Novica Z. Jankovic

First steps in new affordable PIV measurements

Particle image velocimetry (PIV) is an optical, laser based, measurement of fluid velocity and its 2D/3D visualisation. We have presented a new approach in low-cost PIV design using: 1) fast industrial camera, 2) laser pointer, with cylindrical lens for continual fluid flow illumination, 3) acquisition software developed in house, 4) OpenPIV analysis software. Velocity was measured in the glass jar where swirl flow was generated by magnetic stirrer. In this pilot study, results obtained by calibration device based on Laser Doppler anemometry and our PIV results are in good agreement.

Laser Insight Into the Turbulent Swirl Flow Behind the Axial Flow Fan

Complex experimental study of the turbulent swirl flow behind the axial fan is reported in this paper. Axial fan with nine blades, designed to generate Rankine vortex, was positioned in the circular pipe entrance transparent section with profiled free bell mouth inlet. Two test rigs were built in order to study the turbulent swirl flow generated on the axial fan pressure side in the case of axially unrestricted and restricted swirl flows. One-component laser Doppler anemometry (LDA) and stereo particle image velocimetry (SPIV) were used in the first test rig in the measuring section 3.35D, measured from the test rig inlet. One of the latest measurement techniques, high speed SPIV (HSS PIV), was used for the measurements in the second test rig in the section 2.1D downstream the fan’s trailing edge. Achieved Reynolds numbers in the first test rig are Re = 182600 and 277020, while in the second Re = 186463. Turbulent velocity field non-homogeneity and anisotropy is revealed using the LDA system. Calculated turbulent statistical properties, such as moments of the second and higher orders, reveal complex mechanisms in turbulent swirl flow. It is shown for the used axial fan construction that swirl number has almost constant value for two various duty points generated by changing rotation number. Study of the instant and mean velocity fields obtained using SPIV discovers vortex core dynamics. Obtained percentage of the unique positions of the total velocity minimum are 10% for the first regime, while 11.5% for the second regime in the first test rig. HSS PIV experimental results have also shown the three-dimensionality and non-homogeneity of generated turbulent swirl flow. Experimentally determined and calculated invariant maps revealed three-component isotropic turbulence in the vortex core region.© 2014 ASME

Microfluidic Chip Fabrication for Application in Low-Cost DIY MicroPIV

The article presents the process of fabrication of the microfluidic chip to be used with the do-it-yourself (DIY) micro-PIV system previously made and compared to the classic PIV setup. This pilot study is an example of research being conducted in the Scientific fab lab (fabrication laboratory), founded at the Faculty of Mechanical Engineering, University of Belgrade. Fab labs and DIY principle are becoming more and more accepted by the scientific community and this article aims to contribute to such trend.

Centrifugal pumps' impellers design and digital fabrication

Design of three centrifugal pump impellers is presented in this paper. All impellers are designed in Catia software by Dassault Systems. Impellers have the same outer diameter of 50 mm, but various blade numbers: 5, 6 and 8. In addition, various design techniques are applied. These impellers are followed by the same spiral pump casing. The intention is to study the energy characteristics of the pump impellers, originally designed for various purposes on the same test rig. All three impellers are made on the 3D printing machine - Printrbot Simple. Build volume is 150 mm × 150 mm × 150 mm. Used filament is 1.75 mm PLA/PHA colorFabb 3D printing filament 1.75 mm diameter, standard black, with nozzle 0.4 mm. Print bed is not heated. First tests have shown good impeller durability in operating conditions.

Poster: Remote Engineering Education Set-Up of Hydraulic Pump and System

Educational setup for demonstration of a pump operation and determination of full performance curves is presented. The upgrade of the setup has been done in order to implement electronic measurements, data acquisition, computer control, and for preparation of all necessary hardware elements for remote operation via Internet. Used equipment, rationale behind, characteristics and possibilities of the current status of the setup is discussed in detail.

Virtual Instrumentation Used in Engineering Education Set-Up of Hydraulic Pump and System

Numerous students attend courses in hydraulic turbo pumps at the Faculty of Mechanical Engineering University of Belgrade, as well as from other faculties. They have oral lectures and exercises with numerical tasks, but also laboratory exercises. This easily driven upgraded installation is very convenient for laboratory exercises for various groups of students. In this paper is demonstrated upgrade of the present installation with transducers instead of U-tube analogue manometers, acquisition system and LabVIEW application for hydraulic pump diagnostics and flow meter calibration. Pressure transducers are also previously calibrated. This installation has three regulating valves and two for tanks emptying. In this way students could form two simple and one complex pipeline. Serious and parallel combinations of pipe lines could be demonstrated, as well as pump by-pass regulation. Hydraulic pipe curve could be formed for one position of the valve on the pump pressure side and various pump frequencies. This could be repeated for other valve positions. In addition pump head characteristic for one rotation number is formed by changing the valve position. Good overlapping with manufacturer’s curve is demonstrated. Cavitation and turbulent swirling flow phenomena could be also visualized and demonstrated on this installation with transparent pump housing, as well as partly suction and pressure pipes.

Simulating fluid flow in “Shrinky Dink” microfluidic chips — Potential for combination with low-cost DIY microPIV

This paper describes the first steps towards a union of low-cost “Shrinky Dink” (SD) microfluidic chip fabrication with low-cost do-it-yourself (DIY) micro-PIV. The SD microfluidic chip fabrication technique enables rapid development of complex designs using inexpensive materials and reagents, while abrogating the need for a cleanroom. DIY microPIV system provides a low-cost means of accurate flow profile analysis in microchannels, comparable to high-cost, standard microPIV setups. Initially, a simple microfluidic design of a T-junction was created and several chips with the same design were fabricated by the SD technique. We used COMSOL Multiphysics Creeping Flow interface to simulate the flow profiles in the obtained channel geometry. The next step will be to experimentally verify these simulations using our DIY microPIV system, in order to confirm the potential of combined use of these two cost-effective systems, to rapidly produce and analyze microfluidic designs, thereby enabling greater accessibility to these methods in labs with limited resources. It is envisioned that the systems described here can be effectively employed for a wide array of applications in biophysics, fluid mechanics, and bioengineering.

INVESTIGATION OF THE FREE TURBULENT SWIRL JET BEHIND THE AXIAL FAN

Experimental investigation of the free turbulent swirl jet behind the axial fan, by use of the three-component laser Doppler anemometer (LDA) is presented in this paper. Axial fan generates Rankine swirl. Measurements have been performed in five vertical measuring sections downstream for one rotation number 1500 rpm. Time averaged velocity components and their profile transformation downstream were investigated. Statistical moments of the second, third and fourth order have been calculated and presented. The highest turbulence levels are reached in the central zone, more precisely - shear layer zone and in the injection zone. Skew-ness and flatness factors differ from normal Gaussian distributions. Turbulence swirl flow anistropy is investigated by applying invariant maps. Most of the obtained results are positioned in the region of the three-component isotropic turbulence and axisymmetric expansion. [Projekat Ministarstva nauke Republike Srbije, br. TR 35046]