Parametric Effects on Internal Aerodynamics of Lobed Mixer-Ejector With Curved Mixing Duct

2014 ◽  
Vol 136 (6) ◽  
Author(s):  
Pan Cheng-xiong ◽  
Shan Yong ◽  
Zhang Jing-zhou
Keyword(s):  
Flow Characteristics ◽  
Internal Flow ◽  
Area Ratio ◽  
Mixing Efficiency ◽  
Straight Section ◽  
Streamwise Vortices ◽  
Thermal Mixing ◽  
Parametric Effects ◽  
Mixing Distance ◽  
Internal Aerodynamics

The internal flow characteristics inside lobed mixer-ejector with curved mixing duct and the parametric effects on the lobed mixer-ejector performance are investigated numerically and validated by experimental test. The curved mixing duct affects the development of the streamwise vortices induced by the lobed mixer. When the mixing process undergoes the transition from the straight section to the bent section, the flow inside the curved mixing duct is dominated by the impinging and centrifugal effects. In general, the pumping ratio is decreased approximately 20%–30% once the bent section is mounted on the straight duct. The mixer-ejector performance could by improved by increasing the straight section length, due to more fully momentum utilization of primary jet and weaker influence of bent section on the back pressure near nozzle exit. The mixer-ejector pumping capacity is also augmented with the increase of mixing duct area ratio until the area ratio is reached to 3.5. And the fully-utilization of primary jet momentum inside mixing duct with big area ratio needs long mixing distance. The pumping ratio is decreased as the increase of bent angle of curved mixing duct in approximately linear relationship. When the bent angle exceeds 45 deg, the thermal mixing efficiency is decreased rapidly as the increase of bent angle.

Study and Investigation on the Mach of Impeller Outlet and Diffuser Inlet in Stamping and Welding Centrifugal Pump

2012 ◽  
Vol 229-231 ◽  
pp. 2454-2458
Author(s):  
Jian Jun Gan ◽  
Jie Gang Mou ◽  
Shui Hua Zheng ◽  
Bo Zhu
Keyword(s):  
Centrifugal Pump ◽  
Experimental Research ◽  
Static Pressure ◽  
Flow Characteristics ◽  
Internal Flow ◽  
Area Ratio ◽  
Cfd Simulations ◽  
Impeller Outlet ◽  
And Performance

Based on CFD simulations and experimental research, this paper studied the mach of impeller outlet and diffuser inlet in stamping and welding centrifugal pump. The influence of area ratio Y of impeller outlet to diffuser inlet on pump internal flow characteristics and performance was studied. Five different area ratio pump models were analyzed. The results indicate that as the area ratio Y= F3/F2 increase, the velocity of fluid in diffuser inlet decreases continuously, the average static pressure of diffuser outlet increases, and the head and efficiency of the pump are risen. When the area ratio increases from Y=1.48 to Y=3.49, the head increases about 3.0% and the efficiency about 2.0%.

The near-field flow characteristics of some wall-mounted mixing tabs

1999 ◽  
Vol 103 (1023) ◽  
pp. 253-256
Author(s):  
S. C. M. Yu ◽  
L. P. Chua ◽  
E. K. Goh
Keyword(s):  
Boundary Layers ◽  
Near Field ◽  
Flow Characteristics ◽  
Vortex Generator ◽  
Internal Flow ◽  
Vortex Generators ◽  
Streamwise Vortices ◽  
Internal Flows ◽  
Distortion Control ◽  
Flow Feature

It is well known that passive vortex generators can be very effective in controlling separation by ‘re-energising’ the low momentum fluids at the boundary layers. They have been used extensively in many practical aerodynamic applications; both in external and internal flows. Typical examples include aerofoil stall alleviation and engine face distortion control in the jet aircraft intake during high angles of incidence. The general flow feature behind a vortex generator is that a pair of contra-rotating streamwise vortices would be formed which will significantly strengthen the flow at the boundary layers. However, the rationale for successful vortex generator designs is often poorly understood. In many cases, vortex generator designs have even been shown to be arbitrary. Anderson et al and Reichert and Wendt used rectangular fin and tapered fin vortex generators respectively, to eliminate the internal flow separation of S-shaped intake ducts. Both geometries were found to be equally effective. Weng and Guo successfully applied aerofoil shape type of vortex generators to suppress the swirl on the engine face of an S-shaped intake duct at high angles of incidence.

scholarly journals Measurementimprovement of flow quality of slotted test section in transonic wind tunnel

2021 ◽  
Vol 39 (3) ◽  
pp. 660-667
Author(s):  
Shenghao Wu ◽  
Jiming Chen ◽  
Qin Chen ◽  
Haitao Pei
Keyword(s):  
Mach Number ◽  
Wind Tunnel ◽  
Test Section ◽  
Experimental Studies ◽  
Flow Characteristics ◽  
Area Ratio ◽  
Straight Section ◽  
Flow Quality ◽  
Transonic Wind Tunnel

Experimental studies were carried out in the 0.6 m×0.6 m continuous transonic wind tunnel of CARDC in order to investigate the flow characteristics of the slotted test section. Experimental results show that the root-mean-square deviation of axial Mach number in the model area is above 0.01 when the test section Mach number is above 1.0.Numerical simulation under the same conditions to investigate the flow characteristics of the slotted section, together with the experimental studies indicate tow phenomena may directly cause the Mach number fluctuation. Firstly, a straight section was installed to connect the nozzle and the test section in the wind tunnel. Weak shock waves due to the curvature discontinuity at the joint of the test section and the straight section contribute to Mach number fluctuation. Secondly, the open-area ratio of both the upper and lower wall of test section, each with 8 slots, is of 10%. The larger porosity leads to stronger expansion waves in the acceleration zone located at the inlet of the test section. The flow was over accelerated because of the stronger expansion wave and thus fluctuate the flow field severely. Two measures were taken to improve the flow quality of the slotted test section based on the above-mentioned analysis: ①Flexible plate instead of solid straight plate was installed to bridge nozzle and test section to eliminate the curvature discontinuity; ②Decreasing the open-area ratio of the upper and lower test section wall to 6% and the number of slots to 6. Numerical and experimental results show that the Mach number fluctuation in the model area was suppressed to a satisfactory degree.

Effect of Core Flow Inlet Swirl Angle on Performance of Lobed Mixing Exhaust System

2016 ◽  
Vol 32 (3) ◽  
pp. 325-337 ◽  
Author(s):  
Y. Xie ◽  
C. Zhong ◽  
D.-F. Ruan ◽  
K. Liu ◽  
B. Zheng
Keyword(s):  
Total Pressure ◽  
Exhaust System ◽  
Mixing Efficiency ◽  
Streamwise Vortices ◽  
Recovery Coefficient ◽  
Core Flow ◽  
Thermal Mixing ◽  
Swirl Angle ◽  
Inlet Swirl ◽  
Pressure Recovery Coefficient

AbstractGeometric model of a lobed mixing exhaust system is created and its flow field is simulated by using the steady Reynolds Averaged Navier-Stokes (RANS) equations under the condition of different core flow inlet swirl angles. According to the numerical simulation results, due to the guidance effect of the lobe parallel side wall, the structure and vorticity of streamwise vortices change little near the lobe exit with inlet swirl angle, and it is the same with the thermal mixing efficiency. As the flow develops, although the inlet swirl angle has limited influence on the streamwise vorticity, it greatly affects the structure of streamwise vortices. It causes the thermal mixing efficiency to increase with the swirl angle. As for the total pressure recovery coefficient, it falls slightly when the inlet swirl strengthens. At the nozzle exit, the total pressure recovery coefficient of CFISA = 30° model is 0.5% lower than CFISA = 0° model. Moreover, as the inlet swirl strengthens, the thrust fall of lobed mixing exhaust system gradually accelerates, especially when the inlet swirl angle is over 15°.

scholarly journals Effect of Air Injection on the Internal Flow Characteristics in the Draft Tube of a Francis Turbine Model

Processes ◽  
2021 ◽  
Vol 9 (7) ◽  
pp. 1182
Author(s):  
Seung-Jun Kim ◽  
Yong Cho ◽  
Jin-Hyuk Kim
Keyword(s):  
Flow Rate ◽  
Draft Tube ◽  
Pressure Fluctuations ◽  
Flow Characteristics ◽  
Internal Flow ◽  
Air Injection ◽  
Low Flow ◽  
Francis Turbine ◽  
Navier Stokes ◽  
Vortex Rope

Under low flow-rate conditions, a Francis turbine exhibits precession of a vortex rope with pressure fluctuations in the draft tube. These undesirable flow phenomena can lead to deterioration of the turbine performance as manifested by torque and power output fluctuations. In order to suppress the rope with precession and a swirl component in the tube, the use of anti-swirl fins was investigated in a previous study. However, vortex rope generation still occurred near the cone of the tube. In this study, unsteady-state Reynolds-averaged Navier–Stokes analyses were conducted with a scale-adaptive simulation shear stress transport turbulence model. This model was used to observe the effects of the injection in the draft tube on the unsteady internal flow and pressure phenomena considering both active and passive suppression methods. The air injection affected the generation and suppression of the vortex rope and swirl component depending on the flow rate of the air. In addition, an injection level of 0.5%Q led to a reduction in the maximum unsteady pressure characteristics.

Internal Flow Characteristics of a Plastic Kaolin Suspension During Extrusion

2011 ◽  
Vol 95 (2) ◽  
pp. 494-501 ◽  
Author(s):  
Brooks D. Rabideau ◽  
Pascal Moucheront ◽  
François Bertrand ◽  
Stéphane Rodts ◽  
Yannick Mélinge ◽  
...  
Keyword(s):  
Flow Characteristics ◽  
Internal Flow ◽  
Kaolin Suspension

Numerical Simulation of Transient Flow Inside Nozzle on Gasoline Direct Injection Engine

2012 ◽  
Vol 466-467 ◽  
pp. 1237-1241
Author(s):  
Yan Hua Wang ◽  
Shi Chun Yang ◽  
Yun Qing Li
Keyword(s):  
Kinetic Energy ◽  
Transient Flow ◽  
Direct Injection ◽  
Flow Characteristics ◽  
Internal Flow ◽  
Turbulence Kinetic Energy ◽  
Gasoline Direct Injection ◽  
Injection Hole ◽  
Gasoline Direct Injection Engine ◽  
Nozzle Configuration

To achieve transient flow characteristics at exit of nozzle orifice on gasoline direct injection engine, two phase Euler-Euler schemes was used to simulate the internal flow of the swirl nozzle. Different flow characteristics were calculated in the simulation. Different kinds of nozzle configuration were studied. Cavitaion and swirl flow occured in the nozzles. Injection hole configuration matters more than area variation of swirl tangential slot to discharge coefficient of the studied nozzle. Discharge coefficient changes a little along the injection hole length. The area of the swirl tangrntial slot plays an important throttling action in nozzle internal flow. Smaller area of swirl tangential slot generates larger degree cavitation but smaller mean injection velocity. Turbulence kinetic energy changes with the time of cavitation and swirl field occurring and the nozzle configuration. Before the appearance of cavitation, smaller inclination angle of orifice can generate more turbulence kinetic energy. After that moment, turbulence kinetic energy varies with different configuration. Along injection hole length, turbulence kinetic energy obviously varies. These flow characteristics affect primary atomization and will be as input for next spray simulation. They are also applied to design reference for injection nozzle.

scholarly journals Numerical Simulation and Experimental Study on Flow Field in a Swirl Nozzle

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Yicheng Sun ◽  
Yufan Fu ◽  
Baohui Chen ◽  
Jiaxing Lu ◽  
Wanquan Deng
Keyword(s):  
Flow Field ◽  
Velocity Distribution ◽  
Flow Characteristics ◽  
Internal Flow ◽  
Low Pressure ◽  
External Flow ◽  
Droplet Velocity ◽  
Inlet Pressure ◽  
Outlet Section ◽  
Local Pressure

In order to study the internal flow characteristics and external droplet velocity distribution characteristics of the swirl nozzle, the following methods were used: numerical simulations were used to study the internal flow characteristics of a swirl nozzle and phase Doppler particle velocimetry was used to determine the corresponding external droplet velocity distribution under medium and low pressure conditions. The distributions of pressure and water velocity inside the nozzle were obtained. Meanwhile, the velocities of droplets outside the nozzle in different sections were discussed. The results show that the flow rate in the swirl nozzle increases with the increase in inlet pressure, and the local pressure in the region decreases because of the excessive velocity at the internal outlet section of the swirl nozzle, resulting in cavitation. The experimental results show that under an external flow field, the minimum droplet velocity occurs in the axial direction; starting from the axis, the velocity first increases and then decreases along the radial direction. Swirling motion inside the nozzle and velocity variations in the external flow field occur under medium and low pressure conditions. The relationship between the inlet pressure and the distributions of water droplets’ velocities was established, which provides a reference for the research and development of the swirl nozzle.

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