Fundamentals of the fluid mechanics

The solid oxide fuel cell (SOFC) is a simple electrochemical device that operates at 1000°C, and is capable of converting the chemical energy in natural gas fuel to AC electric power at approximately 45% efficiency (net AC/LHV) when operating in a system at atmospheric pressure. Since the SOFC exhaust gas has a temperature of approximately 850°C, the SOFC generator can be synergistically integrated with a gas turbine (GT) engine generator by supplanting the turbine combustor and pressurizing the SOFC, thereby enabling the generation of electricity at efficiencies approaching 60% or more. Conceptual design studies have been performed for SOFC/GT power systems employing a number of the small recuperated gas turbine engines that are now entering the marketplace. The first hardware embodiment of a pressurized SOFC/GT power system has been built for Southern California Edison and is scheduled for factory acceptance tests beginning in Fall 1999 at the Siemens Westinghouse facilities in Pittsburgh, PA. The hybrid power cycle, the physical attributes of the hybrid systems, and their performance are presented and discussed.

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Tubular solid oxide fuel cell/gas turbine hybrid cycle power systems - status

Influence of the dipleg shape on the performance of gas cyclones

Experimental and numerical investigation on the performance of square cyclones with different vortex finder configurations

In solid particle separation process, cyclone separators are commonly used due to their simplicity and low-cost manufacture. A reference design S1 and two novel designs C4, N4 of four-inlet cyclone separator have been investigated computationally using the Reynolds Stress Model for turbulent flow and the Discrete Phase Model for tracking the particles. The numerical model has been validated and confirmed to be a reasonable good candidate for the investigation. The results show that, the design S1 provides the lowest average Euler number (4.415) and the design C4 provides the smallest average cut-off diameter (1.399 μ m ). As comparing the performances using weighted sum method, both two novel designs provide the better performance than the reference design S1. The innovative design N4 delivers the best performance which is 1 % and 0.1 % better in performance than S1 and C4, respectively.

Numerical investigation on the performance and flow pattern of two novel innovative designs of four-inlet cyclone separator

Performance improvement of a Savonius vertical axis wind turbine using a porous deflector

Improving efficiency of conventional and square cyclones using different configurations of the laminarizer

CFD simulation of a novel design of square cyclone with dual-inverse cone

This study focused on delaying and controlling the flow separation over Naca 2415 airfoil by finding the best slot location with the most effective suction velocity ratio and suction angle to apply suction at a compressible and high Reynolds number flow using computational fluid dynamics method. The results were obtained with two dimensional compressible Reynold-averaged Navier-Stokes equations, and the turbulence was simulated with k-e RNG turbulence model. The results indicated that the most effective slot locations for applying suction were between 0.3 to 0.6 of the airfoil chord length. Also, it was found that the maximum value of the lift coefficient was obtained at an angle of attack of 16° on 0.3 of airfoil chord length and suction velocity ratio of 1.5. This value is about 55% compared to the case without suction, and thus the stall angle increased from 10° to 16°.

Numerical study of the effect of suction at a compressible and high Reynolds number flow to control the flow separation over Naca 2415 airfoil

In the present study, special attention is paid to numerically investigate the aerodynamic performance of the NACA 0012 airfoil under rain and icing conditions with the aim to better understand the severe aerodynamic performance penalties of aircraft in flight. Furthermore, in order to control the flow separation and improve the aerodynamic performance of the airfoil under critical atmospheric conditions, the Gurney flap with different heights is attached to the trailing edge of the airfoil. The simulation is done at a Reynolds number of 3.1 × 105 under different atmospheric conditions including dry, rain, icing and coupling of rain and icing conditions. A two-way momentum coupled Eulerian–Lagrangian multiphase method is used to simulate the process of water film layer formed on the airfoil surface due to rainfall. According to the results, accumulation of water due to rainfall and ice accretion on the airfoil surface inevitably provides notable negative effects on the aerodynamic performance of the airfoil. It is concluded that icing induces a higher aerodynamic degradation than rain due to very intensive ice accretion. The Gurney flap as a passive flow control method with a favorable height for each condition is very beneficial. The maximum increment of the lift-to-drag ratio is achieved by Gurney flap with a height of 0.01 of airfoil chord length for dry and rain conditions and 0.02 of airfoil chord length for icing and coupling of rain and icing conditions, respectively.

Hossein Fatahian

Papers

Performance improvement of a Savonius vertical axis wind turbine using a porous deflector

Improving efficiency of conventional and square cyclones using different configurations of the laminarizer

CFD simulation of a novel design of square cyclone with dual-inverse cone

Numerical study of the effect of suction at a compressible and high Reynolds number flow to control the flow separation over Naca 2415 airfoil

Effect of Gurney flap on flow separation and aerodynamic performance of an airfoil under rain and icing conditions