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.

In this paper is presented experimental investigation of the turbulent swirl flow in pipe generated by axial fans. Two various models of industrial axial fans are used. One of these is axial fan W30, model AP 400, Minel, Serbia and has seven blades and outer diameter 0.397m. Second axial fan SP30 is model TGT/2-400-6, S&P, Spain, has six blades and outer diameter 0.386m. This results with greater clearance in the second case. Blades were adjusted for both fans at the angle of 30? at the outer diameter. Test rig length is 27.74-D, where D is average inner diameter app. 0.4 m. Measurements are performed in two measuring sections downstream the axial fans (z/D = 3.35 and z/D = 26.31) with one-component laser Doppler anemometry (LDA) system and stereo particle image velocimetry (SPIV). Obtained Reynolds numbers, calculated on the basis of the average axial velocity (Um) in the first measuring section are for fan SP30 Re = 226757, while for fan W30 Re = 254010. Integral flow parameters are determined such as average circulation and swirl number. Significant downstream axial velocity transformation occurs for both fans, while circumferential velocity is decreased, but non-dimensional velocity profile remains the same. Circumferential velocity distribution for both fans in the central zone corresponds to the solid body, while in r/R > 0.4, where D = 2R, distribution is more uniform. Radial velocity in the case of fan SP30 has almost zero values in the measuring section z/D = 3.35, while its values are significantly increased in the downstream section with the maximum in the vortex core region. On the contrary radial velocity decreases downstream for fan W30 and has also maximum value in the vortex core region for both measuring sections. Level of turbulence, skewness and flatness factors are calculated on the basis of the experimental data. The highest levels of turbulence for circumferential velocity are reached in the vortex core region for both fans. It is shown how statistical moments of the third and fourth order differ from the values for normal Gaussian distribution. In this paper are also analyzed velocity fields by use of SPIV.

Fluid machinery courses demand, besides theoretical approach, also good practice and laboratory exercises. After course completion, students should be aware of all aspects of good practice and possible problems. Focus of this paper is on hydraulic pumps and designed demonstrational-educational test rig. It is possible to demonstrate and educate students in following: Bernoulli equation, Euler equation for turbomachinery, hydraulic losses, Venturi flow meter - geometry and measurements, cavitation and swirling flow phenomena, as well as in practical issues such as pump testing after international standard ISO 9906, pump control and energy efficiency issues, determination of hydraulic system characteristics, volumetric calibration of the Venturi flow meter, and etc. Students are educated how to choose and connect pressure transmitters, as well as how to calibrate them, how to apply and upgrade developed LabVIEW application. In addition, many components of the installation are transparent, such as pipes at the pipe inlet and pressure side, Venturi flow meter, main and calibration tank, as well as pump spiral casing. Flow visualization and application of modern measurement technique, such as particle image velocimetry are possible in this way. Following experiments of this test rig, students are motivated to generate technical electronic report. In addition are presented virtual experiments, designed in LabVIEW for testing pumps in parallel and series modes.

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?, 10.5?, and 12.6?. 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.

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°, 31° and 35°, 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°. 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° in the cylindrical casing.