scholarly journals Control of Wall Pressure Flow Field with Micro Jets and Control Effectiveness

2016 ◽  
Vol 16 (053) ◽  
pp. 99-107 ◽  
Author(s):  
Musavir Bahir ◽  
Qummare Azam ◽  
S. A. Khan ◽  
M. Ahmed Ali Baig
Keyword(s):  
Flow Field ◽  
Wall Pressure ◽  
Pressure Flow ◽  
Control Effectiveness ◽  
And Control

scholarly journals Active Control of Wall Pressure Flow Field at Low Supersonic Mach Numbers

2016 ◽  
Vol 16 (053) ◽  
pp. 90-98 ◽  
Author(s):  
Mohammed Asad Ullah ◽  
Musavir Bashir ◽  
Ayub Janvekar ◽  
S. A. Khan
Keyword(s):  
Flow Field ◽  
Active Control ◽  
Wall Pressure ◽  
Pressure Flow ◽  
Mach Numbers

scholarly journals Analysis and control of flow at suction connection in high-speed centrifugal pump

2017 ◽  
Vol 9 (1) ◽  
pp. 168781401668529 ◽  
Author(s):  
Wen-wu Song ◽  
Li-chao Wei ◽  
Jie Fu ◽  
Jian-wei Shi ◽  
Xiu-xin Yang ◽  
...  
Keyword(s):  
Flow Field ◽  
Centrifugal Pump ◽  
High Speed ◽  
Internal Flow ◽  
Orifice Plate ◽  
Centrifugal Pumps ◽  
Pressure Area ◽  
Negative Effect ◽  
And Control ◽  
Experimental Data Analysis

The backflow vortexes at the suction connection in high-speed centrifugal pumps have negative effect on the flow field. Setting an orifice plate in front of the inducer is able to decrease the negative effect caused by backflow vortexes. The traditional plate is able to partially control the backflow vortexes, but a small part of the vortex is still in the inlet and the inducer. Four new types of orifice plates were created, and the control effects on backflow vortexes were analyzed. The ANSYS-CFX software was used to numerically simulate a high-speed centrifugal pump. The variations of streamline and velocity vectors at the suction connection were analyzed. Meanwhile, the effects of these plates on the impeller pressure and the internal flow field of the inducer were analyzed. Numerically, simulation and experimental data analysis methods were used to compare the head and efficiency of the high-speed pumps. The results show that the C-type orifice plate can improve the backflow vortex, reduce the low-pressure area, and improve the hydraulic performance of the high-speed pump.

scholarly journals Experimental Research of Wall Pressure Distribution and Effect of Micro Jet at Mach 1.5

2019 ◽  
Vol 8 (2S3) ◽  
pp. 1000-1003 ◽  
Keyword(s):  
Adverse Effect ◽  
Flow Field ◽  
Pressure Distribution ◽  
Area Ratio ◽  
Wall Pressure ◽  
Rapid Expansion ◽  
Base Region ◽  
Active Controls ◽  
Circle Diameter

In this paper, a study on the effect of the control on the wall pressure as well as the quality of the flow when tiny jets were employed. The small jet aimed to regulate the base pressure at the base region of the suddenly expanded duct and wall pressure distribution is carried out experimentally. The convergent-divergent (CD) nozzle with a suddenly expanded duct was designed to observe the wall pressure distribution with and without control using small jets. In order to obtain the results with the effect of controlled four tiny jets of 1 mm diameter located at a ninety-degree interval along a pitch circle diameter (PCD) of 1.3 times the CD nozzle exit diameter in the base, region was employed as active controls. The Mach numbers of the rapidly expanded are 1.5. The jets were expanded quickly into an axis-symmetry duct with an area ratio of 4.84. The length-todiameter (L/D) ratio of the rapid expansion duct was diverse from 10 to 1. There is no adverse effect due to the presence of the tiny jets on the flow field as well as the quality of the flow in the duct

scholarly journals Stochastic Estimation and Non-Linear Wall-Pressure Sources in a Separating/Reattaching Flow

2002 ◽  
Author(s):  
A. Naguib ◽  
L. Hudy ◽  
W. M. Humphreys
Keyword(s):  
Flow Field ◽  
Surface Pressure ◽  
Wall Pressure ◽  
Stochastic Estimation ◽  
Piv Measurements ◽  
Non Linear ◽  
The Mean ◽  
The Individual ◽  
Plate Geometry ◽  
Shed Light

Simultaneous wall-pressure and PIV measurements are used to study the conditional flow field associated with surface-pressure generation in a separating/reattaching flow established over a fence-with-splitter-plate geometry. The conditional flow field is captured using linear and quadratic stochastic estimation based on the occurrence of positive and negative pressure events in the vicinity of the mean reattachment location. The results shed light on the dominant flow structures associated with significant wall-pressure generation. Furthermore, analysis based on the individual terms in the stochastic estimation expansion shows that both the linear and non-linear flow sources of the coherent (conditional) velocity field are equally important contributors to the generation of the conditional surface pressure.

Experimental and numerical investigation of the transient characteristics and volute casing wall pressure fluctuations of a single-blade pump

2018 ◽  
Vol 233 (2) ◽  
pp. 280-291 ◽  
Author(s):  
Steffen Melzer ◽  
Tim Müller ◽  
Stephan Schepeler ◽  
Tobias Kalkkuhl ◽  
Romuald Skoda
Keyword(s):  
Flow Field ◽  
Boundary Conditions ◽  
Numerical Simulations ◽  
Pressure Fluctuations ◽  
Wall Pressure ◽  
Pressure Amplitude ◽  
Centrifugal Pumps ◽  
Transient Pressure ◽  
Time Step ◽  
Wall Pressure Fluctuations

In contrast to conventional multiblade centrifugal pumps, single-blade pumps are characterized by a significant fluctuation of head and highly transient and circumferentially nonuniform flow field even in the best-efficiency point. For a contribution to a better understanding of the flow field and an improvement of numerical methods, a combined experimental and numerical study is performed with special emphasis on the analysis of the transient pressure field. In an open test rig, piezoresistive pressure sensors are utilized for the measurement of transient in- and outflow conditions and the volute casing wall pressure fluctuations. The quality of the numerical simulations is ensured by a careful adoption of the real geometry details in the simulation model, a grid study and a time step study. While the power curve is well reproduced by the numerical simulations, the time-averaged head is systematically overpredicted, probably due to underestimation of losses. Transient pressure boundary conditions for the numerical simulation show a better prediction of the measured pressure amplitude than constant boundary conditions, whereas the time-averaged head prediction is not improved. For a more accurate prediction of the transient flow field and the time-averaged characteristics, the utilization of scale-resolving turbulence models is assumed to be indispensable.

CFD-Based Hydrodynamic Analysis for a Ship Sailing Along a Bank in Restricted Waters

2013 ◽  
Vol 155 (A2) ◽  
Keyword(s):  
Flow Field ◽  
Physical Mechanism ◽  
Control Force ◽  
Hydrodynamic Analysis ◽  
Bank Effect ◽  
Ship Steering ◽  
Control Devices ◽  
Cfd Method ◽  
And Control ◽  
Water Depths

For a ship navigating along a bank in restricted waters, it is usually accompanied by obvious bank effect which may cause ship-bank collision. In order to avoid collision, it is necessary to provide control force and moment by using control devices such as a rudder. In this paper, CFD method is applied to numerically simulate the viscous flow around a ship appended with a rudder sailing along a bank. Systematical simulations are carried out for the hull-rudder system with different rudder angles at different ship-bank distances and water depths. The flow field features and the hydrodynamic forces of the hull-rudder system are obtained and analysed. This study is of significance for revealing the physical mechanism behind the bank effect and providing guidance for ship steering and control in restricted waters.

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