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A novel design of cooling air supply system with dual row pre-swirl nozzles (DRPM) is promoted and investigated. Simplified theoretical analysis and numerical simulation are used to estimate the total temperature reduction and mass flow rate characteristic of DRPM and compared with single row pre-swirl nozzle model (SRPM). The results show that, both models have similar flow structure and the variation of total temperature reduction and dimensionless mass flow rate with rotational Reynolds number and pressure ratio is also similar. Which have an inflection point with the increase of rotational Reynolds number but increases monotonically with the variation of pressure ratio. The pre-swirl system has the maximum flow rate and temperature reduction when the inflow Angle equal to 0 or the swirl ratio equal to 1 at the inlet of the receiver hole. The increase in pressure ratio improves the total temperature reduction and dimensionless mass flow rate as well. In the range of rotational Reynolds number calculated, DRPM can increase the dimensionless mass flow rate by 3.0% but the total temperature reduction decreased by 37.8% in average compared with SRPM. On the other hand, the dimensionless mass flow rate increased by 2.8% and total temperature reduction decreased by 14.9% in average in the range of pressure ratio calculated. Numerical results are in good agreement with the results calculated by simplified theoretical formulas.

Polypropylene (PP) plastic packaging waste consists of a variety of different plastic packaging products with a great span in rheological and mechanical behavior. Therefore, the resulting post-consumer recyclates usually show melt mass-flow rates (MFR) in the region of injection molding grades and intermediate mechanical properties. High-quality packaging applications demand a distinct property profile that is met by tailor-made PP grades and cannot be met by recyclates with intermediate performance. One such application with high market volume is high-stiffness thermoforming trays. The aim of this research was to blend intermediate-performance recyclates with a virgin PP grade to obtain compounds that fulfill the rheological and mechanical demands of this application. Three commercially available PP post-consumer recyclates were acquired and compounded with different blending ratios with a high stiffness, low MFR virgin PP grade. As the pure recyclates show different rheological properties, the blending ratios had to be adapted for each of them to fit into the MFR range of 2–4 g/10 min which is desirable for thermoforming applications. The resulting PP recyclate compounds show a distinct correlation of recyclate content with rheological and mechanical performance. However, the resulting property profile was directly dependent on the performance of the originally used recyclate. The best-performing recyclate could be used in a blending ratio of 65 m% recyclate content while adhering to both property limits, the MFR of 2–4 g/10 min and the lower bound tensile stiffness of 1500 MPa.

The objective of the current study is to investigate the performance of the inclined solar panel basin still (ISPBS) incorporated with a spiral tube collector (STC) for various mass flow rates of water ( m f ). The maximum potable water yield of 8.1, 6.9, and 6.1 kg is obtained for different mass flow rates of 1.8, 3.2, and 4.7 kg/h in each instance. Also, for m f of 1.8, 3.2, and 4.7 kg per hour, the daily average energy and exergy efficiency of the ISPBS is recorded to be 47.9, 39.3, and 31.02 % and 9.8, 7.9, and 5.6 %, in each instance. The average electrical, thermal, and exergy efficiency of the PV panel is noted to be 6.5, 7.1, and 7.5 %; 15.67, 17.1, and 18.04 %; and 20.03, 22.21, and 23.36 % for m f of 1.8, 3.2, and 4.7 kg/h in each instance. The rise in m f causes a drop in the fresh water production yield; thermal, exergy, and overall thermal effectiveness; and an enhancement in the power production of the panel, electrical, thermal, exergy, and overall exergy efficiency of the system. Also, the cost of yield production is noted to be low-cost in AISS at minimum m f of 1.8 kg per hour (0.019 $/l) when compared to the other two m f of 3.2 and 4.7 kg per hour (0.022 and 0.025 $/l).

A new method is proposed for thermal protection of high-speed aircraft (HSA) nose cones, which is based on injection of a coolant with a strong temperature dependence of its dynamic viscosity (changing by 3‒5 orders of magnitude upon temperatures variation from 300 to 500 K) into the gas-dynamic boundary layer. This dependence allows the design of an automatic system for coolant delivery through channels formed in the structure onto the blunt cone surface, since, as the temperature of the structure increases, the coolant viscosity drops sharply, its fluidity increases, and, at a constant pressure differential between the coolant reservoir and the surface, its delivery to the boundary layer increases, forming a protective liquid film that flows and evaporates, injecting vapor into the boundary layer. As the structural temperature drops, the coolant delivery decreases. The efficiency of this thermal protection method is related to the fact that, first, the HSA surface temperature does not exceed the coolant evaporation temperature and, second, the HSA structure operates without mass loss and maintains its geometry. Numerical results have been obtained for the mass flow rate, mass evaporation rate of the liquid coolant film, its temperature, and the HSA structure temperature.

This paper introduces a novel mathematical model designed to determine combustion characteristics across the length of the combustion zone, underpinned by logical theoretical foundations and demonstrating notable alignment with experimental findings. The model facilitates the calculation of combustion efficiency based on inlet flow parameters (temperature, pressure, velocity, length, porosity, and air excess ratio), achieving efficiencies beyond conventional limits (η = 0.98–0.99) and reaching high values (η = 0.999–0.9999), which is crucial for optimizing low-emission combustors. Verification of the mathematical model was conducted through a dual approach: experimental validation and computational fluid dynamics (CFD) simulations. Comparative analysis revealed a high degree of consistency among theoretical predictions, CFD results, and experimental data, particularly for temperature and combustion efficiency distributions along the combustor length. This robust agreement affirms the model’s accuracy, reliability, and utility in advancing combustion research and developing efficient, low-emission combustors.

The paper deals with the determination of vibration emission frequency depending on the impact of abrasive particles during cutting of materials. In order to verify the investigated hypothesis, the factor of the abrasive mass flow rate m a  = 250 and 400 g min −1 at the traverse speed of cutting head v  = 50, 75, 100 and 150 mm min −1 was determined. The Barton Garnet with MESH 80 and focusing tube with diameter of 0.8 and 1.4 mm were used in the experiment. Vibrations were recorded during experimental cutting by sensors PCB IMI type 607A11 placed on the stainless steel AISI 309. During the experimental sample cutting, vibrations were monitored and consequently processed by the LabVIEW 8.5 software. Research results are useful for improving the quality of surface created by abrasive water jet, and they can encourage the on-line process control of abrasive water jet cutting with the minimum human intervention in case of a fault or error during the supply of abrasives to cutting head.

This paper describes about the design, fabrication and flow simulation of a choked flow nozzle which is used to supply constant mass flow rate to the air heater which can provide supersonic conditions for Supersonic Engine Test Facilities. The test facility is considered to be capable of delivering working gas at 5-20 kg/s flow rate, stagnation temperature at 800-2200 K and stagnation pressure at 8-40 bar to the inlet of combustion chamber of the engine for specified duration. The outlet condition for the choked nozzle is considered to be known and the required inlet pressure for the nozzle has to be found out. This converging nozzle should be capable of providing constant mass flow rate.

The paper deals with the tangential abrasive water jet turning of hybrid aluminium matrix composite fabricated by electromagnetic stir casting technology, consisting A359 aluminium alloy as base matrix and 2% B 4 C and 2% Al 2 O 3 as reinforcing particles with final workpiece diameter of 14.5 mm. The influence of abrasive mass flow rate within 100–400 g/min using two different abrasive grains—olivine and Barton garnet—was studied. Abrasive grains were fed to the water stream created by water orifice of diameter 0.33 mm at pressure level of 300 MPa and a stand-off distance 8 mm. Abrasive type and abrasive mass flow rate, as important technological factors, are evaluated, and topography of created surfaces is analysed using optical profilometry and microscopy methods. A diameter reduction of 25–30% was observed during the experiments. The lowest average roughness value of 6.64 μm was obtained using olivine grains at an abrasive mass flow rate of 400 g/min. The topographical detail of the machined surface revealed several cutting traces, grooves and furrows which show the ploughing nature.

Worldwide the radiant cooling system is used as an energy-efficient alternative to conventional air conditioning systems. Understanding the heat extraction characteristics of the radiant cooling system is necessary to understand the system’s thermal performance. The radiant cooling system’s heat extraction characteristic differs from conventional air conditioning system. The predominant form of heat transfer is through radiation, that is more than 50% of heat transfer takes place by radiation. In this study, the focus is to evaluate the heat extraction characteristic of the radiant cooling system by varying panel position, area of cooling panel, water mass flow rate, and water set temperature. The ratio of radiative heat flux to total heat flux ( q r / q tot ) is used to evaluate the system’s thermal characteristics. The study’s outcome indicates that the radiative heat transfer coefficient ( h r ) varies from 5.7 to 6.03 W/m 2  K throughout the experimental study, indicating that the h r value remains relatively constant. The study shows that at steady state, increase in mass flow rate of water and water set temperature increases the percentage of radiative heat flux to total heat flux ( q r / q tot ). At steady state, increase in area of radiant cooling panel decreases the ratio of q r / q tot . The radiant cooling panel area restricts the cooling capacity of a radiant cooling system. The cooling capacity can be enhanced for a given area of radiant cooling system by adding fins to the radiant panel or by increasing convective heat transfer. In this study, the cooling capacity of the radiant cooling system is enhanced using a ceiling fan. The outcome shows that when Wall B is active at T w of 25 °C, there is a 19% increase in the cooling capacity of the radiant cooling system as air velocity in the chamber increases from 0 to 0.95 m/s.

This manuscript brings out with an enhancement of the freshwater productivity from the active inclined solar panel basin solar still (AISPBSS). The research was conducted on the AISPBSS by the diversified mass flow rate of water (mf). The maximum freshwater yield obtained at mf at 1.8, 3.2 and 4.7 kg/h is 7.5, 6.5 and 5.4 kg, respectively. The daily average thermal and exergy efficiency of the AISPBSS at mf at 1.8, 3.2 and 4.7 kg/h is 43.71, 38.27 and 29.62% and 8.39, 6.94 and 5.08%, respectively. The daily average PV panel power production of 47.71, 49.84 and 53.83 watts, electrical efficiency of 7.2, 7.6 and 8.1%, thermal efficiency of 17.3, 18.3 and 19.7%, exergy efficiency of 18.32, 20.23 and 22.39%, the overall thermal efficiency of 61.39, 57.44 and 51.37% and the overall exergy efficiency of 26.52, 27.14 and 27.40% are obtained from the system under mf at 1.8, 3.2 and 4.7 kg/h, respectively. When mf increases, there are decreases in the AISPBSS distillate yield, thermal, exergy and the overall thermal efficiency and increases in the PV panel power production and electrical, thermal, exergy and the overall exergy efficiency. Further, energy return term and carbon credit attained for the AISPBSS have been calculated. It was found that payback period of 20, 18.7 and 17.5 years and carbon credit earned of 21, 25 and 30 $ are obtained at mf at 1.8, 3.2 and 4.7 kg/h, respectively.