scholarly journals Model and Simulation Studies of the Method for Optimization of Dynamic Properties of Tachometric Anemometers

Sensors ◽  
2018 ◽  
Vol 18 (8) ◽  
pp. 2677 ◽  
Author(s):  
Paweł Ligęza
Keyword(s):  
Measurement Uncertainty ◽  
Flow Velocity ◽  
Average Velocity ◽  
Dynamic Properties ◽  
Simulation Studies ◽  
Average Flow Velocity ◽  
Measuring Element ◽  
Model And Simulation ◽  
Model Research ◽  
Dynamic Uncertainty

Mechanical tachometric anemometers, based on the phenomenon of the exchange of momentum between the flow and rotating measuring element, represent an important class of instruments used in flow metrology. In particular, they are used in meteorological and ventilation measurements. Mechanical anemometers with rotating measuring element are, however, known for their drawback related to their poor dynamic properties resulting from relatively large dimensions and mechanical inertia of the measuring element. In these instruments, the phenomenon of overestimating the measured average velocity caused by the inertia of the rotor takes place. Optimization of the dynamics of the measurement process, as well as the estimation and minimization of the measurement uncertainty, can be performed based on mathematical model of anemometer. In this study, a new, original concept of optimization of dynamic properties of tachometric anemometers is proposed, and the results of model and simulation studies are presented. The new concept of measuring instrument is based on the use of feedback and active control of the rotor. The new method was tested using model research, where two types of flow velocity excitations were applied: sinusoidal and rectangular. The tests carried out showed that the developed method allows for minimization of the dynamic uncertainty of the measurement and minimizes the phenomenon of average flow velocity overestimation occurring in time-varying flows. It has been shown that the use of optimization system allows for approximately tenfold reduction of the error of average velocity measurement in the case of pulsating flows. In addition, the optimization systems allow for anemometer’s transmission bandwidth to be extended about a hundred times. This creates new application possibilities for these instruments and allows for a large reduction of measurement uncertainty.

About time lag and some morphometric characteristics of streams of the forest zone

2016 ◽  
Author(s):  
Н.А. Белоногова ◽  
А.Ю. Виноградов ◽  
Т.А. Виноградова ◽  
Д.А. Догановский ◽  
А.Н. Кондратьев ◽  
...  
Keyword(s):  
Flow Velocity ◽  
Average Rate ◽  
Time Lag ◽  
High Water ◽  
Spatial And Temporal Variability ◽  
Forest Zone ◽  
Average Flow Velocity ◽  
Small Watersheds ◽  
Maximum Water ◽  
General Movement

Расчет максимальных расходов воды дождевых паводков на малых водосборах, в целях эффективного проектирования лесохозяйственных инженерных дорожных сооружений, представляет собой весьма сложную задачу вследствие отсутствия достаточных наблюдений за характеристиками дождевого стока. Кроме того, характеристики дождевого стока и определяющие их факторы обладают большой пространственной и временной изменчивостью, что еще больше затрудняет их определение. Рекомендуемая действующими нормативами методика определения максимального дождевого стока, как показывает практический опыт, нуждается в незамедлительном редактировании с точки зрения сопоставления размерностей и правильности ссылок. Особое внимание в статье уделено определению времени добегания, включенного в расчетные формулы в качестве определяющего параметра. В настоящее время понятие «время добегания» однозначно не определено. В связи с тем, что наполненность русел рек имеет высокую пространственную и временную неоднородность и изменчивость, общее движение воды в створе проектируемого инженерного сооружения можно представить достаточно упорядоченным и единообразным, с практически постоянной паводковой средней скоростью. На основе натурных наблюдений известно, что во время паводка средняя по сечению скорость потока сохраняется постоянной в пределах верхней десятипроцентной части амплитуды уровней воды. Такие данные с конца 70-х годов не публикуются. Обработка имеющихся данных говорит о том, что существует незначительное увеличение скоростей течения с ростом площади бассейнов. Поэтому предлагается принять время добегания τi, определенное по характерным отрезкам руслового пути от исследуемого створа до истока с помощью интерполяции измеренных на гидрометрических постах данных по скоростям течения. The calculation of the maximum water flow during the high water, especially on small watersheds, in order to effectively design engineering of road structures, is a very difficult task due to the lack of sufficient observations. In addition, the characteristics of rainfall, and their determinants have a high spatial and temporal variability, which further complicates their definition. Currently recommended method of determining the characteristics of the maximum rainwater, as the experience, needs immediate clarification of dimensions and verify links. Particular attention is paid to the calculation of lag time, included in the formulas as the defining parameter. Fullness riverbeds has high spatial and temporal heterogeneity and variability. The general movement of water in the closing alignment ordered and uniform. The average rate of slightly increased or decreased depending on the dryness of the season. Each cross-section corresponds to the value of average flow velocity. These data are from the late 70-ies are not published. Processing of existing data suggests that there is a slight increase in the flow velocity with increasing basin areas. Therefore, as a constant time lag is invited to take the time determined by the characteristic segments of the channel path from the source to the alignment of the test.

On the stable geometry of self-formed alluvial channels: theory and practical applicationThis article is one of a selection of papers in this Special Issue in honour of Professor M. Selim Yalin (1925–2007).

2009 ◽  
Vol 36 (10) ◽  
pp. 1667-1679 ◽  
Author(s):  
Ana Maria Ferreira da Silva
Keyword(s):  
Flow Velocity ◽  
Laboratory Data ◽  
Alluvial Channels ◽  
Cross Sectional ◽  
Late Professor ◽  
Average Flow Velocity ◽  
Effective Roughness ◽  
Self Formation ◽  
Gibb's Equation ◽  
Selection Of

On the basis of previous work by the late Professor M. Selim Yalin and the author, the process of self-formation of alluvial streams and the final (equilibrium or regime) geometry of the self-formed stream are considered in the light of thermodynamic principles, including the first and second laws, and the Gibb’s equation; the stream is treated as an isolated and irreversible system. The present analysis suggests that stream self-formation is guided by the need of the stream to progressively decrease its average flow velocity to accommodate the increase in the entropy of the system with the passage of time. The reduction in flow velocity is achieved by an appropriate alteration of stream slope, cross-sectional geometry, and effective roughness, the regime development being the process of this appropriate alteration. A method is presented for the computation of regime width, depth, and slope. The method rests on the channel formation criterion derived from thermodynamic principles and the expression of regime flow width determined on the basis of zero net cross sediment transport rate at the regime state. The regime channels computed from this method are compared with field and laboratory data from various sources.

scholarly journals The Cascade device – In vitro tests to assess coil protrusion into the parent vessel

2020 ◽  
Vol 26 (4) ◽  
pp. 494-500 ◽  
Author(s):  
P Bhogal ◽  
K Wong ◽  
HLD Makalanda
Keyword(s):  
Flow Velocity ◽  
In Vitro Tests ◽  
Parent Vessel ◽  
Single Episode ◽  
Average Flow Velocity ◽  
Velocity Reduction ◽  
Temporary Support ◽  
Aneurysmal Neck ◽  
Aneurysm Model

Background Balloon and stent-assisted coiling of aneurysms have increased the number of aneurysms available for endovascular treatment. Newer devices that allow flow within the parent vessel but coverage at the neck have recently entered the market. The Cascade is a new non-occlusive fully retrievable neck-bridging support device that has been designed to provide temporary support during coil embolisation of intracranial aneurysms. Methods Using a silicone aneurysm model three different aneurysms were catheterised with the coiling microcatheter placed in three different positions within each aneurysm – at the neck, centrally, and looped within the aneurysm. Multiple different coils were then deployed within each aneurysm with the Cascade device deployed across the neck to provide protection. In total 480 attempted coilings were performed. Aneurysm flow was used to calculate the change in intra-aneurysmal flow with the Cascade device deployed across the neck of the aneurysm. Results We did not observe a single episode of coil protrusion through the Cascade mesh nor did we observe any coil protrusion into the parent vessel when the Cascade was deployed across the neck. There was an average flow velocity reduction of 23% with the Cascade device deployed across the neck of the aneurysm. Conclusion The Cascade device offers robust protection of the aneurysmal neck and parent vessel as well as inducing significant intra-aneurysmal flow velocity reduction.

scholarly journals Integrating XAJ Model with GIUH Based on Nash Model for Rainfall-Runoff Modelling

Water ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 772 ◽  
Author(s):  
Yingbing Chen ◽  
Peng Shi ◽  
Simin Qu ◽  
Xiaomin Ji ◽  
Lanlan Zhao ◽  
...  
Keyword(s):  
Flow Velocity ◽  
Network Flow ◽  
Model Performance ◽  
Efficiency Coefficient ◽  
Effective Rainfall ◽  
Unit Hydrograph ◽  
Nash Model ◽  
Average Flow Velocity ◽  
Time To Peak ◽  
Flood Estimation

The geomorphologic instantaneous unit hydrograph (GIUH) is an applicable approach that simulates the runoff for the ungauged basins. The nash model is an efficient tool to derive the unit hydrograph (UH), which only requires two items, including the indices n and k. Theoretically, the GIUH method describes the process of a droplet flowing from which it falls on to the basin outlet, only covering the flow concentration process. The traditional technique for flood estimation using GIUH method always uses the effective rainfall, which is empirically obtained and scant of accuracy, and then calculates the convolution of the effective rainfall and GIUH. To improve the predictive capability of the GIUH model, the Xin’anjiang (XAJ) model, which is a conceptual model with clear physical meaning, is applied to simulate the runoff yielding and the slope flow concentration, integrating with the GIUH derived based on Nash model to compute the river network flow convergence, forming a modified GIUH model for flood simulation. The average flow velocity is the key to obtain the indices k, and two methods to calculate the flow velocity were compared in this study. 10 flood events in three catchments in Fujian, China are selected to calibrate the model, and six for validation. Four criteria, including the time-to-peak error, the relative peak flow error, the relative runoff depth error, and the Nash–Sutcliff efficiency coefficient are computed for the model performance evaluation. The observed runoff value and simulated series in validation stage is also presented in the scatter plots to analyze the fitting degree. The analysis results show the modified model with a convenient calculation and a high fitting and illustrates that the model is reliable for the flood estimation and has potential for practical flood forecasting.

The Airflow Analysis for CAP1400 Control Rod Drive Mechanisms Cooling System

2017 ◽  
Author(s):  
Hao Yu ◽  
Xingliang Zhang ◽  
Wei Zhang ◽  
Guofeng Hao
Keyword(s):  
Flow Velocity ◽  
Nuclear Power ◽  
Cooling System ◽  
Flow Characteristics ◽  
Operating Conditions ◽  
Control Rod ◽  
Average Flow Velocity ◽  
Head Assembly ◽  
Axial Fans ◽  
Cfd Method

The CAP1400 nuclear power plant (NPP) reactor integrated head package (IHP) refers to the assembly of all of the equipment and structures that are either mounted to the reactor closure head or provide services to the reactor head assembly. One of the main functions of the IHP in the reactor is to provide cooling for the control rod drive mechanism (CRDM) magnetic coils. The IHP cooling system is realized by axial fans connected to the vent tubes of the CRDM cooling shroud. Under normal operating conditions, two of four fans are required to be in operation. The IHP cooling system shall meet the requirements of “keeping the coil temperature within the magnetic coil component below 200°C”. This requirement is achieved by ensuring that the average flow velocity around the CRDM coil assembly is above 15 m/s and that the minimum flow velocity at any location on the outer surface of the coil assembly is not less than 9 m/s. The main purpose of this paper is to study the flow characteristics of the IHP cooling system under various operating conditions. The CFD method is used to obtain the flow field and temperature field in the IHP and to support the rationality of IHP design.

scholarly journals Thermal-Plume fibre Optic Tracking (T-POT) test for flow velocity measurement in groundwater boreholes

2015 ◽  
Vol 5 (1) ◽  
pp. 161-175 ◽  
Author(s):  
T. Read ◽  
V. F. Bense ◽  
O. Bour ◽  
T. Le Borgne ◽  
N. Lavenant ◽  
...  
Keyword(s):  
Flow Velocity ◽  
Fractured Rock ◽  
Electrical Heating ◽  
Multiple Point ◽  
Thermal Plume ◽  
Fibre Optic ◽  
Distributed Temperature Sensing ◽  
Pumping Rate ◽  
Average Flow Velocity ◽  
Pumping Rates

Abstract. We develop an approach for measuring in-well fluid velocities using point electrical heating combined with spatially and temporally continuous temperature monitoring using Distributed Temperature Sensing (DTS). The method uses a point heater to warm a discrete volume of water. The rate of advection of this plume, once the heating is stopped, equates to the average flow velocity in the well. We conducted Thermal-Plume fibre Optic Tracking (T-POT) tests in a borehole in a fractured rock aquifer with the heater at the same depth and multiple pumping rates. Tracking of the thermal plume peak allowed the spatially varying velocity to be estimated up to 50 m downstream from the heating point, depending on the pumping rate. The T-POT technique can be used to estimate the velocity throughout long intervals provided that thermal dilution due to inflows, dispersion, or cooling by conduction do not render the thermal pulse unresolvable with DTS. A complete flow log may be obtained by deploying the heater at multiple depths, or with multiple point heaters.

scholarly journals Влияние на аномальную интенсификацию отрывного турбулентного течения угла наклона однорядных овально-траншейных лунок на стабилизированном гидродинамическом участке узкого канала

2020 ◽  
Vol 46 (21) ◽  
pp. 18
Author(s):  
С.А. Исаев ◽  
А.Б Мазо ◽  
Д.В. Никущенко ◽  
И.А. Попов ◽  
А.Г. Судаков
Keyword(s):  
Flow Velocity ◽  
Narrow Channel ◽  
Swirling Flows ◽  
Secondary Flows ◽  
Average Flow ◽  
Dramatic Effect ◽  
Average Flow Velocity ◽  
Negative Friction

The slope of the oval-trench dimple in the corridor package on the hydrodynamic stabilized section of the narrow channel has a dramatic effect on the anomalous intensification of returned and swirling flows in the dimple, leading to a 3–4-fold decrease in relative negative friction in the range of angles from 40° to 60°, an increase in the highest speed return and secondary flows up to 0.8 and 1.18 with respect to the mass-average flow velocity in the channel.

scholarly journals The use of modelling of impacts exerted by means of transport on the environment for ensuring safety

2018 ◽  
Vol 188 (2) ◽  
pp. 162-175
Author(s):  
Joanna Bril ◽  
Edward Rydygier
Keyword(s):  
Rigid Body ◽  
Half Space ◽  
Dynamic Properties ◽  
Elastic Half Space ◽  
Transport Systems ◽  
Concentrated Force ◽  
Foundation Soil ◽  
Infinite Mass ◽  
Model Research ◽  
Surface Rayleigh Wave

The article presents the model research on impacts exerted by means of transport on the structures. In modelling the dynamics of transport systems the dynamic properties of the ground forming the foundation soil for tracks or roadways have been taken into account. The ground has been modelled as an elastic half-space. The dynamics of an infinite mass band being in contact with an elastic half-space has been investigated. As part of the research on impacts exerted by means of transport on structures a model of a problem has been examined where an automotive vehicle, representing a concentrated force in motion, is in contact with a roadway described as a rigid body coupled with an elastic half-space. It has been demonstrated that a surface (Rayleigh) wave propagates in the ground, being a continuous (elastic) medium, and acts on a structure modelled as a rigid body. The research results have been presented in the form of vertical and horizontal transmittances of the ground for different frequencies of loading with different unit forces.

scholarly journals Analysis of Risks Associated With Water Pipes in Rapid Flow Waterways Through Waterway Modeling Experiments

2021 ◽  
Vol 35 (5) ◽  
pp. 51-58
Author(s):  
Sin-Woong Choi ◽  
A-Young Choi ◽  
Dong-Hun Han
Keyword(s):  
Flow Velocity ◽  
Maximum Flow ◽  
Water Pipe ◽  
Lower Side ◽  
Water Pipes ◽  
Average Flow Velocity ◽  
Standard Operating ◽  
Rapid Flow ◽  
Water Rescue ◽  
Maximum Flow Velocity

In this study, waterway modeling experiments were conducted by incorporating the information obtained by analyzing accident sites to prevent frequent accidents of firefighters that occur during water rescue operations conducted near water pipes in rapid flow waterways. Based on the conducted experiments, it was observed that the flow velocity increased with decreasing distance from the water pipe. Furthermore, the maximum flow velocity was found to be 3.99 times higher at the posterior end than at the anterior end of the water pipe, and the flow velocity was found to be higher at the lower side than at the upper side of the water pipe’s anterior end. The maximum flow velocity was measured to be 1.65 m/s at a distance of 10 cm from the entrance to the pipe, 2.63 m/s at a distance of 5 cm from the entrance to the pipe, 7.12 m/s within the pipe, and 5.33 m/s at a distance of 5 cm from the pipe’s exit. The average flow velocity was measured to be 0.94 m/s at a distance of 10 cm from the entrance to the pipe, 5.53 m/s within the pipe, and 4.64 m/s at a distance of 5 cm from the pipe’s exit. Furthermore, in this study, relevant standard operating procedures and regulations were taken into consideration. Based on the results obtained from this study, recommendations and guidelines were then accordingly devised for preventing accidents of firefighters that occur during water rescue operations.

scholarly journals ASYMMETRIC FLOW VELOCITY MEASUREMENT USING MULTIPATH ULTRASONIC FLOWMETER WITH ADAPTIVE WEIGHTING METHOD GUIDED BY TOMOGRAPHY

2019 ◽  
Vol 82 (1) ◽  
Author(s):  
Khairul Amri ◽  
Suprijanto Suprijanto ◽  
Deddy Kurniadi ◽  
Endang Juliastuti
Keyword(s):  
Flow Velocity ◽  
Mapping Function ◽  
Flow Profile ◽  
Asymmetric Flow ◽  
Weighting Method ◽  
Alternative Scheme ◽  
Average Flow ◽  
Average Flow Velocity ◽  
Adaptive Weighting ◽  
Flow Profiles

A conventional transit time ultrasonic flowmeter (USM) has a high accuracy for symmetric flow profiles but inaccurate for asymmetric flow profiles. Flow profile shapes can also change over time and difficult to predict. USM with tomographic configuration (USM-Tomo) can adapt to the flow profile changes but result in low temporal resolution. Meanwhile, USM with an adaptive weighting method can measure asymmetric flow velocity but limited to specific asymmetric flow profiles. An alternative scheme to determine adaptive weighting in various asymmetric flow profiles, we proposed a hybrid USM-Tomo. This scheme proposes programmable acoustic path configuration that could set the path mode between USM and tomography. Reducing computation of time of flight in each acoustic can be done by applying the dual-transducers technique. An adaptive weighting of hybrid USM-Tomo is calculated based on the mapping function between the set of velocity on 6 parallel paths of USM and average flow velocity from USM-Tomo. The mapping function is determined using machine learning, i.e., Artificial Neural Network (ANN) and Support Vector Regression (SVR). In the measurement phase, the average flow velocity is determined using the mapping function with input 6 parallel acoustic paths.  Based on various types of asymmetric flow profiles used in the experiment, the 6 parallel acoustic paths of USM could produce average flow velocity with error below 1% compared to USM-Tomo. Therefore, the proposed hybrid USM-Tomo scheme has potential to be an alternative scheme for flow meter in industrial application.

Sign in / Sign up

Export Citation Format

Share Document