Pressure swirl atomizers with tangential inputs are widely used in various industries, including power generation and gas turbines. For example, in combustion chambers with increasing time, a lot of factors, such as sediments and corrosions, cause their dimensions to reduce, and therefore, the working condition of these chambers moves outside of the design point. The main purpose of this work is to study the properties of spray at the design point and outside of the design point. To satisfy this objective, design and fabrication of an injector were done first based on some physical parameters, such as pressure difference, spray cone angle, flow rate, fluid type, and so on, and then, it was tested experimentally. Afterward, the effects of the main parameters at the design point and outside of the design point were studied numerically. The results showed a 50% increase in the number of tangential inputs from the design point lowers the pressure difference and spray cone angle by 63.72% and 10.53%, respectively. The increment of the swirl chamber length to 17% can reduce the respective pressure difference and spray cone angle up to 34.2% and 4.5%, respectively. This study also demonstrates that an increase in the length of the orifice lessens the total velocity and pressure as well. A reduction of 22.73% of the outlet nozzle diameter raises the average droplet diameter and flow number to 12.98%, and 11.8%, respectively. Finally, for the requirement of spray properties in a practical situation, the present study can be adopted to predict them accurately.

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Centrifugal (radial flow) turbines are widely used in various industries, including power generation industries, so the study on them is of particular importance. The aim of this study was to investigate the thermodynamic properties of fluid flow in Trailing Edge (TE) and (LE) Leading Edge. For this purpose, first, the rotor (impeller) of the radial flow turbine was designed based on some design data such as flow rate, number of blades, rotational speed, diameter and length of the impeller, and then the designed rotor was simulated in 3D. The simulation done in the pressure based method and the turbulence model is SST and the rotational speed was 140,000(RPM). The results showed that the pressure, temperature and enthalpy in TE are less than LE and the areas close to the hub have the highest pressure. Another phenomenon observed is that in the section LE we see the separation of the flow from the blade surface, which then approaches the blade surface again and follows a relatively regular path,so the entropy in TE is greater than LE. At the end, the results of numerical solution were compared with valid data and the error rate and its reasons were discussed.

Studies on pressure-swirl atomizers have mainly focused on pressure-swirl atomizers with tangential input while there are limited studies on pressure-swirl atomizers with a spiral path. This study applies experimental and computational methods to provide a better understanding of flow development in this type of atomizer at the design point and outside the design point. Experimental results showed that as the pressure increases, the spray cone angle increases. This increase initially occurs with a higher slope and then the slope is toned down. While the drainage coefficient remains constant, the droplet diameter decreases as the pressure increases. It is observed that similar to the pressure-swirl atomizer with tangential input, the pressure-swirl atomizer with a spiral path has a conical hollow spray. At the constant mass flow rate, as the spiral path cross-section, the length of the swirl chamber and orifice diameter increase, the fluid film thickness and average diameter of droplets increase while the spray cone angle reduces. Further, increasing the number of spiral paths causes a wider spray cone angle, higher discharge coefficient, larger fluid film thickness, and larger droplet diameter. The results also showed that increasing the length of the orifice marginally affected the properties of the spray while significantly reducing the spray cone angle. It is important to note that the numerical results are in good agreement with the experimental data.

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