scholarly journals Multiobjective Hydraulic Design and Performance Analysis of a Vortex Pump Based on Orthogonal Tests

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Hui Quan ◽  
Yongkang Wu ◽  
Ying Guo ◽  
Kai Song ◽  
Yanan Li
Keyword(s):  
Model Test ◽  
Fluid Dynamic ◽  
Vortex Formation ◽  
Flow Simulation ◽  
Test Method ◽  
Structure Parameters ◽  
Dynamic Simulations ◽  
Vortex Pump ◽  
Orthogonal Test Method ◽  
Orthogonal Tests

We design optimization on the overall blade structure of a vortex pump conducted by using the orthogonal test method to clarify the matching relationship of impeller and casing structures and then improve the hydraulic performance of the vortex pump. Based on two different impeller structures of forward-deflecting (denoted as R1 − F2) and backward-deflecting (denoted as F1 − R2), key parameters describing the impeller structure are calculated through optimization for the objective function of hydraulic efficiency by means of orthogonal tests and computational fluid dynamic simulations. Optimization computations show that the forward-deflecting blade impeller is superior to the backward-deflecting one. Model test of the optimized vortex pump is carried out calculating the error from the comparison of pump efficiencies calculated by model test and numerical simulation is calculated to be less than 6%. The experimental verification shows that the flow simulation has some errors. The weight of structure parameters such as the blade installation angle (α), the blade deflecting angle (β), the position of blade deflecting point (L), the radius (r) of smoothing arc at the deflecting point, the wedge type (W) of blade, to the lift head, the flow rate, and the efficiency of the pump is investigated, through multiparameter optimizations. Visualization observation of flows in the model pump consisted of a back-placed impeller and a front vaneless chamber is further performed. The characteristic of vortex formation predicted by flow simulation agrees with the result of visualization observation. The above results demonstrate that the optimum impeller type of vortex pump is forward-deflecting blade impeller. The optimum combination of the key structure parameters is that the deflection angle of the blade inlet (α) equals 30°, the position of blade deflecting point lM = 2/3 L, the chamfering radius (r) at the deflecting point r = 3 mm, and the best wedge type is axial deflecting blade.

Towards real-time fire data synthesis using numerical simulations

2021 ◽  
pp. 073490412199344
Author(s):  
Wolfram Jahn ◽  
Frane Sazunic ◽  
Carlos Sing-Long
Keyword(s):  
Real Time ◽  
Computational Fluid Dynamic ◽  
Dynamic Models ◽  
Fluid Dynamic ◽  
Near Field ◽  
Computing Time ◽  
Temperature Correction ◽  
Dynamic Simulations ◽  
Conservation Of Energy ◽  
Fire Scenarios

Synthesising data from fire scenarios using fire simulations requires iterative running of these simulations. For real-time synthesising, faster-than-real-time simulations are thus necessary. In this article, different model types are assessed according to their complexity to determine the trade-off between the accuracy of the output and the required computing time. A threshold grid size for real-time computational fluid dynamic simulations is identified, and the implications of simplifying existing field fire models by turning off sub-models are assessed. In addition, a temperature correction for two zone models based on the conservation of energy of the hot layer is introduced, to account for spatial variations of temperature in the near field of the fire. The main conclusions are that real-time fire simulations with spatial resolution are possible and that it is not necessary to solve all fine-scale physics to reproduce temperature measurements accurately. There remains, however, a gap in performance between computational fluid dynamic models and zone models that must be explored to achieve faster-than-real-time fire simulations.

scholarly journals Analysis of Radial Inflow Turbine Losses Operating with Supercritical Carbon Dioxide

Energies ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3561
Author(s):  
Antti Uusitalo ◽  
Aki Grönman
Keyword(s):  
Fluid Dynamic ◽  
Dynamic Simulations ◽  
Average Deviation ◽  
Loss Analysis ◽  
Specific Speed ◽  
Loss Models ◽  
Rotor Losses ◽  
Radial Turbines ◽  
Design Power ◽  
Good Agreement

The losses of supercritical CO2 radial turbines with design power scales of about 1 MW were investigated by using computational fluid dynamic simulations. The simulation results were compared with loss predictions from enthalpy loss correlations. The aim of the study was to investigate how the expansion losses are divided between the stator and rotor as well as to compare the loss predictions obtained with the different methods for turbine designs with varying specific speeds. It was observed that a reasonably good agreement between the 1D loss correlations and computational fluid dynamics results can be obtained by using a suitable set of loss correlations. The use of different passage loss models led to high deviations in the predicted rotor losses, especially with turbine designs having the highest or lowest specific speeds. The best agreement in respect to CFD results with the average deviation of less than 10% was found when using the CETI passage loss model. In addition, the other investigated passage loss models provided relatively good agreement for some of the analyzed turbine designs, but the deviations were higher when considering the full specific speed range that was investigated. The stator loss analysis revealed that despite some differences in the predicted losses between the methods, a similar trend in the development of the losses was observed as the turbine specific speed was changed.

Computational fluid dynamic simulations of coal-fired utility boilers: An engineering tool

Fuel ◽  
2009 ◽  
Vol 88 (1) ◽  
pp. 9-18 ◽  
Author(s):  
Efim Korytnyi ◽  
Roman Saveliev ◽  
Miron Perelman ◽  
Boris Chudnovsky ◽  
Ezra Bar-Ziv
Keyword(s):  
Computational Fluid Dynamic ◽  
Fluid Dynamic ◽  
Dynamic Simulations ◽  
Utility Boilers

scholarly journals Tests of the sorption and olfactory “fovea” hypotheses in the mouse

2017 ◽  
Vol 118 (5) ◽  
pp. 2770-2788 ◽  
Author(s):  
David M. Coppola ◽  
Brittaney E. Ritchie ◽  
Brent A. Craven
Keyword(s):  
Olfactory Epithelium ◽  
Water Solubility ◽  
Fluid Dynamic ◽  
Water Soluble ◽  
Quiet Breathing ◽  
Cfd Simulations ◽  
Dynamic Simulations ◽  
Consistent Finding ◽  
Sensory Epithelia ◽  
Tactile Stimuli

The spatial distribution of receptors within sensory epithelia (e.g., retina and skin) is often markedly nonuniform to gain efficiency in information capture and neural processing. By contrast, odors, unlike visual and tactile stimuli, have no obvious spatial dimension. What need then could there be for either nearest-neighbor relationships or nonuniform distributions of receptor cells in the olfactory epithelium (OE)? Adrian (Adrian ED. J Physiol 100: 459–473, 1942; Adrian ED. Br Med Bull 6: 330–332, 1950) provided the only widely debated answer to this question when he posited that the physical properties of odors, such as volatility and water solubility, determine a spatial pattern of stimulation across the OE that could aid odor discrimination. Unfortunately, despite its longevity, few critical tests of the “sorption hypothesis” exist. Here we test the predictions of this hypothesis by mapping mouse OE responses using the electroolfactogram (EOG) and comparing these response “maps” to computational fluid dynamics (CFD) simulations of airflow and odorant sorption patterns in the nasal cavity. CFD simulations were performed for airflow rates corresponding to quiet breathing and sniffing. Consistent with predictions of the sorption hypothesis, water-soluble odorants tended to evoke larger EOG responses in the central portion of the OE than the peripheral portion. However, sorption simulation patterns along individual nasal turbinates for particular odorants did not correlate with their EOG response gradients. Indeed, the most consistent finding was a rostral-greater to caudal-lesser response gradient for all the odorants tested that is unexplained by sorption patterns. The viability of the sorption and related olfactory “fovea” hypotheses are discussed in light of these findings. NEW & NOTEWORTHY Two classical ideas concerning olfaction’s receptor-surface two-dimensional organization—the sorption and olfactory fovea hypotheses—were found wanting in this study that afforded unprecedented comparisons between electrophysiological recordings in the mouse olfactory epithelium and computational fluid dynamic simulations of nasal airflow. Alternatively, it is proposed that the olfactory receptor layouts in macrosmatic mammals may be an evolutionary contingent state devoid of the functional significance found in other sensory epithelia like the cochlea and retina.

scholarly journals Numerical study of hydrogen mild combustion

2009 ◽  
Vol 13 (3) ◽  
pp. 59-67 ◽  
Author(s):  
Enrico Mollica ◽  
Eugenio Giacomazzi ◽  
Marco di
Keyword(s):  
Numerical Study ◽  
Fluid Dynamic ◽  
Thermal Gradients ◽  
Radiation Model ◽  
Dynamic Simulations ◽  
Mild Combustion ◽  
Preheating Temperature ◽  
Nitric Oxide Emissions ◽  
Gas Recirculation ◽  
Good Agreement

In this article a combustor burning hydrogen and air in mild regime is numerically studied by means of computational fluid dynamic simulations. All the numerical results show a good agreement with experimental data. It is seen that the flow configuration is characterized by strong exhaust gas recirculation with high air preheating temperature. As a consequence, the reaction zone is found to be characteristically broad and the temperature and concentrations fields are sufficiently homogeneous and uniform, leading to a strong abatement of nitric oxide emissions. It is also observed that the reduction of thermal gradients is achieved mainly through the extension of combustion in the whole volume of the combustion chamber, so that a flame front no longer exists ('flameless oxidation'). The effect of preheating, further dilution provided by inner recirculation and of radiation model for the present hydrogen/air mild burner are analyzed.

scholarly journals REGRESI LINEAR BIVARIAT SIMPEL DAN APLIKASINYA PADA DATA CUACA DI CILACAP

2014 ◽  
Vol 6 (1) ◽  
pp. 45 ◽  
Author(s):  
Saniyah Saniyah ◽  
Budi Pratikno
Keyword(s):  
Linear Regression ◽  
Regression Model ◽  
Air Temperature ◽  
Model Test ◽  
Predictor Variable ◽  
Error Model ◽  
Test Method ◽  
Weather Data ◽  
Mean Deviation ◽  
Response Variables

This study discusses the simple bivariate linear regression on weather data in Cilacap district. This simple bivariate linear regression using the two response variables, rainfall () and humidity of an area (), and one predictor variable, the air temperature (). Regression model test method is a Wilk's Lamda test, the value of Wilk's Lamda = 0.881101 less than lambda table 0.903. The results show that the model and the both parameters are significant, with mean deviation error model is .

Sign in / Sign up

Export Citation Format

Share Document