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2024 CSAA/IET International Conference on aircraft Utility Systems, AUS 2024

作者： Liu, Zhen Li, Yanjun Wang, Siying Li, Haowen Key Laboratory of Aircraft Environment Control and Life Support Ministry of Industry and Information Technology Nanjing University of Aeronautics & Astronautics Nanjing China

The aircraft cabin is special confined space with various overloads during motion, whose effect on fires is not clear yet. To understand the fire behaviours at different overloads in cabin atmosphere, numerical simulation was performed on upward flame spread over thin solids by solving the governing equations of both gas and solid phase. The main parameter is the overloads and Og to 2g was considered. At most overloads, the flame accelerates and grows continuously before extinction while at Og, flame propagates only with imposed flow. The transient flame positions and spread rates was compared against the overloads and mathematical correlations were proposed. To further understand the effect of overloads on fire behaviours, the local flow speed, solid temperature and heat flux were studied in detail. With the increase of the overloads, the induced flow due to buoyancy increased significantly, which enhanced the oxygen transfer to the flame and heat transfer to the solids. As a consequence, both the gaseous reaction and solid pyrolysis was stimulated, which resulted in longer flame and faster spread rate. The results in this paper revealed that fire safety concern is more serious at high overloads and can contribute to the fire protection design in aircrafts. © The Institution of Engineering & Technology 2024.

关键词： Fire extinguishers

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Numerical simulation of dynamic characteristics of exhalation valve of aviation oxygen mask

Numerical simulation of dynamic characteristics of exhalatio...

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CSAA/IET International Conference on aircraft Utility Systems 2020, AUS 2020

作者： Lu, Shengfang Chen, Weijian Wang, Ning Ma, Yifan Cheng, Qian Key Laboratory of Aircraft Environment Control and Life Support Ministry of Industry and Informa tion Technology Nanjing University of Aeronautics and Astronautics Nanjing China

ISBN: (纸本)9781839535635

In this paper, taking the expiratory valve of the air supply mask as the research object, combined with the knowledge of aviation physiology, using fluent dynamic grid and UDF technology, the dynamic performance of the expiratory valve under the condition of small flow on the ground is studied, and the influencing factors of the flow resistance of the expiratory valve are analyzed. The correctness of the numerical method is verified by comparing the calculated results with the experimental results. © 2020 Institution of Engineering and Technology. All rights reserved.

关键词： Numerical methods

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EXPERIMENTAL STUDY ON HEAT DISSIPATION PERFORMANCE OF aircraft MOTOR BASED ON VAPOR CHAMBER

EXPERIMENTAL STUDY ON HEAT DISSIPATION PERFORMANCE OF AIRCRA...

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2024 CSAA/IET International Conference on aircraft Utility Systems, AUS 2024

作者： Rao, Xuewei Liu, Shuting Ma, Hui Zhang, Penglei Key Laboratory of Aircraft Environment Control and Life Support MIIT Nanjing University of Aeronautics and Astronautics Nanjing210016 China AVIC Nanjing Engineering Institute of Aircraft System China

An integrated radiator made of vapor chamber (VC) and fins for aircraft motor heat dissipation is proposed and developed, which exhibits superior performance in terms of heat dissipation and temperature equalization. A comparative analysis was conducted to estimate the thermal performance of the VC radiator against the traditional aluminum plate (AP) radiator under various flight conditions. The results demonstrate a significant enhancement in heat transfer and temperature equalization capabilities when utilizing the VC radiator compared to the conventional AP radiator. The maximum temperature of the heat source is effectively kept below 90oC by VC radiator during flat flight, take-off and landing, as well as extreme conditions, which is able to satisfy the aircraft motor's requirements of heat dissipation. © The Institution of Engineering & Technology 2024.

关键词： Radiators

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Theoretical study of ullage washing with mixed inert gas in a non-equilibrium state

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Chinese Journal of Aeronautics 2020年第12期33卷 3167-3175页

作者： Shiyu FENG Xiaotian PENG Lei SHAO Yan YAN Chen CHEN Weihua LIU Key Laboratory of Aircraft Environment Control and Life Support of MIIT College of Aerospace EngineeringNanjing University of Aeronautics and AstronauticsNanjing 210016China College of Aeronautics Chongqing Jiaotong UniversityChongqing 400074China College of Mechanical and Electrical Engineering Xi'an Polytechnic UniversityXi'an 710000China

The Mixed Inert Gas(MIG)produced by the novel Green On Board Inerting Gas Generation System(GOBIGGS)mainly consists of carbon dioxide,nitrogen and *** of the large solubility of carbon dioxide in jet fuel compared with nitrogen,the no gas release or equilibrium model could not be employed any *** this paper,first,a mathematical model of the ullage washing was set up to predict the variation of the oxygen concentration on ullage and in the fuel,and the gas evolution and dissolution rate were calculated by Fick's second ***,an experimental apparatus was constructed to verify the accuracy of the ***,the numerical comparisons of ullage washing using Nitrogen Enriched Air(NEA)and MIG are presented under various flow rates and fuel loads,and the result reveals that the variation of the oxygen concentration on ullage is nearly identical whatever the inert gas is NEA or ***,the variation of the oxygen concentration in the fuel is disparate,and the oxygen concentration decreases rapidly if the inert gas is MIG,especially when the fuel load is low or the flow rate of the inert gas is ***,MIG could suppress the rising trend of the oxygen concentration on ullage when the aircraft ascends if the fuel tank is fully washed into an equilibrium state on ground.

关键词： Inert gas Mixed inert gas Nitrogen enriched air Non-equilibrium Washing

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PERFORMANCE ANALYSIS AND IMPROVEMENT OF TURBINE-POWERED AIR CYCLE SYSTEM

PERFORMANCE ANALYSIS AND IMPROVEMENT OF TURBINE-POWERED AIR ...

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2024 CSAA/IET International Conference on aircraft Utility Systems, AUS 2024

作者： Li, Kaining Wu, Yan Lu, Qihang Zhang, Dalin Key Laboratory of Aircraft Environment Control and Life Support Ministry of Industry and Information Technology Nanjing University of Aeronautics and Astronautics Nanjing China Nanjing Engineering Institute of Aircraft Systems Nanjing China

In order to reduce the engine bleed air consumption of fighter jet environmental control systems with high-power electronic equipment compartments, a comparative analysis was conducted on the typical turbine-powered closed cycle systems TP-ACS/HPWS and PTMS-ACS/HPWS. On this basis, improvements were made to PTMS-ACS/HPWS, and the TP-CACS architecture was proposed. The influence of flight conditions, electronic cabin heat load, and other parameters on the engine bleed air consumption of the three systems was analysed through modelling and calculation. The calculation results show that by adjusting the operating pressure and flight altitude, PTMS-ACS/HPWS generally consumes less engine bleed air than TP-ACS/HPWS, and its operation adjustment is more convenient;on this basis, a turbine-powered closed air cycle system TP-CACS with independent regulation of cabin air supply is proposed, and under different electronic cabin thermal loads and flight conditions, the TP-CACS engine has the lowest bleed airflow consumption and the best performance;one of the development directions for future environmental control systems is to combine closed loop systems with independent cabin air supply. © The Institution of Engineering & Technology 2024.

关键词： CLOSED AIR CYCLE SYSTEM ELECTRONIC EQUIPMENT COOLING PERFORMANCE ANALYSIS POWER TURBINE

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Numerical investigation of influence of structure and operating parameters on performance of vortex oil filter

Numerical investigation of influence of structure and operat...

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CSAA/IET International Conference on aircraft Utility Systems, AUS 2018

作者： Wang, Ning Chen, Weijian Ning, Guoli Hui, Ma Key Laboratory of Aircraft Environment Control and Life Support MIIT Nanjing University of Aeronautics and Astronautics Nanjing China Aviation Key Laboratory of Science and Technology on Aero Electromechanical System Integration Nanjing China

ISBN: (纸本)9781785617911

In this paper, the three-dimensional numerical simulation of solid-liquid two-phase flow in a vortex oil filter is performed by means of numerical simulation. The Reynolds stress turbulence model is used in the simulation flow field, and the DPM model is used for solid particle tracking. The influence of key structural parameters and operating parameters on the filtering effect was mainly studied, such as the inlet width, the size of the overflow pipe, the wall thickness and the insertion depth, the size of the cone angle and the length of the cone end. The results provide the basis for the rational design of the vortex oil filter. © 2018 IET Conference Publications. All rights reserved.

关键词： Vortex flow

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Oxygen concentration variation in ullage influenced by dissolved oxygen evolution

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Chinese Journal of Aeronautics 2020年第7期33卷 1919-1928页

作者： Shiyu FENG Chaoyue LI Xiaotian PENG Tao WEN Yan YAN Rongjie JIANG Weihua LIU Key Laboratory of Aircraft Environment Control and Life Support of MIIT College of Aerospace EngineeringNanjing University of Aeronautics and AstronauticsNanjing 210016China Department of Building Services Engineering Hong Kong Polytechnic UniversityHong KongChina College of Mechanical and Electrical Engineering Xi'an Polytechnic UniversityXi'an 710000China

To determine the oxygen concentration variation in ullage that results from dissolved oxygen evolution in an inert aircraft fuel tank,the CFD method with a mass transfer source is applied in the present *** experimental system is also designed to evaluate the accuracy of the CFD *** dissolved oxygen evolution is simulated under different conditions of fuel load and initial oxygen concentration in ullage of an inert fuel tank with stimulations of heating and pressure *** increase in the oxygen concentration in ullage ranges from 0.82%to 5.92%upon stimulation of heating and from 0.735%to 12.36%upon stimulation of a pressure decrease for an inert ullage in the *** heating accelerates the release of the dissolved oxygen from the fuel by increasing the mass transfer rate in the mass transfer source and decreasing the pressure,thereby accelerating the dissolved oxygen evolution by increasing the concentration difference between the gas and the *** time constant that represents the oxygen evolution rate is independent of the initial oxygen concentration in ullage of an inert tank but depends closely on the fuel load,temperature and *** time constant can be fitted using a polynomial equation relating the fuel load to temperature in the heating stimulation with an accuracy of 4.77%.Upon stimulation of a pressure decrease,the time constant can be expressed in terms of the fuel load and the pressure,with an accuracy of 5.02%.

关键词： Computational Fluid Dynamics(CFD) Dissolved oxygen evolution Mass transfer Stimulation Time constant Volume of fluid

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Numerical simulation of aircraft icing based on the szilder random-walk model

Numerical simulation of aircraft icing based on the szilder ...

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CSAA/IET International Conference on aircraft Utility Systems, AUS 2018

作者： Yu, Li Chen, Weijian Yu, Xiaoxiao Hao, Shen Key Laboratory of Aircraft Environment Control and Life Support Ministry of Industry and Information Technology Nanjing University of Aeronautics and Astronautics Nanjing China Shanghai Aircraft Airworthiness Certification Center of CAAC Shanghai China

ISBN: (纸本)9781785617911

Due to the fact that the traditional Messinger model cannot capture the microscopic characteristics of the ice surface well, in this paper, a random-icing model based on the behavior of individual fluid elements is established to simulate the shape and structural details of aircraft ice accretions. The random-icing model includes the ballistic part and the random-walk part. The relevant programs are written by this method, and the icing simulations on NACA 0012 airfoil under different conditions are also carried out. Finally, we compare the simulated ice shapes with the experimental values and the calculation results of CIRAMIL software based on the Messinger model. Although there are some discrepancies between experimental and predicted accretion shapes, the overall agreement is good. In particular, the ice shapes obtained by the random-icing model are rougher and their structural details are more obvious. Therefore, the random-icing model has advantages in predicting the aerodynamic characteristics of icing airfoils. © 2018 IET Conference Publications. All rights reserved.

关键词： Airfoils

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MOTION AND EVAPORATION CHARACTERISTICS OF WATER DROPLETS ON DIFFERENT HEATING SURFACES

MOTION AND EVAPORATION CHARACTERISTICS OF WATER DROPLETS ON ...

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2024 CSAA/IET International Conference on aircraft Utility Systems, AUS 2024

作者： Tang, Hao Ren, Zhefan Hu, Weixue Chen, Weijian Zhang, Dalin Zhu, Guangya Key Laboratory of Aircraft Environment Control and Life Support Ministry of Industry and Information Technology Nanjing University of Aeronautics and Astronautics Nanjing China COMAC Shanghai Aircraft Design and Research Institute Shanghai China

Anti-icing systems are crucial subsystems for ensuring aircraft safety. The movement of water droplets on protective surfaces and evaporation are common phenomena during flight. Understanding water droplets' movement and evaporation characteristics is critical to designing an effective active or passive anti-icing system. Experimental setups were conducted to investigate water droplets' motion characteristics and evaporation performance on heating surfaces with various coatings. The results indicated that the critical diameter for droplet motion was affected by surface hydrophilicity. A water droplet of the same size could move more readily on hydrophobic surfaces. The results also revealed that the evaporation time of water droplets decreased with increasing surface hydrophilicity. This effect was more pronounced with the droplet size increase, as larger droplets exhibited higher temperature gradients than smaller droplets. The evaporation time of 6 |iL water droplets on superhydrophobic coating surfaces was more than 3.5 times longer than that on hydrophilic coating surfaces. The findings of this paper reveal the mechanisms of water droplet motion and evaporation, which can benefit future anti-icing system design. © The Institution of Engineering & Technology 2024.

关键词： Evaporation

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Numerical Simulation of Rain Accumulation on aircraft Windshield

Numerical Simulation of Rain Accumulation on Aircraft Windsh...

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2022 CSAA/IET International Conference on aircraft Utility Systems, AUS 2022

作者： Lu, Shengfang Chen, Weijian Shen, Hao Zhu, Guangya Shi, Ruxin Key Laboratory of Aircraft Environment Control and Life Support Ministry of Industry and Information Technology Nanjing University of Aeronautics & Astronautics Nanjing China Shanghai Aircraft Airworthiness Certification Center of CAAC Shanghai China

ISBN: (数字)9781839537769

ISBN: (纸本)9781839537769

aircraft windshield rainfall process is a complex two-phase flow problem that includes the movement, collision, fragmentation, merging of raindrops, water film adsorption and water film flow. In this paper, a numerical method based on FLUENT is proposed to simulate this process. And the experiment of rain accumulation on flate-plate is carried out to verify the numerical method. This method combines the Discrete Phase Model and the Lagrangian Water Film Model. The control variable method is adopted to study the effects of aircraft flight speed, Angle of Attack(AOA), rainfall intensity and raindrop temperature on windshield rainfall. The results show that the impact of aircraft AOA on the windshield rainfall is relatively low, while the aircraft flight speed and rainfall intensity are positively correlated with the degree of windshield rainfall. The raindrop temperature has no significant effect on the windshield rainfall, but the lower temperature will bring more difficulty to remove raindrops. © 2022 IET Conference Proceedings. All rights reserved.

关键词： Rain

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