Total and Static Quantity Measurements in Unsteady Flow — Effect of Unsteadiness

1998 ◽  
Author(s):  
Weiliang Lou ◽  
Christian Aalburg ◽  
Jean Hourmouziadis
Keyword(s):  
Unsteady Flow ◽  
Measuring System ◽  
Slow Response ◽  
Dynamic Measurements ◽  
Quantitative Investigation ◽  
Physical Similarity ◽  
Response Characteristics ◽  
Response Dynamic ◽  
Measurement Results ◽  
Static Quantity

The effects of unsteadiness both on high-response dynamic measurements and on time-averaged measurements with slow-response probes are analytically investigated separately from the response characteristics of the measuring system. The approach is based on physical similarity and dimensional analysis. The potential errors from flow unsteadiness and the major parameters which influence the measurement results are discussed. In the case of five sensor spherical probes a quantitative investigation for inviscid, incompressible, irrotational flow is carried out with the help of potential theory.

Research on Precision Measuring System for Motor Speed

2012 ◽  
Vol 588-589 ◽  
pp. 1103-1107
Author(s):  
Yu Hai Gu ◽  
Qiu Shi Han ◽  
Xiao Li Xu ◽  
Hai Tao Zhang
Keyword(s):  
Control Systems ◽  
Precise Measurement ◽  
Serial Communication ◽  
Measuring System ◽  
Motor Speed ◽  
Precision Measuring ◽  
Measurement Results ◽  
Improve Accuracy ◽  
Improving Accuracy ◽  
Motor Control Systems

In order to improve accuracy of measuring motor speed in precision motor control systems, a method of precise measurement of speed with CPLD is proposed, which measures the truncated parts of the measured pulse on the basis of measuring raster count pulse within the equal period, and takes them as compensation, thus improving accuracy of measuring the raster pulse. In this paper, a speed measuring formula is given. Measuring system is provided with parallel and serial communication interfaces for output of measurement results.

Investigation of the Unsteady Rotor Flow Field in a Single HP Turbine Stage

2000 ◽  
Author(s):  
Friedrich Kost ◽  
Frank Hummel ◽  
Maik Tiedemann
Keyword(s):  
Flow Field ◽  
Unsteady Flow ◽  
Turbine Rotor ◽  
Navier Stokes ◽  
Blade Surface ◽  
Turbine Stage ◽  
Numerical Work ◽  
Pressure Transducers ◽  
Measurement Results ◽  
Flow Vectors

Within a European project a high-pressure turbine stage was investigated at DLR, Göttingen. The investigations consisted primarily of experiments carried out in the windtunnel for Rotating Cascades (RGG), but some numerical work was also performed. Detailed measurements were carried out at mid section of a turbine rotor using a Laser-2-Focus device which served as a velocimeter measuring 2D-velocity vectors and turbulence quantities and as a tool to determine the concentration of coolant ejected at the trailing edge of the stator blades. The measurement of coolant concentration downstream of the stator and inside the rotor provided a detailed picture of the stator wake development and its interaction with the moving rotor. Axial measurement locations reached from the stator exit through the rotor to a downstream measurement plane. Measurement results are presented as instantaneous flow values. Unsteady flow vectors and turbulence intensities could be related at 16 time instants representing one rotor blade passsing period to the wake development made visible by the coolant concentration. The measured unsteady flow vectors and unsteady pressures, measured with semi-conductor pressure transducers, are compared with results from a numerical calculation using the Navier-Stokes code “TRACE-U” which allows the computation of the unsteady flow field. The measured steady and unsteady flow quantities served to validate the Navier-Stokes code. A comparison of the wake entropy trajectories outside the blade boundary layers and at the wall gives an impression of the lag between the arrival time of the wake in the freestream near the blade surface and the time the boundary layer quantities at the blade surface itself are affected.

scholarly journals Comparison of selected theoretical models of bubble formation and experimental results

2014 ◽  
Vol 35 (2) ◽  
pp. 21-36 ◽  
Author(s):  
Mariusz R. Rząsa
Keyword(s):  
Measurement Method ◽  
Formation Rate ◽  
Bubble Formation ◽  
Theoretical Models ◽  
Measuring System ◽  
Gas Bubble ◽  
Measurement Results ◽  
Intermediate States ◽  
Determination Of Parameters

Abstract Designers of all types of equipment applied in oxygenation and aeration need to get to know the mechanism behind the gas bubble formation. This paper presents a measurement method used for determination of parameters of bubbles forming at jet attachment from which the bubles are displaced upward. The measuring system is based on an optical tomograph containing five projections. An image from the tomograph contains shapes of the forming bubbles and determine their volumes and formation rate. Additionally, this paper presents selected theoretical models known from literature. The measurement results have been compared with simple theoretical models predictions. The paper also contains a study of the potential to apply the presented method for determination of bubble structures and observation of intermediate states.

scholarly journals Liquid Level Detection in Standard Capacity Measures with Machine Vision

Sensors ◽  
2021 ◽  
Vol 21 (8) ◽  
pp. 2676
Author(s):  
Gregor Bobovnik ◽  
Tim Mušič ◽  
Jože Kutin
Keyword(s):  
Machine Vision ◽  
Vision System ◽  
Liquid Level ◽  
Measuring System ◽  
Legal Metrology ◽  
System A ◽  
Measurement Results ◽  
Capacity Measure ◽  
Measuring Scale ◽  
Liquid Level Detection

Capacity measures are commonly used volume standards for testing measuring systems for liquids other than water. Manual readings from the measuring scale can often be difficult due to the location of the capacity measure or to the nature of the measured liquid. This article focuses on the automation of this procedure by using a single camera machine vision system. A camera positioned perpendicular to the transparent neck captures the image of the liquid meniscus and the measuring scale. The volume reading is determined with the user-defined software in the LabVIEW programming environment, which carries out the image preprocessing, detection of the scale marks and the liquid level, correction of lens distortion and parallax effects and final unit conversions. The realized measuring system for liquid level detection in standard capacity measures is tested and validated by comparing the automated measurement results with those taken by the operators. The results confirm the appropriateness of the presented measuring system for the field of legal metrology.

Application of Video Image Interpretation Technology in the Angular Distortion Measurement System

2013 ◽  
Vol 373-375 ◽  
pp. 795-798
Author(s):  
Yao Yu Zhang ◽  
Ming Hui Zhang
Keyword(s):  
Image Processing ◽  
Image Interpretation ◽  
Video Image ◽  
Measuring System ◽  
Angular Distortion ◽  
Video Signals ◽  
Measurement Results ◽  
Interpretation System ◽  
Miss Distance ◽  
Video Image Processing

A new video image interpretation technology applied mainly to the angular distortion measuring system of navy vessel is developed in this paper. The video interpretation system incepts two video signals coming from two CCD of photoelectric self-collimation parallel optic equipment. Real-time video image processing and interpretation, as well as dynamic miss distance are achieved by using concurrent working mode, and the relatively distortion of vessel can be obtained by combining the two measurement results.

scholarly journals Testing of a torque sensor used to measure the parameters of the briquetting process of lignocellulosic materials

2019 ◽  
Vol 254 ◽  
pp. 05013 ◽  
Author(s):  
Krzysztof Talaśka ◽  
Dominik Wojtkowiak ◽  
Ireneusz Malujda ◽  
Krzysztof Wałęsa
Keyword(s):  
Calibration Method ◽  
Thermomechanical Properties ◽  
Measuring System ◽  
Torque Sensor ◽  
Study Results ◽  
Measurement Results ◽  
Rye Straw ◽  
Working Principle ◽  
Oat Straw ◽  
Open Working

The study presents a control and measurement system for the drive parameters of screw compactor machine with open working chamber for shredded materials. The study demonstrates the construction and working principle of the torque sensor for measuring the torque of the motor driving the compacting screw. The calibration method for the measuring system was presented together with example measurement results for compaction of broken up rye straw, oat straw and hay. The study results were analyzed for feasibility of use for the compaction of materials with specific thermomechanical properties. The conclusion presents the possible forms of application of the established solution in mass production.

Unsteady Flow Numerical Simulation in a Double Channel Pump and Measurements of Pressure Fluctuation at Volute Outlet

2009 ◽  
Author(s):  
Hou-lin Liu ◽  
Ming-zhen Lu ◽  
Bin-bin Lu ◽  
Ming-gao Tan ◽  
Yong Wang ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Unsteady Flow ◽  
Pressure Fluctuation ◽  
Operating Conditions ◽  
Navier Stokes ◽  
Navier Stokes Equation ◽  
Sliding Mesh ◽  
Measurement Results ◽  
Double Channel ◽  
Fft Analysis

Adopting the Reynolds averaged Navier-Stokes equation and RNG k-ε turbulent model, the unsteady flow in the double channel pump is simulated with sliding mesh technique. Detecting points in the impeller and volute passages are to capture the pressure fluctuation law at different time. The pressure fluctuation around the outlet of the volute is measured by pressure transducer, then the frequency domain pattern under different conditions comes out. With the Fast Fourier transform (FFT) analysis, the pressure changing law of time domain at the outlet of the volute is investigated under different operating conditions. It shows that the pressure fluctuation in the volute differs under different conditions. The pressure changing law obtained by the numerical simulation at the outlet of the volute accords with the measurement results. Also the pressure fluctuation at the outlet of the volute is closely related to the interaction between impeller and volute.

Experimental Research and Modeling of the Underwater Sound in Marine Environment

2013 ◽  
Vol 430 ◽  
pp. 285-289 ◽  
Author(s):  
Delicia Arsene ◽  
Claudia Borda ◽  
Larisa Butu ◽  
Marinela Marinescu ◽  
Victor Popovici ◽  
...  
Keyword(s):  
Acoustic Field ◽  
Measuring System ◽  
The Black Sea ◽  
Underwater Sound ◽  
Dynamic Measurements ◽  
Marine Habitat ◽  
Data Measurement ◽  
Impact Area ◽  
Measurement Methodology ◽  
Acoustic Impact

The paper presents a modeling of the acoustic field emitted by a rig tender located offshore exploration in the Black Sea. Are presented measuring system, experimental context, the types of noise that participate in the overall noise budget and the conditions in which measurements were made, also are mentioned and the project established through were measured the parameters and were defined devices which these measurements were made. Measurement system used is adaptable, allowing dynamic measurements and operative analysis of the acquired data. Measurement methodology was determined by an acoustic project, which was set to be purchased both: sizes and ways of interpreting them. Modeling acoustic field shows that the maximum acoustic impact area, below 120 dB re 1μPa criterion (proposed and accepted by Marine Directive) was extended to 3-5Km distance around the ship. It is expected to produce adverse effects on the marine habitat and on the underwater life.

Key Technique of Tip Clearance Measurement for Rotational Blades

2008 ◽  
Vol 381-382 ◽  
pp. 427-430 ◽  
Author(s):  
Yu Zhen Ma ◽  
F.J. Duan ◽  
Yi Zhong Zheng ◽  
Chang Sheng Ai ◽  
S.H. Ye
Keyword(s):  
Scattered Light ◽  
Measurement Techniques ◽  
Tip Clearance ◽  
Fiber Optic Sensor ◽  
Measuring System ◽  
Radial Clearance ◽  
Single Bundle ◽  
Contact Mode ◽  
Measurement Results ◽  
Beam Delivery

It’s an important problem for power industry; energy industry, aviation and shipping to real-time measure the rotating blades’ tip clearance of engine. The conventional measurement techniques have different limitations. To achieve applied level for tip clearance measurement technique, according to the use request and application environment of tip clearance sensor, a new fiber-optic sensor was put forward to measure the blade tip radial clearance of engine in non-contact mode. The sensor was consist of single-bundle transmitting fiber in the center for laser beam delivery and three groups receiving fibers located in all around for collecting the scattered light. The sensor can not only eliminate the effect to measurement results of light source fluctuation and reflectivity variety of tip surface, but also reduce the effect of angle between the tip surface and sensor end face to measurement results. From the measurement results obtained from sensor on different clearance points, it proves that the sensor measuring system has well feasibility and reliability in blades tip clearance detection.

Sign in / Sign up

Export Citation Format

Share Document