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J F Harrington - One of the best experts on this subject based on the ideXlab platform.

  • final report of forge wp4 1 1 the stress path permeameter experiment conducted on callovo oxfordian claystone
    2012
    Co-Authors: Robert J. Cuss, J F Harrington
    Abstract:

    This report describes in detail the stress-path permeameter (SPP) apparatus and the test programme conducted on Callovo-Oxfordian (COx) Claystone from the Bure underground research laboratory (URL) in France. Funding for this study has been provided by the French radioactive waste management operator, Andra, the European Union (FORGE Project, Project number 230357) and the British Geological Survey through its well-founded laboratory programme and the Geosphere Containment project (part of the BGS core strategic programme). The results from the first test conducted using the SPP showed that COx has a very pronounced time-dependent component of deformation. This had implications for the following test conducted on COx and also has implications when comparing tests that have been deformed at a much faster rate. Test SPP_COx-1 was conducted with water as a test permeant at constant pore-pressure along a pre-defined stress-path. Volumetric deformation was observed during 16 steps along the stress-path, with considerable time-dependent deformation and anisotropy seen in radial strain. The 16th stage saw the sample fail through the formation of a fracture after the sample had experienced constant stress conditions for 5.5 days; this emphasises the observed time dependent deformation. The results from test SPP_COx-2 clearly showed that the sample dilated at the onset of Gas propagation; dilatancy was observed in three radial and one axial direction. A component of this volumetric deformation was associated with changes in pore-pressure. However, pore-pressure variation cannot account for the full amount of strain recorded and a proportion of the strain observed was the result of Gas migration by dilatant pathway formation. Prior to the sample attaining steady-state flow, outflow from the sample slowly reduced and the conductive features experienced self-Sealing. Gas injection pressure was raised and back-pressure was carefully lowered; neither course of action re-initiated flow through the sample.

  • final report of forge wp4 1 1 the stress path permeameter experiment conducted on callovo oxfordian claystone
    2012
    Co-Authors: Robert J. Cuss, J F Harrington
    Abstract:

    This report describes in detail the stress-path permeameter (SPP) apparatus and the test programme conducted on Callovo-Oxfordian (COx) Claystone from the Bure underground research laboratory (URL) in France. Funding for this study has been provided by the French radioactive waste management operator, Andra, the European Union (FORGE Project, Project number 230357) and the British Geological Survey through its well-founded laboratory programme and the Geosphere Containment project (part of the BGS core strategic programme). The results from the first test conducted using the SPP showed that COx has a very pronounced time-dependent component of deformation. This had implications for the following test conducted on COx and also has implications when comparing tests that have been deformed at a much faster rate. Test SPP_COx-1 was conducted with water as a test permeant at constant pore-pressure along a pre-defined stress-path. Volumetric deformation was observed during 16 steps along the stress-path, with considerable time-dependent deformation and anisotropy seen in radial strain. The 16th stage saw the sample fail through the formation of a fracture after the sample had experienced constant stress conditions for 5.5 days; this emphasises the observed time dependent deformation. The results from test SPP_COx-2 clearly showed that the sample dilated at the onset of Gas propagation; dilatancy was observed in three radial and one axial direction. A component of this volumetric deformation was associated with changes in pore-pressure. However, pore-pressure variation cannot account for the full amount of strain recorded and a proportion of the strain observed was the result of Gas migration by dilatant pathway formation. Prior to the sample attaining steady-state flow, outflow from the sample slowly reduced and the conductive features experienced self-Sealing. Gas injection pressure was raised and back-pressure was carefully lowered; neither course of action re-initiated flow through the sample.

Bing Wang - One of the best experts on this subject based on the ideXlab platform.

  • flow dynamics of a spiral groove dry Gas seal
    Chinese Journal of Mechanical Engineering, 2013
    Co-Authors: Bing Wang, Huiqiang Zhang
    Abstract:

    The dry-Gas seal has been widely used in different industries. With increased spin speed of the rotator shaft, turbulence occurs in the Gas film between the stator and rotor seal faces. For the micro-scale flow in the Gas film and grooves, turbulence can change the pressure distribution of the Gas film. Hence, the seal performance is influenced. However, turbulence effects and methods for their evaluation are not considered in the existing industrial designs of dry-Gas seal. The present paper numerically obtains the turbulent flow fields of a spiral-groove dry-Gas seal to analyze turbulence effects on seal performance. The direct numerical simulation (DNS) and Reynolds-averaged Navier-Stokes (RANS) methods are utilized to predict the velocity field properties in the grooves and Gas film. The key performance parameter, open force, is obtained by integrating the pressure distribution, and the obtained result is in good agreement with the experimental data of other researchers. Very large velocity gradients are found in the Sealing Gas film because of the geometrical effects of the grooves. Considering turbulence effects, the calculation results show that both the Gas film pressure and open force decrease. The RANS method underestimates the performance, compared with the DNS. The solution of the conventional Reynolds lubrication equation without turbulence effects suffers from significant calculation errors and a small application scope. The present study helps elucidate the physical mechanism of the hydrodynamic effects of grooves for improving and optimizing the industrial design or seal face pattern of a dry-Gas seal.

  • numerical analysis of a spiral groove dry Gas seal considering micro scale effects
    Chinese Journal of Mechanical Engineering, 2011
    Co-Authors: Bing Wang
    Abstract:

    A dry-Gas seal system is a non-contact seal technology that is widely used in different industrial applications.Spiral-groove dry-Gas seal utilizes fluid dynamic pressure effects to realize the seal and lubrication processes,while forming a high pressure Gas film between two Sealing faces due to the deceleration of the Gas pumped in or out.There is little research into the effects and the influence on seal performance,if the grooves and the Gas film are at the micro-scale.This paper investigates the micro-scale effects on spiral-groove dry-Gas seal performance in a numerical solution of a corrected Reynolds equation.The Reynolds equation is discretized by means of the finite difference method with the second order scheme and solved by the successive-over-relaxation(SOR) iterative method.The Knudsen number of the flow in the Sealing Gas film is changed from 0.005 to 0.120 with a variation of film depth and Sealing pressure.The numerical results show that the average pressure in the Gas film and the sealed Gas leakage increase due to micro-scale effects.The open force is enlarged,while the Gas film stiffness is significantly decreased due to micro-scale effects.The friction torque and power consumption remain constant,even in low Sealing pressure and spin speed conditions.In this paper,the seal performance at different rotor face spin speeds is also described.The proposed research clarifies the micro-scale effects in a spiral-groove dry-Gas seal and their influence on seal performance,which is expected to be useful for the improvement of the design of dry-Gas seal systems operating in the slip flow regime.

Robert J. Cuss - One of the best experts on this subject based on the ideXlab platform.

  • final report of forge wp4 1 1 the stress path permeameter experiment conducted on callovo oxfordian claystone
    2012
    Co-Authors: Robert J. Cuss, J F Harrington
    Abstract:

    This report describes in detail the stress-path permeameter (SPP) apparatus and the test programme conducted on Callovo-Oxfordian (COx) Claystone from the Bure underground research laboratory (URL) in France. Funding for this study has been provided by the French radioactive waste management operator, Andra, the European Union (FORGE Project, Project number 230357) and the British Geological Survey through its well-founded laboratory programme and the Geosphere Containment project (part of the BGS core strategic programme). The results from the first test conducted using the SPP showed that COx has a very pronounced time-dependent component of deformation. This had implications for the following test conducted on COx and also has implications when comparing tests that have been deformed at a much faster rate. Test SPP_COx-1 was conducted with water as a test permeant at constant pore-pressure along a pre-defined stress-path. Volumetric deformation was observed during 16 steps along the stress-path, with considerable time-dependent deformation and anisotropy seen in radial strain. The 16th stage saw the sample fail through the formation of a fracture after the sample had experienced constant stress conditions for 5.5 days; this emphasises the observed time dependent deformation. The results from test SPP_COx-2 clearly showed that the sample dilated at the onset of Gas propagation; dilatancy was observed in three radial and one axial direction. A component of this volumetric deformation was associated with changes in pore-pressure. However, pore-pressure variation cannot account for the full amount of strain recorded and a proportion of the strain observed was the result of Gas migration by dilatant pathway formation. Prior to the sample attaining steady-state flow, outflow from the sample slowly reduced and the conductive features experienced self-Sealing. Gas injection pressure was raised and back-pressure was carefully lowered; neither course of action re-initiated flow through the sample.

  • final report of forge wp4 1 1 the stress path permeameter experiment conducted on callovo oxfordian claystone
    2012
    Co-Authors: Robert J. Cuss, J F Harrington
    Abstract:

    This report describes in detail the stress-path permeameter (SPP) apparatus and the test programme conducted on Callovo-Oxfordian (COx) Claystone from the Bure underground research laboratory (URL) in France. Funding for this study has been provided by the French radioactive waste management operator, Andra, the European Union (FORGE Project, Project number 230357) and the British Geological Survey through its well-founded laboratory programme and the Geosphere Containment project (part of the BGS core strategic programme). The results from the first test conducted using the SPP showed that COx has a very pronounced time-dependent component of deformation. This had implications for the following test conducted on COx and also has implications when comparing tests that have been deformed at a much faster rate. Test SPP_COx-1 was conducted with water as a test permeant at constant pore-pressure along a pre-defined stress-path. Volumetric deformation was observed during 16 steps along the stress-path, with considerable time-dependent deformation and anisotropy seen in radial strain. The 16th stage saw the sample fail through the formation of a fracture after the sample had experienced constant stress conditions for 5.5 days; this emphasises the observed time dependent deformation. The results from test SPP_COx-2 clearly showed that the sample dilated at the onset of Gas propagation; dilatancy was observed in three radial and one axial direction. A component of this volumetric deformation was associated with changes in pore-pressure. However, pore-pressure variation cannot account for the full amount of strain recorded and a proportion of the strain observed was the result of Gas migration by dilatant pathway formation. Prior to the sample attaining steady-state flow, outflow from the sample slowly reduced and the conductive features experienced self-Sealing. Gas injection pressure was raised and back-pressure was carefully lowered; neither course of action re-initiated flow through the sample.

Huiqiang Zhang - One of the best experts on this subject based on the ideXlab platform.

  • flow dynamics of a spiral groove dry Gas seal
    Chinese Journal of Mechanical Engineering, 2013
    Co-Authors: Bing Wang, Huiqiang Zhang
    Abstract:

    The dry-Gas seal has been widely used in different industries. With increased spin speed of the rotator shaft, turbulence occurs in the Gas film between the stator and rotor seal faces. For the micro-scale flow in the Gas film and grooves, turbulence can change the pressure distribution of the Gas film. Hence, the seal performance is influenced. However, turbulence effects and methods for their evaluation are not considered in the existing industrial designs of dry-Gas seal. The present paper numerically obtains the turbulent flow fields of a spiral-groove dry-Gas seal to analyze turbulence effects on seal performance. The direct numerical simulation (DNS) and Reynolds-averaged Navier-Stokes (RANS) methods are utilized to predict the velocity field properties in the grooves and Gas film. The key performance parameter, open force, is obtained by integrating the pressure distribution, and the obtained result is in good agreement with the experimental data of other researchers. Very large velocity gradients are found in the Sealing Gas film because of the geometrical effects of the grooves. Considering turbulence effects, the calculation results show that both the Gas film pressure and open force decrease. The RANS method underestimates the performance, compared with the DNS. The solution of the conventional Reynolds lubrication equation without turbulence effects suffers from significant calculation errors and a small application scope. The present study helps elucidate the physical mechanism of the hydrodynamic effects of grooves for improving and optimizing the industrial design or seal face pattern of a dry-Gas seal.

Offne G - One of the best experts on this subject based on the ideXlab platform.

  • Coupled Elastodynamics of Piston Compression Ring Subject to Sweep Excitation
    'SAGE Publications', 2017
    Co-Authors: Turnbull R, Mohammad Pou M, Rahmani R, Rahneja Home, Offne G
    Abstract:

    The piston compression ring's primary function is to seal the combustion chamber, thus mitigating Gas leakage to the crankcase and avoiding loss of pressure loading. As a result, the ring is meant to conform closely to the cylinder surface which promotes increased friction. The compression ring is subjected to combustion pressure loading, ring tension, varying inertial force and friction. It is a slender ring of low mass, thus undergoes complex elastodynamic behaviour, when subjected to a multitude of forces. These motions occur in the ring's radial in-plane and axial out-of-plane dynamics, which comprise flutter, ring axial jump, compression-extension, ring twist and rotational drag. An implication of these motions can be loss of Sealing, Gas blow-by, loss of power and lubricant degradation/oil loss, to name but a few. Consequently, understanding and accurately predicting ring dynamic behaviour under transient conditions is an important step in any subsequent modelling for evaluation of cylinder system efficiency. There have been a plethora of investigations for ring dynamics, often decoupling the ring behaviour in its in-plane and out-of-plane motions. This approach disregards any transfer of dynamic energy from one degree of freedom to another which is only applicable to rectangular ring cross-sections. Alternatively, there are computationally intensive approaches such as finite element analysis which are not conducive for inclusion in any subsequent system level engine modelling where ring response alters in an instantaneous manner. This would require embedded finite element analysis within a transient analysis. This paper presents a finite difference numerical analysis for coupled in-plane and out-of-plane motions of compression rings with practical cross-sectional geometries, which are mostly not rectangular. The formulated method can be integrated into a system level transient cyclic analysis of ring-bore contact. The presented approach takes into account the energy transfer between different degrees of freedom. The predictions are validated against precise non-contact measurements of ring elastodynamic behaviour under amplitude-frequency sweeps. This approach has not hitherto been reported in literature and constitutes the main contribution of the paper