Effect Of Nozzle Structure Research Articles

Effects of Nozzle Structure on Bubble Deformation and Coalescence in Quiescent Liquid

Effects of Nozzle Structure on Bubble Deformation and Coalescence in Quiescent Liquid

Supersonic separation technology for carbon dioxide and hydrogen sulfide removal from natural gas

Abstract A cleaner approach was proposed for removing CO2 and H2S from highly acid natural gas by supersonic separation technology. For this purpose, different structures of Laval nozzles and supersonic swirling separation devices were designed. The mathematical models of gas flow in the nozzle were established, and the supersonic flow characteristics of CH4–H2S–CO2 ternary mixture were accurately predicted by adding the real gas state equation and the transport equation to describe the rotational and irrotational flow field. The effects of nozzle structure, swirl angle of static vanes and inlet parameters on the refrigeration performance of the nozzle and the separation characteristics of the swirl device were systematically investigated. The results show that the average temperature at the nozzle outlet can be as low as 135.2 K under the condition of inlet temperature 293.15 K, inlet pressure 4 MPa and 20 mol % acid gas. It indicates that the refrigeration effect produced by high speed expansion of acid natural gas in the supersonic nozzle can provide a favorable liquefying environment for the acid components, which confirms the feasibility of capturing acid components by supersonic separation device. Better refrigeration performance can be achieved in the nozzle with higher outlet Mach number, but the pressure recovery capacity of the device will be suppressed accordingly. As swirl angle increases from 73.90° to 81.79°, the maximum tangential velocity in the nozzle rises from 119.6 m/s to 212.5 m/s, the separation performance of the swirl device increases, while the pressure and temperature at the same location decrease slightly. However, the increase of swirl intensity will restrict the flow capacity of the separator. For the given supersonic swirling separation device, it shows a good adaptability in separation performance when changing the inlet parameters.

Effect of nozzle structure on coal breakage of SC-CO2 used for well drilling

Supercritical carbon dioxide (SC-CO2) jet is a promising technology for the extraction of coalbed methane. As a key component in the process of jet formation, the nozzle is an essential factor affecting the efficiency with which an SC-CO2 jet breaks coal and rock. The nozzle structure directly affects the energy conversion rate and flow field structure of the jet. Thus, the use of a suitable nozzle can maximize SC-CO2 energy utilization, reducing energy loss and engineering costs while achieving energy conservation and emission reduction. Based on the conical convergent nozzle and the Laval nozzles, this study conducted an SC-CO2 jet coal breakage experiment and an I-Scan pressure testing experiment using experimental research methods. The influence of nozzle structure on SC-CO2 jet coal breakage was studied and the results indicate that when the inlet pressure is constant, the Laval nozzle has a higher energy conversion rate and a stronger coal breakage effect than the conical convergent nozzle. Furthermore, considering the combined effects of the energy conversion rates of Laval nozzles and energy dissipation under ambient pressure, a key parameter for assessing Laval nozzles was discovered: the expansion ratio. The results indicate that the impact of jet temperature on the expansion ratio is small and that increasing the erosion effect of an SC-CO2 jet by increasing the jet temperature is an energy-consuming and inefficient method. Essentially, the optimum coal breakage effect of the SC-CO2 jet is obtained when the expansion ratio of the Laval nozzle is between 1.07 and 1.29.

Optimizing conical nozzle of venturi ejector in ejector loop reactor using computational fluid dynamics

The structure of a conical nozzle is critical to the gas induction of a venturi ejector. In this work, the effect of nozzle structure on the gas induction was investigated by means of multiphase CFD and validating experiments. Under different structures, the maximal gas induction was obtained through analyzing the nozzle outlet velocity (NOV), nozzle inlet velocity (NIV), as well as nozzle shrinking angle (NSA). The simulated inlet pressure is positively proportional to inlet flow rate, which is in good agreement with experimental results. The simulated results reveal that the inlet pressure and gas induction increase with the increasing NOV. Considering the operational characteristics of centrifugal pump, the recommended NOV is about 21.8 m/s. NIV and NSA show little impact on gas induction and inlet pressure. Based on the pipeline energy consumption, the recommended NIV is the same as the outlet velocity of centrifugal pump. The recommended NSA is about 20o to obtain the maximal gas induction.

The effect of nozzle structure and initial state on the primary breakup of diesel spray

The quality of atomization dominates the efficiency of combustion and the number of emissions. The primary breakup and nozzle internal flow with a single bubble under different location are studied by employing RNG k-ε and VOF models with experimental validation. The effects of nozzle structure (cylinder nozzle and conical nozzle), namely the convergence, are also investigated. The formation of C-shaped fuel dividing the bubble into three parts is analyzed. It is found that the thickness of the fuel film affects the formation of mushroom-shaped spray head due to the energy stored in the compressed bubble. The energy releases a lot when the bubble is far from the nozzle outlet and the energy is the lowest when the bubble is close to the nozzle outlet without enough compression. The second peak of the bubble area is lower when the bubble is far from the outlet inside the conical nozzle due to the acceleration effect. However, the second peak of the bubble area is higher when the bubble is at the middle location in the conical nozzle due to the compression from the environment gas. There is almost no difference between these two nozzles when the bubble is close to the outlet.

Combustion Characteristics in Growth Chamber for Verneuilgrown Rutile Crystal

Combustion characteristics of three-tube burner in growth chamber for preparation of single crystal by the Verneuil method were investigated, and the effects of nozzle structure and flow rate on the surface temperature of molten cap were analyzed. The results showed that hydrogen flowed out from the nozzle diffused with inner and outer oxygen, and two flame produced in the center and near the wall of growth chamber. The surface temperature of molten cap were gradually reduced from the center outward. The temperature of molten cap decreased gradually with increasing the nozzle aperture of inner oxygen, and varied slightly with the diameter of hydrogen and outer oxygen nozzle. The temperature of molten cap decreased gradually with increasing the flow rate of inner and outer oxygen, while increased with the flow rate of hydrogen.

Effects of nozzle structure on the gas mixture uniformity of marine gas engine

Natural gas is a preferred fuel choice owing to its easy availability, clean combustion, and low emission levels, especially in the field of marine engines. Recently, manifold multi-point gas injection technology was adopted by engine manufactures to improve the response of the marine gas engine to load changes and the consistency of gas fuel supplied to each cylinder. The characteristics of manifold gas injection have a significant influence on the combustion and emissions of marine gas engines. It is therefore vital to investigate the effect of gas nozzle structures on the gas mixture formation and combustion process. In this study, based on the validation through experimental method, a computational fluid dynamics simulation method was adopted to analyze the influence of the nozzle structure on the uniformity of the intake gas mixture in a natural gas engine, and the combustion process was analyzed to show the further effects of nozzle structure on combustion characteristics. The results show that, at high engine load, the structure of the cross multi-hole gas nozzle can help achieve a more homogeneous gas mixture, which is beneficial to the in-cylinder combustion; it yet yields higher NO emission. The single-hole gas nozzle structure yields an inhomogeneous mixture during the intake stroke and has negative effects on combustion. However, at lower engine load, employing a cross multi-hole gas nozzle results in the deposition of gas fuel residue in the intake port during the intake process, thereby inhibiting complete combustion. The structure of the single-hole gas nozzle can provide higher kinetic energy, which has positive effects on fuel intake efficiency and combustion intensity, although there is still an increased NO emission associated with it, owing to a higher cylinder temperature.

Research on the steam jet length with different nozzle structures

The effect of nozzle structure on the steam jet lengths of submerged condensation in quiescent water is investigated theoretically and experimentally. Two typical nozzles are analyzed and tested. Theoretical analysis shows that nozzle structure has a great influence on the steam jet length but was paid little attention before. Then a theoretical model for steam jet length with different nozzle structures is proposed based on the expansion and compression wave theory. Theoretical model indicates that steam jet length is greatly affected by nozzle structure. The steam jet length of straight pipe nozzle is longer than that of orifice nozzle under the same pool water temperature and steam mass flux, and the steam jet length is inverse proportion to the maximum expansion ratio, approximately. Then the theoretical model is verified by the experimental results. Finally, a universal semi-empirical correlation considering the nozzle structure is proposed. The prediction length corresponds to the experimental data very well and the discrepancy is within ±25% for different nozzle structures for the steam mass flux 400–800kg·m−2·s−1 and water temperature 10–70°C.

Influence of Internal Cavitating Flow of the Nozzle on Spray Characteristics in a Diesel Engine

Fuel atomization and penetration are known to significantly affect the combustion and emission processes in diesel engines. In the fuel supply system of diesel engines, the internal cavitaing flow of the nozzle is one of the most important effects on fuel spray characteristics. So it is necessary to simulate fuel spray coupling with internal cavitaing flow of the nozzle. In order to analyze the influence of cavitaing flow in the nozzle hole on spray, a coupling spray simulation was carried out with the output data of cavitaing flow in nozzles using FIRE v2010. The results of this work show that the characteristics of cavitating flow in orifice have an effect on both macroscopic properties, such as spray tip penetration and spray symmetry, and microscopic properties, like Sauter Mean Diameter-SMD. Moreover, the spray characteristics from three different types of nozzle were simulated to study the effect of nozzle structure on internal cavitating flow and subsequent spray, which supplies the theoretical foundation for the optimization design of the injector.

Effect of Nozzle Structure on Unstable Flow of Polymer Melts

Effect of Nozzle Structure on Unstable Flow of Polymer Melts