Enhancement of a Centrifugal Pump Performance by Simultaneous Use of Splitter Blades and Angular Impeller Diffuser

Davood Khoeini,Ebrahim Shirani 한국유체기계학회 2018 International journal of fluid machinery and syste Vol.11 No.2

The influences of different configurations of impeller diffusers and splitter blades on performance of a centrifugal pump have been analyzed experimentally and numerically. Each impeller with different configurations including three different splitter blades with lengths of 0, 0.45L and 0.75L (L is the length of impeller blades) and three different cases of impeller with diffuser of α=0o (α is the divergence angle of diffuser walls) and angular diffuser of α=10o and impeller without diffuser have been investigated in this study. Data analyses revealed that there is good compatibility among experimental and numerical results and the highest head discrepancy is only 7 percent. Results showed that simultaneous use of impeller diffuser and splitter blade have profound impact on the centrifugal pump performance. Actually, among all configurations, the maximum performance is achieved for the impeller equipped with angular diffuser of α=10o and splitter blades of 0.75L concurrently. In that case, the head at high flow rate is 1.51 times of the head value of original impeller without impeller diffuser. In addition, at BEP (Best Efficiency Point), efficiency increased by 3.4 percent and its position displaced towards the high flow rate as well.

Influences of Impeller Splitter Blades on the Performance of a Centrifugal Pump with Viscous Fluids

Davood Khoeini,Ebrahim Shirani 한국유체기계학회 2018 International journal of fluid machinery and syste Vol.11 No.4

In the present study, influences of impeller splitter blades on the performance of a centrifugal pump when handling viscous fluids have been investigated numerically and experimentally. In order to approach this aim, various splitter blades have been inserted on the impellers that pump viscous fluids ranging from 1 cSt to 500 cSt and the optimum splitter blade length based on the numerical results were constructed and tested thoroughly. Effects of splitter blades with lengths of 0.3, 0.45, 0.6 and 0.75 times of the main impeller blades were analyzed numerically. Results revealed that splitter blades have significant effect on the performance of a centrifugal pump. In fact, splittered impellers extend the operating region of centrifugal pumps remarkably and also among different surveyed splitter blades the head and efficiency increase by 20% and 3% respectively by using splittered impeller of 0.75L in comparison with the original impeller (without splitter blade). Moreover, the data analyses shows that splittered impellers can be used for pumping viscous fluids in the almost all operating conditions of non-splittered impellers with less viscous working fluid and obtained reasonable performance.

A model for mass diffusion in infarcted tissues by using LBM

Mina Alafzadeh,Ebrahim Shirani,Effat Yahaghi,Nasser Fatouraee 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.11

In the present study, a new mathematical model for mass transfer in extra-vascular space is presented to indicate the effect of dead cells in infarcted tissues. This model is useful for predicting the results of experiments which are designed to distinguish normal from infarcted tissues and it can be used to approximate the percent of damaged cells in the infarcted tissue. The increase of permeability due to existence of dead cells caused by infarction is modeled as a sink term. The present model is validated for two different solutes by comparing their results with the existing experimental data. It is shown that the presented model is an appropriate model for simulating mass transfer in tissues. Furthermore, the sensitivity of the model to the effective diffusion coefficient, Schmidt number, porosity and Damkohler number is examined. The simulations show that permeability of dead cells significantly affects the volume of the contrast agent in the infarcted tissue. The results also indicate that the Schmidt number not only affects the mass diffusion through damaged tissues, but also influences the partition coefficient. The other parameters mentioned above have effects on the amount of mass diffusion into the infarcted tissue when the extent of damage in tissues is changed.

A novel model for effective diffusion coefficient in brain capillary

Mina Alafzadeh,Ebrahim Shirani,Effat Yahaghi,Nasser Fatouraee 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.6

A new and rather accurate correlation for prediction of effective diffusion coefficient is proposed for the biological tissue in the brain. Blood flow in brain capillaries and mass diffusion process in the tissues as a porous media, surrounding the capillaries, are simulated byusing the random nature of tissue structure and the lattice Boltzmann method. The present correlation which is obtained from the latticeBoltzmann method and is taken into account the effects of the pore or cell structure is validated by comparing it with that of theoretical,statistical and experimental data. A very good coincidence between experimental data and present results have been found. So, the resultsshow that the new model for the effective diffusion coefficient is a good choice for normal and damaged brain tissue and it producesmore accurate results than existing models.

3D tomographic PIV, POD and vortex identification of turbulent slot jet flow impinging on a flat plate

Mahmoud Charmiyan,Ahmad Reza Azimian,Ebrahim Shirani,Fethi Aloui,Cedric Degouet,Dirk Michaelis 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.11

The impinging turbulent slot jet was investigated experimentally using tomographic particle image velocimetry technique. The jet Reynolds number was considered equal to 9000 and the nozzle to plate distance was 10 times the width of the nozzle. The mean flow and turbulent statistics were evaluated at different cross-sections. Then, the dominant three-dimensional structures of the turbulent flow were identified using the Proper orthogonal decomposition (POD) method, and the contribution of different energy modes to the total energy was determined. It is observed that the first 40 POD modes can be considered as the dominant flow modes which contain about 89 % of total kinetic energy of the flow. Also, horseshoe form structures were observed in some POD modes on both sides of the jet central plane. Finally, three-dimensional vortex structures were specified using vorticity, Q and λ 2 criteria, and compared with each other.

A novel optimization approach for axial turbine blade cascade via combination of a continuous-curvature parameterization method and genetic algorithm

Mehrdad Nafar Sefiddashti,Mahdi Nili-Ahmadabadi,Behnam Saeedi Rizi,Ebrahim Shirani,Kyung Chun Kim 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.9

A continuous-curvature parameterization method was coupled with the genetic algorithm and a RANS flow solver to optimize the cascade of VKI and Aachen turbine blades. The main advantage of the method is to generate blades with a continuous curvature distribution, which results in a smooth distribution of pressure and velocity on the blade surface. The geometry of the blade cascade was parameterized by 33 variables, and two objective functions were considered for the optimization. The first cost function was to reduce the total pressure loss with the constraints of mass flow rate, blade loading, and outlet flow angle. At the second cost function, the constraint of constant cross-sectional area was added to the previous constraints to preserve the structural strength of the turbine blade. The total pressure loss for the VKI blade decreased by 14.7 % and 10.6 % for the first and second objective functions, respectively. The total pressure loss for the Aachen blade was also reduced by 9.5 % and 7.5 % for the first and second objective functions, respectively. Due to the efficient geometry parameterization, the proposed method quickly converged to a high-efficiency blade at the early generations. The proposed method can be developed for optimizing the different blades of turbine, compressor, and airfoil types.