Hypersonic Vehicle Research Articles

Study of the thermal/thermodynamic performance of a bionic flat heat pipe designed to integrate thermal management and bearing capacity

When a hypersonic vehicle is flying at high speed, its rudder wing is subjected to severe aerodynamic thermal loads. In this paper, to meet thermal protection and load-bearing requirements during flight, a novel structure that integrates thermal management and carrying capacity is designed. A novel bionic flat heat pipe structure for integrating thermal management and bearing capacity requirements is designed using a beetle sheath wing as a biological template, and the thermal and mechanical performance of the structure is analysed. The interior consists of a 6061 aluminium bionic core covered with a nickel foam wick, and water is used as the working fluid. Ground tests are performed to verify the accuracy of the simulation results. The results show that the bionic flat heat pipe structure has a superior isotherm and bearing capacity, and the experimental data and finite analysis model results are in good agreement.

Aerodynamic Exergy-Based Analysis and Optimization of the Generic Hypersonic Vehicle Using FUN3D

The development of future novel aircraft concepts requires a holistic approach to vehicle design, analysis, and optimization. Aircraft designers can no longer consider components individually as systems become more interconnected and multidisciplinary. Hence, a new approach to aircraft design and a new way to measure the performance of aircraft are needed. A novel approach to aircraft design is the use of exergy methods that can evaluate typically disparate systems using a universal measure of performance mapped to global system performance. This paper introduces a new functional and its adjoint gradient in FUN3D to determine aerodynamic exergy destruction rates. The functional is verified using the Oswatitsch relationship by comparing it to native, surface-based drag coefficients. The adjoint gradient is verified using the FUN3D native complex step method, and discrete agreement is demonstrated for flowfields and geometric derivatives. The new functional is then used for aerodynamic exergy-based analysis and optimization of the generic hypersonic vehicle. An inverse design problem is conducted first to verify the design optimization framework. Finally, a planform and airfoil aerodynamic inviscid exergy optimization of the GHV is conducted, improving exergy destruction rates by 7.1% while making substantial improvements to the cruise trim characteristics of the vehicle.

Trajectory optimization of hypersonic vehicle considering the quasi-static assumption of pitch motion

The re-entry flight velocity of hypersonic vehicles is extremely high. If the trajectory precision can be improved in the optimization phase, the burden on the flight control system can be effectively reduced. Based on the phenomenon that the velocity of vehicle moving around the center of mass is small during the re-entry, a quasi-static assumption of the pitching motion for the re-entry vehicle is proposed. That is, the instantaneous balance of its pitching torque is assumed, and the torque balance is taken as the path constraint. Thus, a trajectory optimization method is established while considering the quasi-static assumption of pitching motion. When the minimum heating rate of the stagnation point or the smoothest trajectory is used as the optimization objective, respectively. Compared to traditional trajectory optimization methods that treat the vehicle as a mass point, the trajectory optimization method considers the quasi-static assumption of pitching motion, which can improve trajectory accuracy by an order of magnitude. In addition, solving the trajectory takes less than twice as long. This method can provide a reference for the offline/online trajectory design of re-entry vehicles.

Switching Polytopic Linear Parameter-varying Control for Hypersonic Vehicles in Full Envelope

Switching Polytopic Linear Parameter-varying Control for Hypersonic Vehicles in Full Envelope

Experimental study of the effects of isolated roughness elements on the stability and transition of a hypersonic boundary layer on a flat plate

Surface roughness elements on hypersonic vehicles can cause early boundary layer transition, increasing wall skin friction and heat flux and affecting aircraft range and thermal protection systems. Accurate prediction of the transition caused by these roughness elements is crucial for the design of hypersonic vehicles. In this work, wind tunnel experiments on isolated roughness-induced boundary layer transition at Ma = 6 are conducted. Infrared thermography and high-frequency pressure sensors are utilized to investigate the effects of different roughness element configurations (cylindrical, diamond, ramp) on the hypersonic boundary layer instability and transition. The experimental results show that all three roughness elements can effectively enhance the generation of second mode waves and promote boundary layer transition. Compared to smooth surfaces, they exhibit similar frequency band range, faster growth, and earlier saturation. Among them, the ramp roughness element most effectively triggers the boundary layer transition, with a relatively small heat flux increase. Furthermore, bispectral analysis illustrates that all three roughness elements undergo self-interactions that lead to spectral broadening, ultimately resulting in boundary layer transitions.

Study of the effect of rotating channel rib structure on fuel flow and heat transfer characteristics

Hypersonic vehicles can be affected by incoming hot air. In order to ensure that the power generation turbine blades can operate properly, the fuel in the engine is used to cool the turbine blades. In this paper, the heat transfer characteristics of fuel in smooth and 45° ribbed channels under rotating conditions are investigated. Their results show that, unlike the smooth channel, the heat transfer coefficient of the 45° ribbed channel decreases as Ro increases under the combined influence of the rib structure and the physical properties of the fuel. The rib structure disrupts the high-velocity fluid near the trailing surface of the centrifugal section, which promotes doping between the fuels and weakens the effect of the Coriolis force. The Nu increase in ribbed channels ranged from 11.4% to 55.1% compared to smooth channels.

Multi-objective optimization of a hypersonic airbreathing vehicle

Multi-objective optimization of a hypersonic airbreathing engine (scramjet technology) was carried out with the aim of maximizing thrust and minimizing drag while satisfying a series of design constraints, such as avoiding unstart (blockage of supersonic flow within the combustion chamber) by ensuring that the pressure ratio across the shock waves remains below the adverse pressure gradient given by the Korkegi limit, geometry correction to achieve shock on-lip condition, and temperature and pressure requirements at the inlet exit. Using the relations presented in the literature, pressure and viscous drag are estimated analytically. The analytical approach is verified against computational fluid dynamics data from Ansys Fluent to solve two-dimensional compressible Reynolds-averaged Navier–Stokes flow equations, with transition shear stress transport as the turbulence closure model. Comparing the total drag and the flow properties at the combustion chamber entrance shows the model's feasibility for the optimization approach. Three different approaches were conducted to formulate the multi-objective function to determine the one that can find the highest number of geometries satisfying the Korkegi limit with the highest net thrust. The best approach was the multi-objective function formulated with the uninstalled thrust, total pressure recovery, and pressure drag, concentrating the search in the region with greater uninstalled thrust and lower drag and nearly doubling the value of net thrust compared to the first formulation, which uses the uninstalled thrust, pressure drag, and viscous drag.

Accurately Tracking Hypersonic Gliding Vehicles via an LEO Mega-Constellation in Relay Tracking Mode

Accurately Tracking Hypersonic Gliding Vehicles via an LEO Mega-Constellation in Relay Tracking Mode

Finite-Time Neural Optimal Control for Hypersonic Vehicle With AOA Constraint

Finite-Time Neural Optimal Control for Hypersonic Vehicle With AOA Constraint

State Constrained Fault-Tolerant Control of Hypersonic Vehicle With Unknown Centroid Shift Based on Zero-Sum Game

State Constrained Fault-Tolerant Control of Hypersonic Vehicle With Unknown Centroid Shift Based on Zero-Sum Game

Effects of horizontal self-rotation on flow and heat transfer of supercritical n-decane in regenerative circular/rectangular cooling channels

Concerning the rotation flight of a hypersonic vehicle centered on its geometric axis, the rotational flow and heat transfer characteristics of supercritical n-decane in horizontal circular and rectangular tubes were comprehensively analyzed based on numerical simulation. The computational domain was established and the corresponding governing equations of mass conservation, momentum conservation, and energy conservation were mathematically formulated as well were the thermophysical properties and boundary conditions. A procedure for setting up the numerical simulation was finally implemented. A mesh independence study in the case of a rotating speed of 300 rpm and a turbulence model study based on a stationary/swinging tube were comprehensively conducted and the RANS model was well validated. For the circular tube, the wall temperature distribution trend along the flow direction is similar but the magnitude is not uniform. Also, the fluid temperature near the upper wall is larger than that in the vicinity of the lower wall, i.e., the relaminarization plays an essential role in this phenomenon. The velocity difference near the wall can be weakened by the centrifugal force. For the rectangular tube, the velocity magnitude and temperature distribution are found to be greatly affected by the rotation (i.e., centrifugal force). The relative temperature magnitude near the upper and lower walls will be reversed at a rotation speed of n = 100–500 rpm. Subsequently, a symmetrical temperature distribution can be observed once the speed increases to a certain value (e.g., n = 700–900 rpm). In summary, the centrifugal force plays a more important role in a rectangular tube than in a circular tube.

On the shock wave boundary layer interaction in slightly rarefied gas

The shock wave and boundary layer interaction (SWBLI) plays an important role in the design of hypersonic vehicles. However, discrepancies between the numerical results of high-temperature gas dynamics and experiment data have not been fully addressed. It is believed that the rarefaction effects are important in SWBLI, but the systematic analysis of the temperature-jump boundary conditions and the role of translational/rotational/vibrational heat conductivities are lacking. In this paper, we derive the three-temperature Navier–Stokes–Fourier (NSF) equations from the gas kinetic theory, with special attention paid to the components of heat conductivity. With proper temperature-jump boundary conditions, we simulate the SWBLI in the double cone experiment. Our numerical results show that, when the three heat conductivities are properly recovered, the NSF equations can capture the position and peak value of the surface heat flux, in both low- and high-enthalpy inflow conditions. Moreover, the separation bubble induced by the separated shock and the reattachment point induced by impact between transmitted shock and boundary layer are found to agree with the experimental measurement.

Parasitic modulation effect caused by dynamic plasma in low frequency

Abstract-dynamic plasma sheath can severely interfere with the communication of hypersonic vehicles during atmospheric reentry. Theoretical and experimental results show that low-frequency (LF) electromagnetic (EM) waves could penetrate the plasma sheath, building a feasible method to solve the “radio blackout” problem. This paper discovers that the propagation of LF EM waves in plasmas is still influenced by parasitic modulation effects. Compared to microwave frequencies, the impact of parasitic modulation effects on signal modulation patterns is more distinct for LF EM waves. In contrast to the microwave frequency range, where the rotation direction of QPSK signal constellation points changes with the ratio of plasma frequency to electromagnetic wave frequency, in the LF range, the constellation points undergo limited clockwise rotation. This phenomenon can be attributed to the unique magnetic field propagation mechanism of LF EM waves in dynamic plasmas. This paper analyzes the mechanism of this specific parasitic modulation effect and discovers a sinusoidal transformation relationship between amplitude attenuation and phase shift. Meanwhile, the experimental and simulation results proved that the time-varying plasma could cause the parasitic modulation effect of LF EM wave, resulting in a limited clockwise rotation of orthogonal phase-shift keying constellation points, which is consistent with the theoretical analysis.

Numerical Investigation on Transpiration Cooling Performance of Oriented Porous Structure Under Local Block Conditions

With the development of an active thermal protection system (TPS) for hypersonic vehicles, reliability improvement and weight reduction of TPS are key issues to be considered. In this paper, an oriented porous structure (OPS) is proposed to solve the local overheating problem in transpiration cooling. The transpiration cooling performances are investigated in a two-dimensional computational domain using a local thermal nonequilibrium model. The cooling mechanisms of OPS and uniform porous structure (UPS) under local block conditions have been numerically analyzed and compared. The results show that OPS leads to effective cooling of the overheated region by regulating the coolant flow behavior, especially in the case of serious block conditions. The maximum temperature reduction can be up to more than 200 K, and the maximum optimization rate can reach up to 23% compared to UPS. Moreover, OPS consumes less coolant and uses less driving force to deliver coolant when reaching the same peak temperature as OPS. This study shows that OPS has a better thermal protection effect in transpiration cooling, which can improve the reliability of TPSs, and that OPS can also achieve the lightweight of the aircraft.

RBFNN-Based Anti-Input Saturation Control for Hypersonic Vehicles

In hypersonic flight control, characterized by challenges posed by input saturation, model parameter uncertainties, and external disturbances, this paper introduces a pioneering anti-input saturation control method based on RBFNN adaptivity. We have developed adaptive laws to enhance control system adaptability and robustness by integrating mission profiles, actuator saturation failure modes, and self-evolving neural network design. Furthermore, our approach introduces a novel anti-input saturation auxiliary system, effectively addressing input saturation constraints. This innovation ensures system stability and precise tracking, even in severe input saturation constraints. The results reveal that the system’s steady-state tracking error remains under 2% under input saturation constraints, and the convergence speed demonstrates an impressive 20% improvement. These findings underscore this research’s substantial advancement in hypersonic flight control. It may significantly enhance the controllability and performance of hypersonic vehicles in real-world scenarios.

Evolution of Airy Beams in Turbulence Plasma Sheath

In order to study the transmission characteristics of Airy beams in the plasma sheath, the flow field around a hypersonic vehicle was numerically simulated and analyzed based on the Navier–Stokes (N-S) equation and a turbulence model. Then, according to the characteristics of the thickness of the plasma flow field around the supersonic vehicle at the centimeter level, the double fast Fourier transform (D-FFT) algorithm and multi-random phase screens theory were used to predict the propagation characteristics of the Airy beams in the turbulent plasma sheath. The results show that the lower the height and the higher the speed, the smaller the thickness of the plasma sheath shock layer. The refractive index variation in the sheath shock layer has a significant influence on Airy beam transmission. At the same time, the transmission distance and the attenuation factor of the Airy beams also change the transmission quality of the Airy beams. The larger the attenuation factor, the smaller the drift, and the standard deviation decreases with an increase in the refractive index. Airy beams have smaller drifts compared to Gaussian beams and have advantages in suppressing turbulence.

Preliminary design of a hypersonic airbreathing vehicle based on four steps: An academic approach to learning

This article proposes a systematic approach for the preliminary design of a hypersonic airbreathing (scramjet) vehicle within an academic context. The goal is to serve as an educational tool, focusing on teaching students the fundamental physical concepts behind scramjets. The article provides essential equations for generic scramjet designs while explaining the simplifications made from an academic perspective. It demonstrates the use of spreadsheets as a user-friendly tool to modify parameters and observe the behavior of shock waves. The article outlines a four-step procedure. It includes estimating atmospheric properties, designing the supersonic inlet, calculating combustion chamber parameters, and determining postcombustor properties. An academic exercise illustrates these steps for a scramjet flying at a specific velocity and altitude. The results show that this procedure, combined with spreadsheets, enables a rapid prediction of thermodynamic properties, enhancing the understanding of the fundamental physics behind hypersonic airbreathing vehicles.

Research on guided wave propagation characteristics of quartz ceramic thermal protection structure for ablation monitoring

ABSTRACT Monitoring the thermal protection structure (TPS) of hypersonic vehicles is vital for ensuring safe flight. The guided wave(GW) structure health monitoring（SHM）method is promising for TPS health monitoring due to its high sensitivity, ability to detect small damages, and wide monitoring coverage, both online and offline. However, there is currently a clear research gap in monitoring hypersonic aircraft TPS in real-service environments. This paper addresses this gap by conducting GW monitoring research on hypersonic vehicles TPS under simulated real-service conditions, involving high-temperature and high-speed airflow ablation. This study takes quartz ceramic TPS as the object, undertaking a preliminary investigation into its GW propagation characteristics. Subsequently, the TPS underwent high-temperature and high-speed oxygen-acetylene ablation at 2100°C to induce damages. GW monitoring was then conducted to capture GW signals in both undamaged and various damage scenarios. Through signal analysis, characteristic parameter extraction, and application of the damage index method, rules governing how GW signals respond to damage were established. Results indicate significant impacts on amplitude and phase of GW signals with increasing damage severity, validating the feasibility of the GW monitoring method for detecting high-temperature and high-speed airflow damage to TPS and supporting its expansion for damage monitoring.

Disturbance observer-based fixed-time control for hypersonic morphing vehicles with uncertainties

Abstract The attitude-tracking problem of hypersonic morphing vehicles (HMVs) is investigated in this research. After introducing variable-span wings, the optimal aerodynamic shape is available throughout the entire flight mission. However, the morphing wings cause significant changes in aerodynamic coefficients and mass distribution, challenging the attitude control. Therefore, a complete design procedure for the flight control system is proposed to address the issue. Firstly, the original model and the control-oriented model of HMVs are built. Secondly, in order to eliminate the influence caused by the multisource uncertainties, an adaptive fixed-time disturbance observer combined with fuzzy control theory is established. Thirdly, the fixed-time control method is developed to stabilise hypersonic morphing vehicles based on a multivariable sliding mode manifold. The control input can be obtained directly. Finally, the effectiveness of the proposed method is proved with the help of the Lyapunov theory and simulation results.

Novel numerical method for uncertainty analysis of coupled vibro-acoustic problem considering thermal stress

Uncertainty is pervasive and exerts a profound influence in engineering practice. Uncertainty quantification is a primary task and of paramount importance in uncertainty analysis. To deal with both dependent and independent uncertain parameters in engineering problems, an improved multidimensional parallelepiped model (IMPM) is subsequently developed. Compared with traditional methods that entirely based on statistical features, more accurate uncertainty quantification results can be obtained by means of IMPM. To enhance the efficiency of uncertainty propagation analysis under IMPM, a radial basis function neural network (RBFNN) surrogate model is constructed to replace the original time-consuming finite element simulation model. Eventually, the effectiveness of proposed models and numerical methods is validated through an engineering example involving the coupled vibro-acoustic system considering thermal stress of a hypersonic vehicle.