scholarly journals A Novel Way to Enhance the Spark Plasma-Assisted Ignition for an Aero-Engine Under Low Pressure

2018 ◽  
Vol 8 (9) ◽  
pp. 1533 ◽  
Author(s):  
Shengfang Huang ◽  
Zhibo Zhang ◽  
Huimin Song ◽  
Yun Wu ◽  
Yinghong Li
Keyword(s):  
High Altitude ◽  
Penetration Depth ◽  
Power Supply ◽  
Arc Discharge ◽  
Burning Velocity ◽  
Discharge Energy ◽  
Aero Engine ◽  
Multichannel Discharge ◽  
Spark Plasma ◽  
Long Endurance

Finding a new ignition strategy for ignition enhancement in a lean-burn combustor has always been the biggest challenge for high-altitude, long-endurance unmanned aerial vehicles (UAVs). It is of great importance for the development of high-altitude, long-endurance aircraft to improve the secondary ignition ability of the aero-engine at high altitude where the ignition capability of the aero-engine igniter rapidly declines. An innovative ignition mode is therefore urgently needed. A novel plasma-assisted ignition method based on a multichannel discharge jet-enhanced spark (MDJS) was proposed in this study. Compared to the conventional spark igniter (SI), the arc discharge energy of the MDJS was increased by 13.6% at 0.12 bar and by 14.7% at 0.26 bar. Furthermore, the spark plasma penetration depth of the MDJS was increased by 49% and 103% at 0.12 bar and 0.26 bar, respectively. The CH* radicals showed that the MDJS obtained a larger initial spark kernel and reached a higher spark plasma penetration depth, which helped accelerate the burning velocity. Ignition tests in a model swirl combustor showed that the lean ignition limit was extended 24% from 0.034 to 0.026 at 25 m/s with 20 °C kerosene and 17% from 0.075 to 0.062 at 12 m/s with −30 °C kerosene maximally. The MDJS was a unique plasma-assisted ignition method, activated by the custom ignition power supply instead of a special power supply with an extra gas source. The objective of this study was to provide a novel multichannel discharge jet-enhanced spark ignition strategy which would help to increase the arc discharge energy, the spark plasma penetration depth and the activated area without changing the power supply system and to improve the safety and performance of aero-engines.

Dynamic Analysis of the Joined-Wing Configuration in High-Altitude Long-Endurance Aircraft Using Fluid-Structure Interaction Model

2007 ◽  
Author(s):  
Prabu Ganesh Ravindren ◽  
Kirti Ghia ◽  
Urmila Ghia
Keyword(s):  
Finite Element ◽  
High Altitude ◽  
Fluid Structure Interaction ◽  
Structural Deformation ◽  
Time Step ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Finite Element Software ◽  
Joined Wing ◽  
Long Endurance

Recent studies of the joined-wing configuration of the High Altitude Long Endurance (HALE) aircraft have been performed by analyzing the aerodynamic and structural behaviors separately. In the present work, a fluid-structure interaction (FSI) analysis is performed, where the fluid pressure on the wing, and the corresponding non-linear structural deformation, are analyzed simultaneously using a finite-element matrix which couples both fluid and structural solution vectors. An unsteady, viscous flow past the high-aspect ratio wing causes it to undergo large deflections, thus changing the domain shape at each time step. The finite element software ANSYS 11.0 is used for the structural analysis and CFX 11.0 is used for the fluid analysis. The structural mesh of the semi-monocoque joined-wing consists of finite elements to model the skin panel, ribs and spars. Appropriate mass and stress distributions are applied across the joined-wing structure [Kaloyanova et al. (2005)], which has been optimized in order to reduce global and local buckling. The fluid region is meshed with very high mesh density at the fluid-structure interface and where flow separation is predicted across the joint of the wing. The FSI module uses a sequentially-coupled finite element equation, where the main coupling matrix utilizes the direction of the normal vector defined for each pair of coincident fluid and structural element faces at the interface [ANSYS 11.0 Documentation]. The k-omega turbulence model captures the fine-scale turbulence effects in the flow. An angle of attack of 12°, at a Mach number of 0.6 [Rangarajan et al. (2003)], is used in the simulation. A 1-way FSI analysis has been performed to verify the proper transfer of loads across the fluid-structure interface. The CFX pressure results on the wing were transferred across the comparatively coarser mesh on the structural surface. A maximum deflection of 16 ft is found at the wing tip with a calculated lift coefficient of 1.35. The results have been compared with the previous study and have proven to be highly accurate. This will be taken as the first step for the 2-way simulation. The effect of a coupled 2-way FSI analysis on the HALE aircraft joined wing configuration will be shown. The structural deformation history will be presented, showing the displacement of the joined-wing, along the wing span over a period of aerodynamic loading. The fluid-structure interface meshing and the convergence at each time step, based on the quantities transferred across the interface will also be discussed.

Unimpeded migration of ions in carbon electrodes with bimodal pores at an ultralow temperature of −100 °C

2019 ◽  
Vol 7 (27) ◽  
pp. 16339-16346 ◽  
Author(s):  
Xi Wang ◽  
Jiang Xu ◽  
Joselito M. Razal ◽  
Ningyi Yuan ◽  
Xiaoshuang Zhou ◽  
...  
Keyword(s):  
Energy Storage ◽  
Low Temperature ◽  
High Altitude ◽  
Space Missions ◽  
Carbon Electrodes ◽  
Discharge Energy ◽  
Energy Storage Devices ◽  
Storage Devices ◽  
Ultralow Temperature ◽  
Temperature Applications

The ability to rapidly charge (and discharge) energy storage devices at extremely low temperature (down to −100 °C) is critical for low-temperature applications such as high altitude exploration and space missions.

Technical Design of Arc-Discharge and Deceleration Power Supply for MW Level NBI System on HL-2A Tokamak

2012 ◽  
Vol 14 (10) ◽  
pp. 936-940 ◽  
Author(s):  
Wenguang Chen ◽  
Jun Rao ◽  
Bo Li ◽  
Guangjiu Lei ◽  
Jianyong Cao ◽  
...  
Keyword(s):  
Power Supply ◽  
Arc Discharge ◽  
Technical Design

scholarly journals Stepwise fusion algorithm with dual correction for multi-sensor navigation

2018 ◽  
Vol 15 (3) ◽  
pp. 172988141877993 ◽  
Author(s):  
Rong Wang ◽  
Zhi Xiong ◽  
Jianye Liu ◽  
Yuxuan Cao
Keyword(s):  
High Altitude ◽  
Unmanned Aerial Vehicle ◽  
Error Estimation ◽  
Attitude Determination ◽  
Vehicle Navigation ◽  
Fusion Algorithm ◽  
Aerial Vehicle ◽  
Determination System ◽  
Long Endurance ◽  
Sensor Navigation

In high-altitude, long-endurance unmanned aerial vehicles, a celestial attitude determination system is used to enhance the inertial navigation system (INS)/global positioning system (GPS) to achieve the required attitude performance. The traditional federal filter is not applicable for INS/GPS/celestial attitude determination system information fusion because it does not consider the mutually coupled relationship between the horizontal reference error in the celestial attitude determination system and the navigation error; this limitation results in reduced navigation accuracy. This article proposes a novel stepwise fusion algorithm with dual correction for multi-sensor navigation. Considering the horizontal reference error, the celestial attitude determination system measurement model is constructed and the issues involved in applying the federal filter are discussed. Then, preliminary error estimation and horizontal reference compensation are added to the navigation architecture. In addition, a sequential update strategy is derived to estimate the attitude error with the compensated celestial attitude determination system based on the preliminary estimation. A stepwise correction filtering algorithm with interactive preliminary and sequential updates that can effectively fuse celestial attitude determination system measurements with the INS/GPS is constructed. High-altitude, long-endurance unmanned aerial vehicle navigation in a remote sensing task is simulated to verify the performance of the proposed method. The simulation results demonstrate that the horizontal reference error is effectively compensated, and the attitude accuracy is significantly improved after stepwise error estimation and correction. The proposed method also provides a novel multi-sensor integrated navigation architecture with mutually coupled errors; this architecture is beneficial in unmanned aerial vehicle navigation applications.

Impact of solar storms on high altitude long endurance unmanned aircraft and airship design and operations

2006 ◽  
Vol 110 (1111) ◽  
pp. 623-626 ◽  
Author(s):  
L. R. Newcome
Keyword(s):  
High Altitude ◽  
Space Weather ◽  
Research Data ◽  
Unmanned Aircraft ◽  
Storm Effects ◽  
Solar Storm ◽  
Solar Storms ◽  
Hr Roles ◽  
New Research ◽  
Long Endurance

Abstract This paper applies existing information on solar storms to unmanned aviation; no new research data is presented. The purpose of this paper is to alert the unmanned aviation community to the potential hazards posed by solar storms, to familiarise it with the effects of solar storms and how to mitigate them, and to encourage research on solar storm effects on high altitude long endurance (HALE) aircraft and airship design and operations. As unmanned aircraft and airships move increasingly into high altitude (50,000+ft), endurance (24+ hr) roles, they will become vulnerable to the effects of space weather, specifically that of solar storms. Although solar storms are commonly associated with their impact on satellites, they affect the routing and timing of airline flights flying for six to eight hours at 30,000 to 40,000ft. Operating twice as high and with flight times twice as long (or longer) than those of airliners, HALE aircraft and airships occupy a middle zone of vulnerability, being more so than airliners but less so than satellites. A key difference however is that satellites are designed for space weather, whereas some current HALE vehicles are not. The paper concludes that unmanned HALE aircraft and airships can be one to three orders of magnitude more vulnerable to solar storms than a trans-Pacific airliner.

Heliplat®: high altitude very-long endurance solar powered UAV for telecommunication and Earth observation applications

2004 ◽  
Vol 108 (1084) ◽  
pp. 277-293 ◽  
Author(s):  
G. Romeo ◽  
G. Frulla
Keyword(s):  
Fuel Cells ◽  
High Altitude ◽  
Parametric Study ◽  
Storage System ◽  
Fem Analysis ◽  
Energy Storage System ◽  
Aerodynamic Performances ◽  
Solar Powered ◽  
One Year ◽  
Long Endurance

Abstract Research is at present being carried out at the Turin Polytechnic University with the aim of designing an HAVE/UAV (high altitude very-long endurance/unmanned air vehicle). The vehicle should climb to 17-20km by mainly taking advantage of direct Sun radiation and thereafter maintain a level flight; during the night, a fuel cells energy storage system would be used. A computer program has been developed to carry out a parametric study for the platform design. The solar radiation change over one year, the altitude, masses and efficiencies of the solar and fuel cells, and the aerodynamic performances have all been taken into account. The parametric studies have shown how fuel cells and solar cells efficiency and mass have the most influence on the platform dimensions. A wide use of high modulus CFRP has been made in designing the structure in order to minimise the airframe weight. A first configuration of HELIPLAT® (HELIos PLATform) was worked out, following a preliminary parametric study. The platform is a monoplane with eight brushless electric motors, a twin-boom tail type with an oversized horizontal stabiliser and two rudders. The co-ordinates at the root and along the wing span as well as the wing planform were optimised to achieve the best efficiency. Several profiles and wing plans have been analysed using the CFD software Xfoil and Vsaero. Several wind-tunnel tests were carried out to compare the analytically predicted performances. A preliminary design of a scale-sized technological demonstrator was completed with the aim of manufacturing a proof-of-concept structure. A FEM analysis was carried by using the Msc/Patran/Nastran code to predict the static and dynamic behaviour of the UAV structure.

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