Search results for "STIR"

CFD MODELLING OF PARTICLE SUSPENSION IN STIRRED TANKS

2011

Mixing of solid particles into liquids in mechanically agitated vessels is a topic of primary importance for several industrial applications. A great deal of research efforts has been devoted so far to the assessment of the minimum impeller speed (Njs) able to guarantee that all particles are suspended. Conversely, only little attention has been paid to the evaluation of the amount of solid particles that are suspended at impeller speeds N lower than Njs, despite the fact that in a number of industrial applications agitation speeds smaller than Njs are actually adopted [1,2]. The present work deals with dense solid-liquid partial suspensions in baffled stirred tanks and particularly focuses…

Fabrication of Billet from Aluminum Alloys AA 2011-T3/7075 Chips through Friction Stir Consolidation

2022

Recently evolving Solid-State Recycling (SSR) techniques have shown promising features to recycle metals scraps more efficiently compared to remelting-based approaches. Among these SSR methods, Friction Stir Consolidation (FSC) has been successfully tested to transform metals chips directly into semi or final solid products. Therefore, researchers explored FSC critical process parameters and their subsequent effects on quality in terms of the mechanical and metallurgical properties of the billet. All the previous studies of FSC were limited to developing billet of mono materials. Therefore, in this research, an attempt was made to go beyond the idea of recycling; in fact, a billet of two di…

Recent advances in sheet metal single point incremental forming and friction stir welding

2011

The work-family interface and its correlates : integrating variable and person oriented approaches

2017

The aim of this research was to examine key correlates of the interaction between work and family in one Nordic country, Finland, using a person- oriented and variable-oriented approach. The correlates that were chosen and examined over the course of three studies were job control and work-family boundary management styles, turnover intention, core self-evaluations, and vigor at work. Study I was part of a 2-year longitudinal study which was conducted in two Finnish universities (n = 700); Study II consisted of two samples, one of university employees (University 1, n = 666; University 2, n = 644), and the other of nurses (n = 301) from one healthcare district in Finland; and Study III used…

For the oppressed teacher: stay real!

2018

This article addresses teachers’ challenges in relation to other stakeholders, in light of funding policies and evaluation mechanisms. In particular, a condition where pressures toward high pass rates or ‘throughput’ in the degree system provide a good negotiation position for students with little learning orientation as to their aspirations after credit units is considered. This condition is intensified by the fact that the mere completion goals of non-learning-oriented students align with the collective goals of administration (university), given the throughput-based funding policies. A teacher willing to honorably exercise the profession is, then, ‘squeezed in between.’ Daily teaching end…

Influence of distinct tool pin geometries on aluminum 8090 FSW joint properties

2023

Abstract. Aluminum Lithium alloys are recuperating substantial interest from automotive and aerospace industries owing to their extraordinary specific strength as compared to conventional aluminum (2xxx, 6xxx, and 7xxx) alloys. The goal of the present investigation is to study AA 8090 joints produced with the unique solid-state welding technique friction stir welding (FSW). Tool pin profile induces remarkable influence on friction and further plastic deformation during FSW. Therefrom, the influences of three distinct but constant dynamic area conditioned tool pin geometries namely, square trapezoidal, hexagonal trapezoidal, and threaded taper on the resulting material flow patterns, mechani…

Measurements of Njs and Power Requirements in Unbaffled Bioslurry Reactors

2012

The remediation of urban/industrial polluted lands is a topic of crucial importance nowadays. Bioremediation techniques are widely employed to remove organic pollutants from contaminated soils because of their simplicity and cheapness. The bioslurry reactors mechanically agitated by stirrers represent one of the most promising bioremediation techniques. In the present work an unbaffled stirred vessel filled with solids and water is experimentally investigated from a fluid dynamic point of view. Air presence within the tank is guaranteed by the central vortex formation (typical occurrence concerning stirred vessels unprovided with baffles) instead of an intrinsically more expensive insufflat…

Influence of activated carbon on performance and microbial communities in the treatment of solvent pollutant mixtures in a continuous stirred tank re…

2020

The influence of the addition of granular activated carbon (GAC) on the anaerobic treatment of wastewater with a mixture of ethanol and 1-ethoxy-2-propanol (E2P), which are typical pollutants from the flexographic/printing industry, was evaluated. For this purpose, the reactor performance and microbial community in two continuous stirred tank reactors (CSTRs), i.e. control and GAC supplemented, were assessed. Both reactors, seeded with anaerobic granular biomass, showed similar global performance (RE > 93%), except after organic load shocks and after E2P addition. GAC supplementation substantially enhanced the response of the biological system to organic load shocks and reduced the acclimat…

Friction Stir Welding of 3D Industrial Parts: Joint Strength Analysis

2006

In the recent years Friction Stir Welding (FSW) has become an important joining technique since it allows to weld light weight alloys rather difficult to be welded or even “un-weldable” with the classic fusion welding operations. In the paper the authors present the application of the FSW process to the joining of 3D complex shapes typical of the industrial environment. In particular the research was aimed to highlight the joint mechanical strength at the varying of the 3D geometry of the welding line.Copyright © 2006 by ASME

Experimental and fluid dynamic study of continuous supercritical water gasification of glucose

2016

Abstract The supercritical water gasification (SCWG) of glucose as a model compound for H 2 production is studied in term of process development at 25 MPa and 650 °C. Gasification has been investigated using a laboratory scale continuous plant comprising a continuous down flow reactor with a volume of 200 cm 3 , a heat recovery section and pre-heat of the biomass to simulate more closely an industrial design. Feed streams (pure water and glucose solution) are introduced at the top of the vessel and products are extracted from the bottom. The reactor is equipped with various inlet points that allow to modify the inlet position of reacting streams in order to study the effect of stream mixing…