Rheology of polymer blends: Simultaneous slippage and entrance pressure loss in the ethylene-propylene-diene (EPDM)/viton system

1982 ◽  
Vol 22 (8) ◽  
pp. 507-511 ◽  
Author(s):  
R. C. Kanu ◽  
M. T. Shaw
Keyword(s):  
Polymer Blends ◽  
Pressure Loss ◽  
Ethylene Propylene ◽  
Entrance Pressure ◽  
Entrance Pressure Loss

A Study of Entrance Pressure Loss in Filled Polymer Melts

2007 ◽  
Vol 17 (5) ◽  
pp. 57191-1-57191-9 ◽  
Author(s):  
Velichko Hristov ◽  
John Vlachopoulos
Keyword(s):  
Pressure Loss ◽  
Polymer Melts ◽  
Wood Flour ◽  
Filler Loading ◽  
Filled Polymer ◽  
Branched Polyethylene ◽  
Glass Spheres ◽  
Entrance Pressure ◽  
Entrance Pressure Loss ◽  
Polyethylene Composites

Abstract The influence of the molecular structure of the polymer matrix and filler loading on the entrance pressure loss of polyethylene/wood flour composites has been investigated in this research by means of a capillary rheometer equipped with an orifice die. The entry flow of talc- and glass-filled polyethylene composites has been investigated as well. It was found that the entrance pressure loss of wood filled polyethylene composites greatly increased with increasing the wood flour loading. Talc and solid glass spheres also increase the entrance pressure loss, however not as much as wood flour. It was also observed that composites based on narrow molecular weight distribution (MWD) resins exhibited larger entrance pressure loss than the broad MWD and branched polyethylene based ones. It was concluded that measurements of the entrance pressure loss reveal some interesting features of the polymer-filler interactions and could provide significant insights in the processing of highly filled polymer melts.

On the Influence of the Entrance Section on the Rotordynamic Performance of a Pump Seal With Uniform Clearance: A Sharp Edge vs. a Round Inlet

2018 ◽  
Author(s):  
Jing Yang ◽  
Luis San Andres
Keyword(s):  
Pressure Drop ◽  
Pressure Loss ◽  
Loss Coefficient ◽  
Operating Conditions ◽  
Sharp Edge ◽  
Inlet Section ◽  
Force Coefficients ◽  
Pressure Loss Coefficient ◽  
Entrance Pressure ◽  
Entrance Pressure Loss

Secondary flows thru annular seals in pumps must be minimized to improve their mechanical efficiency. Annular seals, in particular balance piston seals, also produce rotordynamic force coefficients which easily control the placement of rotor critical speeds and determine system stability. A uniform clearance annular seal produces a direct (centering) static stiffness as a result of the sudden entrance pressure drop at its inlet plane when the fluid flow accelerates from an upstream (stagnant) flow region into a narrow film land. This so called Lomakin effect equates the entrance pressure drop to the dynamic flow head through an empirical entrance pressure loss coefficient. Most seal designs regard the inlet as a sharp edge or square corner. In actuality, a customary manufacturing process could produce a rounded corner at the seal inlet. Furthermore, after a long period of operation, a sharp corner may wear out into a round section. Notice that to this date, bulk flow model (BFM) analyses rely on a hitherto unknown entrance pressure coefficient to deliver accurate predictions for seal force coefficients. This paper establishes the ground to quantify the influence of an inlet round corner on the performance of a water lubricated seal reproducing a configuration tested by Marquette et al. (1997). The smooth surface seal has clearance Cr = 0.11 mm, length L = 35 mm, and diameter D = 76 mm (L/D = 0.46). The test case considers design operation at 10.2 krpm and 6.9 MPa pressure drop. Computational fluid dynamics (CFD) simulations apply to a seal with either a sharp edge or an inlet section with curvature rc varying from ¼Cr to 5Cr. Note the largest radius (rc) is just 1.6% of the overall seal length L. Going from a sharp edge inlet plane to one with a small curvature rc = ¼Cr produces a ∼20% decrease on the inlet pressure loss coefficient (ξ). A further reduction occurs with a larger circular corner; ξ drops from 0.43 to 0.17. That is, the entrance pressure loss will be lesser in a seal with a curved inlet. This can occur easily if the inlet edge wears due to solid particles eroding the seal inlet section. Further CFD simulations show that operating conditions in rotor speed and pressure drop do not affect the inlet loss coefficient, while the inlet circumferential swirl velocity does. In addition, further CFD results for a shorter (half) length seal produce a very similar entrance loss coefficient, whereas an enlarged (double) clearance seal leads to an increase in the entrance pressure loss parameter as the inlet section becomes less round. CFD predictions for most rotordynamic coefficients are within 10% relative to published test data, except for the direct damping coefficient C. For the seal with a rounded edge (rc = 5 Cr) at the inlet plane, both the direct stiffness K and direct damping C decrease about 10% compared against the coefficients for the seal with a sharp inlet edge. The other force coefficients, namely cross-coupled stiffness and added mass, are unaffected by the inlet edge geometry. The same result holds for seal leakage, as expected. A BFM incorporates the CFD derived entrance pressure loss coefficients and produces rotordynamic coefficients for the same operating conditions. The CFD and BFM predictions are in good agreement, though there is still ∼10% discrepancy for the direct stiffnesses delivered by the two methods. In the end, the analysis of the CFD results quantifies the pressure loss coefficient as a function of the inlet geometry for ready use in engineering BFM tools.

On the Influence of the Entrance Section on the Rotordynamic Performance of a Pump Seal With Uniform Clearance: A Sharp Edge Versus A Round Inlet

2018 ◽  
Vol 141 (3) ◽  
Author(s):  
Jing Yang ◽  
Luis San Andrés
Keyword(s):  
Pressure Drop ◽  
Pressure Loss ◽  
Loss Coefficient ◽  
Operating Conditions ◽  
Sharp Edge ◽  
Inlet Section ◽  
Force Coefficients ◽  
Pressure Loss Coefficient ◽  
Entrance Pressure ◽  
Entrance Pressure Loss

Secondary flows through annular seals in pumps must be minimized to improve their mechanical efficiency. Annular seals, in particular balance piston seals, also produce rotordynamic force coefficients, which easily control the placement of rotor critical speeds and determine system stability. A uniform clearance annular seal produces a direct (centering) static stiffness as a result of the sudden entrance pressure drop at its inlet plane when the fluid flow accelerates from an upstream (stagnant) flow region into a narrow film land. This so-called Lomakin effect equates the entrance pressure drop to the dynamic flow head through an empirical entrance pressure loss coefficient. Most seal designs regard the inlet as a sharp edge or square corner. In actuality, a customary manufacturing process could produce a rounded corner at the seal inlet. Furthermore, after a long period of operation, a sharp corner may wear out into a round section. Notice that to this date, bulk-flow model (BFM) analyses rely on a hitherto unknown entrance pressure coefficient to deliver accurate predictions for seal force coefficients. This paper establishes the ground to quantify the influence of an inlet round corner on the performance of a water lubricated seal reproducing a configuration tested by Marquette et al. (1997). The smooth surface seal has clearance Cr = 0.11 mm, length L = 35 mm, and diameter D = 76 mm (L/D = 0.46). The test case considers design operation at 10.2 krpm and 6.9 MPa pressure drop. Computational fluid dynamics (CFD) simulations apply to a seal with either a sharp edge or an inlet section with curvature rc varying from ¼Cr to 5Cr. Note the largest radius (rc) is just 1.6% of the overall seal length L. Going from a sharp edge inlet plane to one with a small curvature rc = ¼Cr produces a ∼20% decrease on the inlet pressure loss coefficient (ξ). A further reduction occurs with a larger circular corner; ξ drops from 0.43 to 0.17. That is, the entrance pressure loss will be lesser in a seal with a curved inlet. This can occur easily if the inlet edge wears due to solid particles eroding the seal inlet section. Further CFD simulations show that operating conditions in rotor speed and pressure drop do not affect the inlet loss coefficient, while the inlet circumferential swirl velocity does. In addition, further CFD results for a shorter (half) length seal produce a very similar entrance loss coefficient, whereas an enlarged (double) clearance seal leads to an increase in the entrance pressure loss parameter as the inlet section becomes less round. CFD predictions for most rotordynamic coefficients are within 10% relative to published test data, except for the direct damping coefficient C. For the seal with a rounded edge (rc = 5 Cr) at the inlet plane, both the direct stiffness K and direct damping C decrease about 10% compared against the coefficients for the seal with a sharp inlet edge. The other force coefficients, namely cross-coupled stiffness and added mass, are unaffected by the inlet edge geometry. The same result holds for seal leakage, as expected. A BFM incorporates the CFD derived entrance pressure loss coefficients and produces rotordynamic coefficients for the same operating conditions. The CFD and BFM predictions are in good agreement, though there is still ∼10% discrepancy for the direct stiffnesses delivered by the two methods. In the end, the analysis of the CFD results quantifies the pressure loss coefficient as a function of the inlet geometry for ready use in engineering BFM tools.

Influence of calcium carbonate filler and mixing type process on structure and properties of styrene-acrylonitrile/ethylene-propylene-diene polymer blends

2012 ◽  
Vol 126 (4) ◽  
pp. 1257-1266 ◽  
Author(s):  
Ljerka Kratofil Krehula ◽  
Anita Ptiček Siročić ◽  
Zvonimir Katančić ◽  
Jasenka Jelenčić ◽  
Vera Kovačević ◽  
...  
Keyword(s):  
Calcium Carbonate ◽  
Polymer Blends ◽  
Structure And Properties ◽  
Ethylene Propylene ◽  
Type Process ◽  
Carbonate Filler ◽  
Styrene Acrylonitrile

scholarly journals Ordered Structures of High-Performance Propylene/Ethylene-Propylene Rubber Polymer Blends.

1995 ◽  
Vol 52 (2) ◽  
pp. 90-96 ◽  
Author(s):  
Takao NOMURA ◽  
Takeyoshi NISHIO ◽  
Hideaki TANAKA ◽  
Kenji MORI
Keyword(s):  
Polymer Blends ◽  
High Performance ◽  
Ordered Structures ◽  
Ethylene Propylene ◽  
Ethylene Propylene Rubber

The effect of talc on the crystal orientation in polypropylene/ethylene-propylene rubber/talc polymer blends in injection molding

2001 ◽  
Vol 41 (3) ◽  
pp. 408-416 ◽  
Author(s):  
Yutaka Obata ◽  
Takashi Sumitomo ◽  
Toshikazu Ijitsu ◽  
Masatoshi Matsuda ◽  
Takao Nomura
Keyword(s):  
Injection Molding ◽  
Polymer Blends ◽  
Crystal Orientation ◽  
Ethylene Propylene ◽  
Ethylene Propylene Rubber

Polymer Blends of PBT and PP Compatibilized by Epoxidized Ethylene Propylene Diene Rubber

2006 ◽  
Vol 58 (2) ◽  
pp. 447-455 ◽  
Author(s):  
Yu-Hui Ao ◽  
Shu-Lin Sun ◽  
Zhi-Yong Tan ◽  
Chao Zhou ◽  
Na Xu ◽  
...  
Keyword(s):  
Polymer Blends ◽  
Ethylene Propylene ◽  
Ethylene Propylene Diene Rubber ◽  
Diene Rubber
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