A Preliminary Numerical CFD Analysis of Transonic Compressor Rotors When Subjected to Inlet Swirl Distortion

2011 ◽  
Author(s):  
Javier Castaneda ◽  
Ahad Mehdi ◽  
Domenico di Cugno ◽  
Vassilios Pachidis
Keyword(s):  
Vortex Core ◽  
High Performance ◽  
Preliminary Investigation ◽  
Angle Distribution ◽  
Transonic Compressor ◽  
Aspect Ratios ◽  
Swirl Angle ◽  
Inlet Swirl ◽  
System Life ◽  
The Impact

A preliminary investigation of a CFD capability to assess the impact of inlet swirl distortion on transonic compressor rotors has been carried out. In the late 1960s with the advent of turbo fan engines, industry and government agencies became increasingly aware of the inlet total pressure distortion problem. Since then, the inlet/engine compatibility assessment has become a significant issue within the propulsion system life cycle. Nowadays the development of high-performance military aircraft and UAV with maneuvers before unthinkable, entail considerable levels of inlet flow angularity. The importance of developing a rigorous methodology to understand the effect of inlet swirl distortion on turbomachinery has also become one of the major concerns of present day. NASA rotor 67 and 37 were selected for this investigation having different hub to tip radius and aspect ratios. The steady state CFD simulations were carried out on two types of inlet swirl distortion scenarios: Bulk swirl (both Rotor 37 and 67) and Ground vortex (only Rotor 67). A parametric study to define the swirl angle distribution for ground vortex cases was also accomplished. The non-dimensional ground clearance, wind conditions and core vortex location at the inlet/engine AIP were the parameters taken into account. The study carried out suggests that ground vortex core location and vortex rotational direction greatly affect the shift of the speedline. This emphasizes the importance of identifying the radial location of ingested vortex core at the AIP as the turbomachinery response differs depending on it. Similar shift in speedlines for the bulk swirl cases were also observed.

Analysis of the Vortex Series Around Tabs in the Bent Marine Exhaust Ejector

2017 ◽  
Author(s):  
Aoyu Ren ◽  
Hai’ou Sun ◽  
Zhongyi Wang ◽  
Xudong Chen
Keyword(s):  
High Performance ◽  
Streamwise Vortex ◽  
Streamwise Vorticity ◽  
Gas Temperature ◽  
Cross Sectional ◽  
Swirl Angle ◽  
Calculation Results ◽  
Inlet Swirl ◽  
Hybrid Grid ◽  
Tube Exit

In order to facilitate the application of special structural ejectors, which improve the ability of pumping the secondary flow without additional power consumption, reducing the flue gas temperature at the export and enhancing the ship viability under the threat of infrared guided weapons, this paper regardes the 90 ° bend tabs ejector as the research object according to the actual situation of our country’s ships, focuses on the inner effect of the existence of tabs on the flow field in the bent channel, and mainly revealed the transformation of the vortex around the tabs, for providing an explanation to a certain extent about how the tabs affect the macro performance of ejector. With ANSYS software, ring 8 equilateral triangles tabs were designed with 120 ° wall surface mounting angle. With adjusting the blocking ratio of the main outlet area based on the similar zoom, setting inlet swirl angle, and building a hybrid grid to compute, the vortex structure distribution and the development around tabs were observed. The maximum vorticity of vortex at different distances in the mixing tube to the mix tube exit had been calculated to reflect the change of vortex intensity. The final results show that although the streamwise vortices are still located in an axial symmetrical distribution, the swirl angle leads to an uneven distribution of the flow on both sides of a single tab. The inlet swirl angle can make the symmetry of the steamwise vortex vaguer, but the effect of the convection to the vortex is enhanced. The blocking area ratio of the nozzle cross-sectional surface has a large effect on the vorticity of the streamwise vortex. The calculation results show that the larger the blocking area is, the greater the vorticity of streamwise vortex is, which also shows that when the tab shape is fixed, the tab surface area will increase the streamwise vorticity. Through the above research, the shape and the change of the streamwise vortex generated by the tabs in the bent ejector are clearly demonstrated, which can be a reference for the design of high performance bent ejector.

On stationary and travelling vortex breakdowns

1971 ◽  
Vol 45 (3) ◽  
pp. 545-559 ◽  
Author(s):  
Turgut Sarpkaya
Keyword(s):  
Turbulent Mixing ◽  
Vortex Core ◽  
Vortex Breakdown ◽  
Double Helix ◽  
Cylindrical Tube ◽  
Axial Component ◽  
Angle Distribution ◽  
Swirl Angle ◽  
Abrupt Changes ◽  
Downstream Flow

This paper describes some experiments in swirling flows in a diverging cylindrical tube in which various types of vortex breakdowns were observed.In one set of experiments, the position of the breakdown, axial component of the velocity of the vortex core, swirl angle distribution ahead of the breakdown, and the pressure distribution along the tube were determined for various flow rates and for various values of circulation imparted to the fluid (water). Basically, three types of vortex breakdown were observed, viz. mild (double helix) breakdown, spiral breakdown (followed by turbulent mixing), and axisymmetric breakdown (followed by a thicker vortex core, then a spiral breakdown, and finally by turbulent mixing). The type and the location of the stationary breakdowns were found to be dependent, for the particular vortex tube used, upon the Reynolds and circulation numbers of the flow. In a spiral breakdown, the vortex core filament maintained the same sense of rotation as the upstream fluid elements. In an axisymmetric breakdown, the bubble included an inclined vortex-ring whose axis gyrated about the axis of the tube.In a second set of experiments, the response of the abrupt structural change along the axis of flow to gradual and abrupt changes in the upstream and downstream flow conditions was examined. The axisymmetric breakdown responded in a manner analogous to the hydraulic jump in open-channel flow before if reached a new stationary position along the axis of the tube.The observations reported and the evidence presented herein revealed that the axisymmetric breakdown is a finite transition between two sequent states of flow as proposed by Benjamin (1962, 1965, 1967) on theoretical grounds.

Experimental and Numerical Investigation of the Impact of Swirl on the Performance of Industrial Gas Turbines Exhaust Diffusers

2003 ◽  
Author(s):  
V. Vassiliev ◽  
S. Irmisch ◽  
M. Claridge ◽  
D. P. Richardson
Keyword(s):  
Mach Number ◽  
Gas Turbines ◽  
Modular Design ◽  
Numerical Procedure ◽  
Angle Distribution ◽  
Flow Angle ◽  
Industrial Gas Turbines ◽  
Inlet Swirl ◽  
Inlet Conditions ◽  
The Impact

In order to investigate the effect of inlet conditions on the performance of an axial strutted annular exhaust diffuser, as used in heavy duty gas turbines, a scaled test-rig was built which allows the systematic variations of inlet conditions like inlet swirl, Mach number and turbulence level. This rig, which is of modular design, is used for the analysis of the flow-structures in typical GT-exhaust configurations and provides the performance data used in the diffuser design process. The present work shows the influence of inlet swirl and Mach number on the performance of a specific diffuser configuration. The first strut was designed for a certain flow angle distribution (so-called design conditions), and the measurements have been done for a range of inflow parameters including design and off-design conditions. The measurements allowed to reveal the impact of 3D effects on the diffuser characteristic. Comparison of measurements with correlations available from literature (annular diffuser configurations) show that the application of the latter is of limited use for the design of real GT diffusers, because standard correlations do not account for inlet swirl / struts interaction. The experimental data has been used to validate the numerical procedure developed by the authors for the analysis of axial GT exhaust diffusers. The results of computations are in reasonable agreement with measurements.

Numerical Investigation on Effect of Aspect Ratio of Axisymmetric Circumferential Groove Casing Treatment Coupled to a Transonic Axial Flow Compressor Stage

2015 ◽  
Author(s):  
Nishit J. Mehta ◽  
Dilipkumar Bhanudasji Alone ◽  
Harish S. Choksi
Keyword(s):  
Aspect Ratio ◽  
Flow Field ◽  
Flow Behavior ◽  
Geometrical Parameters ◽  
Compressor Stage ◽  
Casing Treatment ◽  
Transonic Compressor ◽  
Circumferential Groove ◽  
Aspect Ratios ◽  
The Impact

While the effects of axisymmetric casing treatment on performance of an axial compressor stage have been extensively studied numerically as well as experimentally, the major geometrical parameters which govern these effects have been identified. Studies are now focused on understanding how each of these parameters individually impacts the performance of a casing treatment. The present work aims to study the impact on performance of casing treatment geometry when aspect ratio of the grooves is varied in a circumferential groove casing treatment. The compressor geometry chosen for this study has design characteristics of a transonic compressor stage. Flow field solutions were derived for baseline model by solving steady state 3-D Reynolds-Averaged Navier-Stokes (RANS) equations for three grid densities and the grid independence was proved. The basic casing treatment geometry has 10 circumferential grooves of width 4mm and axial spacing of 2mm between each groove. The aspect ratio was varied by changing the depth of the grooves in each case. These casing treatment geometries were superimposed over the rotor domain with the grooves extending over the entire blade tip chord and flow field solutions were again obtained for various aspect ratios of grooves. These results depict improvement in the range of operation in terms of mass flow rate. Results also show that the aspect ratio of the grooves significantly influences the overall effectiveness of casing treatment on the performance of compressor stage. Improvement in overall compressor efficiency is noted with lower aspect ratio casing treatments when compared to those with higher aspect ratios, however, the range improvement is higher with higher aspect ratios. It is also observed that, after a certain depth of grooves is reached, there is no significant improvement in performance on further increasing the depth and hence the aspect ratio. Post processing results of the flow solutions are presented which confirm the trends and show that the flow behavior near rotor tip governs this effect.

Dietary Vitamin and Stability of Oral Anticoagulation: Proposal of a Diet with Constant Vitamin K1 Content

1997 ◽  
Vol 77 (03) ◽  
pp. 504-509 ◽  
Author(s):  
Sarah L Booth ◽  
Jacqueline M Charnley ◽  
James A Sadowski ◽  
Edward Saltzman ◽  
Edwin G Bovill ◽  
...  
Keyword(s):  
Dietary Intake ◽  
Vitamin K ◽  
High Performance ◽  
Case Reports ◽  
Food Composition ◽  
Dietary Guidelines ◽  
Dietary Vitamin ◽  
Vitamin K1 ◽  
The Stability ◽  
The Impact

SummaryCase reports cited in Medline or Biological Abstracts (1966-1996) were reviewed to evaluate the impact of vitamin K1 dietary intake on the stability of anticoagulant control in patients using coumarin derivatives. Reported nutrient-drug interactions cannot always be explained by the vitamin K1 content of the food items. However, metabolic data indicate that a consistent dietary intake of vitamin K is important to attain a daily equilibrium in vitamin K status. We report a diet that provides a stable intake of vitamin K1, equivalent to the current U.S. Recommended Dietary Allowance, using food composition data derived from high-performance liquid chromatography. Inconsistencies in the published literature indicate that prospective clinical studies should be undertaken to clarify the putative dietary vitamin K1-coumarin interaction. The dietary guidelines reported here may be used in such studies.

Considering the impact of intermittent discharges when modelling overflows

1998 ◽  
Vol 38 (10) ◽  
pp. 23-30
Author(s):  
Sarah Jubb ◽  
Philip Hulme ◽  
Ian Guymer ◽  
John Martin
Keyword(s):  
Water Quality ◽  
Dissolved Oxygen ◽  
Preliminary Investigation ◽  
Oxygen Demand ◽  
Sediment Oxygen Demand ◽  
Combined Sewer Overflows ◽  
River Hydraulics ◽  
Combined Sewer ◽  
The Impact ◽  
Curve Equation

This paper describes a preliminary investigation that identified factors important in the prediction of river water quality, especially regarding dissolved oxygen (DO) concentration. Intermittent discharges from combined sewer overflows (CSOs) within the sewerage, and overflows at water reclamation works (WRW) cause dynamic conditions with respect to both river hydraulics and water quality. The impact of such discharges has been investigated under both wet and dry weather flow conditions. Data collected from the River Maun, UK, has shown that an immediate, transient oxygen demand exists downstream of an outfall during storm conditions. The presence of a delayed oxygen demand has also been identified. With regard to modelling, initial investigations used a simplified channel and the Streeter-Phelps (1925) dissolved oxygen sag curve equation. Later, a model taking into account hydrodynamic, transport and dispersion processes was used. This suggested that processes other than water phase degradation of organic matter significantly affect the dissolved oxygen concentration downstream of the location of an intermittent discharge. It is proposed that the dynamic rate of reaeration and the sediment oxygen demand should be the focus of further investigation.

Alpha Tocopherol Loaded in Liposome: Preparation, Optimization, Characterization and Sperm Motility Protection

2020 ◽  
Vol 10 (3) ◽  
pp. 228-236 ◽  
Author(s):  
Lamia Taouzinet ◽  
Sofiane Fatmi ◽  
Allaeddine Khellouf ◽  
Mohamed Skiba ◽  
Mokrane Iguer-ouada
Keyword(s):  
Vitamin E ◽  
Sperm Motility ◽  
High Performance ◽  
Positive Impact ◽  
Alpha Tocopherol ◽  
Ethanol Injection ◽  
Liposome Preparation ◽  
Liposome Size ◽  
Optimum Solution ◽  
The Impact

Background: Alpha-tocopherol is a potent antioxidant involved in sperm protection particularly during cryopreservation. However, its poor solubility limits the optimal protection in aqueous solutions. Objective: The aim of this study was to enhance the solubility of α-tocopherol by the use of liposomes. Methods: The experimental approach consisted to load vitamin E in liposomes prepared by ethanol injection method and the optimization carried out by an experimental design. The optimum solution was characterized by high performance liquid chromatography and scanning electron microscope. Finely, the impact on sperm motility protection was studied by the freezing technic of bovine sperm. Results: The optimum solution was obtained when using 10.9 mg/ml of phospholipids, 1.7 mg/ml of cholesterol and 2 mg/ml of vitamin E. The liposome size was 99.86 nm, providing 78.47% of loaded efficiency. The results showed also a significant positive impact on sperm motility after hours of preservation. Conclusion: In conclusion, the current results showed the interest of liposome preparation as an alternative to enhance vitamin E solubility and to protect spermatozoa during cryopreservation.

scholarly journals Technology Entrepreneurship and the Performance of Enterprises in the Conditions of Covid-19 Pandemic: The Fuzzy Set Analysis of Waste to Energy Enterprises in Poland

Energies ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3891
Author(s):  
Piotr Kordel ◽  
Radosław Wolniak
Keyword(s):  
Fuzzy Set ◽  
High Performance ◽  
Qualitative Comparative Analysis ◽  
Flexible Structures ◽  
Implementation Strategies ◽  
Waste To Energy ◽  
Energy Industry ◽  
Technology Entrepreneurship ◽  
Research Results ◽  
The Impact

This article’s aim is to explain the impact of technology entrepreneurship phenomenon on waste management enterprise performance in the conditions of COVID-19 pandemic. The concept of technology entrepreneurship according to the configuration approach and the category of high-performance organization are the theoretical bases of empirical investigation. For the implementation of empirical research, Fuzzy set Qualitative Comparative Analysis (FsQCA) was adopted. The research sample included a group of producers of Refused Derived Fuel (RDF) as a central part of the waste to energy industry located in Poland. The research results showed that the waste to energy sector is highly immune to pandemic threats. While during COVID-19, the basic economic parameters (i.e., sales, profitability and employment) of the entire industry in Poland clearly decreased, the same parameters in the case of the waste to energy industry remained at the same level. The research results allow the formulation of two high-performance models of technology entrepreneurship in the waste to energy industry under COVID-19 conditions. The first model is based on traditional technologies and hierarchical organizational structures, and the second is using innovative technologies and flexible structures. Both technology entrepreneurship models are determined by their emergence as complementary to implementation strategies and the opportunity-oriented allocation of resources within business model portfolios.

scholarly journals Effects of Steel Fiber Percentage and Aspect Ratios on Fresh and Harden Properties of Ultra-High Performance Fiber

2021 ◽  
Vol 2 (3) ◽  
pp. 501-515
Author(s):  
Rajib Kumar Biswas ◽  
Farabi Bin Ahmed ◽  
Md. Ehsanul Haque ◽  
Afra Anam Provasha ◽  
Zahid Hasan ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Aspect Ratio ◽  
High Performance ◽  
Steel Fiber ◽  
Setting Time ◽  
Fiber Reinforced Concrete ◽  
Future Research ◽  
Manufacturing Cost ◽  
Aspect Ratios ◽  
High Performance Fiber

Steel fibers and their aspect ratios are important parameters that have significant influence on the mechanical properties of ultrahigh-performance fiber-reinforced concrete (UHPFRC). Steel fiber dosage also significantly contributes to the initial manufacturing cost of UHPFRC. This study presents a comprehensive literature review of the effects of steel fiber percentages and aspect ratios on the setting time, workability, and mechanical properties of UHPFRC. It was evident that (1) an increase in steel fiber dosage and aspect ratio negatively impacted workability, owing to the interlocking between fibers; (2) compressive strength was positively influenced by the steel fiber dosage and aspect ratio; and (3) a faster loading rate significantly improved the mechanical properties. There were also some shortcomings in the measurement method for setting time. Lastly, this research highlights current issues for future research. The findings of the study are useful for practicing engineers to understand the distinctive characteristics of UHPFRC.

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