scholarly journals The Investigation on the Flow Distortion Effect of Header to Guarantee the Measurement Accuracy of the Ultrasonic Gas Flowmeter

2021 ◽  
Vol 11 (8) ◽  
pp. 3656
Author(s):  
Wenlin Chen ◽  
Jianjun Wu ◽  
Chunhui Li
Keyword(s):  
Flow Field ◽  
Measurement Accuracy ◽  
Cross Flow ◽  
Experimental Tests ◽  
Flow Distortion ◽  
Field Distortion ◽  
Measurement Results ◽  
Distortion Effect ◽  
Computational Fluid Dynamics Cfd ◽  
Double Cross

The quantification of the flow distortion effect on the measurement accuracy of the ultrasonic gas flowmeter downstream of the header is important but an area that has been of less concern in the research. By experiments and computational fluid dynamics (CFD), the influence of flow field distortion was studied. Experimental results under three different installation conditions showed that when there was flow field distortion downstream of the header, the measurement results of the gas ultrasonic flowmeter were 1% higher than those when there was no distortion, while a flow conditioner could effectively eliminate flow field distortion. Based on the experimental tests, the flow field distribution was analyzed with CFD, which showed that the flow field distortion effect generated by the header had a significant influence on the parameter of nonconforming Profile factor, while the parameters of Symmetry and Cross-flow could be obviously eliminated by the double-cross-section designing.

scholarly journals Study on flow field and measurement characteristics of a small-bore ultrasonic gas flow meter

2021 ◽  
pp. 002029402110075
Author(s):  
Desheng Chen ◽  
Haibin Cao ◽  
Baoling Cui
Keyword(s):  
Flow Field ◽  
Gas Flow ◽  
Measurement Accuracy ◽  
Flow Region ◽  
Signal Propagation ◽  
Low Flow ◽  
Flow Distortion ◽  
Flow Meter ◽  
Accuracy Class ◽  
Pipeline Flow

A new structure is proposed for a DN25-type ultrasonic gas flow meter with a V-shape double sound channel arrangement. The flow field characteristics are analyzed including velocity curves for the four channel lines, velocity profiles for different cross-sections of the flow meter, and streamlines of the transducer channel sections. The metering characteristics of the flowmeter are measured using a Venturi nozzle device. When the pipeline flow rate is less than 2.26 m/s, the pipe installation does not have a significant effect on the velocity profile and the velocity in the channel lines. However, the error in the low-flow region is large, and the flow distortion directly affects the measurement accuracy. When an ultrasonic gas flow meter with an accuracy class of 1.5 is used with pipes containing a single or double bend upstream, the linear error doubles, low-flow error becomes a negative deviation, and reference error in the low-flow region becomes approximately 700%–949%. The installation structure of the first pair of transducers also affects the signal propagation of the transducers behind it. Therefore, it is critical to process the ultrasonic signal according to the flow field distribution and adopt different weighted algorithms to obtain accurate pipeline flow rates to improve the measurement accuracy of the ultrasonic flow meter.

scholarly journals Effects of probes with different structures on the flow field and measurement results of imported compressors

2021 ◽  
Vol 39 (4) ◽  
pp. 858-864
Author(s):  
Guanghua Zheng ◽  
Fei Shui ◽  
Jinxin Hu ◽  
Xin Liu ◽  
Huazhong Xiao
Keyword(s):  
Measurement Error ◽  
Flow Field ◽  
Flow Rate ◽  
Total Pressure ◽  
Measurement Accuracy ◽  
Probe Measurement ◽  
Pressure Probe ◽  
Temperature Probe ◽  
Measurement Results ◽  
Total Temperature

In this paper, the measurement accuracy of two different types of total pressure probe and total temperature probe in turboshaft engine compressor inlet channel and the influence of these two probes on the flow field through numerical simulation was studied. At the same time, the influence of the probe structure and installation position on probe measurement results under three typical working conditions of cruise, maximum continuous and takeoff was analyzed. The simulation results showed that the higher the engine inlet flow rate, the greater the measurement error of the probe. Comparing with the total temperature probe, the total pressure probe measurement accuracy is more influenced by the flow rate. The velocity uniformity is less affected by the engine operating conditions and is mainly related to the structure of the inserted probes. The closer the total pressure probe to the support plate, the greater the measurement error. The probe installation position has a small effect on the total pressure loss coefficient at the outlet.

Hydrodynamic Performance Study on Flow Field in Rod Bundles With Spacer Grids

2014 ◽  
Author(s):  
Li-feng Song ◽  
Rui-feng Tian ◽  
Lan-xin Sun ◽  
Cong Shi ◽  
Peng Li
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Flow Field ◽  
Nuclear Reactor ◽  
Cross Flow ◽  
Hydrodynamic Performance ◽  
Performance Study ◽  
Rod Bundles ◽  
Spacer Grids ◽  
Computational Fluid Dynamics Cfd

With the dramatic progress in the computational fluid dynamics (CFD) methodology, this technology can be used in researching the knowledge of thermal–hydraulic characteristics in the rod bundles, particularly with the spacer grids. These characteristics, including fluid flow, turbulence, and heat transfer and so on, all of this information can be applied in design and the improvement of rod bundles. This paper calculated the single-phase flow field in rod bundles with different spacer grids respectively by numerical method, which was based on the experiment performed by Korea Atomic Energy Research Institute (KAERI). Two types of grid designs are used, including the Split-type and Swirl-type, respectively. By analyzing the calculated results, discussing the feasibility of computational fluid dynamics (CFD) methodology in thermal-hydraulic analysis of nuclear reactor, and obtaining the hydrodynamic performance of the two different types of spacer grids. The result showed that both of the two spacer grids led to intense cross-flow in the channel, and the cross-flow intensity decayed with the increasing of downstream distance after the spacer grids. Axial velocities were distributed uniformly in the channel.

scholarly journals Effect of Modifying the Membrane Surface with Microcapsules on the Flow Field for a Cross-Flow Membrane Setup: A CFD Study

Membranes ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 555
Author(s):  
Sebastian Osterroth ◽  
Christian Neumann ◽  
Michael Weiß ◽  
Uwe Maurieschat ◽  
Alexandra Latnikova ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Flow Field ◽  
Membrane Surface ◽  
Cross Flow ◽  
Transmembrane Pressure ◽  
Membrane Fabrication ◽  
Membrane Biofouling ◽  
Comparison Results ◽  
Computational Fluid Dynamics Cfd

In this study, the attachment of microcapsules on the membrane surface and its influence on the flow field for a cross-flow membrane setup are investigated. The microcapsules were placed on the top layer of the membrane. The overall purpose of this modification was the prevention of membrane biofouling. Therefore, in a first step, the influence of such a combination on the fluid flow was investigated using computational fluid dynamics (CFD). Here, different properties, which are discussed as indicators for biofouling in the literature, were considered. In parallel, different fixation strategies for the microcapsules were experimentally tested. Two different methods to add the microcapsules were identified and further investigated. In the first method, the microcapsules are glued to the membrane surface, whereas in the second method, the microcapsules are added during the membrane fabrication. The different membrane modifications were studied and compared using CFD. Therefore, virtual geometries mimicking the real ones were created. An idealized virtual geometry was added to the comparison. Results from the simulation were fed back to the experiments to optimize the combined membrane. For the presented setup, it is shown that the glued configuration provides a lower transmembrane pressure than the configuration where microcapsules are added during fabrication.

Study of the Flow Field and Performances of a Centrifugal Pump During Unstable Operating Conditions by CFD

2015 ◽  
Author(s):  
Romain Prunières ◽  
Neo Imai ◽  
Yasuhiro Inoue ◽  
Takashi Okihara ◽  
Takahide Nagahara
Keyword(s):  
Flow Field ◽  
Flow Rate ◽  
Experimental Tests ◽  
Operating Conditions ◽  
Low Flow ◽  
Performance Curve ◽  
Centrifugal Pumps ◽  
Flow Rates ◽  
Computational Fluid Dynamics Cfd ◽  
Local Dent

Centrifugal pumps curve instability, characterized by a local dent and uprising head curve, often causes severe problems such as vibrations and noises. At low flow rates, stability of performance curve is necessary for reliable operation of the pump. Most of the studies regarding centrifugal pumps curves instability focus on flow rate around 60 % of the best efficiency flow rate. The purpose of present investigation is to analyse the causes of the occurrence of performance curve instability by means of Computational Fluid Dynamics (CFD) and to understand the mechanism of such instability at flow rates around 30 % of best efficiency flow rate. In order to understand the causes of the performance curve instability, two impellers with different outlet shape are analysed. During experimental tests, performance curve instability appeared around 30 % of the best efficiency flow rate on the first impeller while the second impeller remains stable. CFD analysis also shows unstable performance curve for the first impeller, and stable for the second one. Hence, a detailed analysis of the flow field of the two impellers and a quantitative comparison are performed in order to characterize the instability phenomenon.

Investigation on the Performance and Flow Structure of Centrifugal Compressor: Understand the Inlet Bent Duct Configurations

2016 ◽  
Author(s):  
Ce Yang ◽  
Yixiong Liu ◽  
Leilei Wang ◽  
Dazhong Lao ◽  
Changmao Yang
Keyword(s):  
Flow Field ◽  
Flow Structure ◽  
Centrifugal Compressor ◽  
Torsion Angle ◽  
Static Pressure ◽  
Experimental Tests ◽  
Aerodynamic Performance ◽  
Flow Distortion ◽  
Surge Margin ◽  
Compressor Impeller

In turbocharger systems, the inlets of centrifugal compressor often connect with bent ducts, producing a non-uniform flow field distribution at the compressor impeller inlet, which degrades the compressor performance and deteriorate the flow structure of the compressor significantly. In present work, a group of typical bent ducts is designed by adjusting the torsion angle of the U-shaped duct to investigate the effects of these bent ducts on the performance and flow field of the compressor. The experimental tests of the compressor with various inlet bent duct configurations were carried out to obtain the aerodynamic performance and pressure distributions. The experimental performance curves showed the bent ducts affect the aerodynamic performance and surge margin of the compressor. To understand these effects fundamentally, the unsteady flow calculations were conducted to capture the detailed flow in the bent ducts and compressor internal. The flow distortion distributions and swirl patterns in various bent ducts were compared by numerical calculation results and analyzed in theory. The results showed the total pressure distorted region at the duct exit expands along the circumferential direction and distortion degree is weakened with the torsion angle of bent duct increases. Moreover, the swirl distortion patterns vary in different inlet ducts. The further analysis showed that an appropriate bent duct configuration is helpful for improving the surge margin of the compressor effectively. By observing the static pressure in the impeller inlet and shroud region, it found that the bent ducts produce non-uniform static pressure at impeller inlet and reduce the static pressure in shroud wall. It also found that the change of the pressure in compressor internal has some relation with the swirl structure of bent duct exit.

Yaw Galloping of a TLWP Platform Under High Speed Currents by Analytical Methods and its Comparison With Experimental Results

2017 ◽  
Author(s):  
Francisco Lamas ◽  
Miguel A. M. Ramirez ◽  
Antonio Carlos Fernandes
Keyword(s):  
High Speed ◽  
Production Systems ◽  
Experimental Tests ◽  
Experimental Results ◽  
Analytical Methodology ◽  
New Approach ◽  
Laboratory Facilities ◽  
Polynomial Curve ◽  
Computational Fluid Dynamics Cfd ◽  
Cfd Analyses

Flow Induced Motions are always an important subject during both design and operational phases of an offshore platform life. These motions could significantly affect the performance of the platform, including its mooring and oil production systems. These kind of analyses are performed using basically two different approaches: experimental tests with reduced models and, more recently, with Computational Fluid Dynamics (CFD) dynamic analysis. The main objective of this work is to present a new approach, based on an analytical methodology using static CFD analyses to estimate the response on yaw motions of a Tension Leg Wellhead Platform on one of the several types of motions that can be classified as flow-induced motions, known as galloping. The first step is to review the equations that govern the yaw motions of an ocean platform when subjected to currents from different angles of attack. The yaw moment coefficients will be obtained using CFD steady-state analysis, on which the yaw moments will be calculated for several angles of attack, placed around the central angle where the analysis is being carried out. Having the force coefficients plotted against the angle values, we can adjust a polynomial curve around each analysis point in order to evaluate the amplitude of the yaw motion using a limit cycle approach. Other properties of the system which are flow-dependent, such as damping and added mass, will also be estimated using CFD. The last part of this work consists in comparing the analytical results with experimental results obtained at the LOC/COPPE-UFRJ laboratory facilities.

scholarly journals Cross-Flow Tidal Turbines with Highly Flexible Blades—Experimental Flow Field Investigations at Strong Fluid–Structure Interactions

Energies ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 797
Author(s):  
Stefan Hoerner ◽  
Iring Kösters ◽  
Laure Vignal ◽  
Olivier Cleynen ◽  
Shokoofeh Abbaszadeh ◽  
...  
Keyword(s):  
Flow Field ◽  
High Speed ◽  
Cross Flow ◽  
Speed Ratio ◽  
Fluid Structure Interactions ◽  
Dimensional Parameter ◽  
Fluid Structure ◽  
Passive Flow Control ◽  
Tidal Turbines ◽  
Tidal Turbine

Oscillating hydrofoils were installed in a water tunnel as a surrogate model for a hydrokinetic cross-flow tidal turbine, enabling the study of the effect of flexible blades on the performance of those devices with high ecological potential. The study focuses on a single tip-speed ratio (equal to 2), the key non-dimensional parameter describing the operating point, and solidity (equal to 1.5), quantifying the robustness of the turbine shape. Both parameters are standard values for cross-flow tidal turbines. Those lead to highly dynamic characteristics in the flow field dominated by dynamic stall. The flow field is investigated at the blade level using high-speed particle image velocimetry measurements. Strong fluid–structure interactions lead to significant structural deformations and highly modified flow fields. The flexibility of the blades is shown to significantly reduce the duration of the periodic stall regime; this observation is achieved through systematic comparison of the flow field, with a quantitative evaluation of the degree of chaotic changes in the wake. In this manner, the study provides insights into the mechanisms of the passive flow control achieved through blade flexibility in cross-flow turbines.

scholarly journals Simulation of Thermal Effects on the Flow Field in a Pilot-Scale Kiln

2021 ◽  
Author(s):  
I. A. Sofia Larsson ◽  
Anna-Lena Ljung ◽  
B. Daniel Marjavaara
Keyword(s):  
Flow Field ◽  
Coal Combustion ◽  
Thermal Effects ◽  
Iron Ore ◽  
Combustion Process ◽  
Pilot Scale ◽  
Mixing Properties ◽  
Process Gas ◽  
Mixing Rates ◽  
Computational Fluid Dynamics Cfd

AbstractThe flow field and coal combustion process in a pilot-scale iron ore pelletizing kiln is simulated using a computational fluid dynamics (CFD) model. The objective of the work is to investigate how the thermal effects from the flame affect the flow field. As expected, the combustion process with the resulting temperature rise and volume expansion leads to an increase of the velocity in the kiln. Apart from that, the overall flow field looks similar regardless of whether combustion is present or not. The flow field though affects the combustion process by controlling the mixing rates of fuel and air, governing the flame propagation. This shows the importance of correctly predicting the flow field in this type of kiln, with a large amount of process gas circulating, in order to optimize the combustion process. The results also justify the use of down-scaled, geometrically similar, water models to investigate kiln aerodynamics in general and mixing properties in particular. Even if the heat release from the flame is neglected, valuable conclusions regarding the flow field can still be drawn.

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