Diagonal Flow Pump Impeller With NACA65 Series Blade (Correction of Blade Geometry)

2011 ◽  
Author(s):  
Yoichi Kinoue ◽  
Norimasa Shiomi ◽  
Toshiaki Setoguchi ◽  
Kazuhiro Sawamura ◽  
Hideaki Maeda
Keyword(s):  
Rotor Blade ◽  
Design Flow ◽  
Numerical Calculations ◽  
Navier Stokes ◽  
Minimum Pressure ◽  
The One ◽  
Suction Performance ◽  
Flow Pump ◽  
Better Than ◽  
Blade Geometry

Using the design method based on the design for axial-flow type turbomachine, the diagonal flow pump impellers were designed for two cases of the centrifugal effect parameter a. In addition, three-dimensional Navier-Stokes numerical calculations for single-phase were conducted in order to examine the tendency of the suction performance as well as the head performance. The head increases from the NS calculation of the impeller are the same between for a = 0.4 and for a = 1.0 because major specification are the same between for a = 0.4 and for a = 1.0. For the minimum pressure on the rotor blade, however, there is a difference between for a = 0.4 and for a = 1.0. The value of minimum pressure for a = 0.4 is −324 kPa, whereas the value for a = 1.0 is −294 kPa. The blade geometry for a = 1.0 is better than the one for a = 0.4 in terms of the suction performance because the trough of the minimum pressure is shallower for a = 1.0 than a = 0.4. Furthermore, Navier-Stokes numerical calculations were also conducted for off-design flow rate. For all cases in this paper, the minimum pressure on the rotor blade occurred at both near the leading edge and near the tip on the suction side of the blade. In addition, for all cases in this paper, the blade geometry for a = 1.0 is better than the one for a = 0.4 in terms of the suction performance.

Large-Eddy Simulation of a Mixed-Flow Pump at Off-Design Conditions

2015 ◽  
Vol 137 (10) ◽  
Author(s):  
Antonio Posa ◽  
Antonio Lippolis ◽  
Elias Balaras
Keyword(s):  
Large Eddy Simulation ◽  
Flow Rate ◽  
Design Flow ◽  
Immersed Boundary ◽  
Mixed Flow ◽  
Eddy Simulation ◽  
Image Velocimetry ◽  
Large Eddy ◽  
The One ◽  
Flow Pump

The flow through turbopumps is characterized by highly unsteady phenomena at part load conditions, involving large separation and generation of vortical structures. This behavior is strongly dependent on the interaction between rotating and steady parts, which is significantly modified, compared to the one at the design flow rate. Therefore, at off-design conditions, eddy-resolving computations are more suitable to analyze the complex physics occurring inside turbomachinery channels. In this work the large eddy simulation (LES), coupled with an immersed-boundary (IB) method, is utilized to study a mixed-flow pump at a reduced flow rate, equivalent to 40% of the nominal one. The present approach has been already validated in a previous study, where a satisfactory agreement with two-dimensional (2D) particle image velocimetry (PIV) experiments has been shown at design conditions. In this paper a comparison with the LES results at the optimal flow rate is also proposed, in order to understand the important modifications of the flow occurring at part loads.

scholarly journals Three-objective optimization of a mixed-flow pump impeller for improved suction performance and efficiency

2019 ◽  
Vol 11 (12) ◽  
pp. 168781401989896 ◽  
Author(s):  
Sung Kim ◽  
Yong-In Kim ◽  
Jin-Hyuk Kim ◽  
Young-Seok Choi
Keyword(s):  
Design Optimization ◽  
Design Flow ◽  
Meridional Plane ◽  
Angle Distribution ◽  
Blade Angle ◽  
Mixed Flow ◽  
Pump Impeller ◽  
Design Variables ◽  
Suction Performance ◽  
Flow Pump

In this article, design optimization was carried out to improve the suction performance and efficiency of a mixed-flow pump impeller. Commercial computational fluid dynamics code and a response surface method were used in the optimization to design a mixed-flow pump impeller. When it comes to a mixed-flow pump, the two main research objectives namely efficiency and suction performance tend to contradict. It is very important that the design technology improves the suction performance while maintaining high efficiency. Meridional plane and vane plane development variables were defined in the design of the impeller. The meridional plane expresses the shapes and sizes of the blades, while the vane plane development describes the impeller inlet and outlet angles as well as the blade angle distribution. The blade angle distribution of the impeller was designed using the traditional method by which inlet and outlet angles are connected smoothly. The surface response method was applied to the design variables of the impeller inlet part in this design optimization because they influence the performance of the mixed-flow pump. Objective functions were set to satisfy the total head at the design flow rate as well as to improve efficiency and suction performance. Design variables of the impeller inlet part of the mixed-flow pump and the changes in performance were analyzed in order to produce the optimal shape. The performance of the optimally designed shape was verified by numerical analysis, and the reliability of the test result was checked by comparative analysis against the reference model.

scholarly journals Numerical study on the cavitation phenomenon for the head drop and unsteady bubble patterns with a difference in the incidence angle of a mixed-flow pump

2020 ◽  
Vol 12 (4) ◽  
pp. 168781402091479 ◽  
Author(s):  
Yong-In Kim ◽  
Hyeon-Mo Yang ◽  
Jun-Won Suh ◽  
Sung Kim ◽  
Kyoung-Yong Lee ◽  
...  
Keyword(s):  
Numerical Study ◽  
Incidence Angle ◽  
Experimental Tests ◽  
Design Flow ◽  
Inlet Pressure ◽  
Mixed Flow ◽  
Bubble Generation ◽  
Cavitation Phenomenon ◽  
Suction Performance ◽  
Flow Pump

In this study, two types of mixed-flow pump models exhibiting different suction performances were investigated to understand the cavitation characteristics of head drop gradients due to the decrease in inlet pressure. Both models were designed with the same specifications except for the shroud inlet blade angle and inlet radius which directly affect the incidence angle. The steady- and unsteady-state analyses were performed using ANSYS CFX, and the results of both models were compared. Bubble generation and patterns were systemically represented at the design flow rate to observe their influence on suction performance. Furthermore, experimental tests were performed to validate the numerical results. From the results, the head drop gradient can determine the suction performance of mixed-flow pumps. The amount and shape of the bubbles concerning the suction performance of a mixed-flow pump exhibit significant differences with the changes in time and inlet pressure. The patterns of generated bubble are not stable even for each blade.

Subjective Time Preference and Willingness to Pay for an Energy-Saving Durable Good

2001 ◽  
Vol 32 (3) ◽  
pp. 133-141 ◽  
Author(s):  
Gerrit Antonides ◽  
Sophia R. Wunderink
Keyword(s):  
Willingness To Pay ◽  
Energy Saving ◽  
Subjective Time ◽  
Durable Good ◽  
Discount Function ◽  
Hyperbolic Discount ◽  
The One ◽  
Two Parameter ◽  
Difference Effect ◽  
Better Than

Summary: Different shapes of individual subjective discount functions were compared using real measures of willingness to accept future monetary outcomes in an experiment. The two-parameter hyperbolic discount function described the data better than three alternative one-parameter discount functions. However, the hyperbolic discount functions did not explain the common difference effect better than the classical discount function. Discount functions were also estimated from survey data of Dutch households who reported their willingness to postpone positive and negative amounts. Future positive amounts were discounted more than future negative amounts and smaller amounts were discounted more than larger amounts. Furthermore, younger people discounted more than older people. Finally, discount functions were used in explaining consumers' willingness to pay for an energy-saving durable good. In this case, the two-parameter discount model could not be estimated and the one-parameter models did not differ significantly in explaining the data.

Exploring the Multidimensional Facets of Authoritarianism: Authoritarian Aggression and Social Dominance Orientation

2008 ◽  
Vol 67 (1) ◽  
pp. 51-60 ◽  
Author(s):  
Stefano Passini
Keyword(s):  
Social Dominance ◽  
Factor Model ◽  
Three Dimensional ◽  
Social Dominance Orientation ◽  
Model Fit ◽  
Regression Analyses ◽  
One Dimensional ◽  
Confirmatory Factor ◽  
The One ◽  
Better Than

The relation between authoritarianism and social dominance orientation was analyzed, with authoritarianism measured using a three-dimensional scale. The implicit multidimensional structure (authoritarian submission, conventionalism, authoritarian aggression) of Altemeyer’s (1981, 1988) conceptualization of authoritarianism is inconsistent with its one-dimensional methodological operationalization. The dimensionality of authoritarianism was investigated using confirmatory factor analysis in a sample of 713 university students. As hypothesized, the three-factor model fit the data significantly better than the one-factor model. Regression analyses revealed that only authoritarian aggression was related to social dominance orientation. That is, only intolerance of deviance was related to high social dominance, whereas submissiveness was not.

Designing Women

2018 ◽  
Author(s):  
J. E. Smyth
Keyword(s):  
Working Women ◽  
Costume Design ◽  
Creative Force ◽  
Women's Fashion ◽  
The One ◽  
Studio Era ◽  
Average Woman ◽  
Better Than

During the early 1940s, journalists observed that after years of men controlling women’s fashion, Hollywood had become “a fashion center in which women designers are getting to be a big power.” In a town where “the working girl is queen,” it was women who really knew how to dress working women. Edith Head’s name dominates Hollywood costume design. Though a relatively poor sketch artist who refused to sew in public, Head understood what the average woman wanted to wear and knew better than anyone how to craft her image as the-one-and-only Edith Head. However, she was one of many women who designed Hollywood glamour in the studio era. This chapter juxtaposes Head’s career with that of a younger, fiercely independent designer who would quickly upstage Head as a creative force. In many senses, Dorothy Jeakins’s postwar career ascent indicated the waning of the Hollywood system and the powerful relationship between female designers, stars, and fans.

scholarly journals Assessment of Numerical Methods for Plunging Breaking Wave Predictions

2021 ◽  
Vol 9 (3) ◽  
pp. 264
Author(s):  
Shanti Bhushan ◽  
Oumnia El Fajri ◽  
Graham Hubbard ◽  
Bradley Chambers ◽  
Christopher Kees
Keyword(s):  
Solitary Wave ◽  
Wave Breaking ◽  
Large Scale ◽  
Turbulence Models ◽  
Navier Stokes ◽  
Wave Crest ◽  
Breaking Wave ◽  
Rans Turbulence Models ◽  
Run Up ◽  
Better Than

This study evaluates the capability of Navier–Stokes solvers in predicting forward and backward plunging breaking, including assessment of the effect of grid resolution, turbulence model, and VoF, CLSVoF interface models on predictions. For this purpose, 2D simulations are performed for four test cases: dam break, solitary wave run up on a slope, flow over a submerged bump, and solitary wave over a submerged rectangular obstacle. Plunging wave breaking involves high wave crest, plunger formation, and splash up, followed by second plunger, and chaotic water motions. Coarser grids reasonably predict the wave breaking features, but finer grids are required for accurate prediction of the splash up events. However, instabilities are triggered at the air–water interface (primarily for the air flow) on very fine grids, which induces surface peel-off or kinks and roll-up of the plunger tips. Reynolds averaged Navier–Stokes (RANS) turbulence models result in high eddy-viscosity in the air–water region which decays the fluid momentum and adversely affects the predictions. Both VoF and CLSVoF methods predict the large-scale plunging breaking characteristics well; however, they vary in the prediction of the finer details. The CLSVoF solver predicts the splash-up event and secondary plunger better than the VoF solver; however, the latter predicts the plunger shape better than the former for the solitary wave run-up on a slope case.

Development of a Single-Code/Default Coding Strategy in Pigeons

2000 ◽  
Vol 11 (3) ◽  
pp. 261-264 ◽  
Author(s):  
Tricia S. Clement ◽  
Thomas R. Zentall
Keyword(s):  
Conditional Discrimination ◽  
The Other ◽  
Matching Accuracy ◽  
Efficient Coding ◽  
Coding Strategy ◽  
One To One ◽  
Retention Intervals ◽  
The Many ◽  
The One ◽  
Better Than

We tested the hypothesis that pigeons could use a cognitively efficient coding strategy by training them on a conditional discrimination (delayed symbolic matching) in which one alternative was correct following the presentation of one sample (one-to-one), whereas the other alternative was correct following the presentation of any one of four other samples (many-to-one). When retention intervals of different durations were inserted between the offset of the sample and the onset of the choice stimuli, divergent retention functions were found. With increasing retention interval, matching accuracy on trials involving any of the many-to-one samples was increasingly better than matching accuracy on trials involving the one-to-one sample. Furthermore, following this test, pigeons treated a novel sample as if it had been one of the many-to-one samples. The data suggest that rather than learning each of the five sample-comparison associations independently, the pigeons developed a cognitively efficient single-code/default coding strategy.

scholarly journals Numerical Study of Pressure Attenuation Effect on Tunnel Structures Subjected to Blast Loads

2021 ◽  
Vol 11 (12) ◽  
pp. 5646
Author(s):  
Cheng-Wei Hung ◽  
Ying-Kuan Tsai ◽  
Tai-An Chen ◽  
Hsin-Hung Lai ◽  
Pin-Wen Wu
Keyword(s):  
Numerical Simulation ◽  
Orifice Plate ◽  
Experimental Result ◽  
Scale Model ◽  
Pressure Reduction ◽  
Expansion Chamber ◽  
Pressure Relief ◽  
Attenuation Effect ◽  
The One ◽  
Better Than

This study used experimental and numerical simulation methods to discuss the attenuation mechanism of a blast inside a tunnel for different forms of a tunnel pressure reduction module under the condition of a tunnel near-field explosion. In terms of the experiment, a small-scale model was used for the explosion experiments of a tunnel pressure reduction module (expansion chamber, one-pressure relief orifice plate, double-pressure relief orifice plate). In the numerical simulation, the pressure transfer effect was evaluated using the ALE fluid–solid coupling and mapping technique. The findings showed that the pressure attenuation model changed the tunnel section to diffuse, reduce, or detour the pressure transfer, indicating the blast attenuation effect. In terms of the effect of blast attenuation, the double-pressure relief orifice plate was better than the one-pressure relief orifice plate, and the single-pressure relief orifice plate was better than the expansion chamber. The expansion chamber attenuated the blast by 30%, the one-pressure relief orifice plate attenuated the blast by 51%, and the double-pressure relief orifice plate attenuated the blast by 82%. The blast attenuation trend of the numerical simulation result generally matched that of the experimental result. The results of this study can provide a reference for future protective designs and reinforce the U.S. Force regulations.

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