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This paper presents the identiflcation of the rotordynamic force coefficients for direct lubrication flve-pad and four-pad tilting pad bearings. The bearing is ¡10 mm in diameter with a UD of 0.4 pad axial length (44 mm). The e.Kperiments include load-on-pad and load-between-pad conflgurations, with 0.5 and 0.6 pivot offsets, for rotor speeds ranging from 7500 rpm to 15,000 rpm. The bearing force coefficients are identifled from multiple frequency excitations (20-300 Hz) exerted on the bearing housing by a pair of hydraulic shakers and are presented as a function of the excitation frequency and rotor speed for a 300 kPa unit load. The experimental results also include temperatures at the trailing edge of three pads. The direct force coefficients, identifled from curve-fits of the complex dynamic stiffness, are frequency independent if considering an added mass term much smaller than the test device modal mass. The force coefficients from the four-pad bearing load-between-pad conflguration show similar coefficients in the loaded and orthogonal directions. On the other hand, as expected, the flve-pad bearing load-on-pad shows larger coefficients (-25%) in the loaded direction. The maximum pad temperature recorded for the 0.5 pivot offset conflgurations is up to 20° C higher than those associated to the 0.6 offset conflguration. Results from a predictive code are within 50% of the experimental results for the direct stiffness coefficients and within 30% for the direct damping coefficients.

Tilting pad journal bearings are usually employed in turbomachines for their stable behavior at high rotational speeds. Devoted test rigs have been realized to validate the predictions of theoretical models. However, the design of new high-performance and large-size bearings needs to be supported by experimental investigations on high-performance large test rigs. The main characteristics of a recently built facility for testing large tilting pad journal bearings with diameters from 150 to 300 mm are described in this work. The test rig is versatile and can be used to test bearings of different size, configurations and to investigate the influence of many parameters, even the effect of misalignment. Sample results of the static characterization of a four-pad high-performance tilting pad journal bearing are reported evidencing some transient effects. A few sample dynamic results are also reported. The presented experimental results demonstrated the capabilities of the rig for investigating the static and the dynamic characteristics of the bearings accurately measuring slow and fast variables.

This paper presents the identification of the rotordynamic force coefficients for a direct lubrication five-pad and four-pad tilting pad bearing. The bearing is 110 mm in diameter with an L/D of 0.4. The experiments include load-on-pad (LOP) and load-between-pad (LBP) configurations, with a 0.5 and 0.6 pivot offset, for rotor speeds ranging from 7500 rpm to 15000 rpm. The bearing force coefficients are identified from multiple frequency excitations (20 to 300 Hz) exerted on the bearing housing by a pair of hydraulic shakers, and are presented as a function of the excitation frequency, rotor speed, for a 300 kPa unit load. The experimental results also include temperatures at the trailing edge of three pads. The direct force coefficients, identified from curve-fits of the complex dynamic stiffness, are frequency independent if considering an added mass term much smaller than the test device modal mass. The force coefficients from the four-pad bearing load-between-pad configuration show similar coefficients in the loaded and orthogonal direction. On the other hand, as expected, the five-pad bearing load-on-pad shows larger coefficients (∼25%) in the loaded direction. The maximum pad temperature recorded for the 0.5 pivot offset configurations are up to 20° C higher than those associated to the 0.6 offset configuration. Results from a predictive code are within 50% of the experimental results for the direct stiffness coefficients and within 30% for the direct damping coefficients.

This study proposes a method of optimizing the dry storage design for nuclear-spent fuel from the G.A. Siwabessy research reactor at National Nuclear Energy Agency of Indonesia (BATAN). After several years in a spent fuel pool storage (wet storage), nuclear spent fuel is often moved to dry storage. Some advantages of dry storage compared with wet storage are that there is no generation of liquid waste, no need for a complex and expensive purification system, less corrosion concerns and that dry storage is easier to transport if in the future the storage needs to be sent to the another repository or to the final disposal. In both wet and dry storage, the decay heat of spent fuel must be cooled to a safe temperature to prevent cracking of the spent fuel cladding from where hazardous radioactive nuclides could be released and harm humans and the environment. Three optimization scenarios including the thermal safety singleobjective, the economic single-objective and the multi-objective optimizations are obtained.The optimum values of temperature and cost for three optimization scenarios are 317.8K (44.7°C) and 11638.1 US$ for the optimized single-objective thermal safety method, 337.1K (64.0°C) and 6345.2 US$ for the optimized single-objective cost method and 325.1K (52.0°C) and 8037.4 US$ for the optimized multi-objective method, respectively.