Laminar flow and pressure loss in planar Tee joints: Numerical simulations and flow analysis

An investigation of flow in valveless micropumps is presented. Numerical simulations are done using ANSYS. It is found that both laminar flow and turbulence phenomena would occurs in the diffuser/nozzle element. And SST (shear stress transport) turbulence model is chosen to be the most appropriate turbulence model,The simulations show when the opening angel gets bigger, the flow in the micropump, especially in the diffuser/nozzle becomes unsteady. When separation flow of fluid appears, pressure loss coefficient decreases rapidly.

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Review on the aerodynamics of intermediate compressor duct

JOURNAL OF MECHANICAL ENGINEERING AND SCIENCES ◽

10.15282/jmes.14.4.2020.13.0587 ◽

2020 ◽

Vol 14 (4) ◽

pp. 7446-7468

Author(s):

Manish Sharma ◽

Beena D. Baloni

Keyword(s):

High Pressure ◽

Pressure Loss ◽

Flow Analysis ◽

Outer Wall ◽

Optimization Techniques ◽

Optimum Pressure ◽

Research Areas ◽

Static Pressure Distribution ◽

High Pressure Compressor ◽

Pressure Compressor

In a turbofan engine, the air is brought from the low to the high-pressure compressor through an intermediate compressor duct. Weight and design space limitations impel to its design as an S-shaped. Despite it, the intermediate duct has to guide the flow carefully to the high-pressure compressor without disturbances and flow separations hence, flow analysis within the duct has been attractive to the researchers ever since its inception. Consequently, a number of researchers and experimentalists from the aerospace industry could not keep themselves away from this research. Further demand for increasing by-pass ratio will change the shape and weight of the duct that uplift encourages them to continue research in this field. Innumerable studies related to S-shaped duct have proven that its performance depends on many factors like curvature, upstream compressor’s vortices, swirl, insertion of struts, geometrical aspects, Mach number and many more. The application of flow control devices, wall shape optimization techniques, and integrated concepts lead a better system performance and shorten the duct length. This review paper is an endeavor to encapsulate all the above aspects and finally, it can be concluded that the intermediate duct is a key component to keep the overall weight and specific fuel consumption low. The shape and curvature of the duct significantly affect the pressure distortion. The wall static pressure distribution along the inner wall significantly higher than that of the outer wall. Duct pressure loss enhances with the aggressive design of duct, incursion of struts, thick inlet boundary layer and higher swirl at the inlet. Thus, one should focus on research areas for better aerodynamic effects of the above parameters which give duct design with optimum pressure loss and non-uniformity within the duct.

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Modeling and Numerical Simulations of an Active Vibration Isolation Module by the Power Flow Analysis

2020 3rd World Conference on Mechanical Engineering and Intelligent Manufacturing (WCMEIM) ◽

10.1109/wcmeim52463.2020.00120 ◽

2020 ◽

Author(s):

Yu Qiang ◽

Xu Deng-feng

Keyword(s):

Numerical Simulations ◽

Power Flow ◽

Vibration Isolation ◽

Flow Analysis ◽

Power Flow Analysis ◽

Active Vibration ◽

Active Vibration Isolation

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Unravelling turbulence near walls

Journal of Fluid Mechanics ◽

10.1017/s0022112009007708 ◽

2009 ◽

Vol 630 ◽

pp. 1-4 ◽

Cited By ~ 23

Author(s):

IVAN MARUSIC

Keyword(s):

Laminar Flow ◽

Turbulent Flow ◽

Numerical Simulations ◽

Turbulent Flows ◽

Direct Numerical Simulations ◽

Aircraft Wing ◽

Physical Mechanisms ◽

Drag And Lift

Turbulent flows near walls have been the focus of intense study since their first description by Ludwig Prandtl over 100 years ago. They are critical in determining the drag and lift of an aircraft wing for example. Key challenges are to understand the physical mechanisms causing the transition from smooth, laminar flow to turbulent flow and how the turbulence is then maintained. Recent direct numerical simulations have contributed significantly towards this understanding.

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Light transmission control technique and correlation with pressure loss characteristics of perforated panels for Hybrid Laminar Flow Applications

Aerodynamic Drag Reduction Technologies ◽

10.1007/978-3-540-45359-8_9 ◽

2001 ◽

pp. 71-78

Author(s):

B. Paluch

Keyword(s):

Laminar Flow ◽

Pressure Loss ◽

Light Transmission ◽

Control Technique ◽

Transmission Control

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Experimental and Numerical Study on Pressure Losses and Flow Fluctuations in a High-Pressure Valve Assembly of Steam Turbine Governing System

Volume 9: Oil and Gas Applications; Organic Rankine Cycle Power Systems; Steam Turbine ◽

10.1115/gt2020-14474 ◽

2020 ◽

Author(s):

Vaclav Slama ◽

Lukas Mrozek ◽

Bartolomej Rudas ◽

David Simurda ◽

Jindrich Hala ◽

...

Keyword(s):

High Pressure ◽

Flow Field ◽

Numerical Simulations ◽

Pressure Loss ◽

Operational Reliability ◽

Operating Conditions ◽

The Real ◽

Pressure Losses ◽

Flow Fluctuations ◽

Valve Assembly

Abstract Aerodynamic measurements and numerical simulations carried out on a model of a high-pressure valve assembly used for nozzle governing of a turbine with 135MW output are described in this paper. Aim of the study is to investigate effects of control valve’s strainers on pressure losses and unsteadiness in the flow field. It is an important task since undesirable flow fluctuations can lead to operational reliability issues. Measurements were carried out in the Aerodynamic laboratory of the Institute of Thermomechanics of the Czech Academy of Sciences (IT) where an aerodynamic tunnel is installed. Numerical simulations were carried out in the Doosan Skoda Power (DSP) Company using ANSYS software tools. The experimental model consists of one of two identical parts of the real valve assembly. It means it consists of an inlet pipeline, a stop valve, a valve chamber with two independent control valves, its diffusers and outlet pipelines. The numerical model consists of both assembly parts and includes also an A-wheel control stage in order to simulate the real turbine operating points. The different lifts of the main cone in each control valve for its useful combinations were investigated. Results were evaluated on the model with control valve’s strainers, which were historically used in order to stabilize the flow, and without them. The results of the experimental measurement were compared with the numerical results in the form of pressure losses prediction. From measured pressure fluctuations, it was found out where and for which conditions a danger of flow instabilities occurs. It can be concluded that there is a border, in terms of operating conditions, where the flow field starts to be unstable and this border is different dependent of the fact whether the control valve’s strainers are used or not. Therefore, the areas of safe and danger operational reliability can be predicted. The influence of the control valve’s strainers on the maximal amplitude of periodic fluctuations appears only for the cases when valves are highly overloaded. For normal operating conditions, there is no difference. As a result, the control valve’s strainers do not have to be used in standard applications of valve assemblies. Furthermore, a loss model for valve pressure loss estimation could be updated. Therefore, a pressure loss should be predicted with a sufficient accuracy for each new turbine bid with similar valve assemblies.

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A New Unified Approach for Flow Analysis of Magneto-Rheological Fluids

Aerospace ◽

10.1115/imece2004-60863 ◽

2004 ◽

Author(s):

Barkan M. Kavlicoglu ◽

Faramarz Gordaninejad ◽

Xiaojie Wang ◽

Gregory Hitchcock

Keyword(s):

Magnetic Field ◽

Surface Roughness ◽

Pressure Loss ◽

Flow Analysis ◽

Volumetric Flow Rate ◽

Mr Fluid ◽

Mason Number ◽

Universal Approach ◽

Shear Yield ◽

Magneto Rheological

The focus of this study is to develop a new universal approach for the flow analysis of magneto-rheological (MR) fluids through channels. An experimental study is conducted to investigate the relationship between the pressure loss of a MR fluid as a function of the applied magnetic field strength, volumetric flow rate, and surface roughness without utilizing the assumption of shear yield stress. A relation for nondimensional friction factor is developed in terms of Mason number and dimensionless surface roughness. It is demonstrated that the pressure loss across the MR fluid flow channel is significantly affected by the magnetic field and the surface roughness.

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Partitioning Waves and Eddies in Stably Stratified Turbulence

Atmosphere ◽

10.3390/atmos11040420 ◽

2020 ◽

Vol 11 (4) ◽

pp. 420 ◽

Cited By ~ 1

Author(s):

Henri Lam ◽

Alexandre Delache ◽

Fabien S Godeferd

Keyword(s):

Dispersion Relation ◽

Kinetic Energy ◽

Laminar Flow ◽

Turbulent Flow ◽

Numerical Simulations ◽

Direct Numerical Simulations ◽

Energy Concentration ◽

Kinetic Energy Density ◽

Stratified Turbulence ◽

The Waves

We consider the separation of motion related to internal gravity waves and eddy dynamics in stably stratified flows obtained by direct numerical simulations. The waves’ dispersion relation links their angle of propagation to the vertical θ , to their frequency ω , so that two methods are used for characterizing wave-related motion: (a) the concentration of kinetic energy density in the ( θ , ω ) map along the dispersion relation curve; and (b) a direct computation of two-point two-time velocity correlations via a four-dimensional Fourier transform, permitting to extract wave-related space-time coherence. The second method is more computationally demanding than the first. In canonical flows with linear kinematics produced by space-localized harmonic forcing, we observe the pattern of the waves in physical space and the corresponding concentration curve of energy in the ( θ , ω ) plane. We show from a simple laminar flow that the curve characterizing the presence of waves is distorted differently in the presence of a background convective mean velocity, either uniform or varying in space, and also when the forcing source is moving. By generalizing the observation from laminar flow to turbulent flow, this permits categorizing the energy concentration pattern of the waves in complex flows, thus enabling the identification of wave-related motion in a general turbulent flow with stable stratification. The advanced method (b) is finally used to compute the wave-eddy partition in the velocity–buoyancy fields of direct numerical simulations of stably stratified turbulence. In particular, we use this splitting in statistics as varied as horizontal and vertical kinetic energy, as well as two-point velocity and buoyancy spectra.

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