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Page 492 of 977 Results 4911 - 4920 of 9762

Philippe Averlant, Pascal Lacipiere, Jean-Marie David
DEVELOPMENT OF THE NEW LNE 5 kN·m DEADWEIGHT TORQUE STANDARD MACHINE

This paper describes the new LNE 5 kN.m deadweight torque standard bench. Information on the design, development, and commissioning of this standard are given. Its design is described focusing on mechanical and metrological characteristics. In particular, three components, developed by LNE, are described: First, the double arm lever, one for deadweight force transmission and the other for localization of this force Then, the air bearing based on used of porous material. Finally, the system should enable us to avoid the wrinkling of the tape related to the positioning of the force at the extremity of the lever arm. The attention given to these elements enables to consider uncertainties compatible with the primary national reference function.

Paththage Priyadarshana, Drew Weaver, Dale Goodson, Peter Syrnyk
SYSTEM AND METHODOLOGY FOR LIQUID ULTRASONIC FLOW MEASUREMENT WITHIN LAMINAR TO TURBULENT TRANSITIONAL ZONE

Applications for liquid ultrasonic Custody Transfer flow measurement are traditionally limited to flow ranges within the meter’s performance capability related to the viscosity of the fluid, particularly in the low Reynolds number region where the flow range is across the laminar, transitional and turbulent flow regimes. This paper discusses new methodology by which the flow meter’s performance can be extended into lower ranges of Reynolds numbers for viscous flows while maintaining the close tolerances needed for Custody Transfer measurement applications. The methodology includes the ability to dynamically measure the Reynolds number as well as the fluid’s kinematic viscosity within the laminar to turbulent transition zone.

He-ming Hu, Tao Meng, Feng Gao, Liang Zhang, Chi Wang
STUDY ON GEOMETRIC PARAMETER MEASUREMENT AND WEIGHT COEFFICIENT CORRECTION OF ULTRASONIC FLOWMETER

Geometric parameter measurement system for multi-path ultrasonic flowmeters based on Leica total station has been established, which can directly measure the 3D coordinates of the conduit points and sensor points and automatically calculate geometric parameters of the flowmeter. Compared with the traditional method using the theodolite and steel tape, the first advantage of this system is the high efficiency and good accuracy, and the second is the path heights can be re-measured after the sensor mounted. Cylinder fitting is its key problem. Lukács algorithm is introduced for the cylinder fitting, and Monte-Carlo simulation method is introduced for its uncertainty estimation.To illustrate the rationality and validity of this measurement system, the calibration data and its uncertainty of 3 flowmeters in three gorges power station have been comparative analysed. Besides, the influences of the water temperature and pressure on the diameter of three gorges steel penstock and then on the other parameters have be estimated. At last, the effect on the flow rate of the path heights which are different from the design values has been analysed. When this effect is not ignorable, the analytical formulas has been deduced for the weight coefficient correction, which can get satisfactory weight coefficient.

P. Klason, O. Büker, P. Lau, O. Penttinen, K. Mattiasson, T. Lederer, K. Tawackolianb, J. Frederiksenc, A. K. Niemannc, P. Milotad
REYNOLDS DEPENDENCE OF FOUR DIFFERENT FLOW METERS USED FOR FEED WATER FLOW MEASUREMENTS

In the ‘Metrology for improved power plant efficiency’ project the Reynolds dependence of four flow meters used for feed water flow measurements were investigated. The four flow meters were ultrasonic, inductive, orifice plate and Venturi tube flow meter. The measurements were performed up to 90 °C to study the temperature dependence of the meters. An extrapolation model up to 230 °C was developed to measure the feed water flow with an uncertainty in the range of 0.3 % – 0.5 %. The influence of a double bend out of plane disturbance on the meters was also investigated. Some meters showed a significant dependence.

N. Furuichi, K. H. Cheong, Y. Terao, S. Nakao, K. Fujita, K. Shibuya
EXPERIMENTAL INVESTIGATION OF DISCHARGE COEFFICIENT AND TAPPING ERROR OF PTC 6 FLOW NOZZLE USING HIGH REYNOLDS NUMBER CALIBRATION RIG

A tap effect of a discharge coefficient of a throat tap flow nozzle based on PTC 6 is investigated by measuring the discharge coefficient in 1.8 × 105 < Red < 1.4 × 107. The measurement error of the differential pressure, when it is normalized by a wall shear stress including the effect of roughness caused by the hole of a tap, is described as a function of tap Reynolds number based on the friction velocity and the tap diameter. The equation of the discharge coefficient of the flow nozzle is proposed, which consists of the two terms that can be physically evaluated, the theoretical discharge coefficient and the measurement error of differential pressure.

Hongbing Ding, Chao Wang, Yakun Zhao
THEORETICAL ANALYSIS ON THE EFFECT OF DIVERGENT SECTION WITH LAMINAR BOUNDARY LAYER OF SONIC NOZZLES

ISO toroidal-throat nozzle with a divergent section differs from the nozzle used for the theoretical research of Hall & Geropp and is highly likely to affect the flow field and discharge coefficient. In this paper, the influence of ISO-type conical divergent section on discharge coefficient was analyzed basing on inviscid transonic flow model and laminar boundary layer respectively. Two coordinate systems namely cylindrical coordinates and curvilinear coordinate were applied to research the velocity distribution of core flow and calculate displacement thickness. The results indicated the influence of conical divergent section decreases with increasing of diffuser angle and Reynolds number, while increases with divergent section length increasing. It meant that the discharge coefficient is significant influence by diffuser angle and divergent section length when the Reynolds number decreases to a certain value. The sonic nozzle which is miniaturized or applied to low Reynolds number flow should be carefully designed.

Liang Zhang, Heming Hu, Tao Meng, Chi Wang
EFFECT OF FLOW DISTURBANCE ON MULTI-PATH ULTRASONIC FLOWMETERS

Experimental study of multi-path ultrasonic flowmeters measurement accuracy in complex flow fields was carried out in the water flowrate standard facility of National Water Large Flowrate Measurement Station. Several muti-path ultrasonic flowmeters with different path arrangement were studied. The flow disturbances were created by bend, tapered pipe, diverging pipe and butterfly valve. By studying the measurement errors of different types of ultrasonic flowmeters, it is confirmed that the cross plane ultrasonic flowmeter is more adaptable to the complex flow field. The installation angle of flowmeter affects measurement accuracy. The sources of measurement error were analysed by CFD simulation.

Stéphane Fischer, Claude Rebattet, Damien Dufour
APPLICABILITY OF ULTRASONIC PULSED DOPPLER FOR FAST FLOW-METERING

Measurement of fluctuating flows in hydraulic machines is an ongoing challenge for which classical flow meter technologies (Differential pressure, Magnetic, Turbine and Propeller) are not well adapted. The ultrasonic pulsed Doppler technique allows to measure instantaneous velocity profiles in a very short time. This paper presents the performances of the ultrasonic velocity profiler UB-Lab to achieve faster velocity flow measurement through hydraulic pipes. The system has been optimized (transducer frequency, beam angle, parameters of sequencing) in order to reduce effect of wall echoes, to keep a good velocity range and to minimize the effect of secondary currents. The paper presents the measurement system with UB-lab's software module dedicated to fast flow-metering, the velocity profile measurement in a mixing tank, the bench demonstrator, the results and the perspectives of development of such solutions.

Moritz Leopoldo Cordova Murillo, Thomas Lederer
A NEW APPROACH TO IMPROVE REPRODUCIBILITY OF ULTRASONIC FLOWMETERS USED IN FULLY DEVELOPED FLOWS

Due to its high repeatibility ultrasonic flow meters (UFMs) are ideqm instruments for interlaboratory comparisons. The present paper attempts to improve the performance of UFM for interlaboratory comparisons by estimating weighing factors that reduce the instrinsic errors of this technology. The results have been tested with a DN500 five parallel path time of flight (TOF) UFM at a Bilateral comparison within the PTB. Oustanding results have been accomplished.

Benjamin E. McDonald, Lei Sui
ULTRASONIC FLOW MEASUREMENT WITH INTEGRATED TEMPERATURE MEASUREMENT COMPENSATION

Compensation for ultrasonic flow measurement has increasingly become the trend for applications that call for higher accuracy and tighter repeatability. Temperature is a variable that tends to have a significant impact on performance. Geometric dimension changes due to thermal expansion and contraction, as well as fluid dynamics, are impacted by temperature and thus have an influence on overall system accuracy. This paper presents a new method for measuring temperature by taking advantage of well characterized material properties that change with temperature and utilizing existing system capability. Integrated temperature measurement can be included as part of the diagnostic support package and used for compensation by using existing capability.

Page 492 of 977 Results 4911 - 4920 of 9762