Development Of Hypersonic Vehicles Research Articles

Review on preparation technology of carbide resistant ultra-high temperature ceramic fiber

The rapid development of hyper-sonic vehicles has put forward an urgent demand for ultra-high temperature resistance ceramic fibers ceramic matrix composites. The properties of ultrahigh-temperature ceramic matrix composites made of carbon-based ultra-high temperature resistance ceramic fibers are excellent. Therefore, the preparation processes of several commonly used carbide-resistant ultrahigh-temperature ceramic fibers are described in detail. This review compares the advantages and disadvantages of five common methods (Molten-salt synthesis method, Chemical Vapor Reaction Method, Chemical Vapor Deposited method, Sol-Gel Method & Polymer-Derived method) for preparing ceramic fibers, summarizes the preparation methods that should be used in the face of different preparation requirements, and evaluates the improvement and prospect of each method. Among them, the polymer-derived method, as the most difficult and effective preparation method, has been given great hope by material scientists.

Flow Field Reconstruction of 2D Hypersonic Inlets Based on a Variational Autoencoder

The inlet is one of the most important components of a hypersonic vehicle. The design and optimization of the hypersonic inlet is of great significance to the research and development of hypersonic vehicles. In recent years, artificial intelligence techniques have been used to improve the efficiency of aerodynamic optimization. Deep generative models, such as variational autoencoder (VAE) and generative adversarial network (GAN), have been used in a variety of flow problems in the last two years, making fast reconstruction and prediction of the full flow field possible. In this study, a hybrid multilayer perceptron (MLP) combined with a VAE network is used to reconstruct and predict the flow field of a two-dimensional multiwedge hypersonic inlet. The obtained results show that the VAE network can reconstruct the overall flow structure of the hypersonic flow field with high accuracy. The reconstruction accuracy of complex flow structures, such as shockwaves, boundary layers, and separation bubbles, is satisfactory. The flow field prediction model based on the MLP-VAE hybrid model has a strong generalization and generation ability, achieving relatively accurate flow field prediction for inlets with geometric configurations outside the training set.

The highest melting point material: Searched by Bayesian global optimization with deep potential molecular dynamics

The interest in refractory materials is increasing rapidly in recent decades due to the development of hypersonic vehicles. However, the substance that has the highest melting point (<i>T</i>_m) keeps a secret, since precise measurements in extreme conditions are overwhelmingly difficult. In the present work, an accurate deep potential (DP) model of a Hf–Ta–C–N system was first trained, and then applied to search for the highest melting point material by molecular dynamics (MD) simulation and Bayesian global optimization (BGO). The predicted melting points agree well with the experiments and confirm that carbon site vacancies can enhance the melting point of rock-salt-structure carbides. The solid solution with N is verified as another new and more effective melting point enhancing approach for HfC, while a conventional routing of the solid solution with Ta (e.g., HfTa₄C₅) is not suggested to result in a maximum melting point. The highest melting point (~4236 K) is achieved with the composition of HfC_0.638N_0.271, which is ~80 K higher than the highest value in a Hf–C binary system. Dominating mechanism of the N addition is believed to be unstable C–N and N–N bonds in liquid phase, which reduces liquid phase entropy and renders the liquid phase less stable. The improved melting point and less gas generation during oxidation by the addition of N provide a new routing to modify thermal protection materials for the hypersonic vehicles.

Application of a Gas-Kinetic BGK Scheme in Thermal Protection System Analysis for Hypersonic Vehicles

One major problem in the development of hypersonic vehicles is severe aerodynamic heating; thus, the implementation of a thermal protection system is required. A numerical investigation on the reduction of aerodynamic heating using different thermal protection systems is conducted using a novel gas-kinetic BGK scheme. This method adopts a different solution strategy from the conventional computational fluid dynamics technique, and has shown a lot of benefits in the simulation of hypersonic flows. To be specific, it is established based on solving the Boltzmann equation, and the obtained gas distribution function is used to reconstruct the macroscopic solution of the flow field. Within the finite volume framework, the present BGK scheme is specially designed for the evaluation of numerical fluxes across the cell interface. Two typical thermal protection systems are investigated by using spikes and opposing jets, separately. Both their effectiveness and mechanisms to protect the body surface from heating are analyzed. The predicted distributions of pressure and heat flux, and the unique flow characteristics brought by spikes of different shapes or opposing jets of different total pressure ratios all verify the reliability and accuracy of the BGK scheme in the thermal protection system analysis.

Exploring Mechanical Properties of SiO2 Elastic Micro-Nano Ceramic Fibres Aerogels

With the development of hypersonic vehicles and the military, SiO2 elastic nano-fibre ceramic aerogel becomes a preferred and potential material due to its ultralight, thermal superinsulation, and superelasticity properties. Compared with traditional ceramic materials which are brittle and easily degraded, SiO2 elastic nano-fibre aerogel shows up with its outstanding characteristics under extreme conditions. Facing a major demand in the national strategy of thermal insulation materials, this study will keep an eye on these growing and famous novel materials. Summarizing current studies and research at home and abroad. And explaining the evolution from traditional SiO2 aerogels to elastic aerogels to new SiO2 nano-fibre aerogels with flexible elastic bonds. Finally, providing regulation factors that can be improved and employed in future experiments. Giving prospects and focus for future research.

The two-tier tissue reinforcing and toughening mechanism caused by dual-granularity Si powders ingredient, and dielectric properties in reaction bonded and sintered reaction bonded Si3N4 porous ceramics

With the rapid development of hypersonic vehicles and broadband wave-transparent radome, Si3N4 porous ceramics (Si3N4-PC) have attracted attention due to their excellent intrinsic properties of Si3N4 and high porosity. However, its high porosity results in low strength and toughness, which are fundamental properties for radome. Reaction bonded (RB) Si3N4-PC has advantages of dielectric properties and cost over general phase transformation sintering (PTS) and sintered reaction bonded (SRB) Si3N4-PC while it has been neglected in recent years. In this study, RB and SRB Si3N4-PC prepared by non-aqueous gelcasting and the influence of Si powders ingredient on their properties are discussed in order to illuminate the potential of RB Si3N4-PC in wave-transparent materials. The results show that RB Si3N4-PC with dual-granularity ingredients of 5 μm & 45 μm produces a two-tier tissue of framework of coarse whiskers enhanced by a network of tiny whiskers. SRB Si3N4-PC evolves into a two-tier tissue of framework of columnar and rod-like grains joining together to brace each other. The two-tier microscopic tissue strongly reinforces and toughens the structure and results in higher σF and γwof. As a result, the RB and SRB Si3N4-PC of dual-granularity of 5 μm & 45 μm obtain the maximum σF of 109.94 MPa and 119.56 MPa as well as maximum γwof of 990.74 J m-2 and 1167.88 J m-2, respectively. Furthermore, the ε′ and tanδ of RB and SRB Si3N4-PC of dual-granularity of 5 μm & 45 μm are about 4.20 and 4.52 as well as 7.01 × 10-3 and 22.90 × 10-3, respectively. It is concluded that RB Si3N4-PC of dual-granularity has good mechanical and dielectric properties, which are favorable for radome.

Integrated Thermal Protection System Design for Hypersonic Vehicle Based on New Thermal–Mechanical Method

With the development of hypersonic vehicles, considerable attention has been paid to thermal protection systems (TPSs). Among the different types of TPS, integrated TPS (ITPS) has attracted extensive interest because of its light weight, cost effectiveness, bearing capacity, and easy maintenance. However, ITPS, with its complex structure and reusable requirement, is facing challenges and it is worth devoting much effort to this. In an effort to overcome these challenges, we develop a novel approximate analytical method based on separation of variables and orthogonal expansion technique, which is presented for the prediction of heat transfer. The approximate analytical method has the ability to consider the effects of temperature-dependent thermal material properties, convection and radiation. Moreover, a C0 higher-order layer-wise finite-element model combined with homogenization techniques and a simplified three-dimensional (3D) finite-element model based on the periodic structure characteristic are proposed to estimate the thermal–mechanical response and stability of ITPS effectively. In addition, an optimization procedure based on the proposed methods for ITPS is developed. Implementation of the optimization is demonstrated by applying it to design the ITPS of space shuttles and hypersonic vehicles. By comparing with conventional thermal protection systems (CTPSs), ITPS exhibits an outstanding advantage in weight and an acceptable disadvantage in size. The objective of this paper is to establish an accurate and efficient design method aiming at determination of the optimal performance of ITPS, and puts forward the foundation for the development of a hypersonic vehicle.

Advanced sandwich structures for thermal protection systems in hypersonic vehicles: A review

A heat shield called the thermal protection system (TPS) is an important structure in hypersonic vehicles as it prevents hot air from entering vehicles and potential impacts from space debris. With the increase in demand for low-cost reusable launch vehicles as well as for searching and exploration of new planets in both unmanned and manned missions, the need for developing an effective TPS has increased across many countries. The structural design of TPSs has become more prominent in the early stage of hypersonic vehicle development. Sandwich structures that have the advantages of low density and high performance are integrated into the structural design of an effective TPS. This paper provides a comprehensive review of recent research efforts on sandwich structures for TPSs. The topics discussed in this paper include aspects of structural and material design, mechanical and thermomechanical performances, and manufacturing methods. In particular, we review and discuss the structural design as well as the material design of sandwich structures for different TPS types with various configurations, including corrugated cores, lattice cores, multilayer cores, foams, honeycomb cores, bio-inspired cores. The materials used for the sandwich structures, such as various types of laminated composite, ceramic matrix composite, and metals, are included. We also discuss the performance of the TPS sandwich structures in terms of temperature gradients, deformation limits, and mechanical strengths and provide a discussion on the manufacturing methods of TPS sandwich structures for hypersonic vehicles. Finally, further research directions and challenges of sandwich structures for TPSs are presented.

Evasion guidance for air-breathing hypersonic vehicles against unknown pursuer dynamics

The rapid development of hypersonic vehicles has motivated the related research dramatically while the evasion of the hypersonic vehicles becomes one of the challenging issues. Different from the work based on the premise that the pursuers’ information is fully known, in this paper the evasion guidance for air-breathing hypersonic vehicles (AHVs) against unknown pursuer dynamics is studied. The gradient descent is employed for parameter estimation of the unknown dynamics of the pursuer. The energy-optimized evasion guidance algorithm is further developed by taking the acceleration constraint and energy optimization into consideration. Under the proposed algorithm, the system can deal with the unknown pursuer dynamics effectively and provide more practical guidance for the evasion process. The simulation results show that the proposed method can enable the AHV to achieve successful evasion.

Evaluation and design methods for high‐efficiency charring composite under complex coupling mechanisms in both material and boundary layer

AbstractWith the development of hypersonic vehicles, reentry vehicles are facing a more severe aerothermodynamic heating environment. It is necessary to design high‐efficiency charring composite used as the heat shield in the thermal protection system (TPS) of reentry vehicles. By taking the material responses (volume‐surface coupled ablation), exothermic gas‐phase reactions of pyrolysis gases in the boundary layer and the flow behavior of chemical nonequilibrium inflow coupling ablative mechanism into consideration, a developed thermal/fluid/chemical/ablation coupling model with the key influencing factor on thermal protection performance of charring composites is built to evaluate the material responses and the chemical responses in boundary layer near its surface. Based on this model, the key factor (fiber volume fraction) influencing on the thermal protection performance is analyzed by using a coupling numerical calculation strategy. By designing the distribution of this parameter along the thickness of the material, a gradient design for charring composite is given. The numerical results indicate that the gradient charring composite can control the temperature distribution and the amount of surface ablation recession. This study will be a guidance for the design of charring composites for thermal protection application in reentry vehicles in a quantitative and efficient manner.

An Exponential-Based DGTD Method for Modeling 3-D Plasma-Surrounded Hypersonic Vehicles

Plasma surrounding a hypersonic vehicle can lead to the absorption of incoming radar radiation or the interruption of communication. Therefore, the development of hypersonic vehicle relies on a clear understanding of the strong interaction between the surrounding plasma and the incident electromagnetic wave. However, because of the presence of complex geometrical features and heterogeneous media, these applications are often multiscale. The modeling of such applications in 3-D is extremely challenging for traditional numerical methods. In this work, an efficient discontinuous Galerkin time-domain (DGTD) method for the 3-D modeling of plasma-surrounded hypersonic vehicles is presented. To overcome the grid-induced stiffness problem arising from the modeling of such multiscale applications with dispersive media, and to improve the modeling efficiency, a high-order exponential-based time integration for the time-domain Maxwell’s equations discretized by DG schemes with a general flux formulation is proposed. This time integration has excellent stability properties in the locally refined part of the mesh and hence enables the usage of larger time steps compared with the explicit time marching scheme. Additionally, the exponential-based time integration is developed to adapt an anisotropic perfectly matched layer for the modeling of open-domain problems. Finally, numerical experiments are presented to investigate the accuracy and convergence properties and to demonstrate the well-modeling capability of the proposed method.

Long time ablation behaviors of designed ZrC-SiC-TiC ternary coatings for environments above 2000 °C

Thermal protection systems with long time anti-ablation property for applications in ultrahigh temperature environments have been a choke point for the development of hypersonic vehicles. In the present work, new ZrC-SiC-TiC ternary composite coatings were designed and fabricated by vacuum plasma spray. The ablation behaviors of the ternary coatings were evaluated by a plasma flame with temperatures about 2200−2500 °C and compared with the ZrC-SiC and ZrC-TiC composite coatings. The characteristics of phases, element distributions and microstructure of the oxidized layers were observed in detail. The results showed that the anti-ablation resistant property of the ternary coatings was much better than those of the ZrC-SiC and ZrC-TiC composite coatings. The oxidation products, like high viscous SiO2 and high thermo stable TiO2, played a mutual promoted role in modifying the oxide layers, which contributing a lot to the improved ablation resistance. The ablation mechanisms of the ZrC-SiC-TiC ternary coatings were analyzed based on microstructure observations and thermodynamic analysis.

Coupling Model and Electronic Compensation of Antenna-Radome System for Hypersonic Vehicle With Effect of High-Temperature Ablation

High-temperature ablation leads to degradation of the electromagnetic performance of the antenna-radome system during flight, which severely restricts the development of hypersonic vehicles with higher performance and higher speed. Therefore, the non-steady ablation process of the antenna-radome system is analyzed. Based on geometrical optics, the transmission performance of the radome under variations of material and structural parameters that are caused by high-temperature ablation is calculated. In addition, the excitation amplitude and phase errors that are output by the transmitter and receiver (T/R) module and amplified by array power supply ripple are analyzed as the temperature of the antenna is increased. An electromechanically coupled model is established accordingly for evaluating the electromagnetic performance of the antenna-radome system with variations of the material and structural parameters of the radome and the excitation current errors of the array elements. A compensation calculation model of the excitation amplitude and phase of the array elements that is based on the coupled model is presented. Finally, a hypersonic vehicle is considered as an example on which to evaluate the effectiveness of the proposed coupled model and compensation method. Aerodynamic heat analysis is applied to determine the boundary heat flux density of the radome. Transient thermal analysis, in combination with the “life and death element” method, is used to obtain the temperature distribution and ablation morphology of the antenna-radome system in real time. The performance of the antenna-radome system is calculated and compensated at multiple frequencies and multiple scanning angles. The results demonstrate that the coupled model could calculate the electromagnetic performance of the antenna-radome system under high-temperature ablation and that the compensation method can significantly improve guidance performance of hypersonic flight vehicle.

Hypersonic transatmospheric and exoatmospheric vehicle design using the SUAVE tool

This work reports the introduction of a set of low-fidelity aerodynamic and propulsion models to the preliminary vehicle design suite SUAVE. This enables the capability to predict transatmospheric and exoatmospheric hypersonic flight performance. Verification and validation for the different subsystem modules have been carried out against existing data, namely regarding the propulsion (ramjet, scramjet, LOX/LH2 rocket, combined-cycle engines) and aerothermodynamic (reentry) subcomponents. Two sample test-cases, based on the vehicular properties of the SR-72 vehicle (size and wing area) have been analyzed. A flight range of about 10,000 km for a flight time between 1 h (exoatmospheric flight) and 2h30 (transatmospheric flight) has been determined for a set of theoretical reasonable efficiencies for the subcomponents (chiefly propulsion). The obtained results provide a contribution to hypersonic vehicle development roadmaps, proposing two credible mission profiles (trans- and exoatmospheric) and highlighting the key role of propulsion technology development for the advancement of the state-of-the-art.

Experimental research of arc heater with three electrodes

As a heat source capable of producing extremely high temperature, the arc heater developed with the development of ballistic missiles and other spacecraft. With the development of hypersonic vehicles, the requirement of thermal protection performance test on ground simulation equipment is higher and higher, the current and power of arc heater are increasing. The traditional single-electrode arc heater can’t run stably for a long time under large current. In order to improve the operation stability of the arc heater under large current, a multi-electrode technique was developed. In this paper, the effects of parameters such as arc current, gas flow rate and resistance on the current distribution of each sub-electrode of the three-electrode arc heater are studied. The results show that when the arc current is constant, increasing the resistance difference of each sub-electrode is beneficial to the average distribution of current. With the increasing of arc current, the current distribution of each sub-electrode is more uniform. The setting of parameters such as arc current, gas flow rate and resistance has great influence on the distribution of cathode current of multi-electrode arc heater, but little influence on the anode.

Metallic integrated thermal protection structures inspired by the Norway spruce stem: Design, numerical simulation and selective laser melting fabrication

With the development of hypersonic vehicles and reusable launch vehicles, the design of integrated thermal protection (ITP) structures needs to meet the demanding requirement of thermal protection. More complex geometries, such as lattice structures and bio-inspired structures, have been introduced into the design of ITP structures, aiming to enhance the thermal protection performance. Additive manufacturing holds high flexibility in processing and enables more complex designs, which is suitable for the fabrication of complex ITP structures. In this paper, inspired by the structures of Norway spruce stem, a series of ITP structures with different gradient hollow designs was proposed and manufactured by selective laser melting (SLM). The steady-state and transient thermal behavior of those bio-inspired ITP structures were investigated by finite element method (FEM). To verify the accuracy of the FEM simulation results, Ti6Al4V components with different bio-inspired ITP structures were fabricated by SLM and thermal conductivities of those SLM-processed components were experimentally measured. The FEM thermal simulation revealed that the gradient-structure with larger hollow tubes near the top and bottom plates and smaller hollow tubes in the center possessed the lowest bottom surface temperature of 262.8 °C, which was 21.4 °C lower than the structure with the highest bottom surface temperature. The thermal conductivity measurement revealed that the gradient-structure, with the lowest bottom surface temperature obtained by FEM thermal simulation, had the lowest thermal conductivity of 2.321 W/(m⋅K), which was about 29% lower than that of the structure possessing the highest thermal conductivity.

Optimization transpiration cooling of nose cone with non-uniform permeability

With the development of active thermal protection techniques (TPTs), optimization transpiration cooling (OTC) design, to enhance the cooling effect in stagnation regions and decrease coolant load, has become a critical issue in the research and development of hypersonic vehicles. One of the possible OTC approaches is using a non-uniform porous material to vary the coolant allocation within pores. This paper presents an experimental and numerical investigation on the transpiration cooling performances of two wedge shaped nose cones. One is for OTC, made of a special porous matrix with non-uniform permeability to ensure the largest porosity near the stagnation point, and the other is for traditional transpiration cooling (TTC), consisting of a general uniform porous matrix. Surface temperature and cooling effectiveness of the two nose cones are investigated in the experiments. The data show that in comparison with TTC, OTC can effectively enhance the cooling effectiveness in stagnation regions through a locally high permeability, and improve the uniformity of the temperature distribution within the entire nose cone. To exhibit the coolant flow characteristics within the pores, two-dimensional numerical simulations are carried out by commercial software FLUENT, and the numerical method is validated by the experimental data. The numerical results indicate that OTC with non-uniform permeability can provide an optimized coolant allocation and decrease the driving force required by the coolant transport to the stagnation region.

Optimal Design for a High-Power Electric Arc Heater

High-power electric arc heaters are the only viable test equipments for heating air to high temperatures (2000-10 000 K) in a few minutes for experimental ground studies of hypersonic flight vehicle thermal protection systems. With the expansion of the exploration of outer space and the rapid development of hypersonic vehicles, more powerful arc heaters are urgently required to meet the demands of the aerospace industry. However, the design of high-power arc heaters faces many technical obstacles such as the need for high structural strength, the need for high-efficiency heat-transfer for cooling, the problem of high internal temperature flow, and the electromagnetic plasma coupling problem. To address these problems, this paper has discussed an optimization scheme, in order to improve the reliability and security of a high-power arc heater in extreme conditions, and at the same time improve the thermal efficiency of the arc heater, and extend the service life of an arc heater.

Deviation analysis of loosely coupled quasi-static method for fluid-thermal interaction in hypersonic flows

Abstract Fluid-thermal interaction plays an important role in the design and development of hypersonic vehicles. Among the different ways to couple the flow field with the material thermal response, the loosely coupled quasi-static method is widely used. In this paper, deviation formulas based on one-dimensional model are derived for uncoupled method and loosely coupled quasi-static method to estimate the structural temperature deviations at the stagnation point in different forward time steps. To verify the formulas, fluid-thermal coupling numerical simulations are conducted for 2-D and 3-D hypersonic fluid-thermal interaction problems. The results show that the temperature deviation formulas agree quite well with the deviations from numerical simulation. The derived deviation formulas can serve as some guidance for selecting an appropriate forward time step for the loosely coupled quasi-static method.

Design and analysis of integrated thermal protection system based on lightweight C/SiC pyramidal lattice core sandwich panel

Thermal protection system (TPS) plays the key role to successful development of hypersonic vehicles. Here, a novel structurally and thermally integrated thermal protection system (ITPS) based on the lightweight C/SiC pyramidal core lattice sandwich panel is proposed. This ITPS integrates advantages of low areal density and high temperature resistance up to 1600°C. Heat transfer characteristics and compressive responses of the C/SiC sandwich panel are established in advance. The results demonstrate that filling alumina fibers in the pore significantly reduce the effective thermal conductivity from 2.45–4.83W/m°C to no more than 0.7W/m°C. The critical relative density is determinated for the failure models under aerodynamic pressure load. Meanwhile, an analysis procedure of the ITPS is exclusively established under typical aerodynamic heat flux and pressure load. With fulfillment of both temperature and mechanical constraints, minimum areal density is obtained. Compared with current metal corrugated core ITPS, the ITPS proposed here significantly raises the temperature limitation up to 1600°C and reduces the areal density up to 35%, and is very promising for potential application in hypersonic vehicles.