Abstract
The mal-distribution of gas-oil-water multi-phase flow in parallel petroleum processing pipelines can directly affect the working condition of the separators. In this paper, the influence of different factors on the flow distribution and the characteristics of gas-oil-water distribution in parallel pipelines was investigated by three-dimensional CFD numerical simulation. Firstly, four different simulation models are established based on different arrangement types of parallel pipelines. The simulation results show that the distribution of gas-oil-water flow in the radial entry symmetrical two-stage pipe-laying simulation model was the most uniform among the four simulation models. Then, four radial entry symmetrical two-stage pipe-laying simulation models with different distance between branch pipes were establish. From the simulated results, it can be found that the distance has no effect on the distribution of gas-oil-water flow in each branch pipe, but great influence on distribution of flow rate in each branch pipe. Finally, the influence of the inlet flow characters on the flow distribution is investigated. It can be found that the “bias flow” phenomenon of the parallel pipelines decreasing with the increase of the inlet flow velocity, the gas content of inlet flow and the water content of inlet liquid.
The aim of this paper is to investigate, first, the effects of screens introduced around bearings and, second, the use of protruded instead of flush installed vent pipes. The investigation focuses on the air and oil flow distributions and on the heat transfer in the scavenge and the vent pipes in an aeroengine bearing chamber. The flow distribution has an impact on the pipe’s wall temperature distribution with the likelihood of generating hot spots. High temperatures may cause substantial effects on the health of the lubrication system. Problems may range from oil quality degradation to oil self ignition. A steady state CFD analysis of the heat transfer involving the two-phase air and oil flow in these pipes is performed using the ANSYS CFX package. It was demonstrated that whereas screens around bearings reduce the parasitic losses and vent protrusion reduces the oil flow to the air/oil separator, however, due to the oil flow distribution the thermal effects may lead to high material temperatures and to malfunctions in the engine’s lube system.
Blade failure in turbomachinery is frequently caused by an excessive resonant response. Forced response of the blades originates from unsteady fluid structure interactions as conditioned in the inlet section by duct bends, struts, or inlet guide vanes. This paper presents the computational part of a research effort that focuses on the blade forced response in a centrifugal compressor. Unsteady fluid flow simulations are used to quantify the forcing function acting on the compressor blades due to inlet flow distortion. The measured inlet flow distribution is applied as inlet boundary conditions in the computation. The unsteady investigation provided the temporal evolution of the distorted flow through the compressor. The time-resolved blade pressure distribution showed the temporal evolution of the dynamic load on the blade surface caused by the inlet distortion. The results suggest that the forcing function is most sensitive in the leading edge region due to inlet angle variations. Toward the impeller stability line the increase in incidence caused separation on the suction side of the main blade and therefore considerably altered the amplitude and the phase angle of the unsteadiness. The investigation of the effect of idealizing the inlet flow distribution on the forcing function showed an increase in the peak amplitude of approximately 30% compared with the actual inlet flow distribution.
The CAP1400 reactor internal is going to use a new component termed the “Even Flow Distributor (EFD)”, instead of the existing flow skirt (FS) design, to help distribute the incoming flow more evenly to the fuel assemblies. To verify the effect of the EFD, a scale model of the reactor and internals was built and hydraulic tests of both the EFD and the FS configurations were conducted. In addition, numerical simulations of the flow fields, using CFD, of both designs were also carried out.
From the scale model test results, the overall flow distribution of EFD is better than that of the FS. The core inlet flow distribution taken from the CFD results is slightly better than that from the hydraulic test. The differences between CFD result and test results are less than 3 percent for the most of fuel assemblies, and about 5 percent for a few assemblies. Based on this study, it is concluded that the EFD is a very effective means of controlling core inlet flow distribution in a CAP1400 reactor.
Effects of inlet flow distribution on performance of radial turbine rotor. Comparison of a 10 blade rotor with a 20 blade rotor.