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Showing 2 results for Multiple Reference Frame (mrf)
Marzieh Naderan Tahan, Seyed Saied Bahrainian,
Volume 13, Issue 14 (3-2014)
Abstract
In this paper the effect of pressure ratios on the performance characteristics of a radial twin entry turbine is investigated using computer aided design (CAD) and computational fluid dynamics (CFD). First, geometric models of the turbine flow passages are constructed by simultaneous use of measuring tools and computer aided design software. Because of geometrical complexity of flow passages, tetrahedral cells are used to generate unstructured grid in the computational domain. Three dimensional flow of steady, viscous, and compressible nature is solved by Multiple Reference Frame (MRF) technique. Characteristic curves of the turbine are obtained by post processing flow simulation results. Mass flow parameter, delivered torque parameter and total to static turbine efficiency are plotted against different pressure ratios. Results show that at constant rotational speed, increasing pressure ratio leads to increase in mass flow parameter until choke limit while the total to static efficiency decreases and delivered torque increases.
B. Rahmati, S.h. Hashemabadi, M. Salemi Mojarrad,
Volume 20, Issue 7 (6-2020)
Abstract
The present study is a numerical model for prediction of turbine flowmeter performance, using the equation of motion based on torque balance theory. In this model, numerical simulations were carried out for a 2-inch diameter G65 and PN/ANSI 150 gas turbine flowmeter which was made by Vemmtec Company, in steady state, using Multiple Reference Frame (MRF) model and Standard k-ε turbulence model using Fluent software. In order to model torque balance equation and calculate angular velocity of rotor, a UDF (User Defined Function) code was created and was added to the software. To evaluate the model's accuracy, simulation results were compared with experimental data which was obtained from manufacturer of the meter. The difference between the simulation results and experimental data was 0.16%, approximately, which indicates the validity of the proposed model in simulating of turbine gas flowmeter performance. The results obtained from the simulation depicted that the velocity distribution asymmetry was more than 0.4Qmax at the downstream of the meter, and because this phenomenon had no negative effect on flow measurement, the suitable length for the flow development for the downstream of meter was done using simulation at least 10 times the diameter of the pipe was proposed. Therefore, using the proposed model, the capital cost of design and optimization of turbine flowmeters can be reduced.
