scholarly journals Analysis of Particle Motion in Wall-Free Concentrated Vortexes in Relation to Flight Safety Problem

10.12737/6633 ◽  
2014 ◽  
Vol 3 (6) ◽  
pp. 31-36
Author(s):  
Вараксин ◽  
A. Varaksin ◽  
Протасов ◽  
M. Protasov
Keyword(s):  
Vortex Core ◽  
Solid Particles ◽  
Flight Safety ◽  
Aircraft Engines ◽  
Dynamic Relaxation ◽  
Air Intake ◽  
Maximal Time ◽  
Flow Duct ◽  
Particles Dynamics ◽  
Made In

The ingestion in aircraft engines is one of the actual problems related to the flight safety. One of possible reasons of ingestion in the gas-air flow duct of compressor is a formation of vortex core under an air intake on a runway surface during engine working on a stop. Calculations of the solid particles’ motion in wall-free concentrated vortexes, being the analogues of vortex core have been made in this paper. The numerical results have allowed to find peculiarities of behavior for particles with different inertia (different density and sizes) in vortexes of various intensity. Based on calculations and available experimental data a dimensionless criterion had been supposed, which determines the particles’ behavior in concentrated vortex structures. Estimations for maximal time of dynamic relaxation for particles involved in the air intake by vortex cores of different intensities have been made with use of this criterion. The knowledge of particles’ dynamics in the vortex cores formed near the air intake of aircraft engines is necessary to develop the methods to protect them from possible ingestion from the runway to ensure the flight safety.

Part 1. Practical Problems

1967 ◽  
Vol 71 (683) ◽  
pp. 773-781
Author(s):  
H. K. Gordon-Burge
Keyword(s):  
Traffic Control ◽  
Safety Information ◽  
Accident Prevention ◽  
Lessons Learned ◽  
Flight Safety ◽  
Aircraft Engines ◽  
Legal Problems ◽  
Safety Committee ◽  
Subsequent Discussion ◽  
Air Safety

At the outset, I must make it quite clear that any views or opinions expressed are my own and are not necessarily those of either British European Airways or the Flight Safety Committee.In this paper, I have attempted to discuss some of the problems which face those whose task is to obtain and to disseminate safety information. At the end, I have posed a number of questions which I believe are relevant and should be posed, and which Harold Caplan will take up in his subsequent discussion of the legal problems.Air Safety is essentially the prevention of accidents by minimising the risk of encountering foreseeable hazards and the consequences of unforeseen situations. Thus the dissemination of air safety information is simply the spreading of accident prevention material. It is undoubtedly best achieved by a sharing among all concerned of the lessons learned from their incident and accident experience. This activity is one that has to be shared by operators, flight and ground crew, air traffic control, the designers and makers of aircraft, engines and equipment, and regulatory authorities.

scholarly journals Short Review on Porous Metal Membranes—Fabrication, Commercial Products, and Applications

Membranes ◽  
2018 ◽  
Vol 8 (3) ◽  
pp. 83 ◽  
Author(s):  
Bo Zhu ◽  
Mikel Duke ◽  
Ludovic Dumée ◽  
Andrea Merenda ◽  
Elise des Ligneris ◽  
...  
Keyword(s):  
Porous Metal ◽  
Short Review ◽  
Hollow Fibre ◽  
Solid Particles ◽  
Significant Progress ◽  
Advantages And Disadvantages ◽  
Membrane Fabrication ◽  
Fibre Metal ◽  
Key Industries ◽  
Made In

Porous metal membranes have recently received increasing attention, and significant progress has been made in their preparation and characterisation. This progress has stimulated research in their applications in a number of key industries including wastewater treatment, dairy processing, wineries, and biofuel purification. This review examines recent significant progress in porous metal membranes including novel fabrication concepts and applications that have been reported in open literature or obtained in our laboratories. The advantages and disadvantages of the different membrane fabrication methods were presented in light of improving the properties of current membrane materials for targeted applications. Sintering of particles is one of the main approaches that has been used for the fabrication of commercial porous metal membranes, and it has great advantages for the fabrication of hollow fibre metal membranes. However, sintering processes usually result in large pores (e.g., >1 µm). So far, porous metal membranes have been mainly used for the filtration of liquids to remove the solid particles. For porous metal membranes to be more widely used across a number of separation applications, particularly for water applications, further work needs to focus on the development of smaller pore (e.g., sub-micron) metal membranes and the significant reduction of capital and maintenance costs.

Digitally Reverse Modeling for the Repair of Blades in Aero-Engines

2011 ◽  
Vol 141 ◽  
pp. 258-263 ◽  
Author(s):  
Tao Wang ◽  
Yi Liu Liu ◽  
Li Wen Wang ◽  
Hao Wang ◽  
Jie Tang
Keyword(s):  
Flight Safety ◽  
Aircraft Engines ◽  
B Spline ◽  
Cloud Data ◽  
Boundary Points ◽  
Digital Modeling ◽  
Engine Blade ◽  
Aero Engines ◽  
Blade Repair

Blades are key components in aircraft engines, and flight safety is directly impacted by the repair quality of blades. Digital modeling for the surfaces of high pressure blades is conducted in this study based on the cloud data collected with scan. Boundary points of blades are obtained with the method of varied step lengths according to curvature, and then the envelope curves are plotted from the approximation of these boundary points with a third power B spline. 3-D digital models of blades in aero-engines are established with the envelope curves and the condensed data cloud. Results illustrate the smoothness and accuracy of the proposed engine blade repair model.

A Comparative Study of the Noise from Turbo-Jet and Reciprocating Aircraft Engines in Flight

1950 ◽  
Vol 54 (479) ◽  
pp. 697-707 ◽  
Author(s):  
S. C. Ghose
Keyword(s):  
Comparative Study ◽  
Frequency Band ◽  
Noise Spectrum ◽  
Aircraft Engines ◽  
Jet Engine ◽  
Reciprocating Engines ◽  
Extended Frequency ◽  
Made In

SummarySources of noise in aircraft are discussed briefly with particular reference to the introduction of the turbo-jet engine.An account is given of a particular investigation made in a Lancastrian aircraft fitted with both turbo-jet and reciprocating engines. The equipment by which the noise spectrum was analysed over, an extended frequency band is described.The results are examined and the effects of the two types of engine on the noise spectrum are compared, under different representative conditions, in the forward and rear sections of the fuselage.

Rotor Crack Detection Using Active Magnetic Bearings

2008 ◽  
Vol 144 ◽  
pp. 9-15 ◽  
Author(s):  
Jerzy T. Sawicki
Keyword(s):  
Crack Detection ◽  
Magnetic Bearings ◽  
Aircraft Engines ◽  
Active Magnetic Bearings ◽  
Proof Of Concept ◽  
Remaining Service Life ◽  
Convenient Means ◽  
Dynamic Forces ◽  
On Line ◽  
Made In

Well-established procedures exist to monitor and diagnose fairly severe problems with rotating machinery but little progress has been made in developing techniques to detect subtle changes in machine condition for both improved diagnostics, and to develop prognostic procedures for determining remaining service life. Of all machine faults, crack initiated problems present probably the most significant safety and loss hazard in modern turbomachinery, including aircraft engines and power generation units. Different approaches are used to model, detect, and localize crack-induced damage in rotating structures. This paper presents novel application of active magnetic bearings (AMBs) for on-line rotor crack detection. AMB-actuators provide convenient means to apply a broad spectrum of known dynamic forces and monitor responses in a rotor-bearing system, which facilitates more sensitive and precise diagnostics. The paper presents theoretical modeling and description of the experimental facility for proof-of-concept testing.

scholarly journals Particle Velocity Fluctuations in Viscous Gas with Random Velocity as the Sum of Two Correlated Color Noises

2020 ◽  
pp. 33-49
Author(s):  
I. V. Derevich ◽  
A. K. Klochkov
Keyword(s):  
Relaxation Time ◽  
Turbulent Flows ◽  
Particle Velocity ◽  
Random Processes ◽  
Solid Particles ◽  
Gas Velocity ◽  
Dynamic Relaxation ◽  
Two Phase ◽  
Velocity Fluctuations ◽  
Stochastic Ordinary Differential Equations

The article focuses on methods for studying the phenomenon of two-phase turbulent flows. The turbulence effect on the movement of solid particles in a viscous gas is under study. Dynamics of particles movement in a gas is written in the Stokes approximation, which allows us to suppose the dynamic relaxation time to be a constant value.The random gas velocity is modeled by the sum of two correlated random noises. It is shown that this approach makes it possible to model noise of any structural complexity. The paper describes two research methods based on fundamentally different Euler and Lagrange approaches to the description of a continuous medium. The first approach uses a well-known generalization of the spectral analysis technique for random processes, a popular method for studying turbulence. The second approach implementation is based on the modern generalizations of the theory of numerical algorithms for solving stochastic ordinary differential equations. The spectral method is used to obtain analytical expressions of correlation functions and variance of random processes describing the velocity of gas and solid particles. The qualitative difference between the correlation of fluctuations of modulated random velocities and the behavior of correlations in the case of a single-component gas velocity composition is analyzed. A method of direct numerical simulation for studied processes based on the numerical solution of a stochastic ordinary differential equations system is proposed and analyzed in detail. An array of statistical data obtained as a result of direct numerical modeling is collected and processed. Analytical results are compared qualitatively with numerical results. The influence of input parameters on the character of turbulent flow is studied. The dynamic relaxation time has a significant effect on the complexity of the autocorrelation function of the particle velocity and the response function of particles to gas velocity fluctuations. It is shown that the obtained functions tend to the known results of the standard theory. The considered methods for describing two-phase turbulent flows hold promise for further research.

scholarly journals Analysis and modelling of icing of air intake protection grids of aircraft engines

2019 ◽  
Vol 160 ◽  
pp. 265-272 ◽  
Author(s):  
Vittorio Vercillo ◽  
Norbert Karpen ◽  
Alexandre Laroche ◽  
Javier Alejandro Mayén Guillén ◽  
Simone Tonnicchia ◽  
...  
Keyword(s):  
Aircraft Engines ◽  
Air Intake

An Unstructured RANS Study of Tip-Leakage Vortex Cavitation Inception

2003 ◽  
Author(s):  
W. H. Brewer ◽  
D. L. Marcum ◽  
S. D. Jessup ◽  
C. Chesnakas ◽  
D. G. Hyams ◽  
...  
Keyword(s):  
Reynolds Number ◽  
Vortex Core ◽  
Experimental Measurements ◽  
Scaling Effects ◽  
Trailing Edge ◽  
Cavitation Inception ◽  
Tip Leakage ◽  
Edge Vortex ◽  
Good Agreement ◽  
Made In

To study the physics of cavitation inception, a ducted propulsor simulation is developed and extensively validated with experimental results. The numerical method is shown to be in good agreement with experimental measurements made in the vortex. The simulation is used as a tool for investigating the minimum pressure, circulation, and axial/tangential velocities in the vortex core. Additionally, the tool is used to study Reynolds number scaling effects of cavitation inception. The simulation reveals that the leakage vortex exhibits little dependence on Reynolds number, while the trailing edge vortex appears to exhibit classical trends. Moreover, the trailing edge, albeit the weaker vortex, appears to be causing inception.

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