Flow Patterns and Wall Stresses in a Mass-Flow Bunker

1973 ◽  
Vol 95 (1) ◽  
pp. 17-26 ◽  
Author(s):  
P. M. Blair-Fish ◽  
P. L. Bransby
Keyword(s):  
Mass Flow ◽  
Small Mass ◽  
Flow Patterns ◽  
Normal Stresses ◽  
Flowing Material ◽  
Intense Deformation

Observations are reported of the shear and normal stresses on the walls of a small mass flow bunker and of the variations of density in the flowing material. Changes in wall stresses which occur as the material discharges are correlated with the formation and reformation of zones of intense deformation within the bunker.

scholarly journals Comparison of Swing and Tilting Check Valves Flowing Compressible Fluids

Micromachines ◽  
2020 ◽  
Vol 11 (8) ◽  
pp. 758
Author(s):  
Zhi-xin Gao ◽  
Ping Liu ◽  
Yang Yue ◽  
Jun-ye Li ◽  
Hui Wu
Keyword(s):  
Mach Number ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Check Valve ◽  
Small Mass ◽  
Working Fluid ◽  
Valve Disc ◽  
Valve Opening ◽  
The Difference

Although check valves have attracted a lot of attention, work has rarely been completed done when there is a compressible working fluid. In this paper, the swing check valve and the tilting check valve flowing high-temperature compressible water vapor are compared. The maximum Mach number under small valve openings, the dynamic opening time, and the hydrodynamic moment acting on the valve disc are chosen to evaluate the difference between the two types of check valves. Results show that the maximum Mach number increases with the decrease in the valve opening and the increase in the mass flow rate, and the Mach number and the pressure difference in the tilting check valve are higher. In the swing check valve, the hydrodynamic moment is higher and the valve opening time is shorter. Furthermore, the valve disc is more stable for the swing check valve, and there is a periodical oscillation of the valve disc in the tilting check valve under a small mass flow rate.

What You Need to Know to Reliably Handle Waste Coal

2003 ◽  
Author(s):  
Roderick J. Hossfeld ◽  
David A. Craig ◽  
Roger A. Barnum
Keyword(s):  
Mass Flow ◽  
Systematic Approach ◽  
Flow Patterns ◽  
Handling System ◽  
Flow Problems ◽  
Energy Facility ◽  
Anthracite Culm ◽  
Funnel Flow ◽  
Major Consideration ◽  
Waste Coal

Many power producers have been designing for, or switching to waste coal. A major consideration when dealing with waste coal is the design of the fuel handling system. Since waste coal is typically finer and more cohesive and therefore harder to handle in silos, bunkers, chutes and feeders, design of the handling system for reliable, non-stagnant flow is essential. This paper describes a systematic approach to designing and retrofitting handling systems to avoid bulk solids flow problems. Potential trouble areas such as coal hoppers, silos, bunkers, and transfer chutes are discussed. Mass flow and funnel flow patterns that develop in silos and bunkers are presented. Funnel flow results in large stagnant regions, which are a major problem for coals that combust easily and are prone to problems such as arching and ratholing. Mass flow patterns, which eliminate the stagnant coal regions, are also explained. Coal properties and bunker designs that result in mass flow and funnel flow are described. Transfer chute design techniques to avoid pluggages, reduce dusting, and minimize chute wear are discussed. The Panther Creek Energy facility in Nesquehoning, Pennsylvania is used as an example where solids flow handling methodologies were used to solve handling problems with anthracite culm. The modifications presented were required for reliable, stagnant-free coal flow, which prevented belt slippage and high belt loading on gravimetric feeders.

Mass Flow Rate Measurements: From Hydrodynamic to Free Molecular Regime

2008 ◽  
Author(s):  
Timothe´e Ewart ◽  
Irina A. Graour ◽  
Pierre Perrier ◽  
J. Gilbert Me´olans
Keyword(s):  
Mass Flow Rate ◽  
Knudsen Number ◽  
Mass Flow ◽  
Flow Rate ◽  
Stationary Flow ◽  
Small Mass ◽  
Accommodation Coefficient ◽  
Navier Stokes ◽  
Number Range ◽  
Free Molecular Regime

An experimental investigation in a single silica microtube in isothermal stationary flow for various gases is made from the hydrodynamic to the near free molecular regime to study the reflection/accommodation process at the wall. This kind of investigation requires, more than other Micro-Electro-Mechanical-Systems (MEMS) experiments, a powerful experimental platform to measure very small mass flow rate. A global analytic expression, based on the Navier-Stokes (NS) equations with second order boundary conditions, is used to yield the Tangential Momentum Accommodation Coefficient (TMAC) in 0.003–0.3 Knudsen number range. Otherwise, the experimental results of the mass flow rate is compared with theoretical values calculated from kinetic approaches using variable TMAC as fitting parameter over the 0.3–30 Knudsen number range. Finally, whatever the theoretical approach the TMAC values obtained from the different gas-surface pairs are rather close one to other, but the TMAC values seem decreasing when the molecular mass increases.

Introduction of an Integrated Turbo-Electrical Machine

2017 ◽  
Author(s):  
Sebastian Schuster ◽  
Christian Kreischer ◽  
Dieter Brillert
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Small Mass ◽  
High Mass ◽  
Electrical Machine ◽  
Flow Area ◽  
Machine Performance ◽  
High Fluid ◽  
Compact Design

Turbomachines are commonly designed for a high mass flow rate. However, because of new cycle concepts, turbomachines are also required to compress or expand at small mass flow rates. One example is the supercritical carbon dioxide Brayton cycle. The mass flow rate can be in the range of one kg/s at an almost high fluid density at the inlet to the compressor. This results in a small through flow area. In this paper, a turbomachine concept is presented that integrates the turbomachine parts into an electrical machine. Specifically, the turbomachine is located in the gap between the rotor and the stator of the electrical machine. In that way, a very compact design can be achieved. This paper aims to explain the basic concept. An aerodynamic design study is performed that demonstrates the important parameters for machine performance. Additionally, the design of the electrical machine is discussed based on a realistic application. Finally, conclusions for further development are drawn.

Development of a transfer standard with sonic Venturi nozzles for small mass flow rates of gases

2000 ◽  
Vol 11 (4) ◽  
pp. 279-283 ◽  
Author(s):  
Masao Hayakawa ◽  
Yoshitaka Ina ◽  
Yoshikazu Yokoi ◽  
Masaki Takamoto ◽  
Shin-ichi Nakao
Keyword(s):  
Mass Flow ◽  
Small Mass ◽  
Flow Rates ◽  
Transfer Standard ◽  
Mass Flow Rates

scholarly journals Experimental Investigation of the Flow Mechanisms and the Performance Change of a Highly Loaded Axial Compressor Stage with/without Stator Hub Clearance

2019 ◽  
Vol 9 (23) ◽  
pp. 5134
Author(s):  
Baojie Liu ◽  
Ying Qiu ◽  
Guangfeng An ◽  
Xianjun Yu
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Three Dimensional ◽  
Axial Compressor ◽  
Large Mass ◽  
Small Mass ◽  
Flow Structures ◽  
Leakage Flow ◽  
Corner Separation

Three-dimensional corner separation is common in axial compressors, which can lead to large flow loss and blockage especially when it evolves into the corner stall (open separation). In this paper, the evolution of the three-dimensional flow structures inside a cantilevered stator of a 1.5 stage low-speed highly loaded axial compressor as the stator hub clearance varies, and its effect on the whole compressor performance are investigated experimentally. Firstly, when the stator hub is sealed, the hub corner stall will occur at small mass flow rate conditions. Then, when a very small stator hub clearance is introduced, the leakage flow tends to strengthen the hub corner separation at large mass flow rate conditions and prompts the occurrence of hub corner stall as the mass flow rate decreases. This is mainly caused by the fact that the leakage flow has relatively low energy due to the viscosity effect in the clearance and large flow loss generation as the clearance flow comes across and mixes with the transverse secondary flow. Finally, when the stator hub clearance increases, the effect of the flow viscosity becomes very weak and could be ignored, so the enhanced leakage flow can suppress the transverse migration of the low energy flow near the hub, and the hub corner separation at large mass flow rate conditions could be weakened and the hub corner stall at small mass flow rate conditions could be removed or delayed. As the stator hub clearance varies, the flow structures inside the stator passage could be summarized into five typical flow structures, and this is closely associated with the performance of the compressor.

scholarly journals Cooling Air Flow in a Multi Disc Industrial Gas Turbine Rotor

1998 ◽  
Author(s):  
D. Brillert ◽  
A. W. Reichert ◽  
H. Simon
Keyword(s):  
Simple Model ◽  
Gas Turbine ◽  
Boundary Layers ◽  
Mass Flow ◽  
Radial Flow ◽  
Flow Patterns ◽  
Navier Stokes ◽  
Mean Flow ◽  
Flow Through ◽  
Secondary Air

The objective of this paper is to investigate the secondary air system in a multidisc rotor. The investigation was performed using Navier-Stokes calculations, network modeling and measurements taking into account new test data from Siemens’ Model V84.3A gas turbine prototype. The objective of the investigation was to better the understanding of flow patterns and to generate a simple model for describing mean flow values. The flow patterns predicted on the basis of Navier-Stokes calculations are described and the losses associated with fluid flow through rotating cavities of multidisc rotors are evaluated. High losses are generated in the radial flow through the corotating discs, and this investigation therefore concentrates on this flow. The investigated mass flowrates are relatively high when compared with the mass flow naturally transported on rotating discs (Cw > 105). One part of the mass flow is forced to flow along the boundary layers. The other part is transported outside of the boundary layers like a free potentially inviscid flow. On the basis of the investigation of the Navier Stokes-calculations, a simple analytical model of the radial flow through the corotating discs is developed. Good agreement was found to exist between the experimental data and the results of the simple model.

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