INFLUENCE OF THE MEASURING TOOLS ON THE FLOW CHARACTERISTICS IN VORTEX CHAMBER PUMP

Problem. Perturbation of the flow by measuring instruments forces researchers to choose optical research methods. But these methods significantly increase the cost of experimental research, due to the high cost of optical-type measuring equipment. On the other hand, using contact methods for measuring the flow velocity, such as Pitot tubes, hot-wire anemometers, the researcher must be sure that the measurement results can really be compared with the calculations results and the equipment influence on the flow parameters is minimal. The aim of this work is to study the measuring tool influence on the flow characteristics in the swirl chamber pump, as well as to compare the results obtained due to the measurements with the parameters of the undisturbed flow. The research methodology consisted of two stages: 1) modeling the flow in the model pump; 2) comparison of flow characteristics, as well as the values of velocity and pressure at the points of installation of the measuring tool. Results. Although the total velocity at the measuring point is practically independent of the measuring tool, the tangential component of the velocity is significantly reduced. It indicates that there is a significant error in velocity measuring. For a more accurate rotational velocity component measurement, it is necessary to orient the instrument perpendicular to the measured component. Scientific novelty. Installing the measuring tool in the end cover of the swirl chamber reduces the flow rate sucked by the pump through the lower axial channel. The size of the tool has practically no effect on the energy characteristics of the swirl chamber pump. Practical value. To ensure measurement accuracy, the ratio of the swirl chamber dimensions and the tool should be ensured in the way that the relative diameter of the tool does not exceed 0.25 of the swirl chamber neck diameter.

Conical Two-Phase Swirl Flow Atomizers—Numerical and Experimental Study

This paper presents the results of numerical simulations for the developed and discussed conical two-phase atomizers with swirl flow, differing in the ratio of the height of the swirl chamber to its diameter. Experiments were carried out for SAN-1 with HS/DS = 1 and SAN-2 with HS/DS = 4 atomizers. The study was conducted over a range of Reynolds number for liquid ReL = (1400; 5650) and for gas ReG = (2970; 9900). Numerical calculations were performed with the use of computational fluid dynamics (CFD), which were verified on the basis of experimental data. Based on the analysis of experimental studies and simulations results the influence of operational parameters and changes of the atomizer geometry on the generated spray was demonstrated. As the gas flow rate increased and the swirl chamber height decreased, the spray angle increased. Higher velocity values of the liquid and greater turbulence occur in the center of the spray. The flow inside the atomizer determines the nature of the spray obtained. The geometry of the swirl chamber influences the air core formed inside the atomizer, and this determines the atomization effect. The results of numerical simulations not only confirm the results of experimental studies, but also provide additional information on internal and external fluid flow.

Heat Transfer Characteristic for Premixed Flame Jet from Swirl Chamber

The objective of this research is to study flame structure and heat transfer characteristics for the premixed flame jet from the swirling chamber. In this study, LPG and air was utilized as gas fuel and oxidizer for a premixed flame. The equivalence ratios () of LPG and air were considered at 0.8, 1.0, and 1.2 under a Reynolds number Re = 4,000. The swirl flame was generated by double tangential inlets in cylindrical chamber. The diameter of chamber was fixed at D = 20 mm and the hydraulic diameter of the inlet was Dh = 5 mm. In this study, the effect of chamber geometry on flame structure was investigated by varying the chamber from H = 2.2Dh to 7.0Dh. The structures and temperature of the free flame jet was recorded with camera and measured with a thermocouple. The heat transfer rate of impinging flame jet was also measured at distance from chamber outlet to flame impingement surface varying from L = 4Dh to 10Dh. The results show that the maximum of flame temperature occurs at =1.2. Impinging flame jet for case of chamber height at H = 4.6Dh and impingement distance at L = 4Dh give the highest heat transfer for all equivalence ratios due to the reaction zone of combustion reached to approach near the heat transfer surface.

Investigation on the Fluctuations of the Spray Angle Generated From Pressure-Swirl Atomizers

The unsteady characteristic of the pressure-swirl atomization system was studied experimentally in this paper. It was found that the fluctuations of the spray can be divided into two modes: high and low frequency mode, among which the frequency of the high mode is within the range of 500–1100Hz, and the low mode is 100–400Hz. The low mode depends on the turbulent exchange of momentum between the liquid and the surrounding stagnant gas. While the high mode depends on the comprehensive effect of the turbulent vortex generated by the liquid flowing through the atomizer and the natural frequency of the atomizer. Experiments show that the peak frequency of the low mode increases but the peak frequency of the high mode decreases when the pressure drop of the atomizer increases. When the atomizer outlet area size increases, both the peak frequency of the low mode and the high mode decrease. When the deflection angle of the swirl chamber increases, the peak frequency of the low mode increases, while the peak frequency of the high mode decreases first and then increases, reaching the minimum at 60°, and the value at 45° is basically the same as at 80°.

Improved Atomization via a Mechanical Atomizer with Optimal Geometric Parameters and an Air-Assisted Component

Atomization of liquid media is a key aim in various technological disciplines, and solutions that improve spray performance, while decreasing energy consumption, are in great demand. That concept is very important in the development of liquid fuel spray atomizers in high-efficiency microturbines and other generator systems with low inlet pressure and a wide range of power supply. Here we present a study of the liquid atomization characteristics for a new mechanical atomizer that has optimal geometric parameters and a preliminary swirl stage. In our air-assisted atomizer, air is introduced through a swirl chamber positioned at the exit of the mechanical atomizer. The optimized mechanical atomizer alone can achieve D32 drop diameters in the range of 80 to 40 µm at water supply pressures of 2 to 5 bar, respectively. The addition of an air swirl chamber substantially decreases drop sizes. At an air–liquid ratio (ALR) equal to 1, water pressures of 2.5 to 3 bar and air supply pressures 0.35 to 1 bar, D32 drops with diameters of 20–30 µm were obtained. In an air-assisted atomizer the parameters of the mechanical atomizer have a much stronger influence on drop diameters than do characteristics of the air-swirl chamber. Using a mechanical atomizer with optimal geometrical dimensions allows limiting the liquid supply pressure to 5 bar; but when an air-assisted component is introduced we can recommend an ALR ≈ 1 and an air supply pressure of up to 1 bar.

Advanced Disc Spray Tip Universal Fan Sprayer

Fan sprayers such as OVH-600 and VP-1 are of indisputable importance in the fight against agricultural pests and diseases, but they have significant disadvantages associated with uneven application of pesticides due to the oscillating movement of their working bodies. To eliminate this drawback, the Agrikhim joint venture developed a universal fan sprayer VP1IB, which processes field crops, orchards and vineyards based on controlled airborne droplets with simultaneous continuous girth of the entire implement width within ± 900 of the sprayer symmetry axis (in a total of 1800), i.e. around the perimeter of the treatment area. The main working element of the universal fan sprayer is the spraying tips quality performance indicators, which largely depends on the correct choice of parameters of its parts, including the radius of the input channels to the swirl chamber on the swirl disk, to justify the rational value of which this article is aimed.