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Force-System Resultants and Equilibrium
Published in Richard C. Dorf, The Engineering Handbook, 2018
FIGURE 24.14 shows a segmented circumferential seal. The seal consists of angular segments with overlapping ends, and the segments are pulled radially inward by garter spring force and the sealed pressure. The seal segments are pushed against the shaft and thus are surface guided. They are also pushed against a radial face by pressure. This seal is similar to the floating-ring seal except that the seal face is pushed tight against the shaft because the segments allow for circumferential contraction. Circumferential segmented seals are commonly used in aircraft engines to seal oil and gas.
Driveline Lubricant Impacts on Dynamic Seal Test Life
Published in Tribology Transactions, 2018
Hongmei Zhao, Jiatong Chai, Xiaoming Lin, Wei Wang, Jeanne Petko, Valerie Woodward, Monica Ford
Laboratory measurement of a seal's radial load is commonly used as an indicator of the interference between the seal lip and shaft surface. The radial load of a seal is related to the tightening force of the seal lip to shaft; that is, the contact pressure in the dynamic sealing zone during service. Usually the radial load of a seal is measured off-line before installation and after dismount using a radiometer, a special seal radial load measurement instrument. In our study, we measured the radial load with and without the garter spring before and after each test in order to characterize changes in interference and thus evaluate each seal's remaining sealing capacity—the larger the loss in radial load, the greater the loss of interference fit and thus the lower the remaining sealing capacity. In addition to the radial load measurement, microscopy was used to characterize the posttest seals in order to understand potential failure modes that lead to seal leakage. We focused on the portions of the seal that had been in contact with the test shaft, noted as “inner side” and “helix ribbed side” in Fig. 1b. When characterizing the inner side of the seal, we looked for any signs of chemical attack by the lubricant or any signs that would indicate that the seal was not lubricated during operation. When characterizing the helix ribbed side of the seal, we looked for any signs of wear of the helix ribs, degradation of the lubricant leading to helix plugging, or other dimensional changes that would inhibit the seal's ability to pump lubricant back into the sealing zone during testing (Yang, et al. (15)).
Data-Driven Analysis of Ultrasonic Inspection Data of Pressure Tubes
Published in Nuclear Technology, 2018
Panagiotis Zacharis, Graeme West, Gordon Dobie, Timothy Lardner, Anthony Gachagan
Each fuel channel (Fig. 1) consists of a thin Zircaloy tube (calandria tube) that contains another, thicker, Zircaloy tube called the pressure tube. The two tubes are separated by annulus garter-spring spacers that create a gap allowing the flow of an insulating gas called annulus gas. The fuel bundles are located inside the pressure tubes, and they are cooled by the hot (300°C) pressurized (10-MPa) heavy water coolant that runs through the pressure tubes. This configuration enables the insulation of the cool (70°C) unpressurized moderator from the hot pressurized coolant.