Rainwater propeller pumps structural integrity

2019 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Sergiu Valentin Galatanu ◽  
Sebastian Muntean ◽  
Liviu Marsavina ◽  
Iulian Ionut Ailinei ◽  
Dan Micota
Keyword(s):  
Shear Stress ◽  
Structural Integrity ◽  
Maximum Shear Stress ◽  
Operating Time ◽  
Operation Time ◽  
Technical Solution ◽  
Catastrophic Events ◽  
Impeller Blade ◽  
Content Type ◽  
Technical Solutions

Purpose The purpose of this paper is to focus on the structural integrity of the rainwater propeller pumps installed in the municipal wastewater treatment plant (WTP). Design/methodology/approach A numerical analysis is performed to determine the maximum shear stress on the fasten bolts. The rainwater propeller pump is examined in operation at normal conditions and when one blade is progressively blocked. Findings The failure mechanism of the rainwater pump impeller is determined. Research limitations/implications The fibbers and wastes are discharged together with rainwater during storms with these types of pumps to avoid the flood of the WTP. Several catastrophic events have occurred in service due to the fibbers clog the gap between the impeller blades and the pump casing. The clogging process is partially understood so actual technical solutions deal with effects rather the main causes. Practical implications The operation time of all seven rainwater pumps installed in Timisoara’s WTP is investigated. Climate changes in Banat region and new waste properties found in the wastewater require appropriate technical solutions. A technical solution is proposed based on these investigations to extend the operation time and to diminish the operation and maintenance costs. Social implications These large pumps are installed in the urban sewage centralised system implemented in the most cities. The access to the sewerage network is a requirement of any community, regardless of the social status. Originality/value The fracture surfaces of both fastening bolts of the rainwater pump impellers produced in service are examined. As a result, it has been identified that the catastrophic events are due to the brittle fracture of both fasten bolts between the impeller blades and the pump hub, respectively. The catastrophic events of the rainwater propeller pumps are directly correlated to the clog level of the impeller. The numerical simulation is performed to determine the maximum shear stress on the fasten bolts. The case with pump operating at normal conditions is performed identifying its vulnerabilities to clog conditions. Next, one impeller blade is progressively blocked considering three time stop scenarios associated with different clog levels. Conclusively, the operating time of the rainwater pump up to the catastrophic failure is correlated to the clog level of the impeller.

scholarly journals Integrity Analysis of the Rainwater Pump Impeller

2018 ◽  
Vol 188 ◽  
pp. 04005 ◽  
Author(s):  
Sergiu-Valentin Galatanu ◽  
Sebastian Muntean ◽  
Liviu Marsavina ◽  
Dan Micota ◽  
Ionel Draghici
Keyword(s):  
Shear Stress ◽  
Numerical Analysis ◽  
Brittle Fracture ◽  
Maximum Shear Stress ◽  
Catastrophic Failure ◽  
Catastrophic Events ◽  
Pump Impeller ◽  
Impeller Blade ◽  
Integrity Analysis

The purpose of this paper is to examine the failure problems encountered during the operation of the rainwater pump impellers installed in a wastewater station. The rainwater pumps are specially designed to operate in wastewater plants. The fibbers and wastes are discharged together with rainwater during storms with this type of pumps to avoid the flood of the wastewater station. Several problems have occurred in service due to the fibbers clog the gap between the impeller blades and the pump casing. The analysis of the catastrophic events associated to the rainwater pumps installed in a wastewater station is performed. As a result, it has been identified that the catastrophic events are due to the brittle fracture of the fasten bolts connecting the impeller blades and the pump hub, respectively. Analytical and numerical analysis were perform in order to determine the maximum shear stress on the fasten bolts. As a conclusion the partial clogging of the gap between one impeller blade and pump casing, inducing the lock of the blade and leading to catastrophic failure.

EFFECT OF OPERATING TIME OF THE WELLS IN THE STEADY DRAINAGE MODE BEFORE STOPPING ON THE RESULTS OF THE STUDY OF PRESSURE BUILD-UP CURVES

2017 ◽  
pp. 48-50
Author(s):  
E. F. Gilfanov
Keyword(s):  
Operating Time ◽  
Previous History ◽  
Operation Time ◽  
Pressure Recovery ◽  
Recovery Curve ◽  
History Of ◽  
Accuracy Of Results ◽  
Theoretical Pressure

Operation time of the well before stopping for investigating the pressure recovery curve in hydrodynamic studies is an important parameter affecting the quality and accuracy of results of research processing. Comparing the actual and theoretical pressure curves and the derivative, it’s possible to eliminate the uncertainty in the choice of previous history of the well operation.

scholarly journals Risk Assessment Framework to Avoid Serial Failure for New Technical Solutions Applied to the Construction of a CLT Structure Resilient to Climate

Buildings ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 247
Author(s):  
Charlotte Svensson Tengberg ◽  
Carl-Eric Hagentoft
Keyword(s):  
Risk Assessment ◽  
Success Factors ◽  
Real Life ◽  
Qualitative Assessment ◽  
Technical Solution ◽  
Functional Requirements ◽  
Assessment Framework ◽  
Construction Period ◽  
Design Build ◽  
Technical Solutions

Design-build contractors are challenged with the task of minimizing failure risks when introducing new technical solutions or adapting technical solutions to new conditions, e.g., climate change. They seem to have a disproportional trust in suppliers and their reference cases and might not have adequate resources or methodologies for sufficient evaluation. This creates the potential for serial failures to spread in the construction industry. To mitigate this, it was suggested that a predefined risk assessment framework should be introduced with the aim of providing a prequalification and requirements for the use of the technical solution. The objectives of this paper are to develop a comprehensive risk assessment framework and to explore the framework’s potential to adequately support the design-build contractor’s decisions. The framework uses qualitative assessment, relying on expert workshops and quantitative assessments, with a focus on simulation and probabilities. Tollgates are used to communicate risk assessments to the contractor. The framework is applied to a real-life case study of construction with a CLT-structure for a Swedish design-build contractor, where exposure to precipitation during construction is a key issue. In conclusion, the chosen framework was successful in a design-build contractor context, structuring the process and identifying difficulties in achieving the functional requirements concerning moisture. Three success factors were: documentation and communication, expert involvement, and the use of tollgates. Recommendations to the design-build contractor on construction of CLT structure are to keep construction period short and to use full weather protection on site.

scholarly journals Studying the performance of fully encapsulated rock bolts with modified structural elements

2021 ◽  
Author(s):  
Jianhang Chen ◽  
Hongbao Zhao ◽  
Fulian He ◽  
Junwen Zhang ◽  
Kangming Tao
Keyword(s):  
Shear Stress ◽  
Load Transfer ◽  
Maximum Shear Stress ◽  
Coupling Model ◽  
Numerical Approach ◽  
Rock Bolt ◽  
Structural Elements ◽  
Rock Bolts ◽  
Two Stage ◽  
Bolt Diameter

AbstractNumerical simulation is a useful tool in investigating the loading performance of rock bolts. The cable structural elements (cableSELs) in FLAC3D are commonly adopted to simulate rock bolts to solve geotechnical issues. In this study, the bonding performance of the interface between the rock bolt and the grout material was simulated with a two-stage shearing coupling model. Furthermore, the FISH language was used to incorporate this two-stage shear coupling model into FLAC3D to modify the current cableSELs. Comparison was performed between numerical and experimental results to confirm that the numerical approach can properly simulate the loading performance of rock bolts. Based on the modified cableSELs, the influence of the bolt diameter on the performance of rock bolts and the shear stress propagation along the interface between the bolt and the grout were studied. The simulation results indicated that the load transfer capacity of rock bolts rose with the rock bolt diameter apparently. With the bolt diameter increasing, the performance of the rock bolting system was likely to change from the ductile behaviour to the brittle behaviour. Moreover, after the rock bolt was loaded, the position where the maximum shear stress occurred was variable. Specifically, with the continuous loading, it shifted from the rock bolt loaded end to the other end.

L'uretere retrocavale: Embriogenesi e correzione laparoscopica con accesso retroperitoneale in un caso ad ansa bassa

1997 ◽  
Vol 64 (1_suppl) ◽  
pp. 18-22
Author(s):  
C. Trombetta ◽  
G. Savoca ◽  
G. Liguori ◽  
M. Raber ◽  
A. Lissiani ◽  
...  
Keyword(s):  
Operating Time ◽  
Oral Intake ◽  
Operation Time ◽  
Ureteral Stent ◽  
Surgical Wound ◽  
Extraperitoneal Approach ◽  
Intravenous Urogram ◽  
Minimal Morbidity ◽  
Urologic Surgery ◽  
Laparoscopic Techniques

With the minimal morbidity attained using laparoscopy, its application in urologic surgery has been increasing. Using laparoscopic techniques we successfully completed the transposition and re-anastomosis of a retrocaval right ureter. Operation time was 240 minutes. The patient was allowed to walk on the first post-operative day and resumed oral intake on the second day. Administration of analgesics was not required. The ureteral stent was removed on the 24th day after operation. An intravenous urogram three months after operation showed a decrease in hydronephrosis. Laparoscopic correction of retrocaval ureter by extraperitoneal approach is a safe, feasible technique, avoiding a large surgical wound with the definite advantage of minimal disfigurement. Operating time is considerably shorter compared to the peritoneal approach as described by Baba (240’ vs 560’).

Flow and Thermal Fields in a Pendant Droplet Moving on Lyophobic Surface

2010 ◽  
Author(s):  
Basant Singh Sikarwar ◽  
K. Muralidhar ◽  
Sameer Khandekar
Keyword(s):  
Heat Transfer ◽  
Contact Angle ◽  
Reynolds Number ◽  
Shear Stress ◽  
Heat Transfer Coefficient ◽  
Wall Shear Stress ◽  
Transfer Coefficient ◽  
Maximum Shear Stress ◽  
Computational Domain ◽  
Wall Shear

Clusters of liquid drops growing and moving on physically or chemically textured lyophobic surfaces are encountered in drop-wise mode of vapor condensation. As opposed to film-wise condensation, drops permit a large heat transfer coefficient and are hence attractive. However, the temporal sustainability of drop formation on a surface is a challenging task, primarily because the sliding drops eventually leach away the lyophobicity promoter layer. Assuming that there is no chemical reaction between the promoter and the condensing liquid, the wall shear stress (viscous resistance) is the prime parameter for controlling physical leaching. The dynamic shape of individual droplets, as they form and roll/slide on such surfaces, determines the effective shear interaction at the wall. Given a shear stress distribution of an individual droplet, the net effect of droplet ensemble can be determined using the time averaged population density during condensation. In this paper, we solve the Navier-Stokes and the energy equation in three-dimensions on an unstructured tetrahedral grid representing the computational domain corresponding to an isolated pendant droplet sliding on a lyophobic substrate. We correlate the droplet Reynolds number (Re = 10–500, based on droplet hydraulic diameter), contact angle and shape of droplet with wall shear stress and heat transfer coefficient. The simulations presented here are for Prandtl Number (Pr) = 5.8. We see that, both Poiseuille number (Po) and Nusselt number (Nu), increase with increasing the droplet Reynolds number. The maximum shear stress as well as heat transfer occurs at the droplet corners. For a given droplet volume, increasing contact angle decreases the transport coefficients.

Design and topological optimization of rear pressure bulkhead for a typical aircraft

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Marshal Thakran ◽  
Meenakshi ◽  
Jitender Sharma ◽  
Charles Gilbert Martin
Keyword(s):  
Numerical Analysis ◽  
Significant Influence ◽  
Design Methodology ◽  
Structural Integrity ◽  
Topological Optimization ◽  
Content Type ◽  
Iterative Design ◽  
Practical Implications ◽  
Insight Into ◽  
Selection Of

Purpose The purpose of this paper is to evaluate the model of a rear pressure bulkhead with different design optimizations to meet the pressurized cabin requirements of an aircraft. Design/methodology/approach This paper presents the results of the static analysis of a dome-shaped rear pressure bulkhead model designed in Catia-v5. Numerical analysis of model meshed in hyper-mesh and solved using Opti-Struct for iterative design optimizations. Findings All the iterative models are analyzed at 9 Psi. Rear pressure bulkhead designed with L-section stringer shows better results than the model optimized with T-section stringer for the same thickness. The model optimized with L-shaped stinger also reduces the weight of the bulkhead without affecting the structural integrity. Practical implications It has been concluded in this paper that the selection of specific shapes of the stringers shows a significant influence on weight reduction. Originality/value This paper provides a topical, technical insight into the design and development of a rear pressure bulkhead. It also outlines the future development of dome-shaped rear pressure bulkhead.

Corrosion resistance and mechanical characteristics of dual-phase steel B500c, after shot blasting processes

2017 ◽  
Vol 8 (5) ◽  
pp. 544-564
Author(s):  
Argyro Drakakaki ◽  
Charis Apostolopoulos ◽  
Alexandros Katsaounis ◽  
Hasa Bjorn
Keyword(s):  
Corrosion Resistance ◽  
Chemical Composition ◽  
Dual Phase Steel ◽  
Structural Integrity ◽  
Positive Impact ◽  
Electrochemical Techniques ◽  
Dual Phase ◽  
Shot Blasting ◽  
Production Mode ◽  
Content Type

Purpose Corrosive agent constitutes a major problem for constructions located in coastal areas, since it keeps affecting their durability. This phenomenon, in synergy with moisture and high temperatures, leads to premature deterioration of the structures. Under these conditions, the need for management of the problem of resistance of steel against corrosion is an issue of paramount importance and a challenge to the structural integrity and reliability. The paper aims to discuss these issues. Design/methodology/approach The need for management of the problem of resistance of steel against corrosion is an issue of paramount importance and a challenge to the structural integrity and reliability. In the present study, an effort was made to increase the corrosion resistance of the high strength and ductility dual-phase steel B500c category, with the use of different shot blasting processes, without any interference in the chemical composition or in the production mode. In particular, shot blasting treatment was used for both cleaning and creating compressive stresses on the surface of steel bars, according to the pertinent protocols. The modified samples were studied via both conventional characterization methods and electrochemical techniques. Findings Through the whole surface treatment process of B500c steel, a positive impact came about not only the corrosion resistance, but also the mechanical performance. Originality/value Shot blasting process aims to increase the corrosion resistance of high ductility dual-phase steel (B500c), without any interference in the chemical composition or in the production mode.

Variable viscosity effects on third-grade liquid flow in post-treatment analysis of wire coating in the presence of nanoparticles

2018 ◽  
Vol 28 (10) ◽  
pp. 2423-2441 ◽  
Author(s):  
B. Mahanthesh ◽  
B.J. Gireesha ◽  
M. Archana ◽  
Tasawar Hayat ◽  
Ahmed Alsaedi
Keyword(s):  
Shear Stress ◽  
Numerical Solutions ◽  
Volume Fraction ◽  
Variable Viscosity ◽  
Post Treatment ◽  
Third Grade ◽  
Coating Process ◽  
Wire Surface ◽  
Content Type ◽  
Wire Coating

Purpose The features of coated wire product are measured by the flow and heat transport occurring in the interior of dies. Therefore, an understanding of characteristics of polymers momentum, heat mass transfer and wall shear stress is of great interest. Enhancement of heat transfer rate is fundamental need of wire coating process. Therefore, this study aims to investigate the effect of suspended nanoparticles in heat and mass transport phenomena of third-grade liquid in post-treatment of wire coating process. Buongiorno model for nanofluid is adopted. Two cases of temperature dependent viscosity are considered. Design/methodology/approach The governing equations are modelled with the help of steady-state conservation equations of mass, momentum, energy and nanoparticle concentration. Some appropriate dimensionless variables are introduced. Numerical solutions for the nonlinear problem are developed through Runge–Kutta–Fehlberg technique. The outcome of sundry variables for dimensionless flow, thermal and nanoparticle volume fraction fields are scrutinised through graphical illustrations. Findings The study’s numerical results disclose that the force on the total wire surface and shear stress at the surface in case of Reynolds Model dominate Vogel’s Model case. Impact of nanoparticles is constructive for force on the total wire surface and shear stress at the surface. The velocity of the coating material can be enhanced by the non-Newtonian property. Practical implications This study may provide useful information to improve the wire coating technology. Originality/value Effect of nanoparticles in wire coating analysis by using Brownian motion and thermophoresis slip mechanisms is investigated for the first time. Two different models for variable viscosity are used.

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