Paper 5: Considerations of Similarity for Hydroelastic Vibrations

1966 ◽  
Vol 181 (1) ◽  
pp. 25-31
Author(s):  
W. A. Lecher
Keyword(s):  
Measured Data ◽  
Model Tests ◽  
Point Of View ◽  
Operating Conditions ◽  
Ratio Model ◽  
Critical Component ◽  
Dynamic Stresses ◽  
Guide Vanes ◽  
Full Size ◽  
Hydroelastic Vibrations

In order to achieve the highest reliability in operation of large hydraulic turbo-machines, it is essential, amongst other things, to determine the magnitude not only of the static but also of the dynamic stresses under all operating conditions. The adjustable guide vanes of reversible turbine-pumps, for example, form a particularly critical component from the point of view of dynamic stresses, especially during pumping operations. This paper deals with the possibilities of predicting resonance conditions and of obtaining the magnitude of dynamic stresses in full-size machines on the basis of tests on model machines. The laws of similarity for forced and self-excited vibrations as well as vibrations in resonance are derived. It is shown that all kinds of hydraulically excited vibrations can be examined by model tests. It is permissible to carry out these measurements under reduced test head, provided that for the tested components different materials are used for the model and full-scale machine, and that the head ratio model-prototype is chosen accordingly. Suitable materials for model tests are recommended. The evaluation of the dynamic stresses for the full-size machine, based on the measured data of model tests, is shown for resonant and non-resonant conditions. Further, as an example, vibration investigations are described on the movable guide vanes of a pump-turbine, that is, using the derived laws of similarity.

Tertiary Nitrification Pilot Plants on Parisian Waste Water

1990 ◽  
Vol 22 (1-2) ◽  
pp. 347-352 ◽  
Author(s):  
C. Paffoni ◽  
B. Védry ◽  
M. Gousailles
Keyword(s):  
Waste Water ◽  
Metropolitan Area ◽  
Fixed Bed ◽  
Point Of View ◽  
Operating Conditions ◽  
Research Center ◽  
Daily Output ◽  
Practical Point ◽  
Fixed Bed Reactors

The Paris Metropolitan area, which contains over eight million inhabitants, has a daily output of about 3 M cu.meters of wastewater, the purification of which is achieved by SIAAP (Paris Metropolitan Area Sewage Service) in both Achères and Valenton plants. The carbon pollution is eliminated from over 2 M cu.m/day at Achères. In order to improve the quality of output water, its tertiary nitrification in fixed-bed reactors has been contemplated. The BIOFOR (Degremont) and BIOCARBONE (OTV) processes could be tested in semi-industrial pilot reactors at the CRITER research center of SIAAP. At a reference temperature of 13°C, the removed load is approximately 0.5 kg N NH4/m3.day. From a practical point of view, it may be asserted that in such operating conditions as should be at the Achères plant, one cubic meter of filter can handle the tertiary nitification of one cubic meter of purified water per hour at an effluent temperature of 13°C.

Fully Parametric High-Fidelity CFD Model for the Design Optimisation of the Cyclic Stagger Pattern of a Set of Fan Outlet Guide Vanes

2009 ◽  
Author(s):  
Andrea Milli ◽  
Olivier Bron
Keyword(s):  
Complex Geometry ◽  
Single Point ◽  
Sensitivity Study ◽  
Operating Conditions ◽  
High Fidelity ◽  
Cfd Model ◽  
Design Optimisation ◽  
Guide Vanes ◽  
High Loss ◽  
Design Variables

The present paper deals with the redesign of cyclic variation of a set of fan outlet guide vanes by means of high-fidelity full-annulus CFD. The necessity for the aerodynamic redesign originated from a change to the original project requirement, when the customer requested an increase in specific thrust above the original engine specification. The main objectives of this paper are: 1) make use of 3D CFD simulations to accurately model the flow field and identify high-loss regions; 2) elaborate an effective optimisation strategy using engineering judgement in order to define realistic objectives, constraints and design variables; 3) emphasise the importance of parametric geometry modelling and meshing for automatic design optimisation of complex turbomachinery configurations; 4) illustrate that the combination of advanced optimisation algorithms and aerodynamic expertise can lead to successful optimisations of complex turbomachinery components within practical time and costs constrains. The current design optimisation exercise was carried out using an in-house set of software tools to mesh, resolve, analyse and optimise turbomachinery components by means of Reynolds-averaged Navier-Stokes simulations. The original configuration was analysed using the 3D CFD model and thereafter assessed against experimental data and flow visualisations. The main objective of this phase was to acquire a deep insight of the aerodynamics and the loss mechanisms. This was important to appropriately limit the design scope and to drive the optimisation in the desirable direction with a limited number of design variables. A mesh sensitivity study was performed in order to minimise computational costs. Partially converged CFD solutions with restart and response surface models were used to speed up the optimisation loop. Finally, the single-point optimised circumferential stagger pattern was manually adjusted to increase the robustness of the design at other flight operating conditions. Overall, the optimisation resulted in a major loss reduction and increased operating range. Most important, it provided the project with an alternative and improved design within the time schedule requested and demonstrated that CFD tools can be used effectively not only for the analysis but also to provide new design solutions as a matter of routine even for very complex geometry configurations.

The Role of Offshore Monitoring in an Effective Deepwater Riser Integrity Management Program

2007 ◽  
Author(s):  
Brittany Goldsmith ◽  
Elizabeth Foyt ◽  
Madhu Hariharan
Keyword(s):  
Failure Modes ◽  
Human Life ◽  
Management Program ◽  
Measured Data ◽  
Operating Conditions ◽  
Environmental Damage ◽  
Positioning Systems ◽  
Integrity Management ◽  
Deepwater Riser

As offshore field developments move into deeper water, one of the greatest challenges is in designing riser systems capable of overcoming the added risks of more severe environments, complicated well requirements and uncertainty of operating conditions. The failure of a primary riser component could lead to unacceptable consequences, including environmental damage, lost production and possible injury or loss of human life. Identification of the risks facing riser systems and management of these risks are essential to ensure that riser systems operate without failure. Operators have recognized the importance of installing instrumentation such as global positioning systems (GPS), vessel motion measurement packages, wind and wave sensors and Acoustic Doppler Current Profiler (ADCP) units to monitor vessel motions and environmental conditions. Additionally, high precision monitoring equipment has been developed for capturing riser response. Measured data from these instruments allow an operator to determine when the limits of acceptable response, predicted by analysis or determined by physical limitations of the riser components, have been exceeded. Regular processing of measured data through automated routines ensures that integrity can be quickly assessed. This is particularly important following extreme events, such as a hurricane or loop current. High and medium alert levels are set for each parameter, based on design analysis and operating data. Measured data is compared with these alert levels, and when an alert level is reached, further response evaluation or inspection of the components in question is recommended. This paper will describe the role of offshore monitoring in an integrity management program and discuss the development of alert levels based on potential failure modes of the riser systems. The paper will further demonstrate how this process is key for an effective integrity management program for deepwater riser systems.

Measurement of Unsteady Flow in Pump-Turbine for Hydropower Using PIV Method

2009 ◽  
Author(s):  
Nobuhiko Fukuda ◽  
Satoshi Someya ◽  
Koji Okamoto
Keyword(s):  
Rotational Speed ◽  
Velocity Measurement ◽  
Numerical Procedure ◽  
Hydraulic Turbine ◽  
Operating Conditions ◽  
High Time ◽  
Pump Turbine ◽  
Guide Vanes ◽  
Runner Blade ◽  
Wide Range

It is thought that the pressure fluctuation can occur due to the interaction between flow through guide vanes and flow into runner blades, resulting in a vibration of turbine and a blade cracking, in a hydraulic turbine operated in a wide range for flexible power demand. High accurate velocity measurement with high time/spatial resolution can help to clarify the mechanism of the interaction and to provide good experimental data for the validation of numerical procedure. So the aim of present study is to estimate the unstable velocity field quantitatively in the area between guide vanes and runner blades, using high time-resolved particle image velocimetry (PIV). Two types of velocity measurements were carried out, i.e., phase-locked measurement and high time sequential velocity measurement, in a pump-turbine model with 20 guide vanes and 6 runner blades. The characteristic of the flow field varied corresponding to the operating conditions such as flow rate and rotational speed. Opening angles of guide vanes were kept uniform. A clockwise vortex was generated at inside of the runner blade under smaller rotational speed. A counterclockwise vortex was separated at the backside of the runner blade under higher rotational speed. At any operating conditions, the velocity between guide vanes and runner blades oscillated periodically at the blade passing frequency.

Managing Flow Induced Vibration in Subsea Jumpers

2021 ◽  
Author(s):  
Rakshith Naik ◽  
Yetzirah Urthaler ◽  
Scot McNeill ◽  
Rafik Boubenider
Keyword(s):  
Dynamic Properties ◽  
Fatigue Analysis ◽  
Management Program ◽  
Measured Data ◽  
Operating Conditions ◽  
Valuable Insight ◽  
Fe Model ◽  
Flow Induced Vibration ◽  
Vibration Measurements

Abstract Certain subsea jumper design features coupled with operating conditions can lead to Flow Induced Vibration (FIV) of subsea jumpers. Excessive FIV can result in accumulation of allowable fatigue damage prior to the end of jumper service life. For this reason, an extensive FIV management program was instated for a large development in the Gulf of Mexico (GOM) where FIV had been observed. The program consisted of in-situ measurement, modeling and analysis. Selected well and flowline jumpers were outfitted with subsea instrumentation for dedicated vibration testing. Finite Element (FE) models were developed for each jumper and refined to match the dynamic properties extracted from the measured data. Fatigue analysis was then carried out using the refined FE model and measured response data. If warranted by the analysis results, action was taken to mitigate the deleterious effects of FIV. Details on modeling and data analysis were published in [5]. Herein, we focus on the overall findings and lessons learned over the duration of the program. The following topics from the program are discussed in detail: 1. In-situ vibration measurement 2. Overall vibration trends with flow rate and lack of correlation of FIV to flow intensity (rho-v-squared); 3. Vibration and fatigue performance of flowline jumpers vs. well jumpers 4. Fatigue analysis conservatism Reliance on screening calculations or predictive FE analysis could lead to overly conservative operational limits or a high degree of fatigue life uncertainty in conditions vulnerable to FIV. It is proposed that in-situ vibration measurements followed by analysis of the measured data in alignment with operating conditions is the best practice to obtain a realistic understanding of subsea jumper integrity to ensure safe and reliable operation of the subsea system. The findings from the FIV management program provide valuable insight for the subsea industry, particularly in the areas of integrity management of in-service subsea jumpers; in-situ instrumentation and vibration measurements and limitations associated with predictive analysis of jumper FIV. If learnings, such as those discussed here, are fed back into design, analysis and monitoring guidelines for subsea equipment, the understanding and management of FIV could be dramatically enhanced compared to the current industry practice.

ADVANCED TYPES OF CHECKERWORK OF REGENERATIVE HEAT EXCHANGERS FOR GLASS FURNACES

2021 ◽  
pp. 3-10
Author(s):  
O. Koshelnik ◽  
S. Hoisan
Keyword(s):  
Phase Transition ◽  
Heat Exchangers ◽  
Heat Storage ◽  
Point Of View ◽  
Operating Conditions ◽  
Flue Gases ◽  
Regenerative Heat ◽  
Exchange Processes ◽  
Glass Furnaces ◽  
Refractory Bricks

One of the ways to increase glass furnaces energy efficiency is to apply heat exchangers for flue gases thermal potential utilization. Flue gases losses is up to 25-40 % of the total amount of heat supplied in the furnace. These losses are influences by such factors as fuel type, furnace and burners design and manufactured product type. Regenerative heat exchangers with various types of heat storage packing is more efficient for high-power furnaces. Such types of regenerator checkerwork as Cowper checkerwork, two types of Siemens checkerwork, Lichte checkerwork and combined checkerwork have already been sufficiently researched, successfully applied and widely used for glass furnaces of various designs. All of its are made of standard refractory bricks. Basket checkerwork and cruciform checkerwork that are made of fused-cast molded refractory materials have been widely used recently as well. Further improvement of regenerative heat exchangers thermal efficiency only by replacing the checkerwork does not seem possible unless their size being increased. But this enlarging is not always realizable during the modernization of existing furnaces. From this point of view heat storage elements with a phase transition, where metal salts and their mixtures are used as a fusible agent look promising for glass furnaces. These elements can accumulate additional amount of heat due to phase transition, which allows to increase significantly heat exchanger thermal rating without its size and operating conditions changing. However, it is necessary to carry out additional studies of this type of checkerwork dealing with analysis of complex unsteady heat exchange processes in regenerators and selection of appropriate materials that satisfy the operating conditions of regenerative heat exchangers so that the checkerwork can be widely used for glass furnaces.

scholarly journals STATE ANALYSIS INTERNET OF THINGS DEVICES BASED ON BAGGING

T-Comm ◽  
2020 ◽  
Vol 14 (12) ◽  
pp. 45-50
Author(s):  
Mikhail E. Sukhoparov ◽  
◽  
Ilya S. Lebedev ◽  
Keyword(s):  
Time Series ◽  
Internet Of Things ◽  
The State ◽  
Point Of View ◽  
Operating Conditions ◽  
Process Time ◽  
K Nearest Neighbors ◽  
Computational Point ◽  
Iot Devices ◽  
The Internet Of Things

The development of IoT concept makes it necessary to search and improve models and methods for analyzing the state of remote autonomous devices. Due to the fact that some devices are located outside the controlled area, it becomes necessary to develop universal models and methods for identifying the state of low-power devices from a computational point of view, using complex approaches to analyzing data coming from various information channels. The article discusses an approach to identifying IoT devices state, based on parallel functioning classifiers that process time series received from elements in various states and modes of operation. The aim of the work is to develop an approach for identifying the state of IoT devices based on time series recorded during the execution of various processes. The proposed solution is based on methods of parallel classification and statistical analysis, requires an initial labeled sample. The use of several classifiers that give an answer "independently" from each other makes it possible to average the error by "collective" voting. The developed approach is tested on a sequence of classifying algorithms, to the input of which the time series obtained experimentally under various operating conditions were fed. Results are presented for a naive Bayesian classifier, decision trees, discriminant analysis, and the k nearest neighbors method. The use of a sequence of classification algorithms operating in parallel allows scaling by adding new classifiers without losing processing speed. The method makes it possible to identify the state of the Internet of Things device with relatively small requirements for computing resources, ease of implementation, and scalability by adding new classifying algorithms.

scholarly journals Coordinating activity of independent legal entities: issues of law enforcement in conditions of economy digitalization

2019 ◽  
pp. 60-67
Author(s):  
Yu. Yu. Borisova ◽  
I. V. Akimova
Keyword(s):  
Law Enforcement ◽  
Economic Activity ◽  
Legal Regulation ◽  
Point Of View ◽  
Operating Conditions ◽  
Negative Effects ◽  
Judicial Practice ◽  
Stage Of Development ◽  
Legislative Changes ◽  
The Coordinator

In article authors investigate questions of the operating legal regulation of coordination of economic activity of independent economic entities, including questions of its legisla- tive definition and signs. Article contains the detailed analysis of the most interesting examples of judicial practice and practice of antimonopoly authorities on the matter. Authors, analyzing the current legal regulation, also give an assessment to the planned changes in the legislation in this part and state the point of view about dependence of legal assessment of actions of the coordinator and the economic entities coordinated by it on operating conditions of commodity markets on which it is carried out. As a result of a research authors drew a conclusion on need of legislative changes in a part of admis- sibility of the forbidden coordination provided that the advantage for consumers of such coordination exceeds negative effects for the competition.A significant amount of works of the modern scientists and experts investigating a per- spective of institutes of the antitrust law is devoted to questions of legal qualification of coordination of economic activity of independent economic entities in legal scientific literature.The matter was also raised in publications and authors of the "Rossiyskoye Konkurent- noye Pravo I Ekonomika" magazine, at the same time, it should be noted that to consid- eration of questions of coordination of activity smaller attention is paid, than, for ex- ample, to questions of cartels.Thus, degree of scientific readiness of the matter in general is rather high, at the same time to authors the relevance of this subject and need of the analysis and assessment of the operating regulation taking into account economic features of the present stage of development of the markets seems to be of high interest.

Missing Combustion Diagnosis: Distinguishing Between Misfire and Misfuel

2003 ◽  
Author(s):  
Enrico Corti
Keyword(s):  
Electronic Control Unit ◽  
Control Unit ◽  
Point Of View ◽  
Operating Conditions ◽  
Electronic Control ◽  
Operating Range ◽  
Fuel Ratio ◽  
Fault Recognition ◽  
System Life ◽  
The Right

On-Board Diagnostics (OBD) regulations impose missing combustions detection within a wide portion of the engine operating range. Missing combustions can be caused either by ignition (misfire) or injection (misfuel) system failures. Missing combustions can damage the catalyst and cause abrupt pollutants increases (especially HC), but misfuels are not as detrimental as misfires, both from the emissions and the after treatment system life point of view. It would be important for the Electronic Control Unit (ECU) to be informed not only about the fault event, but also about its type, for the purpose of setting the right recovery strategy. The aim of this paper is to analyze missing combustion phenomena, in order to find out if a fault recognition strategy able to distinguish between misfire and misfuel can be setup. Different approaches can be found in the literature to diagnose missing combustions: many of them are based on the speed signal analysis, both in time and frequency domains, others use the knock accelerometer signal, or the exhaust manifold pressure information. A Universal Exhaust Gas Oxygen (UEGO) sensor can also be used. Usually diagnosis methodologies consist in observing signals perturbations subsequent to the malfunction event. Observable consequences of missing combustions are, for example, a sudden lack of indicated torque, causing vibrations and speed fluctuations, an increasing in exhaust gases Oxygen content, anomalous exhaust pressure ripples, etc. Many phenomena interact influencing in different ways the engine behavior, during and after the fault event: their effect can depend on the fault cause, thus helping the recognition. The first combustion taking place in the faulty cylinder after a misfire (post-misfiring cycle) usually leads to higher indicated pressure and torque levels if compared to standard values for the same operating conditions, while the same cannot be said for the post-misfueling combustion. On the other side, Air-Fuel Ratio (AFR) assumes different trends during the misfiring and post-misfiring cycles, with respect to misfueling and post-misfueling cycles. A 4 cylinders 1.2 liters spark ignition port injected engine, equipped with a programmable Electronic Control Unit (ECU) has been tested on the test bench, inducing both misfires and misfuels, over a wide engine operating range, while monitoring the engine faulty behavior. Misfire and misfuel-related phenomena have been analyzed showing their “signature” on indicated pressure and torque, engine speed and Air-Fuel Ratio measured signals, in order to define the most reliable recognition strategy.

Sign in / Sign up

Export Citation Format

Share Document