scholarly journals On the Calculation of Recirculating Scheme of Quarry Ventilation

2015 ◽  
Vol 4 (3) ◽  
pp. 22-27
Author(s):  
Старостин ◽  
I. Starostin
Keyword(s):  
Boundary Layer ◽  
Atmospheric Pollution ◽  
Calculation Method ◽  
Integral Method ◽  
Natural State ◽  
Mining Operations ◽  
Air Volume ◽  
Aerodynamic Parameters ◽  
Ventilation Scheme ◽  
Geometry Function

A recirculating scheme of quarry ventilation has been examined. A calculation of the recirculating scheme of a quarry gas interchange employing Karman´s integral method, allowing to account for the parameters of the developed cavity (the angles of leeward and windward sides, their configuration, the size of the bottom, etc.), using the geometry function of the quarry, has been referred. Analytical dependencies for calculation of aerodynamic parameters of the recirculating ventilation scheme (air currents velocity, limits of the boundary layer, circulating air volume, etc.) have been determined. The proposed calculation method allows evaluating the natural state of gas interchange in quarries at various stages of mining operations, which is the basis for the estimation of atmospheric pollution and the development of necessary ventilation techniques.

Construction Ventilation Scheme Optimization of Underground Main Powerhouse Based on CFD

2013 ◽  
Vol 368-370 ◽  
pp. 619-623
Author(s):  
Zhen Liu ◽  
Xiao Ling Wang ◽  
Ai Li Zhang
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Flow Field ◽  
Air Flow ◽  
Scheme Optimization ◽  
Pressure Distributions ◽  
Air Volume ◽  
Computational Fluid Dynamics Cfd ◽  
Traditional Construction ◽  
Ventilation Scheme

For the purpose of avoiding the deficiency of the traditional construction ventilation, the ventilation of the underground main powerhouse is simulated by the computational fluid dynamics (CFD) to optimize ventilation parameters. A 3D unsteady RNG k-ε model is performed for construction ventilation in the underground main powerhouse. The air-flow field and CO diffusion in the main powerhouse are simulated and analyzed. The two construction ventilation schemes are modelled for the main powerhouse. The optimized ventilation scheme is obtained by comparing the air volume and pressure distributions of the different ventilation schemes.

A Review of Technical Potential for Coal Production and Coal Degasification – A Conventional Source of Methane – In Nigeria

2003 ◽  
Vol 14 (1) ◽  
pp. 59-67
Author(s):  
Adepo Jepson Olumide ◽  
Ayodele Charles Oludare ◽  
Balogun Olufemi
Keyword(s):  
Coal Seam ◽  
Fossil Fuels ◽  
Underground Mining ◽  
Simple Calculation ◽  
Gas Content ◽  
Gelling Agent ◽  
Coal Bed ◽  
Natural State ◽  
Mining Operations ◽  
Inorganic Matter

Coal, a solid fuel in its natural state has been identified as one of the world's major fossil fuels. It is a compact, stratified mass of mummified plant debris interspersed with smaller amounts of inorganic matter buried in sedimentary rocks. The use of coal as an energy source can be dated back to the prehistoric times. Methane is associated with many if not all coal seams, and is the dreaded “fire damp” responsible for many pit explosions. Coal mines are designed to vent as much methane as possible. It is present in the pores of coal under pressure, released during mining operations and can be extracted through vertical well bores. This paper highlights the fact that pipeline- quality methane can be extracted economically from coal seems before and during underground mining operations. The stimulation method involves hydraulic fracturing of the coal seam by using water, sand and, a gelling agent in a staged and alternating sand/and no sand sequence. The purpose is to create new fractures in the coal seam(s). The cleating of the coal helps to determine the flow characteristics of the coal formation and is vital in the initial productivity of a coal-methane well. The simple calculation of gas-in-place is achieved by multiplying the gas content of the coal by net coal thickness, the density, and the aerial extent of the drainage. The method is claimed to be suitable for use in Nigeria and potential sites for coal bed methane extraction in Nigeria are identified.

scholarly journals Transition Prediction in Attached and Separated Shear Layers Using an Integral Method

1992 ◽  
Author(s):  
G. Leoutsakos ◽  
K. D. Papailiou
Keyword(s):  
Integral Method ◽  
Adverse Pressure Gradient ◽  
Shear Layers ◽  
Separated Flows ◽  
Prediction Methods ◽  
Accurate Assessment ◽  
Transition Prediction ◽  
Turbomachinery Blades ◽  
Aerodynamic Parameters ◽  
Work Done

Calculation of the aerodynamic parameters of axial turbomachinery blades, and an accurate assessment of the flow over the blade surfaces under today’s increasingly demanding requirements for higher efficiencies and optimized blade shapes, at both design and off-design conditions, impose a need for accurate prediction methods able to compute through two sensitive but highly critical phenomena: separation and transition. The present study describes work done on the modelling and prediction of transitional regions, such as those appearing on turbomachinery blading, covering both attached and separated flows. The concept of an engineering method, cheap to run and avoiding complex CFD and turbulence model formulations was always kept in mind. Results include comparisons of integral quantities and velocity profiles in zero, favourable or adverse pressure gradient attached flows, and velocity distributions including points of separation, transition and reattachment in separated airfoil flows, obtained either from a straightforward shear layer calculation or from a viscous-inviscid interaction procedure.

A Coupled Potential-Boundary Layer Calculation Method for Unsteady Flows Around Airfoils

1993 ◽  
pp. 129-143
Author(s):  
M. Kermarec ◽  
A. F. Decaix ◽  
P. Renon ◽  
D. Favier ◽  
C. Maresca
Keyword(s):  
Boundary Layer ◽  
Calculation Method ◽  
Unsteady Flows

Local Natural Ventilation Registration while Ensuring Aerological Safety at the Mining Enterprises

2021 ◽  
pp. 60-65
Author(s):  
S.S. Kobylkin ◽  
◽  
V.M. Khubieva ◽  
Keyword(s):  
Calculation Method ◽  
Natural Ventilation ◽  
Three Dimensional ◽  
Field Measurements ◽  
Industrial Safety ◽  
Ventilation Network ◽  
Negative Consequences ◽  
Practical Application ◽  
Mining Operations ◽  
Mine Workings

Safety of mining operations is the basis for the efficient functioning of the mines. During mining operations, due to changing conditions in the mine workings, the natural draft began to appear more frequent. Moreover, its influence can be limited to a separate section without affecting the entire ventilation network. In this paper, the new concept is introduced and explained — local natural ventilation. The classification signs and the negative consequences of its manifestation are presented. Main difference between the local natural ventilation as a subspecies of natural ventilation as a whole lies in the limited action both in the spaces of mine workings or individual sections, and in time. Particularly its occurrence depends on the season or the technological processes performed. In this case, the local natural ventilation is not an emergency and is not subject to registration as an incident or accident. However, its manifestations can lead to both incidents and accidents. Taking this factor into account will allow to increase the level of aerological safety at the mining enterprises. A method of three-dimensional computer modeling is proposed for predicting the manifestation of local natural ventilation and making decisions to prevent it. An example of the use of this approach at the Norilsk mine during the construction of shafts with verification of field measurements is given. It confirms the possibility of practical application of the proposed calculation method. The algorithm for registering the local natural ventilation considered in the article makes it possible to develop activities for improving the level of industrial safety at the mining enterprises as a whole.

A simple calculation method for estimating the flow velocity on the roof of a train running through a tunnel using an unsteady incompressible flow model

2019 ◽  
Vol 234 (7) ◽  
pp. 734-748
Author(s):  
Katsuhiro Kikuchi ◽  
Satoru Ozawa ◽  
Yuhei Noguchi ◽  
Shinya Mashimo ◽  
Takanobu Igawa
Keyword(s):  
Boundary Layer ◽  
Flow Velocity ◽  
Calculation Method ◽  
Model Experiment ◽  
Flow Model ◽  
Simple Calculation ◽  
Dimensional Model ◽  
One Dimensional ◽  
Calculation Results ◽  
Tunnel System

Predicting the aerodynamic phenomena in a train-tunnel system is important for increasing the speed of railway trains. Among these phenomena, many studies have focused on the effects of pressure; however, only a few studies have examined the effects of flow velocity. When designing train roof equipment such as a pantograph and an aerodynamic braking unit, it is necessary to estimate the flow velocity while considering the influence of the boundary layer developed on the train roof. Until now, numerical simulations using a one-dimensional model have been utilized to predict the flow velocity around a train traveling through a tunnel; however, the influence of the boundary layer cannot be taken into consideration in these simulations. For this purpose, the authors have previously proposed a simple calculation method based on a steady incompressible tunnel flow model that can take into account the influence of the boundary layer, but this method could not incorporate the unsteadiness of the flow velocity. Therefore, in this study, the authors extend the previous simple calculation method such that it can be used for an unsteady incompressible tunnel flow. The authors compare the calculation results obtained from the extended method with the results of a model experiment and a field test to confirm its effectiveness.

An Accurate Calculation Method for Two-dimensional Incompressible Laminar Boundary Layers, Including Cases with Regions of Sharp Pressure Gradient

1977 ◽  
Vol 28 (3) ◽  
pp. 149-162 ◽  
Author(s):  
N Curle
Keyword(s):  
Boundary Layer ◽  
Pressure Gradient ◽  
Calculation Method ◽  
Boundary Layer Separation ◽  
Pressure Gradients ◽  
Accurate Calculation ◽  
Boundary Layer Equations ◽  
Laminar Boundary Layers ◽  
Displacement Thickness ◽  
Type Boundary

SummaryThe paper develops and extends the calculation method of Stratford, for flows in which a Blasius type boundary layer reacts to a sharp unfavourable pressure gradient. Whereas even the more general of Stratford’s two formulae for predicting the position of boundary-layer separation is based primarily upon an interpolation between only three exact solutions of the boundary layer equations, the present proposals are based upon nine solutions covering a much wider range of conditions. Four of the solutions are for extremely sharp pressure gradients of the type studied by Stratford, and five are for more modest gradients. The method predicts the position of separation extremely accurately for each of these cases.The method may also be used to predict the detailed distributions of skin friction, displacement thickness and momentum thickness, and does so both simply and accurately.

A simple model for low-frequency unsteadiness in shock-induced separation

2009 ◽  
Vol 629 ◽  
pp. 87-108 ◽  
Author(s):  
S. PIPONNIAU ◽  
J. P. DUSSAUGE ◽  
J. F. DEBIÈVE ◽  
P. DUPONT
Keyword(s):  
Boundary Layer ◽  
Shock Wave ◽  
Particle Image ◽  
Mixing Layer ◽  
Low Frequency ◽  
Oblique Shock Wave ◽  
Separation Shock ◽  
Image Velocimetry ◽  
Boundary Layer Interaction ◽  
Aerodynamic Parameters

A model to explain the low-frequency unsteadiness found in shock-induced separation is proposed for cases in which the flow is reattaching downstream. It is based on the properties of fluid entrainment in the mixing layer generated downstream of the separation shock whose low-frequency motions are related to successive contractions and dilatations of the separated bubble. The main aerodynamic parameters on which the process depends are presented. This model is consistent with experimental observations obtained by particle image velocimetry (PIV) in a Mach 2.3 oblique shock wave/turbulent boundary layer interaction, as well as with several different configurations reported in the literature for Mach numbers ranging from 0 to 5.

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