Search Results (5)

Permanent magnet synchronous motors for electric vehicles (EVs) prioritize high power density and lightweight design, leading to elevated thermal flux density. Consequently, cooling methods and heat conduction in stator windings become critical. This paper proposes a compound cooling structure combining direct oil spray cooling on stator windings and housing oil channel cooling (referred to as the winding–housing composite oil cooling system) for permanent synchronous motors in EVs. A systematic design methodology for oil jet nozzles and housing oil channels is investigated, determining the average convective heat transfer coefficient on end-winding surfaces and the heat dissipation factor of the oil channels. Finite element analysis (FEA) was employed to simulate the thermal field of a 48-slot 8-pole oil-cooled motor, with further analysis on the effects of oil temperature and flow rate on motor temperature. Based on these findings, an optimized oil-cooled structure is proposed, demonstrating enhanced thermal management efficiency. The results provide valuable references for the design of cooling systems in oil-cooled motors for EV applications. Full article

In 2013, a slope slide took place at the Santana-AP channel that links to the Lower Amazon River’s North Channel, resulting in the sudden collapse of a substantial section of the Port of Santana and its infrastructure. This area houses liquid bulk terminals and pipelines with high pollution potential. The objective of the research is to evaluate the potential environmental impacts of an eventual oil spill in the very short term using a numerical hydrodynamic simulation model coupled with that of pollutant dispersion. The SisBaHiA^® software, experimentally calibrated using acoustic methods (ADCP), was used to generate hypothetical scenarios in these areas with a substantial risk of landslides. Two hydrological scenarios stand out in the simulations: (a) November S-1 (dry) and (b) May S-2 (rainy). In S-1, the plume dispersion was higher during flood tides S-1a and S-1b, reaching 4 h urban slope areas, river mouths, tributaries (Matapi and Vila Nova), and environmental protection areas. At S-2, the plume spread was greater during the ebb tides S-2c and S-2d, affecting Macapá’s water supply system 12 h after the accident. The scenarios suggest the existence of high risks associated with the study hypotheses. The dispersion of the plume is directly proportional to the flow, indicating that local hydrodynamics is probably the most relevant dispersive factor. We conclude that the mitigation time for more severe effects is critical in the first 4 h because the coastal geographic feature tends to keep the plume in the Santana channel. Full article

In tilting-pad journal bearings (TPJB), power loss corresponds to the internal friction in the shearing of the oil. Besides the lubrication gap, intermediate spaces between the pads account for a notable amount of frictional losses. Against the background of increasing demands for efficiency and sustainable use of resources, the reduction of power loss takes a key position in the further development of bearings. In our research, we compare two bearing lubrication concepts of a five-pad TPJB. Our objective is to work out the influence of different lubrication methods and bearing housing designs on the bearing operation characteristics. We conduct experimental testing of a 500 mm TPJB in two different bearing configurations with respect to the lubrication concept: an oil-flooded and non-flooded bearing design. In the flooded bearing design, oil is supplied via spray-bars and axial seals ensure the inter-pad spaces to be completely filled with oil. The non-flooded design comes without axial seals but oil drain channels to avoid oil accumulation in the bearing. In the latter design, oil is fed in via leading edge grooves (LEG). For the non-flooded bearing design, the experimental data show that the unloaded pads are not completely filled with oil and therefore, no pressure build-up occurs. The absence of additional load on the lower pads compared to the flooded design results in an increase of minimum film thickness. With the non-flooded design, power loss at high speeds is reduced to almost half. As a result, the efficiency of the entire turbomachinery application can be considerably improved. Full article

We have developed new a deep-towed seismic streamer for sub-bottom profiling. To obtain a high-resolution seismic signal, this streamer can be operated at depths of up to 2000 m, and state-of-the-art technology is adopted with electronics circuits, that can withstand high pressures of up to 22 MPa. The streamer houses an ultra-low noise pre-amplifier, micro-processor, AD convertor, high precision clock, gain controller, and other circuitry in an oil-filled vessel. The high S/N ratio gives us high-resolution seismic images. The streamer comprises several catenated single modules and the recorded acoustic data are transmitted to the control computer with the Ethernet protocol. This makes the length of the streamer cable, and the number of hydrophones, flexible. For instance, we can use both single-channel and multi-channel streamers in the same system. Up to 24-channels can be catenated. Full article

Recent advances in high resolution X-ray tomography (μCT) technology have enabled in-situ dynamic μCT imaging (4D-μCT) of time-dependent processes inside 3D structures, non-destructively and non-invasively. This paper illustrates the application of 4D-μCT for visualizing the removal of fatty liquids from kitchen sponges made of polyurethane after rinsing (absorption), squeezing (desorption) and cleaning (adding detergents). For the first time, time-dependent imaging of this type of system was established with sufficiently large contrast gradient between water (with/without detergent) and olive oil (model fat) by the application of suitable fat-sensitive X-ray contrast agents. Thus, contrasted olive oil filled sponges were rinsed and squeezed in a unique laboratory loading device with a fluid flow channel designed to fit inside a rotating gantry-based X-ray μCT system. Results suggest the use of brominated vegetable oil as a preferred contrast agent over magnetite powder for enhancing the attenuation coefficient of olive oil in a multi fluid filled kitchen sponge. The contrast agent (brominated vegetable oil) and olive oil were mixed and subsequently added on to the sponge. There was no disintegration seen in the mixture of contrast agent and olive oil during the cleaning process by detergents. The application of contrast agents also helped in accurately tracking the movement and volume changes of soils in compressed open cell structures. With the in house-built cleaning device, it was quantified that almost 99% of cleaning was possible for contrasted olive oil (brominated vegetable oil with olive oil) dispersed in the sponge. This novel approach allowed for realistic mimicking of the cleaning process and provided closer evaluation of the effectiveness of cleaning by detergents to minimize bacterial growth. Full article