Laboratory Rig Research Articles

Surface Solidification Behaviour of Micro-Alloyed Steels under Continuous Casting Conditions

Micro-alloyed steels are important in steel industry with regard to their unique mechanical properties. Their characterisitcs are mainly caused by the refinement of ferrite grain size by controlled precipitation of nitrides during thermomechanical treatment in hot rolling. Uncontrolled precipitations of titanium nitrides in the surface region during casting and solidification can negatively influence the surface quality of continuously cast steel, particularly when casting, thermal soaking and hot rolling are carried out in a combined process chain. Focus of this work are experimental simulations and mathematical investigations of early solidification in a CC mould, primary precipitation of nitrides, and effects of different influences such as mould contact through casting flux or direct mould contact. A laboratory rig to lead solidification on liquid casting flux was developed. The carbon content of the steel melts was varied.

A New Laboratory Rig for Evaluating Helmets Subject to Oblique Impacts

Current requirements and regulations governing motorcycle helmets around the world are based on test results of purely radial impacts, which are statistically rare in real accidents. This study presents a new impact rig for subjecting test helmets to oblique impacts, which therefore is able to test impacts of increased statistical relevance to real motorcycle accidents. A number of different head-helmet interfaces have been investigated. A test rig was constructed to produce oblique impacts to helmets simulating those occurring in real motorcycle accidents. A Hybrid III dummy head was fitted with accelerometers to measure the accelerations arising during impact testing. The equipment used for data collection was validated in both translational and rotational acceleration. In order to better resemble the human head, an artificial scalp was fitted to the hybrid dummy. The same test rig was used to investigate the performance of a number of different helmets. Impact velocities ranging from 7.3 to 9.9 m/s were tested using a number of different impact angles and impact areas. This study shows that the new test rig can be used to provide useful data at speeds of up to 50 km/h and with impact angles varying from purely tangential to purely radial. The rotational accelerations observed differ greatly depending on both helmet and scalp designs. For example, a helmet with a sliding outer shell placed on an experimental head fitted with an artificial scalp (made to resemble the human scalp) reduces rotational accelerations of the head by up to 56%, compared with those of an experimental head fitted with a fixed scalp and conventional helmet. The degree of slippage between the skull and the scalp, and between the scalp and the helmet, leads to considerable variation in the results. This innovative test rig appears to provide an accurate method for measuring accelerations in an oblique impact to a helmet. In order to obtain a good level of repeatability in oblique impact testing, it is crucial that the helmet be fixed to the head in the exact same way in each individual test. Both the position and the angle of impact must be reproduced identically in each test. The test rig used here has shown that this type of rig can be used to compare different helmet designs, and it therefore is able to contribute to achieving safer helmets.

Investigation of a novel jet deflector to avoid slag accumulation around secondary air jets in incinerators and boilers

AbstractA major problem in the operation of incinerators is the build‐up of slag on the walls in the throat region of the plant between the furnace chamber and the radiation shaft. This slag can accumulate to a thickness of about one meter, with a weight of several tonnes. This accumulation reduces the availability of the plant, and poses a safety problem, since injury can occur when the material is removed by pneumatic drills during maintenance operations. The excessive downtime, labor, and other economic costs of the slag removal can be minimized by developing a novel, no‐moving‐part jet deflector that can prevent or minimize the accumulation of slag around the jets. The jet deflector was developed and designed by understanding the fundamental principles of the fluid and particle dynamics around the high‐speed jet.Two small‐scale laboratory rigs were constructed for this study. The first rig was a wind tunnel specially designed to minimize the turbulent intensity at the main flow inlet. The second was a combustion rig fitted with an ash/burner injection system, a mobile phone networked particle monitor, and a removable refractory panel onto which the jet and deflector were fitted. An extensive series of laboratory experiments were carried out on both rigs. In parallel with the laboratory investigation, computational fluid dynamic (CFD) analysis of the flow field around the jet and deflector under the same experimental conditions were also conducted. Optimization work on the deflector design was also carried out. Fully optimized jet deflectors were then manufactured and tested in a UK municipal waste incinerator plant. Visual inspections of the jets before and after the deflectors were fitted showed a very significant reduction in the slag formation.

Observations of Flow and Turbulence in the Nocturnal Boundary Layer over a Slope

Measurements were conducted on an eastern slope of the Salt Lake Basin (SLB) as a part of the Vertical Transport and Mixing Experiment (VTMX) conducted in October 2000. Of interest was the nocturnal boundary layer on a slope (in particular, katabatic flows) in the absence of significant synoptic influence. Extensive measurements of mean flow, turbulence, temperature, and solar radiation were made, from which circulation patterns on the slope and the nature of stratified turbulence in katabatic winds were inferred. The results show that near the surface (,25‐50 m) the nocturnal flow is highly stratified and directed downslope, but at higher levels winds strongly vary in magnitude and direction with height and time, implying the domination of upper levels by air intrusions. These intrusions may peel off from different slopes surrounding the SLB, have different densities, and flow at their equilibrium density levels. The turbulence was generally weak and continuous, but sudden increases of turbulence levels were detected as the mean gradient Richardson number ( ) dropped to Rig about unity. With a short timescale fluctuated on the order of a few tens of seconds while modulating with Rig a longer (along-slope internal waves sloshing) timescale of about half an hour. The mixing efficiency (or the flux Richardson number) of the flow was found to be a strong function of , similar to that found in laboratory Rig experiments with inhomogeneous stratified shear flows. The eddy diffusivities of momentum and heat were evaluated, and they showed a systematic variation with when scaled with the shear length scale and the rms Rig vertical velocity of turbulence.

Experimental investigation of sensible heat transfer in fin-and-tube cooling coils

The sensible heat transfer characteristics of ‘ at-fin, corrugated-fin and turbulated-fin cooling coils is investigated using a laboratory rig. Measurements at different fin geometry, inlet air conditions and inlet chilled water temperature were conducted. The Nusselt number was found to be largely independent of both inlet air and chilled water temperatures. The turbulated-fin coil was found to have the highest value of heat transfer coefficient. In particular, at the same rate of heat transfer, the corrugated- and turbulated-fin coil types required 11% and 30% less fin surface area than ‘ at-fin, respectively.

Particle Residence Time and Particle Mixing in a Scaled Internal Circulating Fluidized Bed

A process is under development for the steam gasification of biomass to produce a hydrogen-rich gas for use with a fuel cell to generate electricity on a local scale. A pilot plant is currently under construction in southern Italy operated with a circulating fluidized bed, and to predict the fluid dynamic conditions within the plant, a cold laboratory rig was built according to existing scaling laws, and experimental studies were carried out. In this paper, we present the experimental results concerning the solids residence time of particles introduced into the system and the particle mixing in the “gasifier” section of the model. Both parameters are of fundamental importance for the operation of the pilot plant as they determine the performance of the gasification process. It is shown that the biomass particles spend sufficient time in the gasifier to be fully gasified, and an equation is derived to predict the mean residence time of the biomass particles as a function of the dimensionless mass turnover ...

MATHEMATICAL MODELLING AND COMPUTER SIMULATIONS AS AN AID TO GEARBOX DIAGNOSTICS

The paper deals with mathematical modelling and computer simulation as a tool for aiding gearbox diagnostic inference. The results of computer simulations and results obtained by laboratory rigs and field practice are compared. For investigation by computer simulations different factors are taken into consideration. The factors are divided into four groups: design factors, production technology factors, operational factors and change of condition factors. Using computer simulation and taking these factors into account: design, production technology, operation and condition change factors lead to DPTOCC inferring diagnostic information of the gearing system condition. The model for a system with a one-stage gearbox with torsional vibration is presented here as also are models for systems with a one-stage gearbox where both torsional and lateral vibration are taken into consideration and a system with a two-stage gearbox.

Stability of open-channel trickling-filter distributor arms

A method is presented for predicting the stability of the rotating arms of a rotary sewage distributor incorporated into a trickling filter. The method is derived, tested via various laboratory demonstrations and employed for evaluating the stability of experimental and production distributors using a calculation based upon the distributor's experimentally determined stiffness matrix. The method correctly models the stability behaviour of the laboratory rigs and confirms the observation that the experimental distributor is on the borderline of stability, while the production distributor is stable by a comfortable margin. A procedure is then developed for predicting the stability of a distributor prior to construction, using a finite element model to calculate the distributor's stiffness matrix.

AE—Automation and Emerging Technologies: Automatic Mushroom Harvester Development

This paper describes research which demonstrates that robotic harvesting of high-quality mushrooms, for the fresh market, is entirely feasible. The work was undertaken in two stages. First, systems capable of automatic mushroom location, sizing, selection, picking, trimming, conveying and transfer were conceived and implemented on a specially designed laboratory development rig. Once the sub-systems and integrated control software had been proven, the second stage of producing a pilot robotic harvester, based on these ideas, was carried out. Machine vision and image analysis algorithms were used for mushroom location and sizing. A separate strategy algorithm was written for selecting the most appropriate mushroom picking order. Overall system control was achieved using a single 486 DX33 MHz personal computer. Separate suction cup end-effectors were produced for picking in confined (less than 300 mm) or open headroom spaces. New delicate handling techniques for conveying, trimming and transferring mushrooms using flexible fingers, high-speed knives and a padded pneumatic gripper system, were developed. Both the laboratory rig and the pilot harvester were evaluated using imitation mushrooms constructed from dental plaster and a wide range of cultivated Agaricus bisporus mushrooms. In trials on a commercial farm, an average of over 80% of the mushroom pick attempts were successful.

Sensor Fault-Tolerant Control of an Induction Motor Drive System

This paper describes the application of a new fault-tolerant control scheme for nonlinear systems. The approach presented takes into account the stability and design of non-linear fuzzy inference systems based on Takagi-Sugeno (T-S) fuzzy models. The necessary conditions for eigenvalue assignability to a region in the s-plane are derived along with necessary conditions to guarantee the stability of adaptive fuzzy models for both diagnostic T-S fuzzy observers and controllers. The problem is solved using Linear Matrix Inequalities (LMI). The feasibility of this system architecture is demonstrated using a 3-phase induction motor laboratory rig as an example of a fault-tolerant system for applying principles of fault detection and isolation (FDI) and control system reconfiguration. The scheme uses the D space® software and digital signal processing to implement the fault detection and control system reconfiguration on the test rig.

Multiple-Model Fault-Tolerant Control of an Induction Motor in the Presence of Uncertainty

This paper describes the application of a new fault-tolerant control scheme for nonlinear systems. The approach presented takes into account the stability and design of non-linear fuzzy inference systems based on Takagi-Sugeno (T-S) fuzzy models. The necessary conditions for eigenvalue assignability to a region in the s-plane are derived along with necessary conditions to guarantee the stability of adaptive fuzzy models for both diagnostic TS fuzzy observers and controllers. The problem is solved using Linear Matrix Inequalities (LMI). The feasibility of this system architecture is demonstrated using a 3-phase induction motor laboratory rig as an example of a fault-tolerant system for applying principles of fault detection and isolation (FDI) and control system reconfiguration. The scheme uses the D space software and digital signal processing to implement the fault detection and control system reconfiguration on the test rig.

A Laboratory Rig for Testing Runoff from Paved Surfaces

When a process is too complex for rigorous mathematical formulation, and simplifying assumptions are introduced for its solution, experimental verification is …

International Cavitation Erosion Test and quantitative assessment of material resistance to cavitation

In September 1987, during the ELSI VII Conference, the start of the International Cavitation Erosion Test (ICET) project was announced. The experimental programme consisted in testing 6 selected materials (single-phase aluminium and brass alloys, Armco iron, carbon and chromium–nickel steel, and a polyamide 6 plastics) at various laboratory rigs. Tests were conducted at 4 cavitation tunnels, 4 rotating disks, 6 vibratory rigs, 1 liquid jet and 2 cavitating jet facilities. The results, now available in form of a MS Access database and the ICET Preliminary Report, convince that in addition to standardisation of selected experimental techniques, one should strive to develop methods allowing to predict material performance under variable cavitation loading conditions. In the present contribution, a method of quantitative material resistance assessment based on an idea of defining response to individual fractions of cavitation pulses histograms is proposed. Cavitation pulses are classified as micro- and macro pulses, depending on the affected area size, and divided into amplitude fractions. Erosion due to individual fractions is assumed to follow the same general law Δ V= A· ME i · U( k i , E) with A the eroded area, ME i the power flux delivered to a unit area of impinged surface, E the cumulative energy delivered to this area, and k i the material resistance vector consisting of parameters of the erosion progress function U. The erosion progress due to the polyfractional cavitation impingement is assumed to follow a superposition law described by a differential equation presented in the paper. Advantages and weakpoints of the approach are discussed.

A laboratory rig for studying aspects of worker exposure to bitumen fumes.

This study was performed to establish which factors related to the hot application of bitumen products are relevant to worker exposure to benzene-soluble matter (as part of the total fume emission) and to the polycyclic aromatic compound (PAH) content of bitumen fume. Because personal exposure measurements in field surveys can be influenced by many uncontrollable variables, a simple laboratory rig was developed in which bitumen fumes can be generated reproducibly under well-controlled conditions. Laboratory results were related to personal exposure measurements during asphalt paving and roofing. A quantitative relationship for predicting the laboratory fume emission was derived, with bitumen volatility and temperature the only variables. The variable part of the equation is termed the fuming index (FI). The FI correlates well with measured personal exposures in asphalt paving and in roofing and can be used to predict average personal exposures during these activities if bitumen volatility, application temperature, and for paving, the asphalt type, are known. The laboratory fumes, generated at a standard temperature of 160 degrees C, are representative for fumes emitted in the temperature range relevant for asphalt paving, those generated at 250 degrees C for roofing. The PAH profiles of the fumes collected as personal samples during asphalt paving and roofing operations were similar to those of the fumes generated in the laboratory from the same bitumen and at the same temperature. Because it produces conditions representative of actual bitumen operations, this laboratory set-up is an excellent tool for assessing bitumens in terms of fuming tendency and PAH emissions/exposures.

A Laboratory Rig for Studying Aspects of Worker Exposure to Bitumen Fumes

A Laboratory Rig for Studying Aspects of Worker Exposure to Bitumen Fumes

Influence of milking interval on the total bacterial count in a simulated automatic milking system.

An automatic milking system (AMS) uses a robot to attach the teatcups and can be continuously available for cows to present themselves to be milked with minimal human intervention. Milking in an AMS is therefore a continuous rather than a batch process, and the conventional practice of cleaning a milking system after each batch of cows has been milked is not applicable.Milk flow through an AMS is different in scale and in temporal distribution from that in a conventional system. These differences in flow patterns may be significant for hygiene. It has been suggested by Verheij (1992), for example, that milk will flush away much of the residue of the previous milking and that microbial growth will be retarded because of the bacteriostatic properties of fresh milk. Ordolff & Bölling (1992) reported experiments in which batches of milk were passed through a milking installation that was said to simulate an AMS. Their main conclusion was that milk residues left in the system for up to 60 min did not increase the bacterial contamination of the next batch of milk. However, the practical relevance of this conclusion is not clear because the design of the simulated AMS was not specified, so it can not be compared to a practical AMS. Moreover, mixtures of fresh and UHT milk were used, with unknown consequences. The purpose of the experiment reported in this paper was to strengthen the evidence on which to base recommendations for effective cleaning procedures for AMS.The bacterial count of milk that had been passed through a system was used as the indicator of the cleanliness of the system. It was apparent from previous work by Ordolff & Bölling (1992) that this would produce results that varied widely. The experiment was therefore designed to be as simple as possible. In particular, a simple, easily defined laboratory rig was used rather than an AMS.

99/00747 EU clean coal technology-co-combustion of coal and biomass

Apart from a more economical use of fossil fuels, the application of regenerative energy sources should be advanced in order to reduce CO 2 emissions. One of the alternatives considered to decrease the net emissions of CO 2 are the cultivation and combustion of solid biomass, or the thermal utilization of sewage sludge. There are different types of biomass which could be used as energy source in power production: (a) surplus and by-products from agricultural activities within the European Union (EU), e.g., straw, (b) fast growing energy plants from reutilization of areas which become available by a necessary reduction of agricultural overproduction within Europe, and (c) wood waste from forestry or wood processing. In order to achieve a noticeable CO 2 reduction, as well as fossil fuel substitution, it is desirable to use fairly large quantities of biomass for energy production. However, an exclusive biomass utilization would consequently lead to the construction of many decentralized plants, which is time-consuming and would require high financial investments as well as large storage capacities due to the seasonal fuel availability. Co-combustion, in contrast, is considered to be a cheap option for utilizing the existing biomass resources. For these reasons, an EU-project, 'Combined Combustion of Biomass/Sewage Sludge and Coals of High and Low Rank in Different Systems of Semi-industrial and Industrial Scale' was launched in 1993. Under the coordinatorship of the Institut fur Verfahrenstechnik und Dampfkesselwesen (IVD), University of Stuttgart, partners from eight European countries investigated the effects of burning sewage sludge, agricultural residuals, such as straw and manure, as well as especially cultivated energy plants in combination with coals of various ranks and origin. Both the pulverized fuel (PF) and the fluidized bed (FB) mode were tested, ranging from laboratory rigs to large scale utility boilers. This paper provides an overview of the activities of the various partners involved and will, in particular, show the synergetic cooperation towards a common aim. The results of the 2-yr project will be summarized.

EU clean coal technology—co-combustion of coal and biomass

Apart from a more economical use of fossil fuels, the application of regenerative energy sources should be advanced in order to reduce CO 2 emissions. One of the alternatives considered to decrease the net emissions of CO 2 are the cultivation and combustion of solid biomass, or the thermal utilization of sewage sludge. There are different types of biomass which could be used as energy source in power production: (a) surplus and by-products from agricultural activities within the European Union (EU), e.g., straw, (b) fast growing energy plants from reutilization of areas which become available by a necessary reduction of agricultural overproduction within Europe, and (c) wood waste from forestry or wood processing. In order to achieve a noticeable CO 2 reduction, as well as fossil fuel substitution, it is desirable to use fairly large quantities of biomass for energy production. However, an exclusive biomass utilization would consequently lead to the construction of many decentralized plants, which is time-consuming and would require high financial investments as well as large storage capacities due to the seasonal fuel availability. Co-combustion, in contrast, is considered to be a cheap option for utilizing the existing biomass resources. For these reasons, an EU-project, `Combined Combustion of Biomass/Sewage Sludge and Coals of High and Low Rank in Different Systems of Semi-industrial and Industrial Scale' was launched in 1993. Under the coordinatorship of the Institut fur Verfahrenstechnik und Dampfkesselwesen (IVD), University of Stuttgart, partners from eight European countries investigated the effects of burning sewage sludge, agricultural residuals, such as straw and manure, as well as especially cultivated energy plants in combination with coals of various ranks and origin. Both the pulverized fuel (PF) and the fluidized bed (FB) mode were tested, ranging from laboratory rigs to large scale utility boilers. This paper provides an overview of the activities of the various partners involved and will, in particular, show the synergetic cooperation towards a common aim. The results of the 2-yr project will be summarized.

In-plane Vibrations of Tyres and their Dependence on Wheel Mounting Conditions

A study of the small in-plane vibrations of a tyre and suspension system is reported. A laboratory rig, a measurement system, data processing, a mathematical model and parameter identification procedures are described. Results demonstrate good agreement between the model, based on a rigid ring representation of the tyre with a linear force/slip law and test results from the laboratory. The test results are repeatable and show system linearity, as indicated by high coherences. Model results are used to generate suspension system responses to road velocity variation forcing, for different mean road speeds. It is argued that these results are useful for suspension design and trouble shooting purposes.

Laboratory Distillation Column for Education on Process Control

A laboratory rig aimed at education on industrial computer control systems is presented. The laboratory installation consists of a small scale glass distillation column and related technological devices (evaporator, heat exchangers, tanks, pumps), equipped with measurement system (63 sensors) and control valves, connected to industrial programmable digital controllers. The controllers perform primary control tasks. More advanced algorithms (monitoring, MIMO control) are carried out at PC compatible industrial computers working in a network structure (linked with the primary controllers). The laboratory enables demonstration of different control problems, starting from the simple digital control design up to implementation of newest MIMO control techniques.