Study on Influence of Nozzle Structure on Flow in Diesel Nozzle Orifice

2012 ◽  
Vol 246-247 ◽  
pp. 127-130
Author(s):  
Bing Li ◽  
Xue Song Hu ◽  
Xiao Feng Cao ◽  
Gui Qi Jia ◽  
Fang Xi Xie ◽  
...  
Keyword(s):  
Flow Characteristics ◽  
Internal Flow ◽  
Key Factors ◽  
Complex Flow ◽  
Two Phase ◽  
Nozzle Orifice ◽  
Fuel Flow ◽  
Flow Features ◽  
Diesel Nozzle ◽  
Nozzle Hole

The fuel flow characteristics in diesel nozzle orifice are key factors to the atomization of fuel near the nozzle orifice. In the paper, two-phase flow model is used to simulate the complex flow features in nozzle orifice, and to study the influences of the relative position of nozzles orifice axis and nozzle axis, and inclination angle of nozzle hole on the internal flow feature.

Research Analysis and Experiment Study on Flow Field of Hydrodynamic Coupling

2011 ◽  
Vol 418-420 ◽  
pp. 2006-2011
Author(s):  
Rui Zhang ◽  
Cheng Jian Sun ◽  
Yue Wang
Keyword(s):  
Flow Field ◽  
Cfd Simulation ◽  
Two Phase Flow ◽  
Three Dimensional ◽  
Internal Flow ◽  
Phase Flow ◽  
Complex Flow ◽  
Two Phase ◽  
Operation Conditions ◽  
Hydrodynamic Coupling

CFD simulation and PIV test technology provide effective solution for revealing the complex flow of hydrodynamic coupling’s internal flow field. Some articles reported that the combination of CFD simulation and PIV test can be used for analyzing the internal flow field of coupling, and such analysis focuses on one-phase flow. However, most internal flow field of coupling are gas-fluid two-phase flow under the real operation conditions. In order to reflect the gas-fluid two-phase flow of coupling objectively, CFD three-dimensional numerical simulation is conducted under two typical operation conditions. In addition, modern two-dimensional PIV technology is used to test the two-phase flow. This method of combining experiments and simulation presents the characteristics of the flow field when charging ratios are different.

Internal flow and external jet characteristics of double serpentine nozzle with different aspect ratio

2017 ◽  
Vol 233 (2) ◽  
pp. 545-560 ◽  
Author(s):  
Sun Xiao-lin ◽  
Wang Zhan-xue ◽  
Zhou Li ◽  
Shi Jing-wei ◽  
Cheng Wen
Keyword(s):  
Aspect Ratio ◽  
Flow Characteristics ◽  
Internal Flow ◽  
Critical Parameters ◽  
Potential Core ◽  
Suppression Effect ◽  
Symmetric Plane ◽  
Flow Features ◽  
In Series ◽  
Jet Characteristics

In order to increase the survivability of the fighter aircraft, the serpentine nozzle has been applied in series of stealth bombers and unmanned aerial vehicles due to its excellent potentiality of evidently suppressing the infrared radiation signatures and radar cross section emitted by engine exhausts. Among the geometric parameters of the serpentine nozzle, the aspect ratio (AR) at the nozzle exit is one of the most critical parameters for the nozzle design as the infrared suppression effect could be greatly enhanced with the increment of AR by strengthening the mixing between the exhaust plume and atmosphere; the aim of this paper is to study the influence of the AR on the flow characteristics of the double serpentine nozzle. The flow features of six double serpentine convergent nozzles, i.e. AR = 3, 5, 7, 9, 11, 15 respectively, were numerically simulated with the shear stress transport κ–ω turbulent model adopted, which had been validated by the experimental data. The characteristics of internal flow and external jet, and the aerodynamic performances of these six nozzles were compared. Results show that the Ma contours at the symmetric plane are different due to the distinct flow accelerations caused by the change of the curvature and the duct height for diverse AR, and the surface pressure and the shock wave features are different correspondingly. The lateral divergence and the lateral convergence characteristics of the nozzle configuration lead to opposite lateral flow under diverse AR, and the change of lateral width induced different lateral pressure gradient, then lead to various lateral vortex distributions. The length of potential core is the contribution of the comprehensive effects of geometry parameters, and it is decreased with the increase of AR due to the dominated effect of the increased mixing area; however, the declining rate is slowed down. The AR of 5 should be chosen for the best aerodynamic performance of the double serpentine nozzle under the qualifications to completely shield the high-temperature turbine.

Influence of Screw Centrifugal Inducer on Internal Flow Structure of Vortex Pump

2020 ◽  
Vol 142 (9) ◽  
Author(s):  
Hui Quan ◽  
Jing Cheng ◽  
Ying Guo ◽  
Lei Kang ◽  
Guoyi Peng
Keyword(s):  
Energy Conversion ◽  
Flow Structure ◽  
Axial Force ◽  
Flow Characteristics ◽  
Internal Flow ◽  
Good Method ◽  
Power Capacity ◽  
Two Phase ◽  
Pump System ◽  
Vortex Pump

Abstract Installing an inducer upstream of the main impeller is an effective approach for improving the performances of a centrifugal pump. In order to study the influence of inducer on the internal flow characteristics and evolution of vortex pump, the numerical simulation and experimental test of the 150WX-200-20 vortex pump have been done by the principle of computational fluid dynamics, to acquire performance and internal flow structure change of the vortex pump with inducer and without inducer. Based on these, the energy conversion of vortex pump is combined with the changes of the through-flow and circulating-flow of the internal flow structure. Through analyzing the influence of inducer on it, the energy conversion characteristic of vortex pump is revealed. The results show that adding the inducer can guarantee the power capacity of the vortex pump and improve the anticavitation performance, so as to improve the pump head and flows. Equipped with suitable for transporting solid liquid two phase flow of the screw centrifugal inducer, it can effectively weaken the existence of circulating-flow and significantly improve the flow situation in the impeller field. Adding inducer can weaken axial force of vortex pump and enhance stability of pump. And under the condition of no clogging, the conclusions are of great significance for improving the power capacity and fluid energy conversion of the vortex pump. In addition, it is a good method to weaken the axial force of the pump and enhance the stability of the pump system by adding the inducer.

Effects of moisturized inflow on compressor performance and aerodynamic noise

2021 ◽  
Vol 263 (1) ◽  
pp. 5467-5474
Author(s):  
Changhong Sun ◽  
Yipeng Cao ◽  
Chen Liu
Keyword(s):  
Two Phase Flow ◽  
Flow Characteristics ◽  
Water Concentration ◽  
Internal Flow ◽  
Aerodynamic Noise ◽  
Outlet Temperature ◽  
Phase Flow ◽  
Two Phase ◽  
Flow Method ◽  
Compressor Performance

The effects of moisturized inflow on turbocharger compressor performance and aerodynamic noise were numerical analyzed in this paper. The gas-liquid two-phase flow method based on Euler-Lagrange model was firstly introduced. The influence of water concentration and water droplet diameter on compressor performance and internal flow characteristics at design speed were studied using the two-phase flow method. The compressor aerodynamic noise was also predicted at design condition under two different inflow conditions, including ideal inflow and moisturized inflow with 0.1% water concentration. The results indicate that moisturized inflow with an appropriate water concentration can reduce the outlet temperature of the compressor and improve the compressor performance, in which the water concentration is a dominant parameter. There is a phase transition process of water in the compressor with moisturized inflow, but moisturized inflow has little effects on the compressor internal flow characteristics. Moreover, the moisturized inflow also has influence on compressor aerodynamic noise.

NUMERICAL ANALYSIS OF THE INFLUENCE OF DIESEL NOZZLE DESIGN ON INTERNAL FLOW CHARACTERISTICS FOR 2-VALVE DIESEL ENGINE APPLICATION

2013 ◽  
Vol 23 (2) ◽  
pp. 97-118 ◽  
Author(s):  
Joaquin De la Morena ◽  
Kshitij Neroorkar ◽  
Alejandro H. Plazas ◽  
Richard C. Peterson ◽  
David P. Schmidt
Keyword(s):  
Diesel Engine ◽  
Numerical Analysis ◽  
Flow Characteristics ◽  
Internal Flow ◽  
Nozzle Design ◽  
Diesel Nozzle

Flow Characteristics of Double Serpentine Convergent Nozzle With Different Inlet Configuration

2018 ◽  
Vol 140 (8) ◽  
Author(s):  
Sun Xiao-Lin ◽  
Wang Zhan-Xue ◽  
Zhou Li ◽  
Shi Jing-Wei ◽  
Cheng Wen
Keyword(s):  
Flow Characteristics ◽  
Complex Flow ◽  
Convergent Nozzle ◽  
Core Flow ◽  
The Core ◽  
Setting Angle ◽  
Swirl Angle ◽  
Swirl Flows ◽  
Flow Features ◽  
Inlet Swirl

Serpentine nozzles have been used in stealth fighters to increase their survivability. For real turbofan aero-engines, the existence of the double ducts (bypass and core flow), the tail cone, the struts, the lobed mixers, and the swirl flows from the engine turbine, could lead to complex flow features of serpentine nozzle. The aim of this paper is to ascertain the effect of different inlet configurations on the flow characteristics of a double serpentine convergent nozzle. The detailed flow features of the double serpentine convergent nozzle including/excluding the tail cone and the struts are investigated. The effects of inlet swirl angles and strut setting angles on the flow field and performance of the serpentine nozzle are also computed. The results show that the vortices, which inherently exist at the corners, are not affected by the existence of the bypass, the tail cone, and the struts. The existence of the tail cone and the struts leads to differences in the high-vorticity regions of the core flow. The static temperature contours are dependent on the distributions of the x-streamwise vorticity around the core flow. The high static temperature region is decreased with the increase of the inlet swirl angle and the setting angle of the struts. The performance loss of the serpentine nozzle is mostly caused by its inherent losses such as the friction loss and the shock loss. The performance of the serpentine nozzle is decreased as the inlet swirl angle and the setting angle of the struts increase.

scholarly journals A Comparative Study on Centrifugal Pump Designs and Two-Phase Flow Characteristic under Inlet Gas Entrainment Conditions

Energies ◽  
2019 ◽  
Vol 13 (1) ◽  
pp. 65 ◽  
Author(s):  
Qiaorui Si ◽  
Gérard Bois ◽  
Minquan Liao ◽  
Haoyang Zhang ◽  
Qianglei Cui ◽  
...  
Keyword(s):  
Pressure Pulsation ◽  
Two Phase Flow ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Internal Flow ◽  
Phase Flow ◽  
Water Mixture ◽  
Centrifugal Pumps ◽  
Two Phase ◽  
Void Fractions

Capability for handling entrained gas is an important design consideration for centrifugal pumps used in petroleum, chemistry, nuclear applications. An experimental evaluation on their two phase performance is presented for two centrifugal pumps working under air-water mixture fluid conditions. The geometries of the two pumps are designed for the same flow rate and shut off head coefficient with the same impeller rotational speed. Overal pump performance and unsteady pressure pulsation information are obtained at different rotational speeds combined with various inlet air void fractions (α0) up to pump stop condition. As seen from the test results, pump 2 is able to deliver up to 10% two-phase mixtures before pump shut-off, whereas pump 1 is limited to 8%. In order to understand the physics of this flow phenomenon, a full three-dimensional unsteady Reynolds Average Navier-Stokes (3D-URANS) calculation using the Euler–Euler inhomogeneous method are carried out to study the two phase flow characteristics of the model pump after corresponding experimental verification. The internal flow characteristics inside the impeller and volute are physically described using the obtained air distribution, velocity streamline, vortex pattern and pressure pulsation results under different flow rates and inlet void fractions. Pump performances would deteriorate during pumping two-phase mixture fluid compared with single flow conditions due to the phase separating effect. Some physical explanation about performance improvements on handing maximum acceptable inlet two phase void fractions capability of centrifugal pumps are given.

The Influence of Actual Layout and Off-Axis Needle Stroke on Diesel Nozzle Flow Under Ballistic Needle Displacement

2013 ◽  
Vol 135 (10) ◽  
Author(s):  
Fulvio Palmieri
Keyword(s):  
Injection Pressure ◽  
Operating Conditions ◽  
Dynamics Modeling ◽  
Split Injection ◽  
Computational Fluid Dynamics Modeling ◽  
Fuel Flow ◽  
High Injection Pressure ◽  
Flow Features ◽  
Diesel Nozzle

The injection of small amount of diesel fuel relies on the shortening of energizing signal. In such injection conditions, the needle does not reach the mechanical stroke-end and its displacement is defined as ballistic. Some specific experimental work has been performed on how the dynamics of injector needle is reflected on the fuel flow pattern within the nozzle. Due to the intrinsic difficulties of the field, just single axial hole injectors have been optically investigated in real time, by means of the most advanced X-ray techniques. In the current study, based on 3D-computational fluid dynamics modeling, the investigation has been extended to multihole injector layouts, under typical pilot/split injection conditions, namely, high injection pressure and low needle lift. The role of different factors on the flow development within the nozzle has been shown and discussed; the investigations have taken into account actual injector tip layouts and the response to the needle off-axis operating conditions. Results are presented highlighting the flow features within the nozzle and their reflects on the hole-to-hole differences.

scholarly journals Effect of Fuel Mass Flow at the End of Injection on Cavitation and Gas Ingestion in the Nozzle

2020 ◽  
Vol 11 (1) ◽  
pp. 258
Author(s):  
Hua Wen ◽  
Yulong Jiang ◽  
Jinglong Ma
Keyword(s):  
Diesel Engine ◽  
High Speed ◽  
Internal Flow ◽  
Two Phase ◽  
Fuel Mass ◽  
Experimental Platform ◽  
Fuel Atomization ◽  
Fuel Flow ◽  
Mass Flows ◽  
Framing Camera

The fuel flow in the diesel engine nozzle has a vital impact on the fuel atomization and spray, and the fuel mass flux affects the internal flow of the nozzle. The visual experimental platform for a transparent nozzle was built to obtain the image of fuel flow in a nozzle with a small sac combining the back-light imaging technology and a high-speed framing camera. A two-phase three-component numerical model, based on the OpenFOAM solver, was calculated to quantitatively analyze gas ingestion and cavitation in the nozzle. The results indicate that at the end of injection (EOI), fuel cavitation and external air backflow (gas ingestion) occur successively in the nozzle, and both phenomena first appear in the orifice and then transition to the sac. Cavitation collapse is the major factor of gas ingestion, and the total amount of gas ingestion and cavitation mainly depends on the sac. The outflow of fuel largely depends on the total amount of cavitation and the inertial outflow of fuel at the EOI. The type of cavitation in the nozzle mainly presents annular and bulk cavitation, the former primarily exists in the sac, while the latter is established within the orifice. Therefore, larger mass flows will contribute to stronger cavitation and gas ingestion.

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