An Aerodynamic Shroud for Automotive Cooling Fans

2000 ◽  
Vol 123 (2) ◽  
pp. 287-292 ◽  
Author(s):  
Scott C. Morris ◽  
John F. Foss
Keyword(s):  
Experimental Investigation ◽  
System Design ◽  
Flow Rate ◽  
Tip Clearance ◽  
High Momentum ◽  
Near Wake ◽  
Flow Rates ◽  
Cooling Fans ◽  
Flow Features ◽  
Improved Performance

Results from an experimental investigation of an aerodynamic fan shroud are reported. The device was motivated by the relatively large (2.5 cm) tip clearance required in automotive cooling fans which are mounted to the engine. The shroud consists of a pressurized plenum and a Coanda attachment surface to deliver a jet of high momentum air into the tip clearance region. Both the performance and the efficiency for the initial system design were enhanced at higher flow rates, and degraded at lower flow rates. A small tuft was used to observe qualitative flow features in the near wake and tip clearance region of the fan. This information was used to create a modified design. The new geometry was tested and found to provide improved performance characteristics for a wider range of flow rate conditions.

An Experimental Investigation of Oil-Buffered Shaft Seal Flow Rates

1985 ◽  
Vol 107 (1) ◽  
pp. 170-180
Author(s):  
W. N. Shade ◽  
D. E. Hampshire
Keyword(s):  
Experimental Investigation ◽  
Flow Rate ◽  
Primary Objective ◽  
Shaft Seal ◽  
Flow Rates ◽  
Process Gas ◽  
Face Seals ◽  
Oil Flow ◽  
Seal Oil ◽  
Oil Exposure

An experimental investigation was conducted to identify an optimum oil-buffered shaft seal for use on centrifugal compressors, with the primary objective being minimal seal oil exposure to process gases that cause seal oil degradation or are toxic. Types of seals tested included smooth bore cylindrical bushings, spiral groove cylindrical bushings, radial outward-flow face seals, and radial inward-flow face seals. The influence of shaft speed, gas pressure, seal oil differential pressure, oil bypass flow rate, and oil supply temperature on process side seal oil flow rate was determined. The investigation revealed some surprising relationships between seal oil flow rates and the escape of process gas.

Identification of Wake Convection and Flow Outline in the Interface Region of Blade Rows With Axial Gap in a Counter Rotating Turbine

2019 ◽  
Author(s):  
Rayapati Subbarao ◽  
M. Govardhan
Keyword(s):  
Flow Pattern ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Three Dimensional ◽  
Interface Region ◽  
Turbine Stage ◽  
Deviation Angle ◽  
Flow Rates ◽  
Improved Performance

Abstract In a Counter Rotating Turbine (CRT), the stationary nozzle is trailed by two rotors that rotate in the opposite direction to each other. Flow in a CRT stage is multifaceted and more three dimensional, especially, in the gap between nozzle and rotor 1 as well as rotor 1 and rotor 2. By varying this gap between the blade rows, the flow and wake pattern can be changed favorably and may lead to improved performance. Present work analyzes the aspect of change in flow field through the interface, especially the wake pattern and deviation in flow with change in spacing. The components of turbine stage are modeled for different gaps between the components using ANSYS® ICEM CFD 14.0. Normalized flow rates ranging from 0.091 to 0.137 are used. The 15, 30, 50 and 70% of the average axial chords are taken as axial gaps in the present analysis. CFX 14.0 is used for simulation. At nozzle inlet, stagnation pressure boundary condition is used. At the turbine stage or rotor 2 outlet, mass flow rate is specified. Pressure distribution contours at the outlets of the blade rows describe the flow pattern clearly in the interface region. Wake strength at nozzle outlet is more for the lowest gap. At rotor 1 outlet, it is less for x/a = 0.3 and increases with gap. Incidence angles at the inlets of rotors are less for the smaller gaps. Deviation angle at the outlet of rotor 1 is also considered, as rotor 1-rotor 2 interaction is more significant in CRT. Deviation angle at rotor 1 outlet is minimum for this gap. Also, for the intermediate mass flow rate of 0.108, x/a = 0.3 is giving more stage performance. This suggests that at certain axial gap, there is better wake convection and flow outline, when compared to other gap cases. Further, it is identified that for the axial gap of x/a = 0.3 and the mean mass flow rate of 0.108, the performance of CRT is maximum. It is clear that the flow pattern at the interface is changing the incidence and deviation with change in axial gap and flow rate. This study is useful for the gas turbine community to identify the flow rates and gaps at which any CRT stage would perform better.

On the Interactions of a Rotor Blade Tip Flow With Axial Casing Grooves in an Axial Compressor Near the Best Efficiency Point

2018 ◽  
Author(s):  
Huang Chen ◽  
Yuanchao Li ◽  
Joseph Katz
Keyword(s):  
Flow Rate ◽  
Rotor Blade ◽  
Leading Edge ◽  
Secondary Flows ◽  
Leakage Flow ◽  
Flow Rates ◽  
Tip Leakage ◽  
Flow Features ◽  
Blade Tip ◽  
Corner Vortex

Previous studies have shown that axial casing grooves (ACGs) are effective in delaying the onset of stall, but degrade the performance of axial turbomachines around the best efficiency point (BEP). Our recent experimental study [1] in the JHU refractive index-matched liquid facility have examined the effects of ACGs on delaying stall of a one and half stage compressor. The semicircular ACGs based on Müller et al. [2] reduce the stall flow rate by 40% with a slight decrease in pressure rise at higher flow rates. Stereo-PIV (SPIV) measurements at a flow rate corresponding to the pre-stall condition of the untreated machine have identified three flow features that contribute to the delay in stall. Efficiency measurements conducted as part of the present study show that the ACGs cause a 2.4% peak efficiency loss. They are followed by detailed characterizations of the impact of the ACGs on the flow structure and turbulence in the tip region at high flow rates away from stall. Comparisons with the flow structure without casing grooves and at low flow rate are aimed at exploring relevant flow features that might be associated with the reduced efficiency. The SPIV measurements in several meridional and radial planes show that the periodic inflow into the groove peaks when the rotor blade pressure side (PS) overlaps with the downstream end of the groove, but diminishes when this end faces the blade suction side (SS). The inflow velocity magnitude is substantially lower than that occurring at a flow rate corresponding to the pre-stall conditions of the untreated machine. Yet, entrainment of the PS boundary layer and its vorticity during the inflow phase generates counter-rotating radial vortices at the entrance to the groove, and a “discontinuity” in the appearance of the tip leakage vortex (TLV). While being exposed to the blade SS, the backward tip leakage flow causes flow separation and formation of a counter-rotating vortex at the downstream corner of the groove, which migrates towards the passage with increasing flow rate. Interactions of this corner vortex with the TLV cause fragmentation of the latter, creating a broad area with secondary flows and elevated turbulence level. Consequently, the vorticity shed from the blade tip remains scattered from the groove corner to the blade tip long after the blade clears this groove. The turbulence peaks around the corner vortex, the TLV, and the shear layer connecting it to the SS corner. During periods of inflow, there is a weak outflow from the upstream end of the groove. At other phases, most of the high secondary flows are confined to the downstream corner, leaving only weak internal circulation in the rest of the groove, but with a growing shear layer with elevated (but weak) turbulence originating from the upstream corner. Compared to a smooth endwall, the groove also increases the flow angle near the blade tip leading edge (LE) and varies it periodically. Accordingly, the magnitude of circulation shed from the blade tip and leakage flow increase near the leading edge. The insight from these observations might guide the development of ACGs that take advantage of the effective stall suppression by the ACGs but alleviate the adverse effects at high flowrates.

scholarly journals Experimental Analysis of SMART Scrubbing System with the Principle of Dynamic Precipitation

2018 ◽  
Vol 7 (4.35) ◽  
pp. 317
Author(s):  
Nirvenesh Ravindran ◽  
Hasril Hasini
Keyword(s):  
Experimental Investigation ◽  
Water Flow ◽  
Flow Rate ◽  
Experimental Analysis ◽  
Dust Concentration ◽  
Processing Plant ◽  
Dynamic Precipitation ◽  
Flow Rates ◽  
Model Experiments ◽  
Process Line

This paper presents an experimental investigation of a SMART scrubbing system in sugar processing plant. The objectives are to address the problem and develop new technique to increase the efficiency and eliminate sugar sludge production downstream of process line. The SMART scrubbing effect of water with the principal of dynamic precipitation was conducted on-site with calculated flow rate, which simulates the SMART scrubbing system. The on-site and scaled-down model experiments measure the upstream and downstream dust concentration and processes the flow rate of water required to counter the dust concentration based on the feedback flow. The investigation was conducted with a steady airflow of 6 m3/s with variation of water flow rates. The result of the on-site studies shows an excellent increase in average and maximum efficiencies of 98.77% and 99.3% respectively.

Experimental Investigation of Air Flow Through a Perforated Tile in a Raised Floor Data Center

2015 ◽  
Vol 137 (1) ◽  
Author(s):  
Vaibhav K. Arghode ◽  
Yogendra Joshi
Keyword(s):  
Flow Field ◽  
Flow Rate ◽  
Air Flow ◽  
Base Case ◽  
Flow Rates ◽  
Cold Air ◽  
Air Jet ◽  
Image Velocimetry ◽  
Flow Features ◽  
Staggered Arrangement

Raised floor data centers supply cold air from a pressurized plenum to the server racks through perforated floor tiles. Hence, the design of an efficient air delivery scheme requires better understanding of the flow features, through and above the perforated tiles. Different tiles with circular pores in a staggered arrangement and with the same thickness are considered. Tile sheet porosities of 23% and 40%, air flow rates of 0.56 m3/s (1177 CFM) and 0.83 m3/s (1766 CFM), and pore sizes of 3.18 mm (1/8 in.) and 6.35 mm (1/4 in.) are investigated. Tiles with 38.1 mm (1.5 in.) region blocked along the edges is compared to the base case with 12.7 mm (0.5 in.) blocked edges. Width reduced to 0.46 m (1.5 ft) from standard width of 0.61 m (2 ft) is also examined. Reduced tile width is used to simulate 0.91 m (3 ft) cold aisle instead of standard 1.22 m (4 ft) cold aisle, with potential to save floor space. A case where the rack is recessed by 76.2 mm (3 in.) from the tile edge is also included in the investigation, as there is a possibility of having racks nonadjacent to the tile edges. Particle image velocimetry (PIV) technique is used to characterize the flow field emerging from a perforated tile and entering the adjacent rack. Experiments suggest that lower tile porosity significantly increases cold air bypass from the top, possibly due to higher air jet momentum above the tile, as compared to a tile with higher porosity. For the air flow rates investigated here, the flow field was nearly identical and influence of flow rate was nondistinguishable. The influence of pore size was non-negligible, even when the porosity and flow rate for the two cases were same. Larger blockage of the tile edges resulted in higher cold air bypass from the top. Reduction in the tile width showed improved air delivery to the rack with considerably reduced cold air bypass. Recessing the rack did not affect the flow field significantly.

scholarly journals Maximizing the performance of pump inducers using CFD-based multi-objective optimization

2021 ◽  
Vol 65 (1) ◽  
Author(s):  
Trupen Parikh ◽  
Michael Mansour ◽  
Dominique Thévenin
Keyword(s):  
Flow Rate ◽  
Tip Clearance ◽  
Design Parameters ◽  
Multi Objective Optimization ◽  
Sweep Angle ◽  
Flow Rates ◽  
Blade Length ◽  
Multi Objective ◽  
Blade Thickness ◽  
Wide Range

AbstractPump inducers are usually employed within a limited flow rate range since the performance is known to drop out significantly far from their design point. Therefore, finding an optimal geometry that ensures efficient operation for a relatively wide range of flow rates is challenging. The present study tackles this problem using multi-objective optimization to identify optimal inducer configurations, delivering high performance for a wide flow range. 3D RANS single-phase turbulent simulations were performed using the $$k-\omega$$ k - ω turbulence model. The optimization was done by employing the Non-dominated Sorting Genetic Algorithm (NSGA-II) coupled with computational fluid dynamics (CFD). An established in-house flow optimization library (OPAL++) was used to automatically control the numerical simulations. The objective is to optimize the inducer geometrical parameters to simultaneously maximize the efficiency and pressure head curves, considering different flow rates, i.e., 80% (part-load), 100% (nominal), and 150% (overload) of the optimal flow rate for the considered pump. The optimization involves 8 most relevant design parameters, i.e., the axial blade length, blade sweep angle, blade pitch, hub taper angle, tip clearance gap, blade thickness at the hub, blade thickness at the tip, and the number of blades. A total of 5178 simulations over 37 generations have been needed to get a Pareto front containing 5 optimal configurations. This article discusses quantitatively the influence of each geometrical parameter on flow behavior and inducer performance. The results reveal in general that blade length, blade sweep angle, tip clearance gap, and blade thickness should be kept low for the considered application; inducers with high hub taper angles and 3 blades lead to optimal performance.

Effect on Inlet Vent Porosity on Fan Characteristic Performance for Electronics Cooling

2009 ◽  
Author(s):  
Takashi Fukue ◽  
Katsuhiro Koizumi ◽  
Masaru Ishizuka ◽  
Shinji Nakagawa
Keyword(s):  
Flow Rate ◽  
Perforated Plate ◽  
Electronics Cooling ◽  
Maximum Flow ◽  
Flow Area ◽  
Flow Rates ◽  
Fan Performance ◽  
Performance Metric ◽  
Cooling Fans ◽  
The Relationship

Critical fan performance metric such as characteristic output curves and maximum flow rates are affected by various environmental conditions where cooling fans are installed. This paper describes the relationship between the fan performance and configuration factors such as the flow inlet porosity of electronic enclosure, the flow obstacles which imitate high-density packages and narrow flow area configurations. We installed a test enclosure in front of a test fan and measured P-Q curves of the test fan, which were operated in the enclosure. The experiments, it was observed that the pressure difference was increased in the enclosure by the effects of a wall. We installed a perforated plate in front of the fan as an obstacle and investigated how this changed the P-Q curve. In general, addition of the perforated plate in front of the fan decreased the characteristic output of the fan. On the other hand, the flow rate by the fan supply was decreased by the existence of the narrow inlet or obstacles. When an opening area in front of a fan became smaller than double of the fan flow area, the flow rate was significantly decreased. In addition, it was observed that the maximum flow rate depended on the opening area ratio. Finally, a model for predicting flow rates decreases by the enclosure inlet and obstacles was proposed.

scholarly journals Pressure Fluctuation on Casing Wall of Isolated Axial Compressor Rotors at Low Flow Rate

1992 ◽  
Author(s):  
Masahiro Inoue ◽  
Motoo Kurdumaru ◽  
Youichi Anoo
Keyword(s):  
Flow Rate ◽  
Pressure Fluctuation ◽  
Pressure Fluctuations ◽  
Axial Compressor ◽  
Axial Flow ◽  
Tip Clearance ◽  
Low Flow ◽  
Flow Rates ◽  
Flow Compressor ◽  
Low Flow Rate

The pressure fluctuations on the casing wall of two axial flow compressor rotors with various tip clearances have been analyzed by the use of two kinds of correlation functions. Behavior of the pressure fluctuation varies depending on tip clearance and blade solidity. In the case of small tip clearance, the nature of disturbances becomes random as the flow rate is reduced to a stall condition. For moderate tip clearance, coherent-structured disturbances appear intermittently at low flow rate. They appear more frequently as the solidity is increased and the flow rate becomes lower. For large tip clearance, the coherent structured disturbances exist even at considerably higher flow rates. Corresponding to these features there are peculiar patterns in the correlation designated as “phase-locked correlation function”.

Numerical Model for the Unsteady Flow Features of a Squirrel Cage Fan

2009 ◽  
Author(s):  
Rafael Ballesteros-Tajadura ◽  
Francisco Israel Guerras Colo´n ◽  
Sandra Velarde-Sua´rez ◽  
Jesu´s Manuel Ferna´ndez Oro ◽  
Katia Mari´a Argu¨elles Di´az ◽  
...  
Keyword(s):  
Flow Field ◽  
Unsteady Flow ◽  
Flow Rate ◽  
Flow Distribution ◽  
Experimental Tests ◽  
Centrifugal Fan ◽  
Flow Rates ◽  
Squirrel Cage ◽  
Flow Features ◽  
Separation Zones

This paper shows a numerical research on the unsteady flow field inside a squirrel cage fan. The studied features are both the instantaneous flow fields and the average fluid flow associated to the blade passage frequency. The squirrel cage fan studied is a small centrifugal fan with a twin impeller configuration, each with 23 forward curved blades. The blades chord is 0.013 m and each impeller has a diameter of 0.08 m and a width of 0.094 m. The impellers operate inside an external spiral casing with a rectangular exit, followed by the outlet duct. A first series of experimental tests were performed in order to characterize the unit. The performance curves (head, power and efficiency versus flow rate) were measured. These tests show a nominal flow rate at around 0.098 m3/s and a specific speed ωs = 1.9. From there on, three different flow rates were considered to study different flow behaviours in the impeller. In parallel with the mentioned experimental study, the unsteady 3D flow field inside the fan equipped with the same impeller was modelled for the referred flow rates, by means of the commercial CFD code FLUENT. To facilitate the modification of any geometrical feature, the mesh of the modelled fan was divided in several regions: inlet duct, impeller, volute and diffuser with outlet duct. The main goal of the paper is to show the numerical results obtained on the absolute and relative frames. Three main flow features will be analysed: the inlet flow distribution, the blade to blade field and the impeller exit flow. At the fan inlet, special care will be taken to detect possible recirculation or separation zones. On the other hand, and for each studied flow rate, the distribution of outlet flow field is also analysed. Conclusions on flow uniformity are drawn.

Sign in / Sign up

Export Citation Format

Share Document