Single-jet Nozzle Research Articles

Numerical Analysis on the Performance of High Concentration Photovoltaic Systems Under the Nonuniform Energy Flow Density

Photovoltaic panels can directly convert solar energy into electricity, but temperature will have a certain impact on the efficiency of photovoltaic cells. Especially under the condition of nonuniform energy flow density of high-power concentration, it is of great significance to maintain the temperature uniformity of cells. Therefore, based on the radiation under nonuniform heat flux density, four heat exchangers were proposed: single-channel serpentine flow, multi-channel flat plate, full jet, and single-jet nozzle. Taking into account the uniformity of the cell temperature, the single-jet nozzle and single-channel serpentine flow can better maintain the uniformity of the temperature field compared with other heat exchangers. Especially under high-concentration energy flow density, considering the quality of heat and electricity, the performance of the four-jet nozzles is the best from the perspective of exergy efficiency. Under the condition of four-jet nozzles, the electrical efficiency and thermal efficiency of the cell can be maintained at about 29 and 62.5%, respectively, and the exergy efficiency of the system can reach 31%.

Numerical analysis on the flow field structure and deflection characteristics of water jets under nozzle moving conditions

High-pressure water jets under nozzle moving conditions are widely utilized for rock breakage in geotechnical engineering. The nozzle motion state significantly influences the jet flow field and flow characteristics, thus changing its rock-breaking performance. In this paper, a single-jet nozzle model with different traverse speeds was established to investigate the jet flow field features and deflection characteristics and analyze the effects of nozzle traverse speed and jet pressure through numerical simulations. The jet flow fields under nozzle fixed and moving conditions were compared in terms of the distributions of vorticity, velocity, pressure and turbulence kinetic energy, and deflection characterization. Jet flow patterns photographed by an ultra-high-speed camera indicated the deflection of the jet flow field under the nozzle moving condition. The simulation results show that the flow field structure of the moving jet contains the non-deflection zone and deflection zone. The jet time-averaged velocity and vorticity are distributed symmetrically in the non-deflection zone, which is similar to the flow patterns under the nozzle fixed condition. As the jet prolongs further, the vorticity value increases and the vorticity distribution is more concentrated and closer to the nozzle outlet in the moving direction owing to more intense turbulence, resulting in the non-self-similarity of jet velocity dimensionless distribution on cross-sections and jet flow deflection to the opposite direction. The faster the traverse speed and the lower the jet pressure, the greater the jet flow deflection degree. The jet centerline velocities decay exponentially with the standoff distance, and the attenuation degree increases as the traverse speed increases. As the standoff distance increases, the jet deflection distance increases in a quadratic parabola and the deflection angle and impact angle both increase linearly, and decrease exponentially with increasing jet pressure. There is a positive relationship between the jet deflection characterization and the traverse speed.

Performance evaluation of textured carbide tools under environment-friendly minimum quantity lubrication turning strategies

Present investigation is focused to study the impact of different lubricating environments using pure canola oil and graphene mixed in canola oil, on the performance of uncoated carbide textured tools in minimum quantity lubrication (MQL) turning of AISI 4340 hardened steel. The influence of using twin jet and single jet was also studied under MQL. The turning performance was evaluated in terms of flank wear (VBmax), cutting forces, cutting temperature, and chip morphology. The results showed that MQL mist supplied simultaneously on rake and flank face of the textured tool by twin-jet nozzle performed better than MQL mist supplied on the rake face of textured tool by the single-jet nozzle. Out of all the tested lubricating environments, best tool life was achieved with nanoparticle minimum quantity lubrication (NMQL) using the twin jet followed by only oil using twin jet as compared to all other conditions tested in this study. The outcome of the study illustrates that MQL mist of graphene which is mixed in canola oil on a textured tool with the twin-jet nozzle can be successfully applied for finish turning of hardened steel.

Effect of extended single/multi-jet nozzles in a fluidized bed reactor on growth of granular polysilicon

The influence of extended single- and multi-jet nozzles in a fluidized bed reactor on growth of granular polysilicon was studied, experimentally and numerically. Three-dimensional (3D) unsteady computational fluid dynamics (CFD) calculations were performed using the Fluent commercial CFD package. The Eulerian–Eulerian multiphase model was applied for the bulk motion of the two-phase flow, and the kinetic theory of granular flow was used to predict the solid-phase interactions. 3D cold-model reactor experiments were performed to validate the models and conditions used for the CFD simulations. The CFD-predicted pressure drop and bed expansion agreed reasonably well with the cold-model reactor test data. For a single-jet nozzle, superimposed bubbling and spouting behavior were observed in the bed. The effects of the single-jet intensity were also examined. For multi-jet nozzles, the mixing performance was much improved in the reaction zone and the dead reaction zone was reduced compared to the single-jet nozzle. Furthermore, determining the optimal configuration of multi-jets nozzles is necessary to minimize or avoid wall deposition as well as enlarging reaction zone.

Research on the Inlet Pressure Accurate Control Method of the Nozzle for the Single-Jet Nozzle Tester of Aero Engine

This paper introduces the closed loop pressure computer control system which is suitable for the environment of kerosene medium. The system can satisfy the technical requirements of the pressure regulation in the test of the single –jet nozzle of aero engine , the pressure can be accurately controlled and its control precision is within ±0.01MPa. It indicates the principle and composition of the hydraulic system and computer measurement and control system. The paper introduces the design method and treatment process of the key technology, which includes the use of a proportional relief valve and a fixed throttle hole in hydraulic system, the use of PID control in closed loop control system, the use of high precision sensor and measurement method by grade in measuring system and the use of 24V precision steady voltage source. In the same time it indicates the actual application of the closed loop pressure control system.

On Using Multiple-Jet Nozzles to Suppress Industrial Jet Noise

This work investigates the efficacy of multiple-jet nozzles in reducing exposure to noise radiated from high-speed jet flows that are frequently used for cleaning and other purposes. A single-jet nozzle is replaced by one with multiple and smaller outlets with the same combined exit area. Noise generated by multiple-jet nozzles will shift to higher frequencies due to the smaller openings; thus, a portion of the sound energy is moved to the ultrasonic range and the audible noise levels will be reduced. In this study, nozzle outlet sizes of 2.2 mm, 2 mm, 1 mm, and 0.7 mm are tested at various flow rates. Results show that the noise-abating effect of using smaller outlets is significant. Although industrial jet flows, in general, have multiple noise-generating mechanisms, the multiple-jet approach is effective for flows ranging from the subsonic to the highly choked. Noise spectra show that the reduction of noise level in the audible range is related to frequency shifting. The comparison of overall sound pressure levels generated by 1-mm and 0.7-mm outlets shows that even a raise of frequency by 40% can have a notable effect. As for the concern that the multiple-jet nozzles may suffer a drop in thrust, as long as the total exit area is fixed, thrust loss generally is not serious. One potential hazard of the multiple-jet nozzle is that posed by noise at frequencies higher than 10 kHz or ultrasound. More investigations in this field are suggested.

Jet mixing of water in crude oil pipelines for representative sampling

Jet mixers are frequently used in crude oil pipelines to remix uniformly and settled water prior to the sampling point in order to determine the water content when buying and selling crude oil cargoes. Existing jet mixers vary from a single-jet nozzle (e.g. at the bottom of a horizontal pipe) to a complex pattern of nozzles. As the multi-nozzle designs are continuously changing and owing to the complexity of the problem, crude design calculations are usually in error. A laser Doppler anemometry (LDA) experimental study (single phase) was conducted in order to understand and compare the flow fields produced by single- and multi-nozzle mixers.