CFD Analysis of the Influence of Centrifugal Separator Geometry Modification on the Pulverized Coal Distribution at the Burners

This paper presents the results of 3D numerical flow simulation in the ventilation mill (VM) and air mixture channel (AMC) of Kostolac B power plant, where a centrifugal separator with adjustable blade angle is used. Numerical simulations of multiphase flow were performed using the Euler-Euler and the Euler-Lagrange approach of the ANSYS FLUENT software package. The geometry of the numerical model was almost identical to the VM and AMC of Kostolac B, except for the smallest details. An unstructured tetrahedral grid, consisted of almost three million cells, was generated. The main contribution of this paper is the original analysis of the influence of centrifugal separator (CFS) geometry modification on the coal powder distribution at the horizontal burners. The modification of the blade angle, blade shape, and vertical position of the separator and its effect on the coal powder distribution at the burners were analyzed and are published for the first time. Results of the numerical simulations were compared with the measurements and can be used in modifying the separator geometry and position to obtain optimal distribution of the pulverized coal at the burners. Application of these results, obtained by numerical methods, ensures significant savings in time and money, in the process of finding the optimal geometry of CFS

Ispitivanja brzih vlakova u podzvučnom zračnom tunelu

U ovom su radu prikazani rezultati mjerenja raspodjele aerodinamičkih tlakova nastalih pri kretanju vlaka velikih brzina, s ciljem određivanja efekata lokalnih tlakova, koji izazivaju dodatna opterećenja oplate vlaka. Ovaj rad prikazuje rezultate eksperimentalnog istraživanja modela vlaka u zračnom tunelu. Ispitivanje je izvršeno u dvije faze. Prva faza je obuhvatila mjerenje raspodjele tlaka na modelu vlaka. Druga faza obuhvaća mjerenje raspodjele tlaka oko modela vlaka pomoću češlja s 10 sondi. Rezultati eksperimenta uspoređeni su s rezultatima raspodjele tlaka dobivenih numeričkom simulacijom

Ispitivanja brzih vlakova u podzvučnom zračnom tunelu

U ovom su radu prikazani rezultati mjerenja raspodjele aerodinamičkih tlakova nastalih pri kretanju vlaka velikih brzina, s ciljem određivanja efekata lokalnih tlakova, koji izazivaju dodatna opterećenja oplate vlaka. Ovaj rad prikazuje rezultate eksperimentalnog istraživanja modela vlaka u zračnom tunelu. Ispitivanje je izvršeno u dvije faze. Prva faza je obuhvatila mjerenje raspodjele tlaka na modelu vlaka. Druga faza obuhvaća mjerenje raspodjele tlaka oko modela vlaka pomoću češlja s 10 sondi. Rezultati eksperimenta uspoređeni su s rezultatima raspodjele tlaka dobivenih numeričkom simulacijom

Hydro Turbine in a Venturi Tube

U radu su prikazani rezultati istraživanja hidroturbine u Venturijevoj cijevi za zadani broj okretaja i zadanom brzinom vode na ulazu u cijev. Rezultati su dobiveni komercijalnim softverom za numeričku dinamiku fluida. Ispitivanje je obuhvatilo usporedbu snage koju daju jedna i dvije suprotno smjerno rotirajuće hidroturbine u Venturijevoj cijevi. Numeričke simulacije za dvije turbine koje se okreću u suprotnim smjerovima s jednakim kutnim brzinama pokazale su da se javlja znatan pad snage na prednjoj turbini, dok je ukupna snaga nešto veća nego za jednu turbinu.This paper presents results of a research hydro turbine in a Venturi tube for given revolutions per minute and velocity of water at the entry of the tube. The results were obtained with commercial software for numerical fluid dynamics. The research was included comparison of power obtained with one and two contra-rotating hydro turbine in a Venturi tube. The numerical simulations, for two turbines rotating in opposite directions with equal angular velocities, showed that a considerable power drop occurred, whereas the total power is somewhat larger than for the one turbine

CFD Analysis of the Influence of Centrifugal Separator Geometry Modification on the Pulverized Coal Distribution at the Burners

This paper presents the results of 3D numerical flow simulation in the ventilation mill (VM) and air mixture channel (AMC) of Kostolac B power plant, where a centrifugal separator with adjustable blade angle is used. Numerical simulations of multiphase flow were performed using the Euler-Euler and the Euler-Lagrange approach of the ANSYS FLUENT software package. The geometry of the numerical model was almost identical to the VM and AMC of Kostolac B, except for the smallest details. An unstructured tetrahedral grid, consisted of almost three million cells, was generated. The main contribution of this paper is the original analysis of the influence of centrifugal separator (CFS) geometry modification on the coal powder distribution at the horizontal burners. The modification of the blade angle, blade shape, and vertical position of the separator and its effect on the coal powder distribution at the burners were analyzed and are published for the first time. Results of the numerical simulations were compared with the measurements and can be used in modifying the separator geometry and position to obtain optimal distribution of the pulverized coal at the burners. Application of these results, obtained by numerical methods, ensures significant savings in time and money, in the process of finding the optimal geometry of CFS

Defining of necessary number of employees in airline by using artificial intelligence tools

In modern business, uncertainty and risks are increasing, and the available time is not enough to make the right decisions. The consequence of such a dynamic environment is the creation of flexible organizations and efficient managers who are ready to quickly respond to market demands using modern technologies. In this paper the model for preliminary estimation of number of employees in airline by using of artificial intelligence tools. It is assumed that the tools of artificial intelligence can be applied even for complex tasks such as defining the number of employees in the airline. The results obtained can be used for planning the number of employees, ie. planning the necessary financial investments in human resources, and may also be useful for a preliminary analysis of the airlines that choose to do restructuring or plan to increase/decrease the number of operations. Results were compared with those obtained by regression analysis

Determination of braking force on the aerodynamic brake by numerical simulations

Ovaj rad predstavlja rezultate istraživanja uticaja aerodinamičkih kočnica, postavljenih na krov brzog voza, na strujno polje i ukupnu silu kočenja. Voz se sastoji od dve lokomotive, na svakom kraju, i četiri putnička vagona., ukupne dužine 121m. Aerodinamičke kočnice stvaraju silu kočenja povećavanjem aerodinamičkog otpora pomoću izvučenih panela na krovu voza. Simulacije strujanja su urađene softverom Fluent 12.1, za voz bez, sa jednom, dve i tri aerodinamičke kočnice, pri brzinama od 30, 50 i 70m/s. Sila otpora po jedinici površine panela je određena kao funkcija brzine voza i položaja aerodinamičke kočnice. Doprinosi ukupnoj sili kočenja svake od kočnica, određeni simulacijama su: za prvu 24%, za drugu 15% i za treću 14.8% i pokazali su , zajedno sa raspodelama pritisaka po panelima, dobro slaganje sa proračunima aerodinamičkog otpora za ravnu ploču upravno postavljenu prema strujanju.This work presents the research results of the aerodynamic brake influence, mounted on the high-speed train's roof, on the flow field and overall braking force. The train consists of two locomotives at each end and four passenger cars between, with 121m of overall length. Aerodynamic brakes are designed to generate braking force by means of increasing the aerodynamic drag by opened panels over the train. Flow simulations were made by Fluent 12.1 software, for the train without and with one, two and three aerodynamic brakes, and velocities of 30, 50 and 70m/s. Drag force per unit panel area was determined as a function of train's velocity and the brake position. Contributions to train's gross braking force of each brake, obtained by simulations were: for first 24%, for second 15% and third 14.8%, and showed, also with panels' pressure distribution, good correlation with the aerodynamic drag calculations for flat plate orthogonally disposed to flow stream

Determination of braking force on the aerodynamic brake by numerical simulations

Ovaj rad predstavlja rezultate istraživanja uticaja aerodinamičkih kočnica, postavljenih na krov brzog voza, na strujno polje i ukupnu silu kočenja. Voz se sastoji od dve lokomotive, na svakom kraju, i četiri putnička vagona., ukupne dužine 121m. Aerodinamičke kočnice stvaraju silu kočenja povećavanjem aerodinamičkog otpora pomoću izvučenih panela na krovu voza. Simulacije strujanja su urađene softverom Fluent 12.1, za voz bez, sa jednom, dve i tri aerodinamičke kočnice, pri brzinama od 30, 50 i 70m/s. Sila otpora po jedinici površine panela je određena kao funkcija brzine voza i položaja aerodinamičke kočnice. Doprinosi ukupnoj sili kočenja svake od kočnica, određeni simulacijama su: za prvu 24%, za drugu 15% i za treću 14.8% i pokazali su , zajedno sa raspodelama pritisaka po panelima, dobro slaganje sa proračunima aerodinamičkog otpora za ravnu ploču upravno postavljenu prema strujanju.This work presents the research results of the aerodynamic brake influence, mounted on the high-speed train's roof, on the flow field and overall braking force. The train consists of two locomotives at each end and four passenger cars between, with 121m of overall length. Aerodynamic brakes are designed to generate braking force by means of increasing the aerodynamic drag by opened panels over the train. Flow simulations were made by Fluent 12.1 software, for the train without and with one, two and three aerodynamic brakes, and velocities of 30, 50 and 70m/s. Drag force per unit panel area was determined as a function of train's velocity and the brake position. Contributions to train's gross braking force of each brake, obtained by simulations were: for first 24%, for second 15% and third 14.8%, and showed, also with panels' pressure distribution, good correlation with the aerodynamic drag calculations for flat plate orthogonally disposed to flow stream

The Influence of Air Traffic on Climate Change

Growth in the aviation sector has brought great benefits, but also an increased impact on the environment. Air transport has a significant impact on climate change, even to the extent that global climate change dictates the limitations of its development and the areas in which aviation needs to adapt its land and flight operations. The main pollutants emitted by aircraft are carbon dioxide (CO2), nitrogen oxides (NOx), sulfur oxides (SOx), non-flammable hydrocarbons (HC), carbon monoxide (CO), particulate matter (PM) and soot. Some of the key ways to mitigate the environmental impact of aviation are the development of new aircraft technologies and the inclusion of advanced design, the development of alternative fuels for use in aviation, the collection of airport taxes related to environmental protection, which encourages airlines to use quieter aircraft with lower emissions. The introduction of operational measures, in the form of changes in operating procedures, have proven to be very effective in reducing emissions. In addition to minimizing the amount of fuel for service and performance of each flight, in addition to the environmental benefits, they also reduce fuel costs. These changes do not require the introduction of new equipment and expensive technologies, but are based on different ways of operating aircrafts that are already in use

Determination of air and hydrofoil pressure coefficient by laser doppler anemometry

Some results of experiments performed in water cavitation tunnel are presented. Pressure coefficient (Cp) was experimentally determined by Laser Doppler Anemometry (LDA) measurements. Two models were tested: model of airplane G4 (Super Galeb) and hydrofoil of high speed axial pump. These models are not prepared for conventional pressure measurements, so that LDA is applied for Cp determination. Numerical results were obtained using a code for average Navier-Stokes equations solutions. Comparisons between computational and experimental results prove the effectiveness of the LDA. The advantages and disadvantages of LDA application are discussed. Flow visualization was made by air bubbles