Search Results (16)

The fertilizer suction performance of Venturi injectors is jointly governed by fertilizer-solution properties and hydraulic boundary conditions, resulting in multivariable and potentially nonlinear responses that may be difficult to characterize using simplified empirical relationships. In this study, a fixed-geometry downward-eccentric Venturi injector was investigated. Separate single-output models were developed for fertilizer suction flow rate and fertilizer suction efficiency using dynamic viscosity, density, inlet pressure, and pressure differential as input variables. Based on 567 observations obtained from 189 unique experimental conditions, with three replicate measurements per condition, separate RF, SVR, and BPNN models were developed for fertilizer suction flow rate and fertilizer suction efficiency. Under the observation-level random partition used in the present analysis, BPNN achieved the lowest numerical error for fertilizer suction flow-rate prediction, whereas SVR achieved the lowest numerical error for fertilizer suction-efficiency prediction. Because replicates from the same experimental condition were not explicitly grouped during the original partition, these performance estimates should be interpreted as replicate-level predictive agreement within the investigated domain rather than as definitive validation for completely unseen operating conditions. SVR was therefore used only as a provisionally selected working model for the subsequent exploratory analyses. Predictive performance was evaluated using the coefficient of determination (R²), root mean square error (RMSE), mean absolute error (MAE), and mean absolute percentage error (MAPE). The BPNN model achieved the best performance for fertilizer suction flow-rate prediction, with an R² of 0.9871 and an RMSE of 5.7688 L·h⁻¹. SVR achieved the highest accuracy for fertilizer suction-efficiency prediction, with an R² of 0.9953 and an RMSE of 0.0310 percentage points. Considering the four evaluation metrics for both response variables, SVR was selected as the overall preferred model because it achieved the best performance for fertilizer suction-efficiency prediction while maintaining high predictive accuracy for fertilizer suction flow rate. Permutation-importance analysis indicated that the fitted SVR predictions of fertilizer suction flow rate depended most strongly on pressure differential, whereas the predictions of fertilizer suction efficiency depended most strongly on inlet pressure. External validation using actual fertilizer solutions further demonstrated the potential engineering applicability of the developed model. Full article

This study presents a three-dimensional transient Computational Fluid Dynamics (CFD) analysis of a Venturi injector system used in a textile machine for removing excess water from fabrics after dyeing or washing processes. The main objective is to determine the optimum operating conditions by investigating the coupled effects of nozzle diameter and inlet pressure on pressure distribution, velocity field, and suction performance. Numerical simulations were performed for three nozzle diameters (d_n = 14 mm, 15 mm, and 16 mm) and three inlet pressure values (P_i = 10 bar, 12 bar, and 15 bar). The results show that the Venturi injector performance is highly sensitive to the interaction between geometric and operating parameters. Increasing the inlet pressure from 10 bar to 15 bar resulted in approximately a 20% increase in maximum velocity and a 40–45% increase in vacuum pressure in the suction line. Among the investigated configurations, the nozzle diameter of 15 mm provided the most balanced flow structure, producing the highest pressure drop at the throat and the most stable suction behavior. Transient analyses revealed that suction formation occurs rapidly after flow initiation and remains stable throughout the operation period, indicating hydrodynamically stable injector performance under optimal conditions. The optimum operating point is identified as a nozzle diameter of 15 mm and an inlet pressure of 15 bar, where suction capacity is maximized and energy losses are minimized. The results provide a quantitative design guideline for the optimization of industrial Venturi injector system used in textile processing applications. Full article

In a standard diffuser system in a membrane bioreactor (MBR), uneven air distribution scouring the membrane surface causes transmembrane pressure to reach its ultimate value earlier, which requires membrane cleaning more frequently. In this study, a Venturi-integrated innovative diffuser design is proposed to improve membrane bioreactor (MBR) technology. The proposed design aims to increase filtration efficiency by creating a homogeneous scouring effect on the membrane surface. To compare the performance of the proposed diffuser configuration (V-MBR) with that of a conventional diffuser (S-MBR), computational fluid dynamics models were established for each of the two configurations. The results showed that the V-MBR model produced about 50% higher average shear stress on the membrane surfaces. Statistical analysis also showed that the V-MBR model generally produced low variance and non-zero shear stress values. Along with shear stress distribution, other parameters such as volume fraction, velocity, turbulent kinetic energy, and turbulent eddy distribution were evaluated to compare the performance of two diffuser system configurations. These parameters also supported the superior performance of the new V-MBR model over the conventional S-MBR. It is concluded that homogeneous shear stress distribution on the membrane surface is an important parameter that increases filtration efficiency by preventing the formation of dead zones. Full article

Fertilizer suction flow rate is an important performance parameter of the Venturi fertilizer applicator. This study aims to analyze the optimal structure of the Venturi fertilizer applicator with the goal of maximizing the suction flow rate at the same inlet and outlet pressures. A Venturi tube was used as a simplified case for investigating the Venturi injector. A calculation formula for the head loss between the inlet and outlet of the Venturi tube was derived based on the Bernoulli equation and the Darcy–Weisbach formula. Subsequently, it was modified through regression analysis based on the experimental and numerical simulation results of the flow on the Venturi tube. The optimal structure of the Venturi injector was further analyzed based on the head loss calculation formula. The optimal range for the reducing angle and expanding angle of the Venturi injector were determined to be 20–28° and 6–10°, respectively. The optimal throat diameter was identified to be 5–7 mm when the inlet flow rates were within the range of 1.5–2.5 m³/h. The optimum suction pipe diameter and throat pipe length were both equal to the throat diameter. Full article

This work involves the development of a hydrodynamic fertilizer injector (HFI), which uses an integrated axial-flow turbine (AFT) and a diaphragm pump to absorb liquid fertilizer. Three structural parameters—the number of impellers (M₁), average number of blades per impeller (M₂), and arrangement pattern (M₃)—are considered, and 12 AFT designs are developed. Using a combination of CFD numerical simulations and hydraulic performance testing, the response of the AFT output power (P), blade negative pressure (NP), and fertilizer injection flow rate (Q_inj) to structural parameters and inlet pressure (H) is investigated. The results show that the normalized root mean square error between the simulated outlet flow rate (Q_s) and the measured flow rate (Q_m) is 5.1%, indicating high accuracy in the grid motion simulation method. P increases first and then decreases with the increase in impeller speed (n). The maximum P (P_max) ranges from 150.1 to 201.4 W. P_max increases with H, decreases with increasing M₁ and M₂, and shows little change with M₃. At H = 0.14 MPa, M₁ and M₂ have a significant influence, and at H ≥ 0.14 MPa, M₁ becomes the most significant factor (p < 0.05). Low-speed flow and negative pressure cavitation zones at the leading edge of the blade suction surface cause flow blockage and affect the lifespan of the AFT. These regions decrease in size as H increases but increase with M₁. The negative pressure (NP) decreases as M₂ increases. When M₁, M₂, and M₃ are 2, 3, and identical (D33), the P_max of the AFT is maximized, increasing by 6.7% to 33.5% compared with those of the other combinations. The Q_inj of D33, D34, D43, and D44 at H = 0.12~0.18 MPa range from 288.6 to 847.3 L/h, which is 38.7% to 461.0% higher than that of domestic and international venturi injectors. When considering cavitation issues and the manufacturing cost of the AFT mold, D44 may be chosen. Although its Q_inj is 7.0% lower than that of D33, NP is reduced by 37.9%. These findings provide a basis for the development of the HFI with AFT as the driving unit. Full article

To enhance the hydraulic performance of the Venturi injector, the effects of the structural parameters were investigated using response surface methodology (RSM) and computational fluid dynamics (CFD) simulations. The fertilizer suction chamber diameter, contraction angle, and throat diameter ratio were chosen as variables, while the suction flow rate, suction concentration, and suction efficiency were selected as performance indicators. Multiple regression models were established, and the regression models were used for parameter optimization and experimental verification. The results showed that under the same inlet-outlet differential pressure, with the increase in the fertilizer suction chamber diameter, contraction angle, and throat diameter ratio, the suction flow rate, suction concentration, and suction efficiency showed a trend of first increasing and then decreasing, and there were peaks in suction performance. Predictive regression equations were established for the suction flow rate, concentration, and efficiency within the experimental parameter range. The determination coefficients of the three regression equations were 0.9987, 0.9961, and 0.9990, respectively, which indicated that the established regression equations could be used for performance prediction. The optimized combination of structural parameters included a fertilizer suction chamber diameter of 32 mm, a contraction angle of 35°, and a throat diameter ratio of 2.93. The error between the predicted and experimental values was less than 3%, indicating a high level of reliability in the predictive regression model. The performance indicators of the optimized Venturi injector were significantly improved, with an increase of 124.1~793.7 L h⁻¹ in the suction flow rate, 9.52~16.42 percentage points in suction concentration, and 5.4~9.19 percentage points in suction efficiency. Full article

The gas–liquid Venturi injector has been widely applied in industrial production due to its advantages of high entrainment and low energy consumption. In this study, Computational Fluid Dynamics (CFD) was employed to investigate the effect of the gas–liquid interface structure within the mixing section on entrainment behavior by varying the geometry of the mixing section during gas–liquid coaxial flow. The simulation results indicate that along the jet direction, the gas–liquid interface generally transitions from a smooth cylindrical shape to a lobed structure in the mixing section. Surface waves mainly appear in the lobed region. Furthermore, lobed and surface wave structures reduce pressure loss and enhance entrainment. Additionally, the study found that longer mixing sections enhance entrainment under low flow resistance. This study provides valuable insights for achieving high jet entrainment and offers supplementary research on gas–liquid interface structures in jets constrained by solid boundaries. Full article

Recent studies have increasingly focused on integrating detonation processes into engine technologies, advancing beyond the fundamental research phase of detonation research. The present study investigates the detonability and combustion characteristics of liquid fuels, specifically ethanol, with an emphasis on the effects of atomization properties facilitated by different atomizer designs to implement pulse detonation combustion engines. Oxygen was used as the oxidizer. We employed internal injectors (I45, I90, IB4) and atomizer venturis (VA, VB, VR) to examine how variations in liquid fuel atomization and atomizer configurations influence detonation. The occurrence of detonation was assessed using predicted Sauter mean diameters (SMDs) and exit velocities for different atomizer setups. Additionally, we evaluated the effects of nitrogen dilution at concentrations of 0%, 25%, and 50% on velocity variations and changes in detonation characteristics. The findings suggest that while higher exit velocities decrease SMD, facilitating detonation, excessively high velocities hinder detonation initiation. Conversely, lower exit velocities emphasize the role of SMD in initiating detonation. However, the introduction of nitrogen, which reduces the SMD, was found to decrease reactivity and impede detonation. Full article

Detonation engines are gaining prominence as next-generation propulsion systems that can significantly enhance the efficiency of existing engines. This study focuses on developing an injector utilizing liquid fuel and a gas oxidizer for application in detonation engines. In order to better understand the spray characteristics suitable for the pulse detonation engine (PDE) system, an injector was fabricated by varying the Venturi nozzle exit diameter ratio and the geometric features of the fuel injection hole. Analysis of high-speed camera images revealed that the Venturi nozzle exit diameter ratio plays a crucial role in determining the characteristics of air-assist or air-blast atomization. Under the conditions of an exit diameter ratio of R_e/R_i = 1.0, the formation of a liquid film at the exit was observed, and it was identified that the film’s length is influenced by the geometric characteristics of the fuel injection hole. The effect of the fuel injection hole and Venturi nozzle exit diameter ratio on SMD was analyzed by using droplet diameter measurement. The derived empirical correlation indicates that the atomization mechanism varies depending on the Venturi nozzle exit diameter ratio, and it also affects the distribution of SMD. The characteristics of the proposed injector, its influence on SMD, and its velocity, provide essential groundwork and data for the design of detonation engines employing liquid fuel. Full article

A significant amount of energy in wastewater treatment plants is spent on aeration to treat the organic matter with microorganisms in an oxygen-enriched environment. In this study, a novel and simplistic aeration concept known as Confined Tube Aeration (CTA) is proposed, in which the main elements are a Venturi injector and a coiled tube at its outlet. Two Venturi injector diameters were chosen for evaluation in this study, measuring 1 inch (25.4 mm) and 4 inch (101.6 mm). In this study, a relationship was developed between air suction rate and pressure differential across the injector. Then, a numerical model was developed to analyze hydrodynamic conditions and evaluate system performance. The main findings are that the larger diameter aerator performs 20% better than the smaller injector in terms of standard aeration efficiency (SAE), with a maximal value of 0.74 kgO₂/kWh found for the larger diameter system. These results suggest that future SAE improvements may be made for larger diameter systems in full-scale wastewater treatment applications with suitably designed injectors. Full article

Additive manufacturing technologies such as directed energy deposition use powder as their raw material, and it must be deposited in a precise and controlled manner. Venturi injectors could be a solution for the highly precise transport of particulate material. They have been studied from different perspectives, but they are always under high-pressure conditions and mostly fed by gravity. In the present study, an optimization of the different dimensional parameters needed for the manufacturing of a Venturi injector in relation to a particle has been carried out to maximize the amount of powder capable of being sucked and transported for a specific flow in a low-pressure system with high precision in transport. For this optimization, simulations of Venturi usage were performed using the discrete element method, generating different variations proposed by a genetic algorithm based on a preliminary design of experiments. Statistical analysis was also performed to determine the most influential design variables on the objective, with these being the suction diameter (D3), the throat diameter (d2), and the nozzle diameter (d1). The optimal dimensional relationships were as follows: a D3 34 times the particle diameter, a d2 26.5 times the particle diameter, a d1 40% the d2, a contraction angle alpha of 18.73°, and an expansion angle beta of 8.28°. With these proportions, an 85% improvement in powder suction compared to the initial attempts was achieved, with a maximum 2% loss of load. Full article

Aerated drip irrigation is rendered as a new water-saving irrigation method based on drip irrigation technology, which is endowed with the function of effectively alleviating the problem of rhizosphere hypoxia in crop soil, enhancing the utilization rate of water and fertilizer; as a result, it improves the harvest and quality of crops. However, clogged emitters are important indexes, among others, that pose an influence to the service effect and life duration of drip irrigation systems. At present, the working principle and mechanism of the influence of air feeding on the blockage of drip irrigation emitters remain unclear. Therefore, based on the two gas filling methods of the micro/nano bubble generator and Venturi injector, the dynamic change process for the average flow ratio of an air-filled drip irrigation emitter was studied by the method of emitter plugging test. 16S rRNA sequencing was used to analyze the microbial diversity of the emitter plugs. The results show that the air injection can pose influence on the clogging procedure of drip irrigation emitters, and more importantly, it makes the distribution of blocked emitters more uniform, thus improving the uniformity of the system. Different filling methods have different effects on the blockage of the emitter. Among them, the blockage time of drip irrigation system under the micro/nano aerated drip irrigation (MAI) mode is 5.73 times longer than that under unaerated drip irrigation (UVI), and similarly, Venturi gas drip irrigation (VAI) is close to that under UVI. The filling method changed the microbial diversity of the blockage in the emitter. Among them, the number of operational taxonomic unit (OTU) unique to MAI was 2.1 times that of UVI, and the number of OTU unique to VAI was 1.3 times that of UVI. Meanwhile, gas addition will inhibit the growth of Nitrospirae and Proteobacteria microbial communities and promote the growth of Firmicutes and Actinobacteria microbial communities. Furthermore, the increase in microbial extracellular polymer in the plugging material of the emitter was inhibited and the plugging process of the emitter was slowed down. The research results are of great significance in the disclosure of the clogging mechanism of drip irrigation emitter and constructing the green, anti-blockage technology of aerated drip irrigation. Full article

In order to improve the working performance of an Alfalfa air conveyor, a type of horizontal screw conveyor with a seed stirring function was designed. The working process of the horizontal screw conveyor was co-simulated by EDEM software and ADAMS software. The effects of a seed stirring mechanism on population movement characteristics, population stress, the seed mass flow rate and the variation coefficient of each index were obtained. The results showed that the stirring mechanism can effectively improve the mobility of the population, reduce the local dead zone of the population, and increase the material filling coefficient between the spiral blades. Under the same working conditions, the horizontal screw conveyor with a stirring mechanism has a higher conveying efficiency and better conveying uniformity. In order to optimize the structure parameters of the Venturi injector diffuser and improve seeding efficiency and uniformity, EDEM software and Fluent software were used to co-simulate the seeding process. The influence of diffuser structure parameters on the working performance of the Venturi injector was analyzed by taking the changes in pressure and velocity in the inner flow field of the pipeline and the velocity and force of seed particles as indices. The results showed that when the diffusion angle is 5°, the length of the diffusion section is 200 mm and the length of the mixing section is 50 mm, the pressure loss of the Venturi ejector is the smallest, the outlet air velocity is the largest, the uniformity of seed feeding is the best and the seed feeding efficiency is the highest. Taking the inlet air pressure and particle feeding efficiency as test factors and the variation number of ejector discharge as test index, a two-factor and five-level full factor test was carried out, and the range and variance analyses were carried out. The results showed that the seed feeding rate and the inlet wind pressure had significant effects on the coefficient of variation. The optimal combination of working parameters was 1.6 kpa inlet wind pressure and 1.8 g/s particle feeding efficiency. Full article

Fertigation technology is key to solve water pollution and inefficient fertilizer use. However, some early techniques cannot adapt to the current situation of labor shortages and large-scale planting. Therefore, it is necessary to consider farmers’ willingness to adopt more adaptive techniques. Specifically, we focus on whether early technology adoption will hinder technology renewal and whether the factors affecting the adoption of early and latest techniques are consistent. Through theoretical analysis and a survey, we find that farmers’ endowments such as income and labor force only affect the adoption intentions to the high-cost technique (Intelligent Irrigation Control System), but not early techniques (Venturi injector and Differential pressure tank), while farmers’ information processing ability and information acquisition channels affect both. Finally, the results of Propensity Score Matching show that early technology adoption will not become an obstacle to technology renewal. Full article

To study the appropriate numerical simulation methods for venturi injectors, including the investigation of the hydraulic performance, mixing process, and the flowing law of the two internal fluids, simulations and experiments were conducted in this study. In the simulations part, the cavitation model based on the standard k–ε turbulence and mixture models was added, after convergence of the calculations. The results revealed that the cavitation model has good agreement with the experiment. However, huge deviations occurred between the experimental results and the ones from the calculation when not considering the cavitation model after cavitation. Thus, it is inferred that the cavitation model can exactly predict the hydraulic performance of a venturi injector. In addition, the cavitation is a crucial factor affecting the hydraulic performance of a venturi injector. The cavitation can ensure the stability of the fertilizer absorption of the venturi injector and can realize the precise control of fertilization by the venturi injector, although it affects the flow stability and causes energy loss. Moreover, this study found that the mixing chamber and throat are the main areas of energy loss. Furthermore, we observed that the internal flow of the venturi injector results in the majority of mixing taking place at the diffusion and outlet sections. Full article