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292 results on '"Farzaneh-Gord, Mahmood"'

40. Flow and heat transfer in a pre-swirl rotor-stator system

Author

Farzaneh-Gord, Mahmood, Wilson, Michael, and Owen, John

Subjects
621, Thermodynamics
Abstract

This thesis describes the computational study of the flow and heat transfer in a directtransfer pre-swirl rotor-stator system. Pre-swirl cooling air enters the system at low radius through angled pre-swirl nozzles, located on the stator, impinges on the rotor and flows outward in the wheel-space between stator and rotor, and leaves the system through receiver holes, located on the rotor. Computations were carried out using a 3D incompressible model, with one discrete pre-swirl nozzle on the stator and cyclic symmetry boundary conditions applied at the tangential faces of the domain. To permit steady-state computations, an annular outlet was used on the rotor that matched the centerline radius and total area of the receiver holes. The Reynolds-averaged Navier-Stokes equations in cylindrical polar coordinates were solved in primitive-variables using the finite-volume method, hybrid differencing and the SIMPLE pressure-correction scheme. The low-Reynolds-number Launder-Sharma turbulence model was used primarily and the Morse k-c model was also tested. An axisymmetric numerical investigation was conducted to study the effect of the swirl ratio and other flow parameters on the flow and heat transfer in system, with computation times reduced by a factor of around 7 compared with the corresponding 3D computations. The computations were also compared with data obtained from a complementary experimental study. The range of flow parameters tested in the experiments and used in the computations were: for rotational Reynolds numbers, 0.77 x 106 < Red, < 1.2 x 106; for non-dimensional pre-swirl flow rates, 0.6 X 104 < Cw'P < 2.8 x 104 (giving 0.12 AT, p = cw, pReoe'8 < 0.4); for pre-swirl ratio, 0.5 < /3p < 3. The computed and measured values of (tangentially-averaged) non-dimensional tangential velocity, VO/Str, and static and total pressure coefficient are mainly in good agreement. The computed results suggest that free-vortex flow occurs between the pre-swirl inlets and the receiver outlet. The results show a significant loss in total pressure near the pre-swirl inlets. An expression has been derived for calculating the discharge coefficient for the receiver outlet, and there is good agreement between measured and computed values The computed local Nusselt number, Nu, is compared with measured values. There is reasonably good agreement between computation and measurement for the level of Nu apart from the impingement region and radially outward of the receiver outlet. There is a large peak in Nu near the inlet radius, due the behaviour of the low-Reynolds number turbulence model in the impingement region. The measured effects of Red, AT, p and ßp on the level of Nu are reproduced well by the computations.

Published
2003

46. Effect of Compressor Emergency Shutdown in Various Compressor Station Configurations on Natural Gas Transmission Pipeline

Author

Ameri, Hamed and Farzaneh-Gord, Mahmood

Abstract

The transient conduct of compressor stations, especially subject to sudden change in conditions, and its effect on performance of natural gas transmission pipeline is one of the most important concerns of operators. The main objective of this paper is to investigate how compressors are arranged in compressor stations, when there is not any standby compressor. Both parallel and series mode have been analyzed for the transient state and it has been determined which of them has more advantages. Considering the boundary conditions in critical conditions, the series arrangement compared to parallel, provides a longer period for the needs of consumers.

Published
2024
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47. Neural network modeling for rigorous simulation of mid-pressure reciprocating expansion engines performance.

Author

Farzaneh-Gord, Mahmood and Rahbari, Hamid Reza

Subjects
*THERMODYNAMICS, *EXERGY, *NATURAL gas, *MOLE fraction, *EQUATIONS of state, *ENGINES
Abstract

In the Natural Gas (NG) distribution network, the town border stations are used to reduce NG pressure. Currently, pressure reduction is done by using throttling valves that cause a significant amount of physical exergy loss. Reciprocating Expansion Engine (REE) is a new tool to recover this pressure exergy. This study presents a thermodynamic evaluation to simulate the REE rigorously. The GERG-2008 equation of state (EOS) as an accurate model is used to calculate NG thermodynamic properties. As the utilization of GERG-2008 EOS requires specific inputs (pressure, temperature and mole fraction), the Try & Error method is utilized (while the inputs are density, specific internal energy, and NG composition). An Artificial Neural Network (ANN) method is also developed as an additional and alternative tool to overcome a basic limitation of the Try & Error method (knowing the NG composition). The validation results show that the error of the ANN and Try & Error methods for temperature, pressure calculation are reported 0.03%, 0.08%, and 0.04%, 0.9%, respectively. Also, the results show that the NG compositions have a significant impact on REE performance so that the indicated work for Khangiran and Bidboland NG mixtures are reported 165 and 143 kJ/kg, respectively. [ABSTRACT FROM AUTHOR]

Published
2023
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