Experimental investigations of the turbulent swirl flow in straight conical diffusers with various angles

Results of experimental investigations of the turbulent swirl flow in three straight conical diffusers with various diffuser total angles are presented in this paper. All three diffusers have the inlet diameter 0.4 m and total divergence angles 8.6 degrees, 10.5 degrees, and 12.6 degrees. The incompressible swirl flow field is generated by the axial fan impeller, and for each diffuser several regimes were achieved by changing rotation number. Original classical probes were used for measurements. The distributions of the average main swirl flow characteristics along the diffuser are shown. Distributions of the inlet Boussinesq number, outlet Coriolis coefficient, ratio of the swirl and completely axial flow loss coefficients at conical diffuser on the inlet swirl flow parameter are also presented

Experimental investigations of the turbulent swirl flow in straight conical diffusers with various angles

Results of experimental investigations of the turbulent swirl flow in three straight conical diffusers with various diffuser total angles are presented in this paper. All three diffusers have the inlet diameter 0.4 m and total divergence angles 8.6 degrees, 10.5 degrees, and 12.6 degrees. The incompressible swirl flow field is generated by the axial fan impeller, and for each diffuser several regimes were achieved by changing rotation number. Original classical probes were used for measurements. The distributions of the average main swirl flow characteristics along the diffuser are shown. Distributions of the inlet Boussinesq number, outlet Coriolis coefficient, ratio of the swirl and completely axial flow loss coefficients at conical diffuser on the inlet swirl flow parameter are also presented

Numerička simulacija strujanja u modelu Kaplan turbine

Savremeno projektovanje hidrauličnih turbina podrazumeva određivanje njihove geometrije za zadate parametre primenom numeričkih simulacija strujanja i modelskih ispitivanja na opitnim instalacijama. U radu se, korišćenjem najsavremenijih alata za rešavanje parcijalnih diferencijalnih jednačina, numerički simulira strujanje u celokupnom strujnom prostoru modela jedne hidraulične turbine za odabrane radne režime pri optimalnom neto padu. Određivanjem odstupanja rezultata dobijenih numeričkim i laboratorijskim eksperimentima pokazana je pouzdanost primene naponskog SSG turbulentnog modela u određivanju osnovnih energetskih parametara Kaplan turbine

New Design of the Reversible Jet Fan

This paper presents two designs of the axial reversible jet fan, with the special focus on the impeller. The intention was to develop a reversible axial jet fan which operates in the same way in both rotating directions while generating thrust as high as possible. The jet fan model with the outer diameter 499.2 +/- 0.1 mm and ten adjustable blades is the same, while it is in-built in two different casings. The first construction is a cylindrical casing, while the second one is profiled as a nozzle. Thrust, volume flow rate, consumed power and ambient conditions were measured after the international standard ISO 13350. Results for both constructions are presented for three impeller blade angles: 28 degrees, 31 degrees and 35 degrees, and rotation speed in the interval n = 400 to 2600 rpm. The smallest differences in thrust, depending on the fan rotation direction, as well as the highest thrust are achieved for the first design with the cylindrical casing and blade angle at the outer diameter of 35 degrees. Therefore, it was shown that fan casing significantly influences jet fan characteristics. In addition, the maximum thrust value and its independence of the flow direction is experimentally obtained for the angle of 39 degrees in the cylindrical casing

The school of the turbulent swirling flow at the faculty of mechanical engineering university of Belgrade

This review paper provides data about research activities at the School of the turbulent swirling flow at the Faculty of Mechanical Engineering, University of Belgrade, conducted in the period 1941 up to date. An overview is provided of the main directions in this research area. First papers dealt with the turbulent swirling flow in hydraulic turbines to be continued by the experimental and analytical approaches on the axial fans pressure side. The complexity of 3-D, non-homogeneous, anisotropic turbulent velocity fields required complex experimental and theoretical approach, associated with the complex numerical procedures. Analytical approaches, complex statistical analyses and experimental methods and afterwards CFD employed in the research are presented in this paper. The 150 scientific papers, numerous diploma works, several master of science (magister) theses, six Ph. D. theses and two in progress, 40 researchers, national and international projects are the facts about the School. Scientific references are chronologically presented. Numerous abstracts from scientific conferences, presentations, projects with industry and lectures are not given here

New Design of the Reversible Jet Fan

This paper presents two designs of the axial reversible jet fan, with the special focus on the impeller. The intention was to develop a reversible axial jet fan which operates in the same way in both rotating directions while generating thrust as high as possible. The jet fan model with the outer diameter 499.2 +/- 0.1 mm and ten adjustable blades is the same, while it is in-built in two different casings. The first construction is a cylindrical casing, while the second one is profiled as a nozzle. Thrust, volume flow rate, consumed power and ambient conditions were measured after the international standard ISO 13350. Results for both constructions are presented for three impeller blade angles: 28 degrees, 31 degrees and 35 degrees, and rotation speed in the interval n = 400 to 2600 rpm. The smallest differences in thrust, depending on the fan rotation direction, as well as the highest thrust are achieved for the first design with the cylindrical casing and blade angle at the outer diameter of 35 degrees. Therefore, it was shown that fan casing significantly influences jet fan characteristics. In addition, the maximum thrust value and its independence of the flow direction is experimentally obtained for the angle of 39 degrees in the cylindrical casing

Investigation of the turbulent swirl flows in a conical diffuser

Results of the theoretical and experimental investigations of the turbulent mean swirl flows characteristics change along straight conical diffuser of incompressible fluid (air) are presented in this paper. The main swirl flow characteristics review is given. In addition: the specific swirl flow energy, the energy loss, the mean circulation, the swirl flow parameter, the ratio between the swirl and axial flow loss coefficients change along the diffuser are presented. Among other values: the Boussinesq number, outlet Coriolis coefficient and swirl flow loss coefficient dependences on inlet swirl flow parameter are also given. The swirl flow specific energy and outlet Coriolis coefficient calculation procedure are presented in this paper, as well as experimental test bed and measuring procedures. The swirl flow fields were induced by the axial fan impeller. Various swirl parameters were achieved by the impeller openings and rotational speeds

Fluid boundaries shaping using the method of kinetic balance

Fluid flow in curved channels with various cross-sections, as a common problem in theoretical and applied fluid mechanics, is a very complex and quite undiscovered phenomenon. Defining the optimum shape of the fluid flow boundaries, which would ensure minimum undesirable phenomena, like "dead water" zones, unsteady fluid flow, etc., is one of the crucial hydraulic engineering’s task. Method of kinetic balance is described and used for this purpose, what is illustrated with few examples

Bulb turbine hydraulic tests at the HPP 'Đerdap II'

U okviru ovog rada se prikazuju neki rezultati garancijskih hidrauličkih ispitivanja cevne turbine agregata br.9 dopunske HE "Đerdap II". Dati su uslovi pod kojim je merenje izvršeno, kao i analiza dobijenih rezultata. Merenja su obavljena na tri različita pada, srednjih vrednosti: Hr=6,62 m, Hr=7,36 m i Hr=11,77 m.prečnika radnog kola D1=7,5m za padove H=1.5-12,5m za radne uslove tV=20˚C i n=62, 5min-1The authors present some results of the bulb turbine complex commissioning tests of the unit No 9 at the additional HPP "Đerdap II". The conditions under which the tests were performed are described. A brief analysis of the results is also given. Tests were performed at three different average heads: Hr = 6,62 m, Hr = 7,36 m and Hr = 11,77 m