Computation of erosion in a hydro turbine

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Adel Ghenaiet
Keyword(s):  
Strong Dependence ◽  
Maintenance Cost ◽  
Pressure Side ◽  
Erosion Wear ◽  
Content Type ◽  
Hydro Turbine ◽  
Erosion Rates ◽  
Runner Blade ◽  
Sand Particles ◽  
The Impact

PurposeThis study aims to investigate the trajectories of sand particles and erosion wear in a hydraulic turbine model.Design/methodology/approachThe Lagrangian-based approach is used to track large numbers of sand particles and determine their impact through the hydro turbine components. The tracking procedure includes the stochastic eddy interaction model and the squeeze film effect. The number of particles, sizes and release positions are conformed to the particle concentration and size distribution. The impact locations, frequency and conditions of impacts are used to estimate the erosion rates and thereby the eroded mass from the distributor vane and the rotor blade and their deteriorated geometry.FindingsThe patterns of erosion in the stationary and rotating parts differ significantly and the effect of the initial position of the runner blade is elucidated. The distributor vane is characterized by a widespread of erosion over the pressure side. Typically, the surface beyond the throat and the root and tip junctions are the regions prone to erosion wear. The entry region of the runner blade is subject to a high number of impacts resulting in high erosion rates visible from the forepart of the blade pressure side.Practical implicationsThe erosion patterns and geometry deterioration may serve to evaluate the drop in the hydraulic performance and to select the appropriate surface coating to extend the lifetime of the turbomachinery parts and reduce the maintenance cost.Originality/valueErosion developments reveal a strong dependence on the blade position against the distributor vane and the particle size and concentration level.

A Procedure to Predict Solid Particle Erosion in Elbows and Tees

1995 ◽  
Vol 117 (1) ◽  
pp. 45-52 ◽  
Author(s):  
S. A. Shirazi ◽  
J. R. Shadley ◽  
B. S. McLaury ◽  
E. F. Rybicki
Keyword(s):  
Experimental Data ◽  
Impact Velocity ◽  
Erosion Rate ◽  
Operating Conditions ◽  
Fluid Viscosity ◽  
Erosion Rates ◽  
Sand Particles ◽  
Liquid Flows ◽  
The Impact ◽  
Sand Size

A semi-empirical procedure has been developed for predicting erosion rates in pipe geometries, such as elbows and tees. The procedure can be used to estimate safe operating conditions and velocities in oil and gas production where sand is present. In the proposed procedure, a concept is introduced that allows determination of erosion rate for different pipe geometries. In the procedure, based on empirical observations, the erosion rate is related to the impact velocity of sand particles on a pipe fitting wall. A simplified particle tracking model is developed and is used to estimate the impact velocity of sand particles moving in a stagnation region near the pipe wall. A new concept of equivalent stagnation length allows the simplified procedure to be applicable to actual pipe geometries. The “equivalent stagnation regions” of an elbow and a tee geometry of different sizes are obtained from experimental data for small pipe diameters, and a computational model is used to extend the procedure to larger pipe diameters. Currently, the prediction method applies to mild steel and accounts for the effects of sand size, shape, and density; fluid density, viscosity, and flow speed; and pipe size and shape. The proposed method has been verified for gas and liquid flows through several comparisons with experimental data reported in the literature. The results of the model accurately predict the effects of sand size and fluid viscosity observed in the experiments. Furthermore, predicted erosion rates showed good agreement with experimental data for gas, liquid, and gas-liquid flows in several 50.8-mm (2-in.) elbows and tees.

INFLUENCE OF THE IMPACT ANGLE OF A SOLID PARTICLE JET ON THE EROSION WEAR OF 38GSA AND HARDOX 500 STEEL

Tribologia ◽  
2017 ◽  
Vol 273 (3) ◽  
pp. 85-90 ◽  
Author(s):  
Bazyli KRUPICZ ◽  
Wojciech TARASIUK ◽  
Jerzy NAPIÓRKOWSKI ◽  
Krzysztof LIGIER
Keyword(s):  
Mechanical Properties ◽  
Kinetic Energy ◽  
Solid Particle ◽  
Quartz Sand ◽  
Impact Angle ◽  
Erosion Wear ◽  
Sand Particles ◽  
Work Of Deformation ◽  
The Impact

The paper investigated the influence of the impact angle of a solid particle jet on the erosion wear of 38GSA and Hardox 500 steel. The basis of the analysis was the assumption of the existence of a correlation between mechanical properties of the material, represented by the work of deformation (P) determined from the stressstrain diagram (U). The impact angle of quartz sand particles (30, 60, and 90 °) was considered through the separation of kinetic energy of particles impacting the eroded surface perpendicularly and tangentially.

Erosion wear performance of borax filled novel hybrid composites by using the Taguchi experimental design

2016 ◽  
Vol 68 (1) ◽  
pp. 134-140 ◽  
Author(s):  
Mehmet Bagci ◽  
Huseyin Imrek
Keyword(s):  
Erosion Rate ◽  
Hybrid Composites ◽  
Erosive Wear ◽  
Glass Fabric ◽  
Filler Materials ◽  
Erosion Wear ◽  
Reinforced Polymers ◽  
Content Type ◽  
Operational Conditions ◽  
Erosion Rates

Purpose – This study aims to examine solid particle erosion behavior of novel hybrid composite materials where borax (B2O3) particles (∼150 μm) were added to glass fabric and epoxy resin at an amount of 15 and 30 per cent. Design/methodology/approach – The tests that involved slightly rounded and irregular Al2O3 particles having two erodent sizes (200, 400 μm) were conducted at these operational conditions; namely, three impact velocities (23, 34, 53 m/s), two fabric directions (0/90/0, 45/−45/45) and three impingement angles (30°, 60°, 90°). In addition, the design of experiments, which utilizes Taguchi’s robust orthogonal arrays approach, was used and an optimum parameter combination was established, which had a minimum erosion rate. Moreover, scanning electron microscope and X-ray diffraction views show the visual effect of filler material. Findings – All test specimens regardless of their dissimilar characteristics displayed maximum erosion rate at 30° impingement angle. Test specimens with 45/−45/45 fabric direction are more wear-resistant than their counterparts with 0/90/0 fabric direction. The erosion wear of glass fabric reinforced epoxy (GF/EP) composites whose matrix had 15 per cent addition of borax particles was higher than that of neat GF/EP composites. In addition, new composite material formed by including borax particles at a rate of 30 per cent of resin leads to a reduction in erosion rates. Originality/value – While fabric-reinforced polymers take place in most of the studies conducted on erosive wear of composites, studies involving erosion on composites with filler materials can hardly be encountered.

scholarly journals The effects of COVID-19 on job security and unemployment in Portugal

2020 ◽  
Vol 40 (9/10) ◽  
pp. 995-1003
Author(s):  
Fernando Almeida ◽  
José Duarte Santos
Keyword(s):  
Labor Market ◽  
Strong Dependence ◽  
Age Groups ◽  
Job Security ◽  
Strong Impact ◽  
Security Model ◽  
Multiple Perspectives ◽  
Content Type ◽  
Geographical Regions ◽  
The Impact

PurposeThis short communication aims to explore and synthesize the main effects of COVID-19 on the labor market in Portugal regarding the dimensions related to job security and unemployment.Design/methodology/approachField research is used to identify and understand the challenges posed by the COVID-19 pandemic to the labor market in Portugal. Data from the National Institute of Statistics of Portugal are analyzed and compared with artifacts published in the field, which allow us to explore the impact of this phenomenon from multiple perspectives.FindingsThe findings indicate that the impact on the labor market is very asymmetric regarding geographical regions, sectors of activity, age groups and the nature of labor ties. The most touristic regions and those with a strong dependence on the exterior are the most affected. Young people and women with unstable employment relationships and in temporary work situations are also particularly vulnerable.Originality/valueThis study focuses on an emerging area with a strong impact of the COVID-19 pandemic on the labor market. This study seeks both to identify challenges in the Portuguese labor market and to discuss measures that should be taken to mitigate their effects, such as reforming the social security model, the role of teleworking or the more balanced development of the territory.

Maintenance scheduling based on PROMETHEE method in conjunction with group technology philosophy

2018 ◽  
Vol 35 (7) ◽  
pp. 1423-1444 ◽  
Author(s):  
Abdelhakim Abdelhadi
Keyword(s):  
Preventive Maintenance ◽  
Group Technology ◽  
Spare Parts ◽  
Strategic Decision ◽  
Maintenance Cost ◽  
Manufacturing Strategy ◽  
Content Type ◽  
Clustering Problem ◽  
Promethee Method ◽  
The Impact

Purpose The purpose of this paper is to implement a strategic decision-making framework by selecting clusters of maintainable machines and scheduling their maintenance as part of a company’s manufacturing strategy. Design/methodology/approach Multi-criteria clustering problem in conjunction with the application of a group technology is used to establish clusters of maintainable machines based on their need for maintenance according to the type of failures they can encounter. Findings Using the concept of group technology in conducting preventive maintenance will result in the grouping of machines according to the impact of a failure based on the criteria specified by the decision makers. Accordingly, it will facilitate the process of executing the maintenance itself by ordering spare parts and informing the maintenance personnel which will lead to minimize the maintenance cost. Originality/value The results presented in this paper are reliable, objective may be used to minimize the total cost of conducting preventive maintenance in a manufacturing environment.

ABRASIVE EROSION STUDY ON S45C CARBON STEEL USING SAND BLASTING TECHNIQUE

2016 ◽  
Vol 23 (05) ◽  
pp. 1650035 ◽  
Author(s):  
MUHAMMAD YASIN NAZ ◽  
NOOR ILYANA ISMAIL ◽  
SHAHARIN ANWAR SULAIMAN ◽  
SHAZIA SHUKRULLAH
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Mild Steel ◽  
Impact Angle ◽  
Sand Blasting ◽  
Erosion Rates ◽  
Depth Analysis ◽  
Sand Particles ◽  
The Impact ◽  
Scanning Electron

Hydrocarbon fluids recovered from the reservoir are inevitably polluted with sand particles. Sanding is a source of several flow assurance problems in oil and gas industry. This study was aimed at investigating the effect of sand size and impact angle on the mild steel erosion by using a laboratory built sand blasting technique. S45C mild steel coupons were eroded with 45 [Formula: see text]m and 150[Formula: see text][Formula: see text]m sand particles for fixed exposure time of 1 h. Although in-depth analysis revealed an increase in surface erosion with the particle size, the fine sand also notably damaged the metal surface. Topographic scanning electron microscopy (SEM) and universal scanning electron microscopy (USPM) micrographs of the steel coupons showed significantly large difference between the peak and bottom of the eroded samples as compared to the blank coupon. The erosion rates calculated for 45 and 150 [Formula: see text]m sand particles were found in the range of 6.47[Formula: see text]mm/year to 6.84 mm/year and 8.31 mm/year to 8.79 mm/year, respectively. Additionally, a good agreement was seen among the erosion rates calculated using USPM and weight loss methods. The erosion rates calculated for coarse sand at 45[Formula: see text] and 90[Formula: see text] were found in the range of 4.58 mm/year to 4.72 mm/year and 8.31 mm/year to 8.79 mm/year, respectively. A large difference between the angle dependent erosion rates revealed a strong influence of the impact angle on erosion of the flow-lines.

An improved imperfect maintenance strategy for multiperiod randomly failing equipment with stochastic repair times

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Sofiene Dellagi ◽  
Mohamed Noomane Darghouth
Keyword(s):  
Failure Rate ◽  
Planning Horizon ◽  
Maintenance Cost ◽  
Equipment Failure ◽  
Maintenance Strategy ◽  
Imperfect Maintenance ◽  
Maintenance Policy ◽  
Content Type ◽  
Proposed Model ◽  
The Impact

PurposeIn this paper, a maintenance strategy based on improved imperfect maintenance actions with stochastic repair times for multiperiod randomly failing equipment is developed. The main objective is to minimize the total maintenance cost by jointly finding the optimal preventive maintenance (PM) cycle and planning horizon.Design/methodology/approachA model based on the mathematical theory of reliability is developed to minimize the total maintenance cost by jointly finding the optimal couple: PM cycle T* and planning horizon H*. The proposed model aims to characterize the evolutionary impact of imperfect PM actions on the equipment failure rate and the resulting mean number of failures. The conventional threshold accepting (TA) algorithm is implemented to solve the proposed model. A numerical example for a given set of input parameters is presented in order to show the usefulness of the proposed model. A sensitivity analysis of some of the key parameters is performed to demonstrate the coherence of the developed maintenance policy.FindingsThe obtained results showed a sensitive trade-off between PM frequency and the total maintenance cost. Performing PM actions more frequently helps significantly to reduce the expected number of corrective maintenance actions and the corresponding total cost. It has also been found that improving the efficiency of the PM actions allows for maintaining the equipment less frequently by increasing the time between successive PM actions.Research limitations/implicationsGiven the complexity of the objective function to be minimized and the stochastic nature of the model's parameters, the authors limited this study to equally cyclic production periods over the planning horizon.Practical implicationsThe present model aims to provide an integrated maintenance/production comprehensive framework to assist planners in establishing maintenance schedules considering multiperiod randomly failing production systems and the evolutionary impact of imperfect PM actions on the equipment failure rate.Originality/valueContrary to the majority of existing works in the literature dealing with maintenance strategies, the authors consider that repair times are stochastic to provide a more realistic framework. In addition, the developed model considers the impact of imperfect maintenance on the equipment's mean time to failure. Thus, the evolutionary impact of imperfect PM actions on the equipment failure rate and the resulting mean number of failures is characterized. Simultaneously, the production planning horizon along with the length of each PM cycle is optimized in order to minimize the total maintenance cost over the planning horizon.

Modeling the effect of entrained sand particles on pressure transverse in a flowing gas well

2017 ◽  
Vol 14 (5) ◽  
pp. 406-413 ◽  
Author(s):  
Adesina Fadairo ◽  
Olusegun Oyedele-Adeyi ◽  
Adebowale Oladepo ◽  
Temitope Ogunkunle
Keyword(s):  
Pressure Drop ◽  
Solid Particles ◽  
Kinetic Term ◽  
Production Time ◽  
Gas Well ◽  
Pressure Transient ◽  
Content Type ◽  
Wellbore Pressure ◽  
Sand Particles ◽  
The Impact

Purpose The purpose of this study showcase a realistic model for estimating pressure drop at any production time in any location along the vertical flowing solid-gas well. Also to simulate the impact of solid particles on the pressure transient in gas well. The production of natural gas from the reservoir is always associated with entrained solid particle of different sizes, mainly sand particles and crystalline salts. Entrained solid transport along the gas phase has been a great concern for gas production engineer, as the detrimental consequences are often associated to desirable high operational parameters, such as rate and pressure transverse in producing well. Design/methodology/approach A variety of early models for predicting pressure transverse in gas wells were based on steady state flow equation that did not consider time factor, which results in inaccuracy at early production time. Some of the early investigators overlooked the effect of the solid on the pressure transverse phenomena in a gas well. Hence, there is a need for developing a model for estimating pressure transverse at all times in solid–gas well. This study presents an equation for pressure drop in flowing vertical well without neglecting any term in the momentum equation by the inclusion of accumulation and kinetic term. Findings The solution of the resulting differential equation gives functional relationship between solid–gas flow rates and pressure at any point in flowing well at any given production time. The results show improvement over previous studies, as the assumptions previously neglected were all considered. Originality/value A more realistic result that includes the initial unsteadiness phenomenon is obtained; hence, predicting pressure transient at any given production time has been established for both gas that flows along with solid particles and gas without particles. At the onset of production, the effect of all possible wellbore pressure losses is highly pronounced and decreased as the production time increases. The newly developed model, however, can be used at all depths. The effect of using the Sukkar and Cornell model is extremely adverse for the calculation of other parameters, such as flow rate, and carrying out economic analysis.

The More Control, the Better?

2014 ◽  
Vol 26 (2) ◽  
pp. 81-91 ◽  
Author(s):  
Jeeyun Oh ◽  
Mun-Young Chung ◽  
Sangyong Han
Keyword(s):  
Mixed Design ◽  
Negative Effects ◽  
Story Structure ◽  
Content Type ◽  
High User ◽  
User Control ◽  
Rigorous Research ◽  
Control Versus ◽  
The Media ◽  
The Impact

Despite of the popularity of interactive movie trailers, rigorous research on one of the most apparent features of these interfaces – the level of user control – has been scarce. This study explored the effects of user control on users’ immersion and enjoyment of the movie trailers, moderated by the content type. We conducted a 2 (high user control versus low user control) × 2 (drama film trailer versus documentary film trailer) mixed-design factorial experiment. The results showed that the level of user control over movie trailer interfaces decreased users’ immersion when the trailer had an element of traditional story structure, such as a drama film trailer. Participants in the high user control condition answered that they were less fascinated with, absorbed in, focused on, mentally involved with, and emotionally affected by the movie trailer than participants in the low user control condition only with the drama movie trailer. The negative effects of user control on the level of immersion for the drama trailer translated into users’ enjoyment. The impact of user control over interfaces on immersion and enjoyment varies depending on the nature of the media content, which suggests a possible trade-off between the level of user control and entertainment outcomes.

Expected maintenance waste reduction benefits after implementation of Just in Time (JIT) philosophy in maintenance (a statistical analysis)

2019 ◽  
Vol 25 (1) ◽  
pp. 25-40 ◽  
Author(s):  
Sandeep Phogat ◽  
Anil Kumar Gupta
Keyword(s):  
Data Interpretation ◽  
General Information ◽  
Spare Parts ◽  
Waste Reduction ◽  
Maintenance Cost ◽  
Just In Time ◽  
Content Type ◽  
Great Saving ◽  
Research Findings ◽  
Structured Questionnaire

Purpose The maintenance department of today, like many other departments, is under sustained pressure to slash costs, show outcome and support the assignment of the organization, as it is a commonsensical prospect from the business perspective. The purpose of this paper is to examine expected maintenance waste reduction benefits in the maintenance of organizations after the implementation of just-in-time (JIT) managerial philosophy. For this, a structured questionnaire was designed and sent to the 421 industries in India. Design/methodology/approach The designed questionnaire was divided into two sections A and B to assist data interpretation. The aim of the section A was to build general information of participants, type of organization, number of employees, annual turnover of the organization, etc. Section B was also a structured questionnaire developed based on a five-point Likert scale. The identified critical elements of the JIT were included in the questionnaire to identify the maintenance waste reduction benefits in the maintenance of organizations. Findings On the basis of the 133 responses, hypothesis testing was done with the help of Z-test, and it was found out that in maintenance, we can reduce a large inventory of spare parts and also shorten the excessive maintenance activities due to the implementation of JIT philosophy. All the four wastes: waste of processing; waste of rejects/rework/scrap in case of poor maintenance; waste of the transport of spares, and waste of motion, have approximately equal weightage in their reduction. Waste of waiting for spares got the last rank, which showed that there are little bit chances in the reduction of waiting for spares after the implementation of JIT philosophy in maintenance. Practical implications The implication of the research findings for maintenance of organizations is that if maintenance practitioners implement elements of JIT philosophy in maintenance then there will be a great reduction in the maintenance wastes. Originality/value This paper will be abundantly useful for the maintenance professionals, researchers and others concerned with maintenance to understand the significance of JIT philosophy implementation to get the expected reduction benefits in maintenance wastes of organizations which will be helpful in the great saving of maintenance cost and time side by side great increment in the availability of machines.

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