| 1. |
- Brewe, D.E., et al.
(författare)
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Effect of vibration amplitude on vapor cavitation in journal bearings
- 1986
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Ingår i: Nordic Symposium on Tribology, Lulea, Sweden, 15-18 Jun. 1986. - Luleå : Högskolan i Luleå.
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Konferensbidrag (refereegranskat)abstract
- Computational movies were used to analyze the formation and collapse of vapor cavitation bubbles in a submerged journal bearing. The effect of vibration amplitude on vapor cavitation was studied for a journal undergoing circular whirl. The boundary conditions were implemented using Elrod's algorithm, which conserves mass flow through the cavitation bubble as well as through the oil-film region of the bearing. The vibration amplitudes for the different cases studied resulted in maximum eccentricity ratios ranging from 0.4 to 0.9. The minimum eccentricity ratio reached in each case was 0.1. For the least vibration amplitude studied in which the eccentricity ratio varied between 0.1 and 0.4, no vapor cavitation occurred. The largest vibration amplitude (i.e., eccentricity ratios of 0.1 to 0.9) resulted in vapor cavitation present 76 percent of one complete orbit.
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| 2. |
- Brewe, David E., et al.
(författare)
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The effect of vibration amplitude on vapour cavitation in journal bearings
- 1987
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Ingår i: Wear. - : Elsevier BV. - 0043-1648 .- 1873-2577. ; 115:1-2, s. 63-73
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Tidskriftsartikel (refereegranskat)abstract
- Computational movies were used to analyse the formation and collapse of vapour cavitation bubbles in a submerged journal bearing. The effect of vibration amplitude on vapour cavitation was studied for a journal undergoing circular whirl. The boundary conditions were implemented using Elrod's algorithm which conserves mass flow through the cavitation bubble as well as the oil film region of the bearing. In the calculations, 0.1 ε εmax, where ε is the instantaneous eccentricity and 0.4 εmax 0.9 for the different cases studied. For the case 0.1 ε 0.4, no vapour cavitation occurred. For the case in which 0.1 ε < 0.9, vapour cavitation was present for 76% of the total time
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| 3. |
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| 4. |
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| 5. |
- Hamrock, Bernard J., et al.
(författare)
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Elastohydrodynamic lubrication of rectangular contacts
- 1983
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- An isothermal elastohydrodynamically lubricated rectangular contact was evaluated numerically. This required the simultaneous solution of the elasticity and Reynolds equations. In the elasticity analysis the contact zone was divided into equal rectangular areas, and it was assumed that a uniform pressure was applied over each area. The elastohydrodynamic lubrication theory thus developed was used to investigate the influence of the dimensionless speed, load, and materials parameters on minimum film thickness. Ten cases were used in obtaining the minimum film thickness formula. Plots are shown that indicate the details of the pressure distribution, film shape, and flow. The characteristic pressure spike is clearly in evidence as is the parallel film shape through the central portion of the contact, with a minimum film thickness occurring near the outlet of the contact.
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| 6. |
- Hamrock, Bernard J., et al.
(författare)
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Measurement of the Density of Base Fluids at Pressures to 2.2 GPa
- 1986
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Ingår i: ASLE annual meeting.
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Konferensbidrag (refereegranskat)abstract
- The influence of pressure on the density of six base fluids is experimentally studied for a range of pressures from 0.422 to 2.20 GPa. An important parameter used to describe the results is the change in relative volume with change in pressure dv sub r/dp. For pressures less than the solidification pressure (p ps) a small change in pressure results in a large change in dv sub r/ps. For pressures greater than the solidification pressure (p ps) there is no change in dv sub r/dp with changing pressure. The solidification pressures of the base fluids varies considerably, as do the slopes that the experimental data assumes for p ps. A new formula is developed that describes the effect of pressure on density in terms of four constants. These constants vary for the different base fluids tested
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| 7. |
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| 8. |
- Höglund, Erik, et al.
(författare)
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Experimental Investigation of the Shear Strength of Lubricants Subjected to High Pressure and Temperature
- 1986
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Ingår i: Journal of tribology. - : ASME International. - 0742-4787 .- 1528-8897. ; 108:4, s. 571-577
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Tidskriftsartikel (refereegranskat)abstract
- In order to evaluate the relationship between limiting shear strength and pressure for a lubricant an experimental apparatus has been built. Pressures up to 2. 2 GPa and temperatures up to 200 degree C are attainable simultaneously. Thus the limiting shear strength-pressure relationship has been surveyed in a wide range. Several types of natural and synthetic lubricants have been tested. The results show that all the mineral oils tested behave in quite a similar way. Synthetic lubricants do not show this behavior, but the relationship between limiting shear strength and pressure depends strongly upon the chemical base of the synthetic lubricants. The behavior of grease does not differ from that of liquid lubricants. The pressures at which the lubricants change from a liquid to a solid behavior have also been measured.
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| 9. |
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| 10. |
- Jacobson, Bo
(författare)
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A hydrodynamic model of an outer hair cell
- 1982
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Ingår i: Proceedings of the 10. annual Northeast Bioengineering Conference. - New York : IEEE Communications Society. ; , s. 273-278
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Konferensbidrag (refereegranskat)abstract
- A 10000 times enlarged hydrodynamic model of the outer hair cell stereocila in the inner ear was built. On the model it was possible to measure the force and the force direction for each individual hair as a function of the flow direction and velocity. Measurement were made at the mean flow velocity 10-2 m/s, which is equivalent to a flow velocity in the real ear of about 1 μm/s. The kinematic viscosity of the liquid used in the model was 10000 times higher than the viscosity of perilymph to attain hydrodynamic equality. Two different geometries for the stereocilia pattern were tested. First the force distribution for a W-shaped stereocilia pattern was recorded. This is the stereocilia pattern found in all real ears. It was found that the forces acting on the hairs were very regular and perpendicular to the legs of the W when the flow was directed from the outside of the W. When the flow was reversed, the forces were not reversed, but were much more irregular. This can eventually explain the half wave rectification of the nerve signals. As a second experiment, the force distribution for a V-shaped stereocilia pattern was recorded. Here the forces were irregular both when the flow was directed into the V and when it was directed against the edge of the V
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