Different configurations, same performance: A new equivalent criterion for distributed ducted propellers
Peer-Reviewed Publication
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A research team at Beihang University, led by Professor Jianghao Wu, has achieved a significant breakthrough in the design of propulsion systems for future low-altitude transport, particularly electric Vertical Take-Off and Landing (eVTOL) aircraft. Their pioneering work, recently published in the Chinese Journal of Aeronautics, introduces a novel analytical framework for ducted propellers, promising to make these advanced flying vehicles smaller, lighter, and more powerful. This research offers vital support for the burgeoning field of advanced air mobility, aiming to alleviate urban traffic congestion and utilize low-altitude airspace.
In the history of aircraft development, maneuverability has always been an important consideration in the design concept of aircraft. The requirements for aerodynamic characteristics are reflected in high lift-to-drag ratio, high lift coefficient, torque stability and so on. The occurrence of dynamic stall will lead to a sharp drop in lift and a rapid rise in drag, resulting in torque oscillation, which seriously restricts the improvement of aircraft performance, and even leads to aircraft crash in severe cases. The traditional passive flow control cannot cope with the real-time and changeable flow field environment, and the emergence of jet control provides a new way to solve the problem of dynamic stall. Although the research of single jet technology has been relatively sufficient, there are few comparative studies on steady jet and synthetic jet, and there is also a lack of related research on dual synthetic jets. Therefore, it is imperative to fill this research gap.
Operating drones across air and water boundaries poses serious aerodynamic risks due to complex gas-liquid flow interactions. A new finite vortex rotor model developed by researchers in China provides unprecedented insight into how rotors behave near free water surface. The study introduces a predictive boundary that separates safe and unsafe flight zones, offering a powerful tool for the design and control of aerial-aquatic rotorcraft.
A research team from York University in Canada has proposed a revolutionary Dyson-Harrop CubeSat design, capable of harvesting high-density energy from the solar wind using the photoelectric effect. This compact and lightweight system delivers much greater power density than conventional photovoltaic technologies, opening up new possibilities for clean and sustainable space energy applications.
To reduce the vibration of the coaxial helicopter main transmission system considering both level and vertical flight conditions, a vibration evaluation and optimization model was built. A vibration simulation model and a vibration evaluation method was established. A hybrid Gravitational Search Algorithm-Simulated Annealing (GSA-SA) algorithm was combined to balance convergence speed and searching accuracy. The principle test was conducted to prove the accuracy of theoretical method. The optional results show that the vibration of the optimized transmission system decreases significantly, in which the maximum reduction of key vibration indicators reaches more than 20%. The proposed method could be extended to other fields.
Aero-engine hot-end components face grinding challenges due to superalloys' low thermal conductivity, causing high heat, energy consumption, and reliance on unsustainable cooling. Ultrasonic vibration-assisted grinding (UVAG), heat pipe grinding wheels (HPGW), and minimum quantity lubrication (MQL) have been proposed to integrate to reduce heat generation, enhance heat dissipation, and minimize coolant use. In this case, the high-efficiency and sustainable grinding can be achieved with improved surface integrity.
A novel Y4Al2O9/Y2O3 composite exhibits substantial resistance to CMAS infiltration at both temperatures at 1300 ℃ and 1500 ℃, without notable grain-boundary penetration by CMAS glass. More importantly, the incorporation of reaction active compositions in the composite accelerated the consumption of molten CMAS constituents and reduced its corrosive activity, which is recognized as the crucial principle for composition design of anti-CMAS materials. This work provides valuable insights that guide the design of composition and advancement of superior CMAS-resistant materials.
Hypersonic vehicles face critical aerodynamic heating during flight, demanding advanced thermal protection systems (TPS). A team of Chinese researchers has developed a novel carbon-bonded carbon fiber (CBCF) composite modified with SiBCN ceramics (CBCF/SiBCN), enabling efficient in-plane heat dissipation while maintaining thermal insulation. The composite exhibits exceptional anisotropic thermal properties and mechanical strength, addressing long-standing limitations in traditional CBCF materials for aerospace TPS.
The combustion chamber temperature of the new generation aircraft engines can reach an ultra-high temperature of 1800 °C, making temperature monitoring of key components crucial. Thin-film thermocouples (TFTCs) are highly sensitive and have rapid response time; however, their upper temperature limit remains below 1800 °C. This study proposes an ultra-high temperature film thermocouple, enhanced by yttria-stabilized zirconia (YSZ) for positive film, indium oxide (In2O3) for negative film, aluminium oxide (Al2O3) for protect film. The thermocouple is designed based on temperature measurement principles, First-principles, and simulations, and it is manufactured via screen-printing. The results indicate that the maximum working temperature is 1850 ℃. In experiments with different doping ratios at 1800 ℃, the thermocouple achieves a maximum temperature electromotive force (TEMF) of 258.5 mV and a maximum Seebeck coefficient of 180.9 μV/°C, with an In2O3:YSZ92(ZrO2:Y2O3 = 92:8 wt%) ratio of 9:1 wt%. Using the lumped heat capacity method, the response time is measured at 2.8 ms, demonstrating good dynamic response characteristics. The film thermocouple is successfully utilized to measure the gas temperature of 1090 °C at the outlet of air turbine rocket engine, confirming its high-temperature operational capability. To improve the repeatability of the TFTCs without affecting their thermoelectric outputs, a CNN-LSTM-attention neural network is implemented to mitigate repeatability errors, achieving a high repeatability of 99.53%. Additionally, the compensated temperature data are compared with those obtained from a standard B-type thermocouple, showing a full-scale error of ±0.73% FS. This study provides a feasible solution for ultra-high temperature measurements.
To tackle the shortcomings of conventional nano-YSZ thermal-barrier coatings—infrared semitransparency, low nanoparticle retention, and the formation of partially melted agglomerates during plasma spraying—researchers have encased each YSZ nanoparticle in a sacrificial carbon shell that protects it from melting throughout the deposition process. Once burned off, the film leaves nano-pores that, together with the preserved nanoparticles, greatly boost infrared scattering and lower simulated metal temperatures by 111.2 K—offering a scalable route to thermal-barrier coatings with superior radiation blocking and long-term high-temperature stability.