Increasing the Passive Scalar Mixing Quality of Jets in Crossflow With Fluidics Actuators

2011 ◽  
Vol 134 (2) ◽  
Author(s):  
Arnaud Lacarelle ◽  
Christian O. Paschereit
Keyword(s):  
High Speed ◽  
Passive Scalar ◽  
Mixing Efficiency ◽  
Scalar Mixing ◽  
Jet In Crossflow ◽  
Mixing Quality ◽  
Single Jet ◽  
Pulsating Jets ◽  
The One

Jets in crossflow are widely used in the industry for homogenization or cooling tasks. Recently, pulsating jets have been investigated as a mean to increase the scalar mixing efficiency of such configurations, whether for a single jet or for an array of jets. To avoid the disadvantages of mechanically actuated flows (costs, maintenance), a new injector based on a fluidics oscillator has been designed. Four injectors have been implemented in a generical jet in crossflow configuration and the mixing efficiency of the setup was compared with the one of the same setup equiped with standard non oscillating jets. With help of high-speed concentration measurement technique, the scalar mixing quality of both setups was measured at three positions downstream of the injection plane. In all the cases tested, the fluidics injectors present a better temporal homogenization, characterized by the Danckwerts unmixedness criterion, than the standard jets. For a defined mixing quality, a decrease of the mixing length by approximately 50% can be achieved with the fluidics injectors. Furthermore, the new injectors exhibit a mixing quality which is less sensitive to variations of the jet to crossflow momentum. The flapping motion of the fluidics injectors induces a wider azimuthal spreading of the fluidics jets immediately downstream of the injection location. This increases the macro- and micro-mixing phenomea which lead then to the high gains in mixing quality. It is thus demonstrated that fluidics oscillators present a strong potential to improve the passive scalar homogenization of jet in crossflow configurations.

Increasing the Passive Scalar Mixing Quality of Jets in Crossflow With Fluidics Actuators

2011 ◽  
Author(s):  
Arnaud Lacarelle ◽  
Christian O. Paschereit
Keyword(s):  
High Speed ◽  
Passive Scalar ◽  
Mixing Efficiency ◽  
Scalar Mixing ◽  
Jet In Crossflow ◽  
Mixing Quality ◽  
Single Jet ◽  
Pulsating Jets ◽  
The One

Jets in crossflow are widely used in the industry for homogenization or cooling tasks. Recently, pulsating jets have been investigated as a mean to increase the scalar mixing efficiency of such configurations, whether for a single jet or for an array of jets. To avoid the disadvantages of mechanically actuated flows (costs, maintenance), a new injector based on a fluidics oscillator has been designed. Four injectors have been implemented in a generical jet in crossflow configuration and the mixing efficiency of the setup was compared with the one of the same setup equiped with standard non oscillating jets. With help of high-speed concentration measurement technique, the scalar mixing quality of both setups was measured at three positions downstream of the injection plane. In all the cases tested, the fluidics injectors present a better temporal homogenization, characterized with the Danckwerts unmixedness criterion, than the standard jets. For a defined mixing quality, a decrease of the mixing length by approximately 50% can be achieved with the fluidics injectors. Furthermore, the new injectors exhibit a mixing quality which is less sensitive to variations of the jet to crossflow momentum. The flapping motion of the fluidics injectors induces a wider azimuthal spreading of the fluidics jets immediately downstream of the injection location. This increases the macro- and micromixing phenomea which lead then to the high gains in mixing quality. It is thus demonstrated that fluidics oscillators present a strong potential to improve the passive scalar homogenization of jet in crossflow configurations.

scholarly journals Passive Scalar Mixing Downstream of a Synthetic Jet in Crossflow

2008 ◽  
pp. 103-109
Author(s):  
Glen Mitchell ◽  
Emmanuel Benard ◽  
Václav Uruba ◽  
Richard Cooper
Keyword(s):  
Passive Scalar ◽  
Synthetic Jet ◽  
Scalar Mixing ◽  
Jet In Crossflow

scholarly journals Technical parameters of high speed lines as the determinant for selection of rolling stock

2018 ◽  
Vol 180 ◽  
pp. 06007
Author(s):  
Jan Raczyński
Keyword(s):  
High Speed ◽  
Point Of View ◽  
Rolling Stock ◽  
High Speed Rail ◽  
Technical Parameters ◽  
Rail Vehicle ◽  
Railway Infrastructure ◽  
The One ◽  
Selection Of

Choosing a high-speed rail vehicle depends on many factors. On the one hand, there are requirements for ensuring the quality of service for passengers, on the other hand, there are constraints resulting from the parameters of available infrastructure. Also a relation of the benefit and financial costs associated with the purchase and the operation of rolling stock is essential. Technical characteristics of vehicles selected for operating a particular system is a compromise between the three groups of requirements. In this article technical parameters of railway infrastructure and rolling stock are classified and then analysed from the TSI requirements point of view.

Shearing Edging Investigation in High-Speed Blanking Process Applying Precision Progressive Die

2013 ◽  
Vol 668 ◽  
pp. 460-464
Author(s):  
Zhen Yuan Huang ◽  
Feng Ruan
Keyword(s):  
Surface Roughness ◽  
High Speed ◽  
Orthogonal Experiment ◽  
Thin Sheet ◽  
Progressive Die ◽  
Small Complex ◽  
Thin Sheet Metal ◽  
The One ◽  
Blanking Process

The high-speed blanking process applying precision progressive die represents the one of the highest level of today’s stamping technology, mainly is used for the production of the ultra-thin, small, complex electronic components. An orthogonal experiment scheme with three factors (including blanking clearance, surface roughness of the die, stamping speed) was established in this paper based on the actual production. The high-speed blanking process experiment applying precision progressive die was carried out base on this scheme. The quality of the shearing edging of blanking parts was used to evaluate the different influence degree of three factors. The result showed that the surface roughness of the die affected the quality of the shearing edging more than that of the other two. The higher the die surface accuracy, the better the quality of the shearing edging. The result also showed that the high speed can reduce the quantity of the burr of the blanking of the ultra-thin sheet metal.

Compressibility effects in a turbulent annular mixing layer. Part 2. Mixing of a passive scalar

2000 ◽  
Vol 421 ◽  
pp. 269-292 ◽  
Author(s):  
JONATHAN B. FREUND ◽  
PARVIZ MOIN ◽  
SANJIVA K. LELE
Keyword(s):  
Mach Number ◽  
High Speed ◽  
Mixture Fraction ◽  
Mixing Layer ◽  
Passive Scalar ◽  
Momentum Equation ◽  
Mixing Efficiency ◽  
Scalar Flux ◽  
Mach Numbers ◽  
Highly Correlated

The mixing of fuel and oxidizer in a mixing layer between high-speed streams is important in many applications, especially air-breathing propulsion systems. The details of this process in a turbulent annular mixing layer are studied with direct numerical simulation. Convective Mach numbers of the simulations range from Mc = 0.1 to Mc = 1.8. Visualizations of the scalar field show that at low Mach numbers large intrusions of nearly pure ambient or core fluid span the mixing region, whereas at higher Mach numbers these intrusions are suppressed. Increasing the Mach number is found to change the mixture fraction probability density function from non-marching to marching and the mixing efficiency from 0.5 at Mc = 0.1 to 0.67 at Mc = 1.5. Scalar concentration fluctuations and the axial velocity fluctuations become highly correlated as the Mach number increases and a suppressed role of pressure in the axial momentum equation is found to be responsible for this. Anisotropy of scalar flux increases with Mc, and is explained via the suppression of transverse turbulence lengthscale.

Computational Modeling of Turbulent Mixing of a Transverse Jet

2010 ◽  
Vol 133 (2) ◽  
Author(s):  
Elizaveta M. Ivanova ◽  
Berthold E. Noll ◽  
Manfred Aigner
Keyword(s):  
Turbulent Mixing ◽  
Passive Scalar ◽  
Navier Stokes ◽  
Test Case ◽  
Scalar Mixing ◽  
Reynolds Stresses ◽  
Mixing Processes ◽  
Jet In Crossflow ◽  
Turbulent Schmidt Number ◽  
Reynolds Averaged Navier Stokes

This paper presents numerical simulations of turbulent mixing of a jet in crossflow. The test case is chosen to resemble scalar mixing processes in the premixing zones of gas turbine combustion chambers. Steady and unsteady simulations employing three different computational approaches are presented: steady Reynolds-averaged Navier–Stokes, unsteady Reynolds-averaged Navier–Stokes, and scale-adaptive simulations. Presented results comprise the (time-averaged) profiles of flow velocities, turbulent kinetic energy of the flow, Reynolds stresses, passive scalar distribution, turbulent scalar fluxes, and the turbulent variance of the passive scalar. All presented results are directly validated against experimental data. Additionally, two parameter studies are presented. Both studies are related to the accuracy of the turbulent scalar mixing predictions for all used simulation methods. In the first study, the dependence of the scalar mixing predictions on the value of the turbulent Schmidt number is considered. In the second study, the dependence of the predicted turbulent scalar variance on the used modeling approach is analyzed.

scholarly journals Speed tourism: The German Autobahn as a tourist destination and location of “unruly rules”

2020 ◽  
Vol 20 (3) ◽  
pp. 298-313
Author(s):  
Matthias Gross
Keyword(s):  
High Speed ◽  
The Other ◽  
Speed Limit ◽  
Tourist Destination ◽  
Driving Experience ◽  
Native Culture ◽  
The Road ◽  
The One ◽  
The Ideal

The German Autobahn has inspired many people’s imagination with its lack of a general speed limit, the quality of its road surface as well as its allegedly well-behaved drivers. One of the consequences of this positive reputation has been the emergence of a phenomenon I would like to call “speed tourism.” In this article, I treat speed tourism as a special form of tourism that involves viewing the driving experience as an opportunity for either testing the capacity of one’s own car or driving it at high speed as a way of experiencing the native culture at firsthand. I explore speed tourism as an alternative way of getting to know the real Germany as a tourist. Based on an analysis of several of its peculiarities, I argue that the Autobahn can be understood as a location where tourists can mix with “locals” while keeping a distance from them, since the interaction is restricted to learning and obeying the country’s rules of the road. The Autobahn then becomes a time-bound “dream location” created by the ideal of limitless driving freedom on the one hand and the paradoxical requirement of unruliness in relation to strict rules on the other; together, these are believed to offer an “authentic” driving experience according to local cultural customs.

Evaluation of the Properties of Humus Liquid of Earthworm Eisenia Foetida Obtained from Different Rachis

2017 ◽  
Vol 3 (02) ◽  
Author(s):  
Ramiro Remigio Gaibor Fernández ◽  
Abraham Adalberto Bayas Zamora ◽  
Galo Israel Muñoz Sánchez ◽  
Cristhian Adrián Rivas Santacruz
Keyword(s):  
Plant Growth ◽  
Fulvic Acids ◽  
Cattle Manure ◽  
Eisenia Foetida ◽  
Humic And Fulvic Acids ◽  
Livestock Manure ◽  
A Value ◽  
The One ◽  
Liquid Slurry

The objective of the present investigation was to evaluate the physical characteristics of the vermicompost and the quality of the purine of the red Californian (Eisenia foetida) using different substrates of feed for these worms. For this purpose, nine treatments were studied: 75% African palm rachis + 25% cattle manure, 50% African palm rachis + 50% cattle manure, 25% African palm rachis + 75% livestock manure, 50% manure of cattle, 50% of manure of cattle, 25% of manure of cattle, 50% of manure of cattle, 50% of manure of cattle, 50% of rach of coconut + 50% of manure of Livestock, 25% coccus rachis + 75% livestock manure. The substrate made up of 50% of rachis of coconut and 50% of livestock manure can be used in nurseries or nurseries for being the one that registered a value of pH 7.3 plus the closest to the neutral compared to the others, besides this (75% of oil palm rachis and 25% of cattle manure) showed a higher content of humic and fulvic acids (0.87 and 0.45 p / p, respectively), compounds that are important for agriculture by stimulating plant growth, in addition to this reflection 0.06% sulfur content, 4.0 ppm boron, 7.0 ppm copper, 47.5 ppm iron, 6.0 ppm manganese, with a presence of microorganisms of the species Trichoderma, Penicillium, Cladosporium sp. in amounts of 1.91x105 UFC / ml, however in this substrate was obtained between 13.3 and 43.5% less liquid slurry in Comparison with other treatments.

Contribution to a Magnetite Consumption in the Karviná Mine's Preparation Plant of the Lazy Plant / Příspěvek Ke Spotřebě Magnetitu Na Úpravně Dolu Karviná, Závodu Lazy

2012 ◽  
Vol 58 (2) ◽  
pp. 1-6
Author(s):  
Radim Pavlík ◽  
Vlastimil Řepka
Keyword(s):  
The One ◽  
Preparation Plant

Abstract In its introduction, this contribution deals with the usage of magnetite during the process of coal separation in the Karviná Mine's preparation plant of the Lazy Plant. Next it deals with the evaluation of quality of magnetite used in the preparation plant, losses of magnetite adhering to the products leaving the preparation plant, the recovery of a diluted suspension with focus on the efficiency of magnetite separation of the diluted suspension and the comparison of the magnetite consumption with the one in the ČSM preparation plant. In conclusions, the article presents options leading to the reduction of the magnetite consumption in the Karviná Mine's preparation plant of the Lazy plant. For comparison, the data of the ČSM Mine is stated here.

The concept of motivation for effective credit risk management

2020 ◽  
Vol 26 (11) ◽  
pp. 2567-2593
Author(s):  
M.V. Pomazanov
Keyword(s):  
Risk Management ◽  
Economic Modeling ◽  
Type I ◽  
Credit Risk Management ◽  
Curve Modeling ◽  
Business Functions ◽  
The Common ◽  
Lending Decisions ◽  
The One

Subject. The study addresses the improvement of risk management efficiency and the quality of lending decisions made by banks. Objectives. The aim is to present the bank management with a fair algorithm for risk management motivation on the one hand, and the credit management (business) on the other hand. Within the framework of the common goal to maximize risk-adjusted income from loans, this algorithm will provide guidelines for ‘risk management’ and ‘business’ functions on how to improve individual and overall efficiency. Methods. The study employs the discriminant analysis, type I and II errors, Lorentz curve modeling, statistical analysis, economic modeling. Results. The paper offers a mechanism for assessing the quality of risk management decisions as opposed to (or in support of) decisions of the lending business when approving transactions. The mechanism rests on the approach of stating type I and II errors and the corresponding classical metric of the Gini coefficient. On the ‘business’ side, the mechanism monitors the improvement or deterioration of the indicator of changes in losses in comparison with the market average. Conclusions. The study substantiates the stimulating ‘rules of the game’ between the ‘business’ and ‘risk management’ to improve the efficiency of the entire business, to optimize interactions within the framework of internal competition. It presents mathematical tools to calculate corresponding indicators of the efficiency of internally competing entities.

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