Utilization of Zonal Method for Five-Hole Probe Measurements of Complex Axial Compressor Flows

2020 ◽  
Vol 142 (6) ◽  
Author(s):  
Baojie Liu ◽  
Ying Qiu ◽  
Guangfeng An ◽  
Xianjun Yu
Keyword(s):  
Traditional Method ◽  
Large Scale ◽  
Measurement Accuracy ◽  
Axial Compressor ◽  
Correlation Method ◽  
Zonal Method ◽  
Measurement Results ◽  
Measured Flow ◽  
Calibration Accuracy ◽  
Probe Measurements

Abstract Five-hole probe is widely used in the measurement of turbomachinery flows, but in the traditional way the measurable angle range is not big enough for some interested flows. In this paper, the zonal method is introduced to an L-shaped five-hole probe to measure axial compressor flows. First, the calibration theory of the zonal method in five-hole probe is presented, and the effects of some factors on the measurement accuracy of the five-hole probe are discussed. The results reveal that the two-step correlation method can yield a highest calibration accuracy, and the calibration angular grid spacing should not exceed 5 deg. While the overlap region seems to have no effect on the measurement accuracy of the five-hole probe using the two-step correlation method. Reynolds number (Re) has obvious influence on the measurement accuracy of the investigated five-hole probe, and this effect could be ignored only when Re is bigger than 6000. Then, the investigated five-hole probe using the zonal method is used to measure the inter-row flows of a low-speed large-scale axial compressor, and the measurement results are compared with the results using the traditional method. Besides, the Re corrected results using the zonal method are also compared. The measured results have shown that the zonal method has prominent advantages relative to the traditional method in measuring the corner stall flows. While there is no need to correct the Re effect if the probe is calibrated in the velocity nearly equivalent to the measured flow.

Measuring Failures and Correction Methods for Pneumatic Multi-Hole Probes

2012 ◽  
Author(s):  
Herwart T. Hoenen ◽  
Robert Kunte ◽  
Phillip Waniczek ◽  
Peter Jeschke
Keyword(s):  
Measurement Errors ◽  
Measurement Techniques ◽  
Axial Compressor ◽  
Correction Method ◽  
Gradient Field ◽  
Trailing Edge ◽  
Measurement Results ◽  
Real Flow ◽  
Hot Film ◽  
Probe Measurements

Systematic measurements have been performed in a free stream in order to analyse the measuring behaviour of pneumatic multi-hole probes in the gradient field of a wake of an airfoil. The five-hole probe was traversed in different axial distances from the trailing edge and the results were compared to PIV and hot film probe measurements. The direct comparison of the three measurement techniques shows that too small axial distances between a five-hole probe and an airfoil trailing edge introduce significant measurement errors. Different effects were analysed in order to evaluate their influence on the measuring results and to estimate the deviation from the real flow properties. The limitations of probe measurements and the influences of the probe on the flow field are discussed. It is explained how pneumatic multi-hole probe measuring data can be corrected in order to improve the measuring results. In order to demonstrate the suitability of the correction method for turbo machinery application it is applied to measurement results of an axial compressor test rig.

scholarly journals Method of improving large-scale measurement accuracy of laser tracker based on photogrammetry

2019 ◽  
Vol 52 (9-10) ◽  
pp. 1220-1227 ◽  
Author(s):  
Chengyang Zhang ◽  
Xishuang Jing ◽  
Siyu Chen ◽  
Xuanzhe Ling ◽  
Jiarong Zou ◽  
...  
Keyword(s):  
Large Scale ◽  
Measurement Accuracy ◽  
Measurement Data ◽  
Correction Method ◽  
Laser Tracker ◽  
Digital Measurement ◽  
Long Distance ◽  
Measurement Results ◽  
High Measurement ◽  
Coordinate Correction

Background: When performing the spatial large-scale measurements, the measurement accuracy of laser tracker would decreased with the increase of the measurement distances due to the refraction difference of most optical digital measurement devices. Therefore, this paper proposed a method based on photogrammetry system to improve the large-scale measurement accuracy of the laser tracker. Purpose: The purpose of this method is to improve the large-scale measurement accuracy of the laser tracker by considering the advantages of photogrammetry system such as high measurement accuracy and good portability. Methods: The measurement data from the photogrammetry system would be used as a reference to do correction on measurement results from laser tracker. The coordinate correction method based on Rodrigues’ rotation formula has been discussed. The measurement accuracy of the long-distance point of laser tracker can be significantly improved through the coordinate correction method. Conclusion: Based on the advantages of using photogrammetry system, the proposed method can achieve higher accuracy when measuring the common points at a closer distance than the laser tracker can do when measuring objects far away from instrument. The feasibility of the proposed method has been demonstrated by experiment.

High Precision Measurement of Moment of Inertia Based on Compound Pendulum

2011 ◽  
Vol 105-107 ◽  
pp. 2055-2058
Author(s):  
Wen Hou ◽  
Peng Fei Xue ◽  
Tie Hua Ma
Keyword(s):  
Traditional Method ◽  
Large Scale ◽  
Phase Plane ◽  
Diameter Ratio ◽  
Moment Of Inertia ◽  
High Precision Measurement ◽  
Time Curve ◽  
Measurement Results ◽  
Large Length ◽  
Measurement Principle

A new method and equipment based on compound pendulum was designed for measuring moment of inertia (MOI). The measurement principle of the system, being quite different from the traditional method which records the swing period of the compound pendulum, records the “Angle-time” curve and conducts a series of computation featuring phase-plane to obtain the MOI of the object being measured. The proposed method could effectively eliminate the friction moment’s influence on the measurement results and enhance the precision up to 0.12%. The method is suitable for the heavy and large-scale objects, especially those with large length/diameter ratio.

scholarly journals Inverse Infiltration Modeling of Dike Covers Made of Dredged Material Using PEST and AMALGAM

Geosciences ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 41
Author(s):  
Tim Jurisch ◽  
Stefan Cantré ◽  
Fokke Saathoff
Keyword(s):  
Large Scale ◽  
Measurement Data ◽  
Fine Grained ◽  
Dredged Materials ◽  
Measurement Results ◽  
Large Scale Field ◽  
Eigenvalue Ratio ◽  
Ill Posed ◽  
Materials Used ◽  
Installation Technology

A variety of studies recently proved the applicability of different dried, fine-grained dredged materials as replacement material for erosion-resistant sea dike covers. In Rostock, Germany, a large-scale field experiment was conducted, in which different dredged materials were tested with regard to installation technology, stability, turf development, infiltration, and erosion resistance. The infiltration experiments to study the development of a seepage line in the dike body showed unexpected measurement results. Due to the high complexity of the problem, standard geo-hydraulic models proved to be unable to analyze these results. Therefore, different methods of inverse infiltration modeling were applied, such as the parameter estimation tool (PEST) and the AMALGAM algorithm. In the paper, the two approaches are compared and discussed. A sensitivity analysis proved the presumption of a non-linear model behavior for the infiltration problem and the Eigenvalue ratio indicates that the dike infiltration is an ill-posed problem. Although this complicates the inverse modeling (e.g., termination in local minima), parameter sets close to an optimum were found with both the PEST and the AMALGAM algorithms. Together with the field measurement data, this information supports the rating of the effective material properties of the applied dredged materials used as dike cover material.

scholarly journals Heterogeneity and effectiveness analysis of COVID-19 prevention and control in major cities in China through time-varying reproduction number estimation

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Qing Cheng ◽  
Zeyi Liu ◽  
Guangquan Cheng ◽  
Jincai Huang
Keyword(s):  
Prevention And Control ◽  
Large Scale ◽  
Reproduction Number ◽  
Correlation Method ◽  
Control Measures ◽  
Time Varying ◽  
Short Period ◽  
Significant Difference ◽  
Prevention And Control Measures ◽  
And Control

AbstractBeginning on December 31, 2019, the large-scale novel coronavirus disease 2019 (COVID-19) emerged in China. Tracking and analysing the heterogeneity and effectiveness of cities’ prevention and control of the COVID-19 epidemic is essential to design and adjust epidemic prevention and control measures. The number of newly confirmed cases in 25 of China’s most-affected cities for the COVID-19 epidemic from January 11 to February 10 was collected. The heterogeneity and effectiveness of these 25 cities’ prevention and control measures for COVID-19 were analysed by using an estimated time-varying reproduction number method and a serial correlation method. The results showed that the effective reproduction number (R) in 25 cities showed a downward trend overall, but there was a significant difference in the R change trends among cities, indicating that there was heterogeneity in the spread and control of COVID-19 in cities. Moreover, the COVID-19 control in 21 of 25 cities was effective, and the risk of infection decreased because their R had dropped below 1 by February 10, 2020. In contrast, the cities of Wuhan, Tianmen, Ezhou and Enshi still had difficulty effectively controlling the COVID-19 epidemic in a short period of time because their R was greater than 1.

scholarly journals Reduction of Unsteady Blade Loading by Beneficial Use of Vortical and Potential Disturbances in an Axial Compressor With Rotor Clocking

1998 ◽  
Vol 120 (4) ◽  
pp. 705-713 ◽  
Author(s):  
S. T. Hsu ◽  
A. M. Wo
Keyword(s):  
Large Scale ◽  
Axial Compressor ◽  
Leading Edge ◽  
Forced Response ◽  
Suction Surface ◽  
Blade Loading ◽  
Beneficial Use ◽  
Unsteady Loading ◽  
Vortical Disturbance ◽  
First Time

This paper demonstrates reduction of stator unsteady loading due to forced response in a large-scale, low-speed, rotor/stator/rotor axial compressor rig by clocking the downstream rotor. Data from the rotor/stator configuration showed that the stator response due to the upstream vortical disturbance reaches a maximum when the wake impinges against the suction surface immediately downstream of the leading edge. Results from the stator/rotor configuration revealed that the stator response due to the downstream potential disturbance reaches a minimum with a slight time delay after the rotor sweeps pass the stator trailing edge. For the rotor/stator/rotor configuration, with Gap1 = 10 percent chord and Gap2 = 30 percent chord, results showed a 60 percent reduction in the stator force amplitude by clocking the downstream rotor so that the time occurrence of the maximum force due to the upstream vortical disturbance coincides with that of the minimum force due to the downstream potential disturbance. This is the first time, the authors believe, that beneficial use of flow unsteadiness is definitively demonstrated to reduce the blade unsteady loading.

Study of the Standard k-ε Model for Tip Leakage Flow in an Axial Compressor Rotor

2016 ◽  
Vol 33 (4) ◽  
Author(s):  
Yanfei Gao ◽  
Yangwei Liu ◽  
Luyang Zhong ◽  
Jiexuan Hou ◽  
Lipeng Lu
Keyword(s):  
Flow Field ◽  
Large Scale ◽  
Turbulent Viscosity ◽  
Axial Compressor ◽  
Leakage Flow ◽  
Reynolds Stresses ◽  
Mean Flow ◽  
Tip Leakage Flow ◽  
Tip Leakage ◽  
Compressor Rotor

AbstractThe standard k-ε model (SKE) and the Reynolds stress model (RSM) are employed to predict the tip leakage flow (TLF) in a low-speed large-scale axial compressor rotor. Then, a new research method is adopted to “freeze” the turbulent kinetic energy and dissipation rate of the flow field derived from the RSM, and obtain the turbulent viscosity using the Boussinesq hypothesis. The Reynolds stresses and mean flow field computed on the basis of the frozen viscosity are compared with the results of the SKE and the RSM. The flow field in the tip region based on the frozen viscosity is more similar to the results of the RSM than those of the SKE, although certain differences can be observed. This finding indicates that the non-equilibrium turbulence transport nature plays an important role in predicting the TLF, as well as the turbulence anisotropy.

Performance Analysis and Validation of Precision Multisatellite RF Measurement Scheme for Microsatellite Formations

2021 ◽  
Author(s):  
Chen Lin ◽  
Xiaojun Jin ◽  
Shiming Mo ◽  
Cong Hou ◽  
Wei Zhang ◽  
...  
Keyword(s):  
Multiple Access ◽  
High Performance ◽  
Large Scale ◽  
Measurement Accuracy ◽  
Media Access Control ◽  
Satellite Measurement ◽  
Measurement Scheme ◽  
Rf Measurement ◽  
Code Division Multiple ◽  
Time Division

Abstract Almost all existing studies on inter-satellite radio frequency (RF) measurement have focused on two-satellite formations. Although some frequency division multiple access and code division multiple access multisatellite RF measurement schemes have been proposed, their poor scalability does not satisfy the inter-satellite measurement requirements of multisatellite formations, especially large-scale formations. Two-way ranging (TWR), which is based on a time division mechanism, is an effective solution that has been used for inter-satellite links in the global positioning system and Beidou navigation constellations. However, the high measurement accuracy achieved with TWR in these navigation constellations is heavily reliant on high-performance atomic clocks and the assistance of navigation ephemeris, which are not available on microsatellite platforms. This work focuses on a scalable multisatellite measurement scheme that adopts a distributed broadcast-based time division multiple access mechanism as the media access control layer and uses an asymmetric double-side TWR method as the physical layer. The measurement performance of the proposed scheme is evaluated through in-depth theoretical modeling, simulation verification, and experimental validation, along with a comprehensive comparison with the conventional TWR method. The experimental results show that centimeter-level measurement accuracy can be achieved with the proposed scheme when only a common miniaturized frequency source is used. This accuracy level is two orders of magnitude better than that of the TWR method, and thus satisfies the application requirements of general large-scale microsatellite formations.

Block Thickness Measurement of Using the Structured Light Vision

2018 ◽  
Vol 33 (01) ◽  
pp. 1955001 ◽  
Author(s):  
Fenghui Lian ◽  
Qingchang Tan ◽  
Siyuan Liu
Keyword(s):  
Machine Vision ◽  
Measurement Method ◽  
Measurement Accuracy ◽  
Thickness Measurement ◽  
Base Plane ◽  
Vision Measurement ◽  
Measurement Results ◽  
Measurement Equations ◽  
Structured Light Vision ◽  
Measuring Base

A method for measuring block thicknesses is proposed by the machine vision measurement. Equations of the measuring base plane and the light plane are formed by calibration. Then, the equation of the light strip image, that is, the image of the intersection between the base plane and light one, is established by the projection relation. Equation of the image of the light strip on the measured plane can be determined by the fitting. Since the light strip on the measuring base plane is parallel to one on the measured plane, the thickness of the measuring block is measured by using the two equations. The experiment evaluates the measurement accuracy of the measurement method and analyzes the influence of some factors on the measurement results.

Using the Simplified 3D DIC Method to Measure the Deformation of 3D Surface

2011 ◽  
Vol 121-126 ◽  
pp. 3945-3949 ◽  
Author(s):  
Shih Heng Tung ◽  
Jui Chao Kuo ◽  
Ming Hsiang Shih ◽  
Wen Pei Sung
Keyword(s):  
Measurement Accuracy ◽  
Good Accuracy ◽  
Correlation Method ◽  
Image Correlation ◽  
2D Digital Image Correlation ◽  
Plate Specimen ◽  
Before And After ◽  
Out Of Plane ◽  
Plane Displacement ◽  
2D And 3D

In recent years, 2D digital image correlation method (DIC) has been widely used in the measurement of plane strain. However, out-of-plane displacement could be induced during the loading and it would affect the measurement accuracy. Thus, a 3D measurement is necessary. This study utilizes a simplified 3D DIC to measure the geometry of an object before and after deformation. Then the finite element concept is involved to determine the strain after deformation. A flat plate specimen with in-plane and out-of-plane displacement is observed. Both 2D and 3D DIC are used to analyze the strain. The results show that using 3D DIC to measure strain is feasible and with a very good accuracy.

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