scholarly journals A Study on the Effect of the Outer Ring of Annular Cooling Fan on the Aerodynamic Performance

2019 ◽  
Author(s):  
Hengtao Shu ◽  
Zhihong Yin ◽  
Wenbin Shangguan ◽  
Waizuddin Ahmed
Keyword(s):  
Computational Model ◽  
Model Simulation ◽  
Great Influence ◽  
Calculated Data ◽  
Axial Direction ◽  
Aerodynamic Performance ◽  
Outer Ring ◽  
Structure Parameters ◽  
Relative Parameter ◽  
Cooling Fan

We studied the effect of the structure parameters of engine annular cooling fan with outer ring on the aerodynamic performance by means of experiments and model simulation in fluent®. Firstly, based on the experiment, a computational model is developed to calculate and analyze the aerodynamic performance of the tested annular fan. The model is validated by comparing the test results with the calculated data. Besides, the aerodynamic performance differences between two types of fans (common fan without outer ring and annular fan with outer ring) are discussed. Based on the computational model, the relation between aerodynamic performance and the outer ring structure parameters are investigated. The results show that the relative parameter on the axial direction has great influence on the aerodynamic performance; while the effect of radial relative parameter is minor. In addition, the outer ring with arc chamfer structure in the downstream side can improve its static pressure efficiency effectively.

scholarly journals An 1-D Integrated Hydro-Mechanical Model to Unravel Different Hydrological Triggering Processes of Debris Flows

2018 ◽  
Author(s):  
Theo W.J. van Asch ◽  
Bin Yu ◽  
Wei Hu
Keyword(s):  
Mechanical Model ◽  
Debris Flows ◽  
Overland Flow ◽  
Model Simulation ◽  
Slope Angle ◽  
Great Influence ◽  
Source Area ◽  
Material Model ◽  
Flume Experiments ◽  
Bed Material

Many studies, which try to analyze the meteorological threshold conditions for debris flows ignore the type of initiation. This paper focuses on the differences in hydrological triggering processes of debris flows in channel beds of the source areas. The different triggering processes were studied in the laboratory and by model simulation on the field scale. The laboratory experiments were carried out in a flume, 8 m long and a width of 0.3 m. An integrated hydro-mechanical model was developed, describing Hortonian and Saturation overland flow, through flow, maximum sediment transport and failure of bed material. The model was tested on the processes observed in the flume. The flume experiments show a sequence of hydrological processes triggering debris flows, namely erosion and transport by intensive overland flow and by infiltrating water causing failure of channel bed material. Model simulations carried out on a schematic hypothetical source area of a catchment show that the type and sequence of these triggering processes are determined by slope angle and the hydraulic conductivity of the bed material. It was also clearly demonstrated that the type of initiation process and the geometrical and hydro-mechanical parameters may have a great influence on rainfall intensity-duration threshold curves, indicating the start of debris flows.

scholarly journals A general response process theory for situational judgment tests

2019 ◽  
Author(s):  
James Grand
Keyword(s):  
Computational Model ◽  
Web Application ◽  
Model Simulation ◽  
Future Research ◽  
Simulation Code ◽  
Situational Judgment ◽  
Situational Judgment Tests ◽  
Measurement Models ◽  
Reported Data ◽  
General Response

Situational judgment tests (SJTs) have emerged as a staple of assessment methodologies for organizational practitioners and researchers. Despite their prevalence, many questions regarding how to interpret respondent choices or how variations in item construction and instruction influence the nature of observed responses remain. Existing conceptual and empirical efforts to explore these questions have largely been rooted in reflexive psychometric measurement models that describe participant responses as indicative of (usually multiple) latent constructs. However, some have suggested that a key to better understanding SJT responses lies in unpacking the judgment and decision-making processes employed by respondents and the psychological and contextual factors that shape how those processes play out. To this end, the present paper advances an integrative and generalizable process-oriented theory of SJT responding. The framework, labeled Situated Reasoning and Judgment (SiRJ), proposes that respondents engage in a series of conditional reasoning, similarity, and preference accumulation judgments when deciding how to evaluate and respond to an SJT item. To evaluate the theory’s plausibility and utility, the SiRJ framework is translated into a formal computational model and results from a simulation study are analyzed using neural network and Bayesian survival analytic techniques that demonstrate its capability to replicate existing and new empirical effects, suggest insights into SJT interpretation and development, and stimulate new directions for future research. An interactive web application that allows users to explore the computational model developed for SiRJ (https://grandjam.shinyapps.io/sirj) as well as all reported data and the full model/simulation code (https://osf.io/uwdfm/) are also provided.

Virtual Testing and Simulation Methods for Aerodynamic Performance of A Heavy Duty Cooling Fan

2010 ◽  
Author(s):  
Phuriwat Anusonti-Inthra ◽  
William Liou ◽  
Andreas Baumann ◽  
Kenneth Kacynski
Keyword(s):  
Aerodynamic Performance ◽  
Simulation Methods ◽  
Heavy Duty ◽  
Virtual Testing ◽  
Cooling Fan

Effects of Labyrinth Fin Wear on Aerodynamic Performance of Turbine Stages: Part II — Mushrooming Damages

2019 ◽  
Author(s):  
Xinbo Dai ◽  
Xin Yan
Keyword(s):  
Experimental Studies ◽  
Axial Direction ◽  
Labyrinth Seal ◽  
Aerodynamic Performance ◽  
Leakage Rate ◽  
Secondary Flows ◽  
Main Function ◽  
Aerodynamic Loss ◽  
Solution Methods ◽  
Isentropic Efficiency

Abstract The main function of labyrinth seal is to control leakage flow in clearance that involves with rotating and stationary parts. Therefore, the effective of clearance gap in labyrinth seal is critical to sealing, heat transfer and vibration characteristics. However, due to the mechanical expansions, vibrations, thermal stress, misalignment of seal components in transient periods of startup, shutdown and hot restart, the stationary and rotating parts of the labyrinth seal are likely to contact each other, causing wear damages in labyrinth fin. Mushrooming damages are often occurred in the rubbing events when labyrinth fin is made of soft material compared with the opposite component. To investigate how mushrooming damage affects the leakage performance of labyrinth seal, many numerical and experimental studies have been carried out in last decades. However, little attention has been paid on the influence of labyrinth fin mushrooming on aerodynamic performance of turbine stages. In this study, using the RANS equations solution methods, the effect of labyrinth fin mushrooming on isentropic efficiency, leakage rates, outlet flow angles, reaction degrees, profile static pressure distributions and flow fields in turbine stages were investigated at three different mushrooming radii and three effective clearances. It shows the leakage rate is increased with increasing the mushroom radius and effective clearance. At the same effective clearance, as the mushrooming radius increases from 0.2mm to 0.4mm, the leakage rate is increased by about 0.19–0.32%, and the overall isentropic efficiency is decreased by 0.78%. At the same mushrooming radius, as the effective clearance increases from 1mm to 1.4mm, the leakage rate is increased by 0.21–0.31%, and the overall isentropic efficiency is decreased by 0.65%. As mushroom radius and effective clearance increase, the secondary flows near hub and shroud are intensified and developed along axial direction, causing pronounced aerodynamic loss in turbine stages.

Vibrations of the All-Ceramic Ball Bearing

2002 ◽  
Vol 124 (3) ◽  
pp. 448-460 ◽  
Author(s):  
Hiroyuki Ohta ◽  
Shinya Satake
Keyword(s):  
Natural Vibration ◽  
Ball Bearing ◽  
Axial Direction ◽  
Outer Ring ◽  
Ball Bearings ◽  
Ceramic Ball ◽  
Vibration Spectra ◽  
All Ceramic ◽  
Hybrid Ceramic ◽  
Mass Type

All-ceramic ball bearings with silicone nitride balls and silicone nitride rings were tested and the vibration characteristics were compared with those of hybrid ceramic ball bearings and conventional steel ball bearings. The vibration measurement results showed that the overall vibratory velocity levels of the all-ceramic ball bearings are influenced by rotational velocities, and do not change with axial loads. Under a given axial load and rotational velocity, the overall vibratory velocity level of the all-ceramic ball bearing is the lowest, and the hybrid ball bearing the highest. The frequencies of main peaks in the measured vibration spectra of the all-ceramic ball bearing are higher than the frequencies of the corresponding main peaks for the hybrid ceramic ball bearing and the steel ball bearing. To explain the main peaks, modal analysis was done and the relationship between peak and natural vibration was analyzed. The results of the analyses showed that the main peaks are caused by: (1) the mass-type natural vibration of the outer ring in the vertical direction, (2) the bending natural vibration of the outer ring in the radial direction, (3) the moment of inertia-type natural vibration of the outer ring in the angular direction, (4) the mass-type natural vibration of the outer ring in the axial direction, and (5) the bending natural vibration of the outer ring in the axial direction. We also discuss the generating mechanism of the vibration and present the calculation method of the vibration spectra. As a result, it is clear that the vibration spectra of the all-ceramic ball bearing are determined by the amplitude of the waviness of the raceways and ball surface, the mobility, and the non-linear spring constant associated with the contact between the raceways and balls.

scholarly journals Aerodynamic Performance of the Inboard Elevon on a Blendedwing- Body Aircraf

2021 ◽  
Author(s):  
Alexander Gordon Jackson
Keyword(s):  
Computational Model ◽  
Numerical Solutions ◽  
Aerodynamic Performance ◽  
Aerodynamic Design ◽  
Trailing Edge ◽  
Negative Deflection ◽  
Average Change ◽  
Implicit Solver ◽  
Blended Wing Body ◽  
Beveled Trailing Edge

The objectives of this research are to examine the effects of trailing edge modifications of the inboard elevon of a blended-wing-body (BWB) aircraft, the goal being to try and reduce the hinge moment of the inboard elevon through selective aerodynamic design. A computational model was built for 60⁰ and 70⁰ beveled trailing edge modifications, as well as no modification. The inboard elevon was deflected positive 5⁰ and negative 5⁰. The numerical solutions were obtained using an implicit solver and inviscid model. The results of this research showed that, through the use of a beveled trailing edge on the inboard elevon, a maximum of 112% reduction in the hinge moment could be achieved for the negative deflection case and a maximum of 88% reduction in the hinge moment for the positive deflection case. The results showed that there was a significant improvement in the hinge moments, with less that a 2% average change in the overall aerodynamic performance of the BWB for the inviscid models.

scholarly journals Influences of the Flow Cut and Axial Lift of the Impeller on the Aerodynamic Performance of a Transonic Centrifugal Compressor

Energies ◽  
2019 ◽  
Vol 12 (23) ◽  
pp. 4503
Author(s):  
Kun Park ◽  
In Jung ◽  
Sung You ◽  
Seung Lee ◽  
Ali Zamiri ◽  
...  
Keyword(s):  
Flow Rate ◽  
Centrifugal Compressor ◽  
Total Pressure ◽  
Relative Velocity ◽  
Axial Direction ◽  
Aerodynamic Performance ◽  
Design Flow ◽  
Design Point ◽  
Transonic Centrifugal Compressor ◽  
Design Flow Rate

In this study, the influences of the flow cut and axial lift of the impeller on the aerodynamic performance of a transonic centrifugal compressor were analyzed. The flow cut is a method to reduce the flow rate by decreasing the impeller passage height. The axial lift is a method of increasing the impeller passage height in the axial direction, which increases the impeller exit width (B2) and increases the total pressure. A NASA CC3 transonic centrifugal compressor with a backswept angle was used as a base compressor. After applying the flow cut, the total pressure at the target flow rate was lower than the total pressure at the design point due to the increase in the relative velocity at the impeller exit. After applying the axial lift, the total pressure at the design flow rate was increased, which was caused by the reduction in the relative velocity as the passage area at the impeller exit was increased. By applying the flow cut and axial lift methods, it was shown that the variation in relative velocity at the impeller exit has a significant effect on the variation in total pressure. In addition, it was found that the relative velocity at the impeller exit of the target flow rate is maintained similar to the base impeller when the flow cut and the axial lift are combined. Therefore, by combining the flow cut and the axial lift, three transonic centrifugal impellers with flow fractions of 0.7, 0.8, and 0.9 compared to the design flow rate were newly designed.

G602 Experimental and Numerical Studies on Aerodynamic Performance and Flow Field of a Cooling Fan Used in a Narrow Space(2)

2006 ◽  
Vol 2006 (0) ◽  
pp. _G602-1_-_G602-4_
Author(s):  
Ken-ichi FUNAZAKI ◽  
Kazutoyo YAMADA ◽  
Hideo TANIGUCHI ◽  
Mamoru KIKUCHI ◽  
Hon Bin Yuan ◽  
...  
Keyword(s):  
Flow Field ◽  
Aerodynamic Performance ◽  
Cooling Fan ◽  
Numerical Studies ◽  
Narrow Space
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