Studies on Unsteady Flow Characteristics in a High Pressure Turbine Cascade Based on a High-Order Large Eddy Simulation Turbulence Model

2012 ◽  
Vol 134 (5) ◽  
Author(s):  
Tomohiko Jimbo ◽  
Debasish Biswas ◽  
Yoshiki Niizeki
Keyword(s):  
Turbulence Model ◽  
Physical Process ◽  
Pressure Loss ◽  
Flow Behavior ◽  
Flow Analysis ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Measured Data ◽  
High Order ◽  
Loss Mechanism

In the present paper, unsteady viscous flow analysis around turbine blade cascade using a high-order LES turbulence model is carried out to investigate the basic physical process involved in the pressure loss mechanism. This numerical analysis is assessed to the wind tunnel cascade test. Basically, all the physical phenomena occurring in nature are the effect of some cause, and the effect can somehow be measured. However, to understand the cause, detail information regarding the visualization of the phenomena, which are difficult to measure, are necessary. Therefore, in the present paper, firstly the computed results are compared with the measured data, which are the final outcome of the cause (of the phenomena under investigation), to verify whether our physics-based model could qualitatively predict the measured facts or not. It was found that the present model could well predict measured data. Therefore, the rest of the computed information, which were difficult to measure, were used to visualize the overall flow behavior for acquiring some knowledge of the physical process associated with the pressure loss mechanism. The present study led to an understanding that the interaction of the vortex generated on the suction and pressure surface of the blade and the secondary vortex generated on the end wall, downstream of the trailing edge, resulted in the formation of a large vortex structure in this region. This unsteady three-dimensional flow characteristic is expected to play an important role in the pressure loss mechanism.

A High-Order LES Turbulent Model to Study Unsteady Flow Characteristics in a High Pressure Turbine Cascade

2008 ◽  
Author(s):  
Tomohiko Jimbo ◽  
Debasish Biswas ◽  
Yasuyuki Yokono ◽  
Yoshiki Niizeki
Keyword(s):  
Physical Process ◽  
Pressure Loss ◽  
Flow Behavior ◽  
Flow Analysis ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Measured Data ◽  
High Order ◽  
Turbulent Model ◽  
Loss Mechanism

In this work, unsteady viscous flow analysis around turbine blade cascade using a High-Order LES turbulent model is carried out to investigate basic physical process involved in the pressure loss mechanism. This numerical analysis is assessed to the wind tunnel cascade test. Basically, all the physical phenomena occurring in nature are the effect of some cause, and the effect can somehow be measured. However, to understand the cause, detail information regarding the visualization of the phenomena, which are difficult to measure, are necessary. Therefore, in our work, firstly the computed results are compared with the measured data, which are the final outcome of the cause (of the phenomena under investigation), to verify whether our physics-based model could qualitatively predict the measured facts or not. It was found that the present model could well predict measured data. Therefore, the rest of the computed information, which were difficult to measure, were used to visualize the overall flow behavior for acquiring some knowledge of the physical process associated with the pressure loss mechanism. Our study led to an understanding that the interaction of the vortex generated on the suction and pressure surface of the blade and the secondary vortex generated on the end-wall, downstream the trailing edge resulted in the formation of a large vortex structure in this region. This unsteady three-dimensional flow characteristic is expected to play an important role in the pressure loss mechanism.

Modeling and Computation of Flow in a Passage With 360-Degree Turning and Multiple Airfoils

1993 ◽  
Vol 115 (1) ◽  
pp. 103-108 ◽  
Author(s):  
W. Shyy ◽  
T. C. Vu
Keyword(s):  
Porous Medium ◽  
Global Analysis ◽  
Flow Behavior ◽  
Flow Analysis ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Hydraulic Turbine ◽  
Complex Flow ◽  
The Individual ◽  
Spiral Casing

The spiral casing of a hydraulic turbine is a complex flow device which contains a passage of 360-degree turning and multiple elements of airfoils (the so-called distributor). A three-dimensional flow analysis has been made to predict the flow behavior inside the casing and distributor. The physical model employs a two-level approach, comprising of (1) a global model that adequately accounts for the geometry of the spiral casing but smears out the details of the distributor, and represents the multiple airfoils by a porous medium treatment, and (2) a local model that performs detailed analysis of flow in the distributor region. The global analysis supplies the inlet flow condition for the individual cascade of distributor airfoils, while the distributor analysis yields the information needed for modeling the characteristics of the porous medium. Comparisons of pressure and velocity profiles between measurement and prediction have been made to assess the validity of the present approach. Flow characteristics in the spiral casing are also discussed.

The Influence of Transition on CFD Calculations of a Two-Stage Counter-Rotating Turbine

2014 ◽  
Author(s):  
M. Bugra Akin ◽  
Wolfgang Sanz
Keyword(s):  
Turbulence Model ◽  
Flow Analysis ◽  
Three Dimensional ◽  
Measurement Data ◽  
Flow Characteristics ◽  
Turbine Rotor ◽  
Navier Stokes ◽  
Experimental Investigations ◽  
Correct Prediction ◽  
Two Stage

Accurate numerical simulations depend on the correct prediction of all relevant flow phenomena. For many aeronautical devices such as turbomachinery the behaviour of boundary layers, wall shear stress and wall heat transfer are significant for the performance. Turbulence and transition may influence such flow characteristics. Onset and the extent of transition can therefore be of high importance for the design process. In this paper three-dimensional steady-state simulations of a two-stage turbine with and without modeling of transition are performed. The configuration consists of a transonic high pressure turbine stage followed by an S-shaped turning mid turbine frame and a counter-rotating low pressure turbine rotor. The in-house Reynolds-averaged Navier-Stokes solver has been applied to this configuration with the correlation based γ–Reθ transition model developed by Menter et al. which has been added to the SST turbulence model. Also, calculations without transition with the SST and the Spalart-Allmaras turbulence model have been performed. This configuration is also the subject of experimental investigations at the Institute for Thermal Turbomachinery and Machine Dynamics at Graz University of Technology, so that measurement data at two planes are used for the verification of the simulations. After verification and flow analysis, the results are also discussed to evaluate the effect of modeling transition phenomena. An analysis of the overall efficiency of the turbine and the efficiency losses in the blade and vane rows are finally presented.

Flow Behavior Around Stayvanes and Guidevanes of a Francis Turbine

1996 ◽  
Vol 118 (1) ◽  
pp. 110-115 ◽  
Author(s):  
Toshiaki Suzuki ◽  
Tomotatsu Nagafuji ◽  
Hiroshi Komiya ◽  
Takako Shimada ◽  
Toshio Kobayashi ◽  
...  
Keyword(s):  
Viscous Flow ◽  
Flow Behavior ◽  
Flow Analysis ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Francis Turbine ◽  
Good Prediction ◽  
Three Dimensional Flow ◽  
Dimensional Flow ◽  
Pressure Distributions

The three-dimensional computation of steady and incompressible internal flows is of interest in numerical simulations of turbomachinery, and such simulations are currently under investigation, from inviscid to viscous flow analyses. First, surface pressure distributions have been measured for the stayvanes and the guidevanes of a Francis turbine. They are presented to verify the numerical results. Second, both inviscid and viscous three-dimensional flow analyses have been made, so as to predict the flow behavior in the same domain. Comparison of the measured pressure distributions to the predicted pressure distributions has been made to study the usefulness of the present simulations. It can be pointed out that a global analysis which includes a runner flow passage, except runner blades, is necessary to predict the three-dimensional flow characteristics and that inviscid flow analysis has the capability of good prediction for flow without separation. Viscous flow analysis gives similar results, though it is necessary to investigate further the improvement of prediction accuracy. Flow characteristics around the stayvanes and the guidevanes are also discussed.

Numerical study of polymer melt flow in a three-dimensional sudden expansion: viscous dissipation effects

2014 ◽  
Vol 34 (8) ◽  
pp. 755-764
Author(s):  
Mustafa Tutar ◽  
Ali Karakus
Keyword(s):  
Viscous Dissipation ◽  
Stokes Equations ◽  
Numerical Study ◽  
Flow Behavior ◽  
Flow Analysis ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Polymer Melt ◽  
Sudden Expansion ◽  
Melt Flow

Abstract This numerical paper presents the effects of viscous dissipation on both hydrodynamic flow behavior and thermal flow characteristics of fluid included in rheological polymer flow analysis. The shear rate dependence of the viscosity is modeled using a modified form of the Cross constitutive equation, while the density changes are modeled using the modified Tait state of equation. The Navier-Stokes equations are solved in a sequential, decoupled manner with energy conservation equations using a finite volume method based fluid flow solver. Hydrodynamic and thermal boundary layer developments in an asymmetric sudden expansion for different velocity and melt flow injection temperature boundary and geometry conditions are determined under the influence of viscous dissipation effects and the results are compared with each other to measure the relative effects of viscous dissipation on the interactions of these layers for a commercial polymer melt flow, namely polypropylene (PP). The numerical results demonstrate that proposed mathematical and numerical formulations for viscosity and density variations including viscous heating terms lead to more accurate representation of the polymer melt flow and heat transfer phenomena in plane channels or mold cavity associated with a sudden expansion.

scholarly journals Investigation of Flow Behavior around Corotating Blades in a Double-Spindle Lawn Mower Deck

2005 ◽  
Vol 2005 (1) ◽  
pp. 77-89 ◽  
Author(s):  
W. Chon ◽  
R. S. Amano
Keyword(s):  
Flow Pattern ◽  
High Speed ◽  
Flow Behavior ◽  
Flow Analysis ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Video Camera ◽  
Sound Level ◽  
Lawn Mower ◽  
Level Meter

When the airflow patterns inside a lawn mower deck are understood, the deck can be redesigned to be efficient and have an increased cutting ability. To learn more, a combination of computational and experimental studies was performed to investigate the effects of blade and housing designs on a flow pattern inside a1.1mwide corotating double-spindle lawn mower deck with side discharge. For the experimental portion of the study, air velocities inside the deck were measured using a laser Doppler velocimetry (LDV) system. A high-speed video camera was used to observe the flow pattern. Furthermore, noise levels were measured using a sound level meter. For the computational fluid dynamics (CFD) work, several arbitrary radial sections of a two-dimensional blade were selected to study flow computations. A three-dimensional, full deck model was also developed for realistic flow analysis. The computational results were then compared with the experimental results.

Investigations on the Rotordynamic Characteristics of a Hole-Pattern Seal Using Transient CFD and Periodic Circular Orbit Model

2011 ◽  
Vol 133 (4) ◽  
Author(s):  
Xin Yan ◽  
Jun Li ◽  
Zhenping Feng
Keyword(s):  
Circular Orbit ◽  
Flow Analysis ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Numerical Approach ◽  
Deformation Method ◽  
Rotordynamic Coefficients ◽  
Forward Orbit ◽  
Reaction Forces ◽  
Orbit Model

Numerical investigations on the rotordynamic characteristics of a typical hole-pattern seal using transient three-dimensional Reynolds-averaged Navier–Stokes (RANS) solution and the periodic circular orbit model were conducted in this work. The unsteady solutions combined with mesh deformation method were utilized to solve the three-dimensional RANS equations and obtain the transient reaction forces on a typical hole-pattern seal rotor at five different excitation frequencies. The relation between the periodic reaction forces and frequency dependent rotordynamic coefficients of the hole-pattern seal was obtained by considering the rotor with a periodic circular orbit (including forward orbit and backward orbit) of the seal center. The rotordynamic coefficients of the hole-pattern seal were then solved based on the obtained unsteady reaction forces and presented numerical method. Compared with the experimental data, the predicted rotordynamic coefficients of the hole-pattern seal are more agreeable with the experiment than that of the ISO-temperature (ISOT) bulk flow analysis and numerical approach with one-direction-shaking model. Furthermore, the unsteady leakage flow characteristics in the hole-pattern seal were also illustrated and discussed in detail.

scholarly journals Design and analysis of flow rectifier of gas turbine flowmeter

2013 ◽  
Vol 17 (5) ◽  
pp. 1504-1507 ◽  
Author(s):  
Zhi-Fei Li ◽  
Zheng Du ◽  
Kai Zhang ◽  
Dong-Sheng Li ◽  
Zhong-Di Su ◽  
...  
Keyword(s):  
Experimental Data ◽  
Flow Field ◽  
Computational Model ◽  
Pressure Distribution ◽  
Gas Turbine ◽  
Turbulence Model ◽  
Pressure Loss ◽  
Three Dimensional ◽  
Turbine Flowmeter ◽  
Good Agreement

Three-dimensional computational model for a gas turbine flowmeter is proposed, and the finite volume based SIMPLEC method and k-? turbulence model are used to obtain the detailed information of flow field in turbine flowmeter, such as velocity and pressure distribution. Comparison between numerical results and experimental data reveals a good agreement. A rectifier with little pressure loss is optimally designed and validated numerically and experimentally.

CFD Analysis of Composite Axial Water Turbine

2010 ◽  
Author(s):  
Jifeng Wang ◽  
Norbert Mu¨ller
Keyword(s):  
Design Method ◽  
Flow Analysis ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Cfd Analysis ◽  
Computational Investigation ◽  
Rotating Speed ◽  
Fundamental Understanding ◽  
Water Turbine ◽  
Water Turbines

This paper presents computational investigation of the flow in composite material axial water turbines using Finite Volume based commercial CFD package namely Fluent. Based on three dimensional numerical flow analysis and fluid-structure interaction, the flow characteristics of water turbines including nozzle, impeller and diffuser are predicted. Two particulare cases are studied and compared. The extract power of water turbine in different rotating speed and water inlet velocity are analyzed. The calculated results will provide a fundamental understanding of the impeller as water turbine, and this design method is used to shorten the design period and improve the water turbine’s performance.

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