The effect of cohesion on the discharge of a granular material through the orifice of a silo

We present the results of both experimental and numerical investigations of the silo discharge for a cohesive granular material. In our study, thanks to a cohesion-controlled granular material (CCGM) we propose to investigate the effect of the cohesive length lc, on the discharge of a silo for two different configurations, one axisymmetrical, and one quasi-2D rectangular silo. In both configurations, an adjustable bottom is used to control the size of the orifice. As observed for cohesionless granular material by previous studies, the mass flow rate and the density through an orifice are mostly controlled by the diameter of the orifice D. The experimental results of the quasi-2D silo are compared with continuum numerical simulations.

Download Full-text

Behavior of Thermal Effects and Velocity-Slip on Performance of Externally Pressurized Porous Incompressible Gas Thrust Bearing

Journal of Applied Mechanics ◽

10.1115/1.3424577 ◽

1979 ◽

Vol 46 (2) ◽

pp. 465-468 ◽

Cited By ~ 3

Author(s):

V. K. Kapur ◽

J. S. Yadav

Keyword(s):

Mass Flow Rate ◽

Mass Flow ◽

Flow Rate ◽

Thermal Effects ◽

Thrust Bearing ◽

Load Capacity ◽

Velocity Slip ◽

Experimental Results ◽

Slip Condition ◽

Static Stiffness

In the present analysis, the interactions of thermal effects and velocity slip on the performance of externally pressurized porous incompressible gas thrust bearing have been studied. Numerical results for load capacity, mass flow rate, and static stiffness have been obtained and their behavior is illustrated in figures. The results for slip as well as no-slip condition have also been compared with the experimental results of Gargiulo and Gilmour [7].

Download Full-text

On the Mass Flow Rate of Granular Material in Silos with Lateral Exit Holes

Fluid Dynamics in Physics, Engineering and Environmental Applications - Environmental Science and Engineering ◽

10.1007/978-3-642-27723-8_21 ◽

2012 ◽

pp. 261-266

Author(s):

Abraham Medina ◽

G. Juliana Gutiérrez-Paredes ◽

Satyan Chowdary ◽

Anoop Kumar ◽

K. Kesava Rao

Keyword(s):

Granular Material ◽

Mass Flow Rate ◽

Mass Flow ◽

Flow Rate

Download Full-text

Design and Testing of a Can Combustor for a Small Gas Turbine Application

ASME 2013 Gas Turbine India Conference ◽

10.1115/gtindia2013-3691 ◽

2013 ◽

Author(s):

K. V. L. Narayana Rao ◽

N. Ravi Kumar ◽

G. Ramesha ◽

M. Devathathan

Keyword(s):

Mass Flow Rate ◽

Mass Flow ◽

Flow Rate ◽

Gas Turbines ◽

Pressure Loss ◽

High Energy ◽

Experimental Results ◽

High Mass ◽

Test Facility ◽

Design Requirements

Can type combustors are robust, with ease of design, manufacturing and testing. They are extensively used in industrial gas turbines and aero engines. This paper is mainly based on the work carried out in designing and testing a can type combustion chamber which is operated using JET-A1 fuel. Based on the design requirements, the combustor is designed, fabricated and tested. The experimental results are analysed and compared with the design requirements. The basic dimensions of the combustor, like casing diameter, liner diameter, liner length and liner hole distribution are estimated through a proprietary developed code. An axial flow air swirler with 8 vanes and vane angle of 45 degree is designed to create a re-circulation zone for stabilizing the flame. The Monarch 4.0 GPH fuel nozzle with a cone angle of 80 degree is used. The igniter used is a high energy igniter with ignition energy of 2J and 60 sparks per minute. The combustor is modelled, meshed and analysed using the commercially available ansys-cfx code. The geometry of the combustor is modified iteratively based on the CFD results to meet the design requirements such as pressure loss and pattern factor. The combustor is fabricated using Ni-75 sheet of 1 mm thickness. A small combustor test facility is established. The combustor rig is tested for 50 Hours. The experimental results showed a blow-out phenomenon while the mass flow rate through the combustor is increased beyond a limit. Further through CFD analysis one of the cause for early blow out is identified to be a high mass flow rate through the swirler. The swirler area is partially blocked and many configurations are analysed. The optimum configuration is selected based on the flame position in the primary zone. The change in swirler area is implemented in the test model and further testing is carried out. The experimental results showed that the blow-out limit of the combustor is increased to a good extent. Hence the effect of swirler flow rate on recirculation zone length and flame blow out is also studied and presented. The experimental results showed that the pressure loss and pattern factor are in agreement with the design requirements.

Download Full-text

Numerical Analysis of Dust Emission by Powder Discharge and Jet Expansion

Volume 1: Symposia ◽

10.1115/ajkfluids2015-32120 ◽

2015 ◽

Author(s):

F. Audard ◽

P. Fede ◽

O. Simonin ◽

E. Belut

Keyword(s):

Numerical Simulations ◽

Mass Flow Rate ◽

Mass Flow ◽

Flow Rate ◽

Dust Emission ◽

Free Fall ◽

Particulate Flow ◽

Solid Mass ◽

Particulate Flows ◽

Frictional Effects

The paper deals with the Euler-Euler numerical simulation of an experimental study (Ansart et al., 2009 [1]) of freely falling granular jet for investigating the dispersion of dust. The configuration is a bunker, where quasi-static particulate flow takes place, and a free-fall chamber. As a first step, a frictional viscosity model developed by Srivastava and Sundaresan (2003) [2] is implemented to take into account the frictional effects occurring in the quasi-static particulate flows. Without the frictional model for the viscosity, the numerical simulations overpredict the solid mass flow rate at the outlet of the bunker. When using the frictional viscosity, the solid mass flow rate is in better accordance with the experimental value. However, the solid velocity is overestimated in numerical simulations.

Download Full-text

Flow Investigation in a Small High Speed Impeller Passage Using Laser Anemometry

Volume 1: Turbomachinery ◽

10.1115/90-gt-233 ◽

1990 ◽

Cited By ~ 1

Author(s):

N. A. Ahmed ◽

R. L. Elder

Keyword(s):

Mass Flow Rate ◽

Mass Flow ◽

Flow Rate ◽

High Speed ◽

Three Dimensional ◽

Experimental Results ◽

Centrifugal Impeller ◽

Laser Velocimetry ◽

Laser Anemometry ◽

Flow Investigation

The paper describes experimental results obtained using laser velocimetry in a small high speed centrifugal impeller. The formation of wakes and the effect of varying speed and mass flow rate on the flow within the impeller passages are presented. In addition, an indication of the three dimensional nature of the impeller flow is discussed (the three dimensional results being obtained using a novel Doppler anemometer).

Download Full-text

Particle abrasion of lifting elbow in dilute pneumatic conveying

Proceedings of the Institution of Mechanical Engineers Part J Journal of Engineering Tribology ◽

10.1177/1350650120951293 ◽

2020 ◽

pp. 135065012095129

Author(s):

Yun Ji ◽

Songyong Liu ◽

Dianrong Gao ◽

Jianhua Zhao

Keyword(s):

Mass Flow Rate ◽

Mass Flow ◽

Flow Rate ◽

Design Method ◽

Orthogonal Design ◽

Industrial Applications ◽

Experimental Results ◽

Solid Mass ◽

Airflow Velocity ◽

Two Phase

Elbows are widely used in various industrial fields and are important for industrial applications. In this study, Eulerian coupling method was used to address the fluid-particle, and particle-particle interactions in a gas-solid two-phase flow while considering the effects of lifting angle, airflow velocity, and solid mass flow rate. The Hertz-Mindlin contact model and empirical Erosion/Corrosion Research Center erosion model were used to predict erosion in a lifting elbow, and the erosion ratio was used for validation with the experimental results. Experimental results indicated that the established model herein is accurate with different airflow velocities and lifting angles. The orthogonal design method was applied to the simulation scheme design, and range and variance analyses were used for the analysis of the results. Results indicated that the solid mass flow rate most affected elbow erosion comparing with lifting angles and airflow velocities. Additionally, the effect of the elbow lifting angle on the erosion mechanism was considered, and results indicated that the maximum erosion region is independent of the airflow velocity, lifting angle, and solid mass flow rate.

Download Full-text

High-Pressure Turbine Rim Seal Design for Increased Efficiency

Volume 2B: Turbomachinery ◽

10.1115/gt2016-57495 ◽

2016 ◽

Author(s):

M. Chilla ◽

H. P. Hodson ◽

G. Pullan ◽

D. Newman

Keyword(s):

High Pressure ◽

Numerical Simulations ◽

Mass Flow Rate ◽

Mass Flow ◽

Flow Rate ◽

Main Stream ◽

Turbine Stage ◽

High Pressure Turbine ◽

Disc Space ◽

Seal Design

In high-pressure turbines, compressor air is used to purge the disc space in an effort to protect the blade roots and the turbine disc from overheating and failure. The purge air exits the disc space through a rim seal at the hub of the main annulus and is subsequently entrained in the rotor hub endwall flows. The introduction of the purge air into the turbine main stream causes additional losses and therefore reduced turbine efficiency. For a given rim sealing mass flow rate, the rim seal geometry has to be designed in a way that reduces the detrimental impact of the sealing flow on turbine performance. In this study, the rim seal of a generic high-pressure turbine, representative of modern large civil aero-engines, is redesigned under consideration of the pressure field upstream of the rotor. Unsteady numerical simulations of the turbine stage are used to compare the aerodynamic impact of three different rim seal designs. The numerical simulations predict an increase in the time-averaged turbine stage efficiency of over 0.2% for the stage configuration with the final redesigned rim seal compared to the configuration with the original baseline rim seal geometry at the nominal sealing mass flow rate.

Download Full-text

Granular flow through vertical slots: analysis of a general formula

EPJ Web of Conferences ◽

10.1051/epjconf/202124903027 ◽

2021 ◽

Vol 249 ◽

pp. 03027

Author(s):

A. Medina ◽

D.A. Serrano ◽

A. López-Villa ◽

M. Pliego

Keyword(s):

Granular Material ◽

Mass Flow Rate ◽

General Formula ◽

Mass Flow ◽

Flow Rate ◽

Granular Flow ◽

Gravity Driven ◽

Flow Through ◽

Well Data

Currently, very little is known about reliable phenomelogical correlations to estimate the gravity-driven mass flow rate, of dry non-cohesive granular material, outflowing from thin thickness slots in vertical sidewalls of rectangular silos. Here, we validate a simple and general formula that fits pretty well data published elsewhere, including the cases of vertically and horizontally elongated slots.

Download Full-text

Theoretical and Experimental Investigation of a 34 Watt Radial-Inflow Steam Turbine With Partial-Admission

Volume 8: Industrial and Cogeneration; Manufacturing Materials and Metallurgy; Marine; Microturbines, Turbochargers, and Small Turbomachines ◽

10.1115/gt2020-15804 ◽

2020 ◽

Author(s):

Patrick H. Wagner ◽

Jan Van herle ◽

Jürg Schiffmann

Keyword(s):

Steam Turbine ◽

Mass Flow Rate ◽

Mass Flow ◽

Flow Rate ◽

Pressure Ratio ◽

Turbine Blades ◽

Tip Clearance ◽

Experimental Results ◽

Partial Admission ◽

Blade Tip

Abstract A micro steam turbine with a tip diameter of 15 mm was designed and experimentally characterized. At the nominal mass flow rate and total-to-total pressure ratio of 2.3 kg h−1 and 2, respectively, the turbine yields a power of 34 W and a total-to-static isentropic efficiency of 37%. The steam turbine is conceived as a radial-inflow, low-reaction (15%), and partial admission (21%) machine. Since the steam mass flow rate is limited by the heat provided of the system (solid oxide fuel cell), a low-reaction and high-power-density design is preferred. The partial-admission design allows for reduced losses: The turbine rotor and stator blades are prismatic, have a radial chord length of 1 mm and a height of 0.59 mm. Since the relative rotor blade tip clearance (0.24) is high, the blade tip leakage losses are significant. Considering a fixed steam supply, this design allows to increase the blade height, and thus reducing the losses. The steam turbine drives a fan, which operates at low Mach numbers. The rotor is supported on dynamic steam-lubricated bearings; the nominal rotational speed is 175 krpm. A numerical simulation of the steam turbine is in good agreement with the experimental results. Furthermore, a novel test rig setup, featuring extremely-thin thermocouples (ϕ0.15 mm) is investigated for an operation with ambient and hot air at 220 °C. Conventional zero and one-dimensional pre-design models correlate well to the experimental results, despite the small size of the turbine blades.

Download Full-text