream surface.

An airframe/inlet integrated full-waverider vehicle design using as upgraded aerodynamic method

ABSTRACTWith the aims of overcoming the limitations of the existing basic flow model derived from an axisymmetric generating body and extending the aerodynamic design method of the airframe/inlet integrated waverider vehicle, this study develops an upgraded basic flow model derived from an axisymmetric shock wave. It then upgrades the design method for airframe/inlet integration of an air-breathing hypersonic waverider vehicle, which is termed the ‘full-waverider vehicle’ in this study. In this paper, first, the design principle and method for the upgraded full-waverider vehicle derived from an axisymmetric basic shock wave are described in detail. Second, an upgraded basic flow model that accounts for both internal and external flows is derived from an axisymmetric basic shock wave by use of both the streamline tracing method and the method of characteristics (MOC). Third, the upgraded full-waverider vehicle is developed from the upgraded basic flow model by the streamline tracing method. Fourth, the design theories and methodologies of both the upgraded basic flow model and the upgraded full-waverider vehicle are validated by a numerical computation method. Finally, the aerodynamic performances and viscous effects of both the upgraded basic flow model and the upgraded full-waverider vehicle are analysed by numerical computation. The obtained results show that the upgraded basic flow model and aerodynamic design method are effective for the design of the airframe/inlet integration of an air-breathing hypersonic waverider vehicle.

A novel approach for design and analysis of volume-improved osculating-cone waveriders

A novel design methodology for waverider is proposed based on the conical flow field, named volume-improved osculating-cone waveriders. The new waverider is generated through three given curves, including flow capture curve, inlet capture curve, and curve of the center of exit shock. To meet more design requirements, the curve of the center of exit shock, which can be flexibly designed, is newly introduced to generate configurations with different properties and performances. The feasibility and effectiveness of the method have been verified by computational fluid dynamics (CFD) simulation. The discrepancies between the volume-improved osculating-cone waverider and conventional waveriders are numerically analyzed in detail. The results demonstrate that the new waverider takes the advantage of the volumetric efficiency with little loss of performance compared to the conventional waveriders in design conditions. Furthermore, the results of the off-design conditions show excellent aerodynamic performance as the conventional waverider. Moreover, for bluntness with a radius of 10 mm, the new waverider synthetically owns higher viscous lift-to-drag ratio and greater volumetric efficiency than conventional configurations at 0° angle of attack. Therefore, the novel approach is useful to design the hypersonic waverider vehicle.

Design method of a new hypersonic waverider configuration

The waverider configuration has a wide application prospect in the design of hypersonic vehicles due to its excellent aerodynamic efficiency. Various kinds of waveriders have been developed based on different basic flowfield, which can be chosen according to different design requirements. However, it’s generally difficult for the waverider to directly satisfy the engineering requirements of volume efficiency, trim, stability, etc. To overcome these drawbacks, the paper proposes a new design method of hypersonic waverider configuration. In the generation process, the leading edge of the original waverider is kept unchanged. Then at different longitudinal cross section, the profile of the lower surface is determined by the same curve equation, started from the point at the leading edge and cut off at the base plane. The profile function is determined by the sum of a series of power law functions, whose coefficients can be changed according to different design requirements. Different waveriders are obtained according to different constraints. Results show that for this kind of configurations, good shock attachment near the leading edge can be achieved and the pressure distribution on the lower surface is uniform. What’s more, the maximum lift-to-drag ratio is even higher than that of the original waverider. Different waveriders with excellent aerodynamic efficiency can also be generated by different constraints of volume efficiency and stability.

Mach Five to Ten Morphing Waverider: Control Point Study

To determine the capability of a morphing hypersonic waverider, this paper develops an optimal morphing control scheme to quantify the impact that the representative morphing error has on aerodynamic performance. The morphing waverider concept could improve thermal loading, vehicle acceleration, local and global load factors, fuel consumption, and total energy dissipation. The key design limitation of conventional waveriders is that the optimal geometry is highly dependent on the Mach number, and deviations from the design point significantly degrade performance. The Naval Research Laboratory has developed a family of morphing waveriders with a constant leading edge and a top surface with a morphing lower stream surface to enable ondesign performance across a wide Mach number range. To evaluate the morphing waverider concept, a Mach 10 waverider is designed to enable shock attachment from Mach 10 to 5. A Q-DEIM-algorithm sensitivity analysis identifies the optimal control points set (actuator locations). This paper shows that the ideal morphing waverider significantly improves performance and a two-control-point or six-control-point system provides 90 and 97% of the ideal control system performance improvements. This work demonstrates a methodology to actuate the waverider lower stream surface to enable optimum aerodynamic performance across a range of Mach numbers.

Novel Osculating Flowfield Methodology for Hypersonic Waverider Vehicles Based on Variable Shock Angle

AbstractThis study proposes a variable shock angle osculating flowfield waverider design method. The flow field structure and aerodynamic characteristics of osculating flowfield waveriders are also...