Aerodynamic icing poses a critical operational challenge for unmanned aerial vehicles (UAVs), contributing to 25 % of all drone-related incidents, with the primary cause being impaired flight stability resulting from ice accumulation. Therefore, it is necessary to develop an icephobic coating suitable for use on UAV. Although icephobic coatings have achieved significant progress, their effectiveness often diminishes or fails entirely under conditions of subzero temperatures, elevated humidity, and dynamic. In this study, a novel glycerol triglyceridederived epoxy composite coating (GSiC) with efficient dynamic icephobic performance is synthesized through covalent crosslinking between glycerol triglyceride and oil-loaded silica nanoparticles via epoxy-amine reactions. This advanced coating demonstrates exceptional water-repellent characteristics, maintaining a water droplet sliding angle of only 8 degrees. The optimized lubricating properties confer outstanding anti-adhesion performance, selfcleaning capability, and remarkably high adhesion reduction factor (25.9). The GSiC exhibits outstanding efficacy in suppressing both icing and frosting under subzero temperature and elevated humidity conditions. Comparative testing against commercial superhydrophobic coatings (SHC) reveals that GSiC substantially improves ice resistance, achieving a 12.1 times longer ice delay period, and also extends frost formation time by approximately 300 %. A critical distinction emerged during the 150-s dynamic icing evaluation: the GSiC-treated propeller demonstrated two discrete ice-shedding occurrences, whereas the SHC-coated counterpart experienced a total failure in ice-resistant performance. This superior dynamic icephobic capability ensures uninterrupted equipment operation while concurrently minimizing energy expenditure. GSiC also possesses antibacterial and anti-corrosion properties. This advancement may further expand the operational capabilities of UAVs in extreme environments.

Photothermal superhydrophobic coatings hold promise in engineering anti/de-icing but often lack sufficient functional robustness and tend to be performance-unstable under harsh environments. Here, a superhydrophobic polyurea coating (SHPC) without micro/nano fillers or complex processes like laser etching was developed via low-polarity polyurea modification and kinetically driven regulation of polyurea molecular chain conformational domains. Notably, SHPC's contact angle (CA) remained >150 degrees after 2000 400-mesh sandpaper abrasion cycles. Furthermore, by synergizing the presumed nanoconfinement enhancement effect, a superhydrophobic photothermal polyurea coating (SHPPC) was designed to overcome SHPC's robustness bottleneck. With the same thickness, SHPPC's surface robustness is significantly enhanced: CA remains >150 degrees after 16,000 cycles of 400-mesh sandpaper abrasion, 3810 cycles of 60-mesh sandpaper abrasion, 60 min of gravel impact, or 30 min of water jet impact, which, to our knowledge, is one of the more durable superhydrophobic coatings reported recently. Moreover, SHPPC shows outstanding photothermal robustness; after 2000 cycles of 60-mesh sandpaper abrasion, its light-irradiated area remains frost-free and it inhibits water droplet freezing for 90 min at -15 degrees C. Possessing exceptional functional robustness, anti/de-icing performance, and efficient natural light utilization, SHPPC holds substantial application potential in engineering anti/de-icing fields like unmanned aerial vehicle (UAV) propellers.

Photothermal slippery liquid-infused porous surfaces lack durable anti-icing performance in practical applications, owing to insufficient photothermal conversion under weak solar irradiance, lubricant loss in dynamic conditions, or poor mechanical robustness. An innovative bionic "Yin-Yang coupling" principle was proposed, mimicking the rigid skeletons and flexible muscles of organisms. "Yin" regulates dynamic functions, whereas "Yang" ensures functional integrity. Based on this, photothermal F-SiO2@carbon aerogel@hollow SiO2 (FSi@CAA@HSi) aerogel microspheres with micro/nano/nano multiscale nanoconfinement were fabricated. HSi ("Yang"-rigid) optimizes photothermal conduction and inhibits CAA aggregation. CAA and F-SiO2 nanodomains ("Yin"-flexible) anchor photothermal components and enhance light absorption. Combined with silicone oil ("Yin"-lubricant) and polyurea ("Yang"-rigid / "Yin"-flexible), a robust photothermal slippery polyurea coating (PSPC) was prepared. Multiscale nanoconfinement suppresses component migration and oil leakage, securing PSPC's durability. In simulated environments, the PSPC exhibits: (i) excellent photothermal performance (reaching 42.2 degrees C in 300 s under 0.15 sun); (ii) good slipperiness (sliding angle <10 degrees); (iii) high robustness (stable photothermal performance after 2000 abrasion cycles). It also shows excellent dynamic anti-icing performance, with no ice formation after 3600 s dynamic conditions. This design enables scalable, energy-efficient anti/de-icing capabilities in real-world conditions, offering significant potential for use in wind turbines.

Green hydrogen production exacerbates water scarcity and further contributes to climate change when using fossil-based electrical energy. In this work, a device with long-term durability combining solar energy was proposed and designed for the sustainable production of water and green hydrogen over 24 h. The water production device was based on a high-heat-resistant and salt-resistant bio-based moisture sorption gel, whose water sorption capacity is 2.03 times that of pure lithium chloride in a simulated desert environment (18 degrees C, 15% relative humidity [RH]). Notably, the prepared aerogel exhibited cumulative water sorption of 2.045 gwater & sdot;gsample-1 and performance fluctuation < 2% after 2,000 h of cyclic testing. Therefore, we used this material in our device to achieve 24 h of continuous water and electrolytic hydrogen production by atmospheric water harvesting. This study introduces a potential solution aimed at providing a new 24-h continuous production method for both water and green hydrogen in arid regions.

Global wildfires have grown increasingly severe. Conventional fire suppressants exhibit low fire-extinguishing efficiency, re-ignition risks, environmental contamination, and cumbersome preparation procedures. Herein, a biofertilizer-based hydrogel (BBH) was fabricated using food additives and compound fertilizers as all-biomass raw materials. The resultant material is low-cost and suitable for large-scale production. Different from traditional single-functional hydrogels, this material operates via a gas-liquid-solid three-phase coupled flame-retardant mechanism based on bound water cooling, phosphorus radical quenching, and the formation of carbon "aerogel-like" barriers. BBH achieves a high limiting oxygen index (LOI) of 84.2%, and its flame-retardant efficacy delivers a 3.3-fold improvement compared with commercial counterparts. Compared with pure water, this hydrogel shortens the fire-extinguishing time by 60% and reduces material consumption by nearly 70%, and no re-ignition is observed throughout all tests. Furthermore, BBH supports an integrated closed-loop system combining fire suppression and in situ ecological restoration. After BBH effectively extinguishes wildland fires, appropriate residues remaining in soil and on plant surfaces impose no environmental burden; its biodegradable residues can release nitrogen, phosphorus, and potassium, which effectively promote plant growth. This work provides a theoretical foundation and feasible technical route for the development of high-efficiency and eco-friendly wildfire suppression materials.

Endothermic high-energy nanofluid fuels represent a novel fuel type with great potential to address the overheating and thrust deficiency issues of scramjet engines under high Mach number. Boron features a high combustion calorific value, yet its lack of catalytic cracking activity renders it difficult to be directly used as an additive for endothermic nanofluid fuels. Herein, we first report a strategy of confined molecular phase change and boron nanoparticles catalysis for nanofluid stability and enhancement of physical and chemical heat sink. Boron nanoparticles with catalytic activity (NBK, nano-boron KH550) are obtained through ultrasound-assisted in situ surface functionalization treatment. The oxidation degree and calorific value of NBK were enhanced by 3.6

Photo-thermal de-icing offers energy-efficient, safe, and eco-friendly solutions to combat ice accumulation-a critical hazard for aviation, energy, and infrastructure. However, state-of-the-art photothermal materials (e.g., graphene, carbon nanotubes) rely predominantly on infrared absorption (molecular thermal vibrations), limiting thermal equilibrium temperatures under solar irradiation and hindering deployment. To overcome this fundamental spectral gap, we engineer copper nanorods functionalized via in situ growth of poly(hexachlorocyclotriphosphazene-co-4,4'-sulfonyldiphenol). This strategy simultaneously enhances nanorod-polymer substrate compatibility and exploits the photoluminescence of poly(hexachlorocyclotriphosphazene-co-4,4'-sulfonyldiphenol) to convert ultraviolet light into wavelength-resonant visible light, significantly boosting photothermal conversion via the localized surface plasmon resonance effect. Critically, integrating this system with polyaniline (a strong near-infrared light absorber) and polyimide (a strong far-infrared light absorber) yields, for the first time, a nanocomposite capable of full-spectrum solar photothermal conversion. Under 1-sun illumination (1 kW·m-2), it achieves a record-high thermal equilibrium temperature difference of 65.1°C. When mounted on rotating three-blade propellers, the nanocomposite enables rapid solar-thermal de-icing within 6 min. Remarkably, it also maintains effective anti-icing performance under severe conditions simulating supercooled large droplets spray (-20°C, 62.57 µm droplet size), showcasing its potential for demanding real-world environments. This spectrally engineered design establishes a blueprint for energy-efficient dynamic de-icing, offering scalable solutions for aerospace, wind energy, and polar infrastructure protection.

Ice accumulation on aircraft surfaces can distort their aerodynamic profile, leading to diminished lift, increased drag, impaired maneuverability, and an elevated risk of stalling. Currently, the most promising approach for de-icing involves designing surface structures and chemical compositions that minimize ice adhesion. Anti-icing coatings with low ice adhesion strength are typically fabricated from soft materials, but this often results in insufficient durability. To strike a balance between low ice adhesion strength and durability, this study introduces an inhomogeneous elastic modulus coating, developed through finite element simulation. The shear strength at the ice-substrate interface is the most commonly employed metric for describing ice adhesion strength. An ice shedding model for measuring ice adhesion shear strength was established based on the bilinear cohesive zone model and cohesive element method. Utilizing the finite element model, we analyzed the impact of variations in elastic modulus inhomogeneity, size, shape, and spatial distribution on the coating’s ice adhesion strength. It was found that stress concentration induced by elastic modulus inhomogeneity facilitates crack initiation and propagation along the ice-substrate interface, thereby reducing ice adhesion shear strength. Compared to traditional polydimethylsiloxane coatings with low ice adhesion strength, the engineered anti-icing coating demonstrates a roughly 25

In the tandem turbine-based combined cycle engine's hyperburner, the complex intrusive design is usually employed to achieve ignition and stable combustion under high-speed and low-temperature extreme conditions. This paper proposes a concise, non-intrusive coupled swirler-cavity configuration to supply the fuel with good atomization at the cavity-trapped vortex center, thereby ensuring the formation of the initial flame kernel. Under the guidance of the cavity-trapped vortex, the initial flame kernel grows through a dynamic “rotation-diffusion” mechanism. Compared to previous studies, the present work achieves ignition and stable combustion under higher incoming Mach numbers (Ma = 0.3, 0.4, 0.5) and lower temperatures (T0 = 300 K).

The complex environment of ice formation and electromagnetic interference severely impairs the normal functioning of aircraft components. Conventional aircraft electric heating elements suffer from a lack of real-time temperature monitoring of heating and are prone to electromagnetic interference during operation. Therefore, the development of an aircraft outer protected surface film with both temperature monitoring and electromagnetic shielding functions is of great significance. In this work, a dual-layer solid/liquid interpenetrating conductive network composite film was designed, with local mechanical sintered liquid metal (LM)/silicon carbide as the upper-layer coating and comprehensive mechanical sintered LM/PEDOT/fabric as the conductive substrate. Benefiting from the combined effect of the upper surface coating with a thermal conductivity of 1.48 W/mK and the underlying substrate with an electrical conductivity of 1.1 x 103 S/m, the composite coating exhibits excellent electrothermal de-icing and temperature monitoring performance. The composite film, with its outstanding Joule heating characteristics, reaching 89.4 degrees C within 60 s at a low voltage of 3 V and has the capability of static and dynamic de-icing in-15 degrees C environments. The composite film, with its electromagnetic shielding capability of 37.9 dB at 8.2-12.4 GHz (X-band) and flexibility, can provide electromagnetic protection for the entire wing. This work pioneers a material-level solution for the design of a new-generation aircraft electric heating system.

During the thermal de-icing process on the aircraft surface, significant temperature differentials are often induced which results in wasted energy. To optimize heat utilization and prevent overheating, thermal management and temperature warning are particularly important. Here, based on local mechanical sintering methods, liquid metal/boron nitride/thermochromic (LBTC) composite coatings are fabricated for anti-icing, de-icing and ice detection integrated multifunction. Inspired by the rapid shape change ability of mimosa pudica, liquid metal bridges are structured between thermochromic microcapsules (TCM) to improve heat transfer and energy storage efficiency. LBTC coating prepared by this method has a thermal conductivity enhancement of 138 %similar to 255 % and has the ability of rapid color transition. The long-temperature-range phase change LBTC increases the icing delay time to 1121 s without superhydrophobicity. It can maintain a suitable anti-icing temperature (39.7 degrees C) on a -10 degrees C cold plate and melt ice in 412 s under 1 sun radiation. Under the operation of the electric heating element, the surface temperature of the LBTC coating reaches 48 degrees C, and the temperature difference between the front and back is only 20 degrees C, which effectively prevents overheating. In the supercooled water detection experiment, LBTC coating enabled precise detection of the cooling area and cooling time on the surface of the wing model through the rapid color transition mechanism, meanwhile LBTC coating could resist cooling through the stored heat. This is of great significance for aircraft anti-icing and icing detection.

In extreme cold and dynamic environments, active and passive ice-phobic coatings face performance degradation due to surface issues and low photoelectric-thermal conversion. Photothermal solid-like slippery ice-phobic coating (PSSC) is developed using the "yin-yang associative elements" idea. By combining low-thermal-conductivity microspheres, nano-porous aerogels, silicone oil, and epoxy, PSSC forms a micro-nano-nano light-trapping structure and a slippery surface. It has a 2.6 degrees water sliding angle, 9.2 kPa ice adhesion, and an icing delay 79.5 times that of bare aluminium (Al). Moreover, PSSC also exhibits excellent corrosion resistance and environmental durability. After 30 days of ultraviolet (UV) irradiation and saltwater immersion, the sliding angle increases minimally. Its structure boosts photothermal performance, heating 148 degrees C in 20 s under 1 sun irradiation. At -20 degrees C, it melts ice fast with 1 sun irradiation. Notably, at -20 degrees C, 80% Relative Humidity (RH), in an 80 rpm min-1 dynamic photothermal defrosting test, PSSC defrosts in 180 s. The PSSC can achieve rapid ice removal within 180 s at -30 degrees C. PSSC's excellent ice-phobic ability in extreme cold environments offers new thoughts for advanced coating development.

Outdoor icephobic coatings are prone to damage, particularly in extreme weather conditions like freezing temperatures and acid rain. Damage to the coating will result in a loss of icephobic function and may lead to increased icing. Furthermore, it is imperative to incorporate sustainability into icephobic coatings as environmental consciousness grows. Herein, a vanillin-based icephobic coating with anti-extreme-environment selfhealing was prepared by incorporating vanillin-based polyols into prepolymers terminated with isocyanates that include silicone oil. The coating exhibited low ice adhesion with a measurement of 8.8 kPa, which was mainly attributed to the hydrophobicity of PDMS and the hydrophobic and lubricating characteristics of silicone oil. Moreover, the coating's remarkable chemical stability and ability to resist fouling were due to its lubricating and hydrophobic properties. More importantly, the coating retains impressive self-healing abilities in extreme conditions (-20 degrees C, pH = 1, pH = 14) due to the multiple dynamic bonds within the coating and the water-repelling and plasticizing effects of silicone oil. The coating maintained its original hydrophobic characteristics and low ice adhesion strength even after several recycling and self-healing cycles, demonstrating remarkable lifespan and sustainability. This work facilitates meeting the need for anti-icing in outdoor areas, particularly in extremely cold, acidic, and alkaline conditions.

The shock train self-excited oscillation can induce combustor instabilities and reduce engine margin. In a dual-mode scramjet, the shock train undergoes a complete evolution process, exhibiting structural changes closely tied to this inherent unsteadiness. This study aims to elucidate the space–time diversity in shock train self-excited oscillation mode and the underlying mechanisms during wide-range evolution. The experimental investigations were conducted at Ma = 1.95, capturing the complete evolution of the shock train. The results indicate the evolution can be categorized into three regimes based on structural characteristics. In regime I, the shock region gradually forms, followed by the occurrence of the mixing region in regime II. Regime III corresponds to inlet unstart. In regime II, isolator outlet pressure fluctuations exhibit higher frequency and lower amplitude compared to regime I, while the shock motion demonstrates lower frequency and higher amplitude. The shock train behaves in a large-scale, low-frequency (1.53 times the duct height, 10 Hz) unsteady motion in regime II, posing a potential threat to engine operation. Coherence and phase analysis reveal the disturbance source originates downstream. Proper orthogonal decomposition modal analysis shows two oscillation modes: low-frequency components correspond to shock motion, and high-frequency components correspond to pressure fluctuations across the entire pseudoshock. The propagating of downstream disturbance differs between the two regimes. In regime I, the shock train exhibits rigid-body motion synchronously. In regime II, the relative motion between each shock wave and the cumulative effect of pressure disturbance lead to frequency decay upstream, amplifying the shock train motion.

The performance of the traditional turbojet decreases sharply with the increase of the Mach number in the supersonic flight, especially for the turbine-based combined cycle (TBCC) engine in the transition region of the turbojet and scramjet engine. This paper proposes a new high-pressure bleeding-air variable cycle engine (HBVCE) concept that aims to ease the sharp contradiction between thrust output and fuel consumption of TBCC in the transition region. Through the energy and exergy analyses, the HB-VCE shows greater potential in energy utilization under high Mach flight conditions. The performance of HB-VCE significantly improves as the bleed ratio increases, with a more pronounced effect at higher Mach numbers. At Mach 1.5, the HB-VCE increases the specific thrust (ST) by 2.84 % and reduces the specific fuel consumption (SFC) by 2.73 %. At Mach 2.4, it increases the ST by 6.60 % and reduces the SFC by 6.52 %. Additionally, the controlling law of the critical bleeding ratio constrained by the turbine outlet temperature is proposed. Finally, the effect of the turbine inlet temperature, overall pressure ratio, and Mach number on the critical bleeding ratio is analyzed. This paper provides a promising HB-VCE concept with greater energy utilization for the TBCC design in the transition region.

Sustainable aviation fuels (SAFs) manufactured from green feedstocks are desired as fuels for traditional aviation jet engines to address the emissions problems. Bio-ethanol, as a renewable energy fuel, is very compatible with hydrocarbon fuels. However, the poor low-temperature start-up and operating performance of bio-ethanol due to the high latent heat of evaporation hinders the application advantages of renewable aviation fuel containing ethanol in jet engines. In this study, the regulation of the intrinsic properties of fuel was proposed to solve the above problem. The mechanism of the combustion enhancement by co-evaporation and in-situ generation of free radicals for the oxidation of alkanes in the hybrid fuel was analyzed by thermogravimetry-Fourier transform infrared experiments. Single-sector combustion chamber ignition experiments showed that modified fuels can extend the ignition boundaries, allowing fuel ignition at lower fuel-air equivalence ratios (0.015). In addition, flameout experiments showed that E30/K70-10 can broaden the flameout fuel-air equivalence ratio of fuel (from 0.018 to 0.014), attributed to improved oxidation, evaporation, and basic atomization performance. This study provides a reference for the use of ethanol-based SAF in advanced aircraft engines to improve ignition performance and extend the limits of real engine flameout.

A comprehensive theoretical model for the primary breakup of liquid jets in subsonic crossflow was developed. The model theoretically analyzed the jet deformation process, mass stripping process, and the influence of several critical forces and consequently provided highly accurate predictions of the jet trajectory. Deformation of the liquid jet cross section was considered as a two-stage process based on the physical characteristics, including the spring-mass analogy deformation and the mass stripping induced deformation. The mass stripping process was modeled as an exponential function of time based on experimental findings for liquid jets and droplets. Balance of critical forces acting on the jet were analyzed, both along the gas and jet flow directions, which included aerodynamic drag, viscous force, surface tension, and gravitation. The model provided precise prediction to the jet trajectory against experimental data without any initial jet velocity assumption across a wide range of gaseous Weber numbers and gas to liquid momentum ratios. In addition, quantitative effects of viscous force, surface tension force, and aerodynamic drag on jet trajectory were fully investigated based on the new model, which provided more insight into jet breakup characteristics and the effects of fuel properties on jet trajectory and deformation. Furthermore, the three-dimensional structure of the jet was reconstructed through the present model, which matched well against numerical results. Importantly, the current mathematical primary breakup model could be integrated with Lagrangian methods, obtaining more detailed vortex structures and accurate droplet dispersion with reduced computational time.

Controllable hydrocarbon fuel combustion and combustion path adjustment are effective but difficult approaches to achieve reliable ignition under extreme conditions. However, the effective mechanism to control the combustion characteristics of hydrocarbon fuels is still unclear. In this study, the fuel (Fuel 6) based on free radical relay combustion (FRRC) significantly expands the ambient temperature-based ignition limits of pure fuel and shows a weak temperature correlation with ignition delay time. In addition, Fuel 6 still has a 100% ignition probability at 50 kPa (the corresponding ignition limit flight altitude increased from 0.9 km above sea level to 5.4 km). Gaussian simulations show the thermodynamic feasibility of FRRC and prove the relay effect. According to kinetic analysis, the combustion reactions can be adjusted based on FRRC and exhibit three types of oxidation reactions, of which the reaction activation energies are all lower than those of the oxidation reactions of pure fuel. Furthermore, the results of in-situ Fourier transform infrared spectroscopy are consistent with the kinetic analysis based on thermogravimetric and differential thermogravimetric studies. The investigation of the combustion control mechanism under extreme conditions helps to broaden the ignition limit of the aviation engine combustor and to significantly improve the accurate control level of ignition under extreme conditions, providing theoretical support for solving the ignition problems of advanced aviation engines under extreme conditions.

Liquid metals have been expected to be promising photothermal/electrothermal anti-icing materials for their excellent electrical and thermal conductivity. However, inescapable oxidation and corrosion limit the life and efficiency of liquid metal materials. Inspired by the self-assembly of phospholipid molecules in cell membranes, self-assembly corrosion resistant liquid metal composite coating is designed to protect liquid metal from icing and corrosion hazards. Based on self-assembly of fluor‑silicon molecules mimicking phospholipid molecules and micro-nano surface morphology, the coating has water contact angle of 150.8°and icing delay time of 497 s, which is 4.21 times that of unmodified liquid metal. Under the combined action of 80.5 °C photothermal effect and superhydrophobicity, the de-icing efficiency of the coating is 2.04 times that of the unmodified liquid metal. The photothermal de-icing efficiency remains 99.3 % after two months of acid corrosion and 94.4 % after two months of alkali corrosion. In addition, the thermal network of the coating leads to thermal conductivity of 3.66 W/mK and flame retardancy with UL94 at V0 rating. The coating is made into an electrothermal device with 52.5 °C heating temperature and rapidly de-icing property. The cell membrane-inspired self-assembly liquid metal composite coating provides a secure solution for long-term photothermal/electrothermal anti-icing/de-icing in exposed environment.