The Experts below are selected from a list of 852 Experts worldwide ranked by ideXlab platform

Brian Rothwell - One of the best experts on this subject based on the ideXlab platform.

  • investigation of the effects of Pipe Wall Roughness and Pipe diameter on the decompression wave speed in natural gas Pipelines
    2012 9th International Pipeline Conference, 2012
    Co-Authors: Guillaume Michal, Alhoush Elshahomi, Ajit R Godbole, Phillip Venton, Kamal K Botros, Leigh Fletcher, Brian Rothwell
    Abstract:

    The shock tube experimental results have shown clearly that the decompression wave was slowed down in a Pipe with a rough inner surface relative to that in a smooth Pipe under comparable conditions. In the present paper a one-dimensional dynamic simulation model, named EPDECOM, was developed to investigate the effects of Pipe Wall Roughness and Pipe diameter on the decompression wave speed. Comparison with experimental results showed that the inclusion of frictional effects led to a better prediction than that of the widely used model implemented in GASDECOM. EPDECOM simulation results showed that the effect of Roughness on the decompression wave speed is significant for Pipe diameters less than 250 mm. However the decompression wave speed is nearly independent of the Roughness for diameters above 250 mm as the frictional effect becomes negligible at such diameters.Copyright © 2012 by ASME

Amit Agrawal - One of the best experts on this subject based on the ideXlab platform.

  • influence of Wall conditions on friction factor for flow of gases under slip condition
    Experimental Thermal and Fluid Science, 2010
    Co-Authors: Anwar Demsis, S V Prabhu, Amit Agrawal
    Abstract:

    Abstract In this paper, the measurement of friction factor in gas with slip at the Wall is presented; these are made to encompass the following aspects: change in Pipe material, Pipe Wall Roughness, and channel geometry, for various gases. Two different Wall materials (stainless steel and copper), three different grades of Roughness, and two Wall geometries (circular and square) are considered in this study. The gases employed in this investigation are nitrogen, oxygen and argon. The ranges of Knudsen number and Reynolds numbers covered in this study are 0.0022–0.024 and 0.54–13.2, respectively. The experimental setup is validated by comparing the friction factor close to the continuum and slip flow regimes for nitrogen against available results in the literature. The experimental results suggest that the friction factor is affected by the Wall Roughness and geometry of cross-section, in addition to the amount of rarefaction. However, the effect of changing the gas or Pipe material is minimal. A correlation for slip flow in square duct is also proposed. This is one of the first such detailed studies and has implications for both gas flow in microchannels and rarefied gas in large Pipes.

Guillaume Michal - One of the best experts on this subject based on the ideXlab platform.

  • investigation of the effects of Pipe Wall Roughness and Pipe diameter on the decompression wave speed in natural gas Pipelines
    2012 9th International Pipeline Conference, 2012
    Co-Authors: Guillaume Michal, Alhoush Elshahomi, Ajit R Godbole, Phillip Venton, Kamal K Botros, Leigh Fletcher, Brian Rothwell
    Abstract:

    The shock tube experimental results have shown clearly that the decompression wave was slowed down in a Pipe with a rough inner surface relative to that in a smooth Pipe under comparable conditions. In the present paper a one-dimensional dynamic simulation model, named EPDECOM, was developed to investigate the effects of Pipe Wall Roughness and Pipe diameter on the decompression wave speed. Comparison with experimental results showed that the inclusion of frictional effects led to a better prediction than that of the widely used model implemented in GASDECOM. EPDECOM simulation results showed that the effect of Roughness on the decompression wave speed is significant for Pipe diameters less than 250 mm. However the decompression wave speed is nearly independent of the Roughness for diameters above 250 mm as the frictional effect becomes negligible at such diameters.Copyright © 2012 by ASME

Frederic Cegla - One of the best experts on this subject based on the ideXlab platform.

  • The uncertainties induced by internal Pipe Wall Roughness on the measurements of clamp-on ultrasonic flow meters
    2019 IEEE International Ultrasonics Symposium (IUS), 2019
    Co-Authors: Frederic Cegla
    Abstract:

    Clamp-on ultrasonic flow meters (UFMs) have lower accuracy compared with spool piece UFMs because of the uncertainties introduced during the in-field installation process. Internal Pipe Wall Roughness, one of these uncertainties, distorts the flow profile and causes the scattering of ultrasound. The objective of this paper is to carry out a parametric study to quantify the effect of scattering of ultrasound on the uncertainties of clamp-on UFM measurements without considering the flow disturbances. 2D finite element analysis was used to simulate the upstream and downstream signals of the clamp-on UFM based on some simplifying assumptions which were made about the effect of the flow. This simulation method was then verified by experiments which measure the uncertainties relating to the placement of ultrasonic probes at different separation distances. The simulation and experimental results were in good agreement. Then we applied this verified simulation method to investigate the uncertainties caused by the internal Pipe Wall Roughness on the flow measurements. For ultrasonic waves at a frequency of 1 MHz and corroded internal Pipe Wall surfaces (0.2 mm RMS) it was found that systematic errors of 2 percent can result from the Roughness induced scattering. This is a significant part of the measurement uncertainty range (1-5 percent) that is often quoted by manufacturers of clamp-on UFMs. This study therefore demonstrates that the accuracy of the clamp-on UFMs can be limited by the effects of internal Pipe Wall Roughness.

  • the effect of internal Pipe Wall Roughness on the accuracy of clamp on ultrasonic flowmeters
    IEEE Transactions on Instrumentation and Measurement, 2019
    Co-Authors: Xiaotang Gu, Frederic Cegla
    Abstract:

    Clamp-on transit-time ultrasonic flowmeters (UFMs) suffer from poor accuracy compared with spool-piece UFMs due to uncertainties that result from the in-field installation process. One of the important sources of uncertainties is internal Pipe Wall Roughness which affects the flow profile and also causes significant scattering of ultrasound. This paper purely focuses on the parametric study to quantify the uncertainties (related to internal Pipe Wall Roughness) induced by scattering of ultrasound and it shows that these effects are large even without taking into account the associated flow disturbances. The flowmeter signals for a reference clamp-on flowmeter setup were simulated using 2-D finite element analysis including simplifying assumptions (to simulate the effect of flow) that were deemed appropriate. The validity of the simulations was indirectly verified by carrying out experiments with different separation distances between ultrasonic probes. The error predicted by the simulations and the experimentally observed errors were in good agreement. Then, this simulation method was applied on Pipe Walls with rough internal surfaces. For ultrasonic waves at 1 MHz, it was found that compared with smooth Pipes, Pipes with only a moderately rough internal surface (with 0.2-mm rms and 5-mm correlation length) can exhibit systematic errors of 2% in the flow velocity measurement. This demonstrates that Pipe internal surface Roughness is a very important factor that limits the accuracy of clamp on UFMs.

Anwar Demsis - One of the best experts on this subject based on the ideXlab platform.

  • influence of Wall conditions on friction factor for flow of gases under slip condition
    Experimental Thermal and Fluid Science, 2010
    Co-Authors: Anwar Demsis, S V Prabhu, Amit Agrawal
    Abstract:

    Abstract In this paper, the measurement of friction factor in gas with slip at the Wall is presented; these are made to encompass the following aspects: change in Pipe material, Pipe Wall Roughness, and channel geometry, for various gases. Two different Wall materials (stainless steel and copper), three different grades of Roughness, and two Wall geometries (circular and square) are considered in this study. The gases employed in this investigation are nitrogen, oxygen and argon. The ranges of Knudsen number and Reynolds numbers covered in this study are 0.0022–0.024 and 0.54–13.2, respectively. The experimental setup is validated by comparing the friction factor close to the continuum and slip flow regimes for nitrogen against available results in the literature. The experimental results suggest that the friction factor is affected by the Wall Roughness and geometry of cross-section, in addition to the amount of rarefaction. However, the effect of changing the gas or Pipe material is minimal. A correlation for slip flow in square duct is also proposed. This is one of the first such detailed studies and has implications for both gas flow in microchannels and rarefied gas in large Pipes.