Experimental and numerical investigation on total pressure distortion generated by a rectangular movable flat baffle

A distortion generator equipped with a motor-activated movable flat baffle was installed just upstream of a rectangular plenum entrance to investigate the effects of inlet total pressure distortion on the stability and performance of an auxiliary power unit (APU). Experiments and numerical simulations on a direct connect scale inlet model of the APU were carried out to obtain a quantitative relationship between the insertion depth of the flat baffle in the flow stream and the total pressure distortion intensity and region. In the experiments, the blocking coefficient and total pressure distortion coefficient were controlled by adjusting the insertion depth of the flat baffle and the mass flow. In the simulations, detailed flow field was analyzed based on the detached-eddy simulation (DES) method. The results show that the pressure distribution of the distorted flow on the aerodynamic interface plane (AIP) can be divided into a high-pressure region, a transition region, and a low-pressure region. The area affected by the distorted flow was larger than the inserting area of the flat baffle. That area was more related to the relative blocking coefficient, and less affected by the mass flow. The total pressure distortion coefficient had a linear relationship with the mass flow rate and is positively correlated with the relative blocking coefficient. As the relative blocking coefficient increased to a certain value, an exponential growth in the total pressure distortion coefficient occurred, and consequently, the flow field distortion was intensified. In the flow field, a pair of corner vortices were formed at the corner between the flat baffle and the bottom wall of the inlet pipe, and a large separation zone was formed behind the flat baffle and exhibits certain unsteady characteristics.

Modeling of the fouling of inside-out hollow fiber UF membranes

Membrane processes often experience a decline in the permeate flux or an increase in the operating pressure from membrane fouling. A mathematical model that describes the fouling of inside-out hollow fiber ultrafiltration (UF) membranes was derived from hydrodynamic equations coupled with the theory of depth filtration. The correlation predictions obtained in this study are simpler, as the effect of membrane characteristics, water recovery, and membrane washing processes on UF membrane fouling were expressed using a single parameter: the membrane blocking coefficient. Membrane filtration tests were conducted using diluted paper industry wastewater in a constant-pressure and constant-current operational mode. The effects of different operating conditions, such as water recovery and cleaning methods, and membrane characteristics, on the membrane blocking coefficient were evaluated. The predictive capability of the proposed model was excellent, according to a comparison of the experimental results and model simulations.

Research and Application of a Novel Deep Profile Modification Agent for Complex Sandstone Reservoirs

According to low temperature, high salinity, heterogeneous and complex sandstone oil reservoirs in the Qaidam Basin. A novel profile modification agent (PMA) was developed by the author. The microscopic structure of the agent was analyzed by SEM. The PMA of 0.3% has stronger plugging capacity to cores. Its blocking coefficient was larger than 91%, and it was not less than 90% after being flushed with 20PV injected water. In parallel core test the agent could be used to adjust the reservoir permeability and enhance oil recovery substantially. The field test achieved good results.