The electric field can cause changes in the morphological characteristics of droplets by altering the internal flow and accelerating the heat transfer between the droplets and the hot spots. In this paper, a mathematical model of the oscillation process of a droplet under the action of an alternating electric field was constructed, and the effects of the electric field frequency, voltage magnitude and voltage waveform on the droplet oscillation characteristics were investigated. Based on the characteristics of droplet oscillation, the evaporation characteristics of droplets on electrowetting-on-dielectric surfaces were investigated from the perspectives of internal flow and temperature field. The results show that under the action of alternating current, the surface pressure of the droplet rapidly increases to its maximum and then exhibits resonant oscillation. Vortices appear at the gasliquid interface, and the number of vortices corresponds to the electric field frequency. When the voltage frequency increases from 50 Hz to 500 Hz, the amplitude of the oscillation waveform of the droplet wetting radius decreases from 0.036 mm to 0.002 mm. Due to the vortex flow generated inside the droplet under the influence of the electric field, the fluid near the heat source flows toward the droplet apex, while the cold fluid at the top flows to the side close to the heated substrate region for heat exchange. This process repeats cyclically, thereby improving the heat transfer efficiency. The maximum evaporation volume of the droplets increases by 42%. Under the same oscillation mode, the closer the frequency of the electric field is to the resonance frequency, the faster the heat transfer between the droplet and the hot spot.

A novel BDTN-SVTOL with dagger-shaped deflection component, featuring simplified structural design for efficient cruise and short/vertical takeoff and landing (SVTOL) thrust vectoring (TV) with a single nozzle system, is developed, numerically simulated, and experimentally evaluated to investigate the thrust characteristics. The dagger-shaped deflection component serves as the critical flow-control element for BDTN-SVTOL, enabling mainstream large deflection exceeding 90 degrees A parametric optimization framework was established for the deflection surface of dagger-shaped deflection component, quantifying the relationship between critical geometric parameters and thrust characteristics while maximizing angular coverage. A decoupled methodology for profile optimization is proposed guided by the distinct near-wall flow characteristics, and the optimized configuration achieves a TV angle greater than 95 degrees while maintaining a vertical thrust coefficient (cfy) above 0.90 across all operating conditions, matching the SVTOL performance of Three-Bearing Swivel Nozzle (3BSN) while integrating multi-directional deflection capability and simpler mechanical architecture. The experimental model demonstrates dual-mode operational capabilities in wind tunnel tests, capturing nozzle internal flow field schlieren morphology while validating CFD simulation accuracy. In normal flight mode, the nozzle achieves a thrust vector angle exceeding 15 degrees which can enhance high maneuverability. In SVTOL mode, compared to the conventional BDTN with crescent-shaped deflectors exhibiting TV angles of 60 degrees and cfy of 0.7, the nozzle with dagger-shaped deflector demonstrates enhanced performance through more stable single-channel design, achieving TV angles exceeding 90 degrees and thrust coefficients over 0.90, thereby overcoming limitations in angular deflection efficiency and the energy dissipation.

To enhance the safety of helicopter air-to-air refueling, a free-wake model incorporating rotor-wing aerodynamic coupling effects was developed for the specific operational conditions of this scenario. Investigation into the influence of rotor-wing interference on rotor aerodynamic characteristics is conducted.The research results demonstrate that the proposed coupled free-wake model effectively meets the analytical requirements for rotor and wing aerodynamic characteristics during air-to-air refueling. The induced velocity, control inputs, wake structure, and drag of the rotor were analyzed under varying relative azimuthal orientations between the rotor and wing. The vertical azimuthal variation significantly influences rotor aerodynamic performance, with the maximum upwash shifting from approximately 90° to 140° azimuth. Meanwhile, lateral azimuthal changes exhibit the most pro-nounced impact on the rotor disk’s aerodynamic characteristics, leading to substantial variations in induced velocity, control inputs, and drag. Furthermore, when the wingtip vortex is positioned above the retreating side of the rotor, the drag on the retreating blade increases markedly. In the blade root region at an azimuth angle of 270°, a local surge in drag is observed. At approximately 80% of the blade radius, between azimuth angles of 240° and 270°, a pronounced local increase in drag is evident.

Aerodynamic modeling of tiltrotor aircraft is inherently limited by incomplete aerofoil data for blades constructed from multiple aerofoil sections. This data deficiency leads fundamental errors into the blade element theory (BET) inputs, resulting in inaccurate induced velocity and unsteady load predictions that compromise flight control design. To overcome this limitation, a corrective induced inflow factor k is introduced into an augmented Pitt-Peters dynamic inflow model. For fixed tilt angles, k is efficiently identified via an optimisation framework. The fmincon algorithm attains the optimal k with a computational speed 5-6 times faster than the genetic algorithm, while maintaining thrust coefficient errors within 1.26%. For continuous tilting, a direction-aware, time-varying quadratic model for k(t) is proposed, which uses the Fr & eacute;chet distance metric to accurately reconstruct the aerodynamic hysteresis loop and eliminate spurious load predictions during rotation reversal. Validated through wind tunnel tests, the framework reduces the maximum thrust prediction error in dynamic tilting from 34.10 to 10.70%. The corrected aerodynamic model supports real-time simulation and provides a reliable foundation for advanced tiltrotor control system design.

Aero-assisted orbital transfer vehicle (AOTV) offers significant potential for reducing propellant consumption in space missions by exploiting aerodynamic forces to perform orbital maneuvers. However, atmospheric flight introduces tightly coupled multidisciplinary challenges—including aerodynamics, aerothermodynamics, stability, and structural protection—that complicate the conceptual design process. In this paper, an innovative wing-body configuration is proposed based on the prescribed aero-assisted orbital transfer mission scenario, together with a comprehensive multidisciplinary analysis framework integrating aerodynamics, aerothermodynamics, stability, thermal protection, and structural mass. To address the strong interdependencies among these disciplines, a surrogate-model-based multidisciplinary design optimization (MDO) approach is employed. The optimized configuration exhibits consistent design trends, with improvements in aerodynamic, aerothermal, and mass-related responses, and provides larger operational margins and robustness within the fixed orbital transfer mission profile. This study highlights the capability of MDO at the conceptual design stage to enhance mission robustness and system viability, and it provides a systematic methodology for the configuration development of advanced orbital transfer vehicles.

The current helicopters still endure high vibration due to the alternating aerodynamic loads, causing component fatigue and passenger discomfort. However, the capability of traditional passive control is limited by the narrow operating frequency bandwidth and large additional component weight. The active twist rotor technology based on macrofiber piezoelectric composites offers a potential solution for reducing rotor vibratory loads. To explore the mechanism of loads reduction via active twist and analyze the effects of related input parameters on the control capability, a novel comprehensive dynamics analysis model for multilayer anisotropic composite material blades integrated with active materials is developed. This model accounts for the coupling effect of force and electric fields through modifying the section force-strain constitutive equation. The control effects of different piezoelectric fiber ply orientation angles with (Nb 1)P, NbP and (Nb + 1)P inputs on NbP hub vibratory loads are first systematically quantified. The results show that the (Nb 1)P voltage has the best control capability on the NbP hub rolling and pitching vibratory loads, achieving reductions exceeding 92.07%. Meanwhile, the NbP voltage has the best control capability on the NbP hub vertical and yawing vibratory loads, achieving reductions exceeding 95.34%. The reductions in the NbP hub vertical and yawing vibratory loads result from the decrease in the NbP blade lift and drag amplitudes. The reductions in the NbP hub rolling and pitching vibratory loads are primarily from the decrease in the (Nb 1)P aerodynamic amplitudes. Nevertheless, the (Nb + 1)P blade lift may increase or decrease, depending on the harmonic order of the control input. The hierarchical attenuation patterns in aerodynamics amplitude modifications under active twist inputs are analyzed in detail, and the control capabilities of the (Nb 1)P, NbP and (Nb + 1)P inputs on the NbP hub vibratory loads are quantitatively evaluated using the Spearman's rank correlation coefficient for the first time. (c) 2026 The Author(s). Published by Elsevier Ltd on behalf of Chinese Society of Aeronautics and Astronautics. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/ licenses/by-nc-nd/4.0/).

As a periodic excitation device capable of generating oscillating jets without moving parts, fluidic oscillators (FOs) have been widely used in flow control, heat transfer enhancement, and other fields, and have shown great application potential in engineering fields such as food drying and industrial cleaning. However, due to the limitations of practical piping connections and installation space, a circular-to-rectangular inlet transition structure is often required at the inlet of the FO, which increases the risk of internal flow instability. In this study, we employed the unsteady Reynolds-averaged Navier-Stokes (URANS) method to investigate the effects of restricted-inlet conditions on the internal flow characteristics of the FO and its oscillation stability under thicknesses of H = 5-25 mm and inlet-outlet pressure differences of Delta P = 10-700 kPa. The influence of the inlet-restricted structure was quantitatively evaluated by comparison with an unrestricted-inlet fluidic oscillator (UIFO). The results showed that the separation vortices and low-pressure regions in the mixing chamber of the inlet-restricted fluidic oscillator (IRFO) were key to maintaining the oscillating jet. As the thickness H increased, the oscillation performance of the IRFO decreased significantly, and the influence of the inlet-restricted structure on the oscillation performance became more pronounced. Under Delta P = 10 kPa, when H = 15 mm, the oscillation frequency and outlet sweeping angle of the IRFO decreased to 30.5 Hz and 72 degrees, respectively, which were approximately 63.3% and 25.0% lower than those of the UIFO. When the thickness increased to H >= 18 mm, oscillation failure occurred in the IRFO, and no regular dominant frequency could be identified. Increasing Delta P could restore regular oscillation within a certain range, but it became difficult to recover when H >= 20 mm. For the geometry investigated in this study, 1 <= H/D <= 3.4 can be used as a safe reference range to avoid oscillation failure. These findings deepen the understanding of the flow characteristics and oscillation stability of FOs under restricted-inlet conditions and provide a basis for structural design and reliable application under practical engineering constraints.

The development trend of future combat aircraft capabilities represented by airplanes is wide speed range, high stealth ability, high maneuverability, and high energy. The integration of aircraft and engine is a key technology and development trend for future fighter aircraft. It could prevent a situation where “a suitable engine” is installed on “a suitable aircraft,” yet it forms an “unsuitable system.” Aircraft-engine integration is a critical technology and development trend for future fighter aircraft, with its core lying in the integration of aircraft-engine, structure and control. High-speed aircraft afterbodies generate extensive expansion waves/shock waves, leading to shock wave-boundary layer interactions, flow separation, and other complex flow phenomena, which increase the afterbody drag. The Bypass Dual Throat Nozzle (BDTN) constitutes a category of Fluidic Thrust Vectoring Nozzle (FTVN) characterized by fixed geometry. In contrast to conventional fluidic vectoring nozzles, the BDTN employs internal bypass flow to interact with the primary stream, enabling self-adaptive flow control. Symmetric micro holes incorporated within the convergent section of the cavity leverage the pressure gradient between the high-pressure recirculation zone inside the cavity and the low-pressure region near the wall. This differential pressure induces micro-jet formation. These jets effectively compensate for the low-pressure zone and also act as miniature thrust nozzles, contributing additional thrust. Under typical operating conditions, compared to the baseline configuration: The single-hole jet BDTN reduces pressure drag by up to 60.99% and the drag-thrust ratio by up to 43%. The double-hole jet BDTN reduces pressure drag by up to 74% and the drag-thrust ratio by up to 53%.

Thermoelectric power generation (TEG) technology can be used to recover high-temperature waste heat generated during the operation of rotary kilns. However, the TEG device cannot be directly attached to the kiln's surface because of the rotary kiln's constant spinning and the use of water-cooled cooling. There is a lack of research on the reasonable distance and angle range between the TEG device and the kiln surface. This paper uses experimental methods to conduct a systematic study on the distance and angle parameters. The design concept of equal heat flux density is creatively offered based on the rotary kiln waste heat distribution features. The parametric experiments illustrate how the minimum distance and angle between the TEG device and the heat source affects the device's hot end temperature and output voltage. The results show that the hot end temperature of the TEG device can be stably maintained above 220 degrees C, the temperature difference between the hot and cold ends reaches above 200 degrees C, and the output voltage reaches above 3.7 V when the minimum distance is 1-5 mm and the angle is 0-5 degrees. The research result fills the research blank of reasonable control range of distance and angle between the TEG device and heat source, which is of guiding significance in the parameters of utilizing TEG technology to recover industrial waste heat and how to install TEG system. It has important engineering application value for promoting energy saving and emission reduction, reducing emissions from high energy-consuming industries and realizing the goal of "double carbon".

The bypass dual-throat nozzle (BDTN) demonstrates exceptional vectoring performance through the modulation of secondary flow rates. This paper explores the effect of structural variations in the nozzle's rear body, particularly the angle and extended length of its lower wall. The objective is to enhance the concealment of the jet's infrared signature, thereby bolstering the aircraft's stealth capabilities. A parametric investigation, utilizing numerical simulations and experiments, is conducted to analyze the thrust coefficient, vectoring angle, flow coefficient, total pressure recovery, and flow structures. Results indicate that extending the lower wall of the BDTN nozzle has a minimal performance effect in a thrust vectoring condition of pitching-up but poses flow control challenges in a pitch-down state. When the rear body angle exceeds 45°, the asymmetry's influence diminishes with increasing angle. Adjusting the nozzle's extension length can mitigate the asymmetric effects. Overall, modifying the BDTN's base configuration and extending the lower wall enhance stealth performance while minimally affecting thrust and vectoring capabilities.

To improve the flight performance of a compound helicopter, the parameter optimization method based on the adaptive genetic algorithm is used. The flight performance model consists of a rotor model, a propeller model, a wing model, a vertical tail model and a horizontal tail model. The importance of the flight state is represented as weight factor in the objective function. Three different cases are analyzed, which highlight the performance at hover, medium-speed or high speed. The helicopter powers decrease by 34.3

In this paper, we examined the dynamic behaviors of unidirectional (UD) SiC f ${\rm SiC}_{\mathrm{f}}$ /PyC/SiC composites, fabricated via chemical vapor infiltration (CVI), under various loading conditions. These conditions included tension, compression, and shear, applied in both the longitudinal and transverse directions of the composites. To achieve the desired failure patterns, we designed specific specimens and clamping methods. The tests were conducted using a hydraulic servo testing machine and Kolsky tension and compression bar systems to achieve different loading rates. Post-test specimens' typical microstructural characteristics, such as matrix cracks, fiber breakages, and fracture angles, were observed using optical and scanning electron microscopy (SEM). By combining these characteristics with the mechanical responses, we investigated the damage mechanisms and effects of strain rate. Finally, based on the experimental results, we discussed precautions for ceramic matrix composites (CMCs) during manufacturing and service processes.

In this paper, a novel tip clearance control structure, the tip control hole (TCH), is proposed, which is appropriate for the radial turbines with the characteristics of low manufacturing cost, thin blade, insufficient tip space and insufficient strength of winglets. Under the original conditions, when the tip clearance height is 2% of the outlet blade height, the effect from the position and number of holes on the overall turbine performance is discussed, and the physical mechanism of efficiency improvement is analyzed. It is found that the optimal scheme of single hole and multiple-hole structures increase the total-total efficiency by 0.173% and 0.198%, with the relevant the tip leakage decreased by 0.812% and 1.058%. The results show that the closer the holes are to the upstream of the impeller, the better the optimization effect is compared with the original turbine. The main optimization mechanism of leakage control is to restrain the tip leakage vortex. The control hole decreased the scale of the vortex, makes the position of the vortex close to the suction surface. In the optimal scheme, the tip control hole reduced the pressure difference between the suction surface and the pressure surface, suppressed the leakage, and plays an auxiliary role in improving the efficiency.

In this paper, we examined the dynamic behaviors of unidirectional (UD) SiCf/PyC/SiC composites, fabricated via chemical vapor infiltration (CVI), under various loading conditions. These conditions included tension, compression, and shear, applied in both the longitudinal and transverse directions of the composites. To achieve the desired failure patterns, we designed specific specimens and clamping methods. The tests were conducted using a hydraulic servo testing machine and Kolsky tension and compression bar systems to achieve different loading rates. Post-test specimens' typical microstructural characteristics, such as matrix cracks, fiber breakages, and fracture angles, were observed using optical and scanning electron microscopy (SEM). By combining these characteristics with the mechanical responses, we investigated the damage mechanisms and effects of strain rate. Finally, based on the experimental results, we discussed precautions for ceramic matrix composites (CMCs) during manufacturing and service processes.

Dynamic tensile experiments of unidirectional (UD) SiCf/PyC/SiC composites and SiC fiber bundles were performed using a Kolsky tension bar test system. Typical failure characteristics of UD ceramic matrix composites (CMCs), including matrix crack spacing, fiber pull-outs, matrix fracture surfaces and fiber fracture surfaces, were observed through optical and scanning electron microscopes. By combining micro-damage characteristics with mechanical behavior, we analyzed the dynamic damage mechanisms of UD-CMCs. Based on the test results, the dynamic loading effects on micro-mechanical parameters and their subsequent impact on the macro composite were determined. Finally, with these validated micro-parameters, we developed a rate-dependent constitutive model for UD-CMCs.

Photovoltaic/thermal (PV/T) technology and humidification-dehumidification (HDH) seawater desalination systems have attracted attention for their respective advantages, but the intermittent nature of solar irradiation restricts their continuous and stable operation. To address this, a solar-powered humidification-dehumidification system with dual thermal-mass coupling and integrated thermal storage is proposed in this study. Unlike previous studies that focused on optimizing a single performance indicator, this work employs a performance optimization framework to achieve a more practical and balanced operational strategy for system performance and economic efficiency. The optimization process integrates neural network fitting and a genetic algorithm to determine optimal system design parameters. Results indicate that the unit water production cost decreases with increasing gained-output-ratio, reaching a minimum of 324 $/m3 at a top temperature of 65 degrees C and a gainedoutput-ratio of 1.546, before rising again due to higher system costs. To validate the optimization, the optimal design parameters obtained at a top temperature of 65 degrees C and a liquid-to-gas ratio of 2.941 were compared with numerical simulation results. The relative errors for gained-output-ratio and unit cost were only 0.906 % and 0.308 %, respectively, confirming the reliability of the optimization outcomes.

To enhance the thermal performance of pre-charge resistors, the concept of the equivalent specific heat capacity (ESHC) is proposed in this study to evaluate the thermal energy storage characteristics of multiple optimization schemes under short-circuit conditions. Building upon the optimal configuration, a multi-objective optimization framework integrating response surface methodology (RSM) and the nondominated sorting genetic algorithm-II (NSGA-II) is implemented to simultaneously optimize the structural parameters and operational parameters. The results highlight the effectiveness of optimizing both the structural and the operational parameters of the resistor, resulting in marked improvements in its thermal performance. Specifically, the optimized designs achieved a reduction in the average temperature of the resistance core by 12.42% and 7.90% for optimized Models A and B, respectively, underscoring the efficiency of the proposed approach. Moreover, the short-circuit endurance time decreased by 7.64% for Model A but significantly increased by 54.72% for Model B. This study provides valuable theoretical insights and actionable guidance for engineers engaged in the development and optimization of precharge resistors in electric vehicles.

Amidst the global energy crisis and progress in clean energy, this study aims to reduce design costs and improve the adaptability of turbines in small ORC systems. It seeks to offer enhanced renewable energy utilization methods for sustainable development. This paper focuses on the performance of an impulse single-stage turbine with partial admission and analyzes it through numerical simulations using computational fluid dynamics (CFD). The study investigates critical parameters under design and off-design conditions by varying inlet total pressure and rotor speed. The results indicate that the turbine’s isentropic efficiency and power output at design conditions are 64% and 4.78 kW, respectively. The power output ranges from 4.65 kW to 6.81 kW, and the isentropic efficiency ranges from 57% to 62% under off-design conditions. Both experimental and simulation results show good agreement. Furthermore, the velocity triangles under these conditions conform to those of a pure impulse turbine. These findings demonstrate that the turbine could adapt to different conditions and facilitate the design of ORC systems.

Piecewise dynamic twist of rotor blades is studied as a method for reducing rotor power and improving rotor performance. A validated helicopter model is used to predict the rotor power at different flight states. The effects of the parameters of the piecewise dynamic twist, including the phase angle, amplitude, harmonic number, and location, on the rotor performance are investigated. The inboard blade locations with the 1/rev dynamic twist are the most efficient parts to reduce the rotor power at low advance ratios, and the outboard locations are better for high advance ratios. A 2/rev dynamic twist usually can save more power at high advance ratios. Larger twist actuation leads to larger rotor power reduction, while the actuation with fewer actuated piezoelectric patches is more efficient. The dynamic twist with six pairs of the actuated patches is appropriate which can balance the efficiency and power savings. By deploying a piecewise dynamic twist containing the 1/rev and 2/rev twists at the spanwise locations of 10%-40% and 60%-90% of the blade, the rotor power can be significantly reduced and the performance is improved, especially at high advance ratios. A power reduction of 9.0% can be obtained at an advance ratio of 0.375.

To achieve superior energy efficiency and temperature uniformity in cooling system for energy storage batteries, this paper proposes a novel indirect liquid-cooling system based on mechanical vapor recompression falling film evaporation (MVR-FFE-ILCS). Simulation model for MVR module and FFE module are developed, based on which thermodynamic performance and temperature uniformity are evaluated against conventional cooling schemes. The results of MVR module indicate that the novel system offers substantial energy savings, with up to 76.7 % efficiency gains over the reference air conditioning cooling system. Coefficient of performance (COP) and specific cooling capacity reach to 14.1 and 2438.7 kJ/kg, respectively. Higher cooling temperature and lower compression temperature rise can reduce the system's energy consumption. FFE module's findings reveal that the proposed structure outperforms the conventional non-phase-change liquid cooling plate in temperature uniformity, achieving a maximum temperature of 37.20 degrees C (a 7.0 % decrease) and an average maximum temperature difference of 2.53 degrees C (a 15.3 % reduction). Higher cooling water flow velocity and lower cooling temperature are beneficial for the temperature uniformity of battery pack, with a cooling temperature controlled below 35 degrees C. The integrated analysis confirms the superior performance of the MVR-FFE-ILCS, presenting the potential of the novel system for practical application in energy storage.