Performance and Flow Characteristics of an Optimized Supercritical Compressor Stator Cascade

2005 ◽  
Vol 128 (3) ◽  
pp. 435-443 ◽  
Author(s):  
Bo Song ◽  
Wing F. Ng
Keyword(s):  
Boundary Layer ◽  
Numerical Study ◽  
Flow Behavior ◽  
Flow Characteristics ◽  
Navier Stokes ◽  
Flow Conditions ◽  
Supercritical Flow ◽  
Gradient Distribution ◽  
Controlled Diffusion ◽  
Mach Numbers

An experimental and numerical study was performed on an optimized compressor stator cascade designed to operate efficiently at high inlet Mach numbers (M1) ranging from 0.83 to 0.93 (higher supercritical flow conditions). Linear cascade tests confirmed that low losses and high turning were achieved at normal supercritical flow conditions (0.7<M1<0.8), as well as higher supercritical flow conditions (0.83<M1<0.93), both at design and off-design incidences. The performance of this optimized stator cascade is better than those reported in the literature based on Double Circular Arc (DCA) and Controlled Diffusion Airfoil (CDA) blades, where losses increase rapidly for M1>0.83. A two-dimensional (2D) Navier-Stokes solver was applied to the cascade to characterize the performance and flow behavior. Good agreement was obtained between the CFD and the experiment. Experimental loss characteristics, blade surface Mach numbers, shadowgraphs, along with CFD flowfield simulations, were presented to elucidate the flow physics. It is found that low losses are due to the well-controlled boundary layer, which is attributed to an optimum flow structure associated with the blade profile. The multishock pattern and the advantageous pressure gradient distribution on the blade are the key reasons of keeping the boundary layer from separating, which in turn accounts for the low losses at the higher supercritical flow conditions.

Performance and Flow Characteristics of an Optimized Supercritical Compressor Stator Cascade

2005 ◽  
Author(s):  
Bo Song ◽  
Wing F. Ng
Keyword(s):  
Boundary Layer ◽  
Numerical Study ◽  
Flow Behavior ◽  
Flow Characteristics ◽  
Navier Stokes ◽  
Flow Conditions ◽  
Supercritical Flow ◽  
Gradient Distribution ◽  
Controlled Diffusion ◽  
Mach Numbers

An experimental and numerical study was performed on an optimized compressor stator cascade designed to operate efficiently at high inlet Mach numbers (M1) ranging from 0.83 to 0.93 (higher supercritical flow conditions). Linear cascade tests confirmed that low losses and high turning were achieved at normal supercritical flow conditions (0.7 &lt; M1 &lt; 0.8), as well as higher supercritical flow conditions (0.83 &lt; M1 &lt; 0.93), both at design and off-design incidences. The performance of this optimized stator cascade is better than those reported in the literature based on Double Circular Arc (DCA) and Controlled Diffusion Airfoil (CDA) blades, where losses increase rapidly for M1 &gt; 0.83. A 2-D Navier-Stokes solver was applied to the cascade to characterize the performance and flow behavior. Good agreement was obtained between the CFD and the experiment. Experimental loss characteristics, blade surface Mach numbers, shadowgraphs, along with CFD flowfield simulations, were presented to elucidate the flow physics. It is found that low losses are due to the well-controlled boundary layer, which is attributed to an optimum flow structure associated with the blade profile. The multi-shock pattern and the advantageous pressure gradient distribution on the blade are the key reasons of keeping the boundary layer from separating, which in turn accounts for the low losses at the higher supercritical flow conditions.

A Numerical Study of Laminar and Intermittently Turbulent Boundary Layer on an Oscillating Flat Plate Using Pseudo-Compressible RANS Model

2020 ◽  
Author(s):  
Shivank Srivastava ◽  
Brandon M. Taravella ◽  
Kazim M. Akyuzlu
Keyword(s):  
Boundary Layer ◽  
Turbulent Flow ◽  
Flat Plate ◽  
Turbulent Flows ◽  
Numerical Study ◽  
Navier Stokes ◽  
Flow Conditions ◽  
Rans Model ◽  
Explicit Finite Difference ◽  
Turbulent Flow Conditions

Abstract A numerical study was conducted to study the unsteady characteristics of incompressible boundary layer flows over an oscillating flat plate under laminar and intermittently turbulent flow conditions using pseudo-compressible Reynolds Averaged Navier-Stokes (RANS) model. The numerical study is carried out using an in-house code and a commercial CFD package (Fluent). Two equation (k-ε) turbulence closure model, modified near the wall, is used along with RANS equations to simulate intermittently turbulent flows. Fully Explicit-Finite Difference technique (FEFD) is employed to solve the governing differential equations. For validation purposes, the velocity fields predicted by the in-house code and commercial CFD package are compared to the one given by analytical solution to Stokes’ second problem for an oscillating flat plate. Numerical experiments were conducted for unsteady cases for Stokes’ Reynolds number corresponding to laminar and intermittently turbulent flows, respectively. Time dependent velocity profiles, shear stress distribution, turbulence properties during the accelerating and decelerating stages of oscillations are predicted. The above predictions are then compared to ones predicted by commercial CFD code. The velocity magnitudes predicted by the in-house code and commercial CFD code are within acceptable range for laminar and intermittently turbulent flow conditions.

scholarly journals 3D Numerical Study of the Flow Properties in a Double-Spur Dikes Field during a Flood Process

Water ◽  
2018 ◽  
Vol 10 (11) ◽  
pp. 1574 ◽  
Author(s):  
Xun Han ◽  
Pengzhi Lin
Keyword(s):  
Water Surface ◽  
Numerical Study ◽  
Flow Characteristics ◽  
Field Measurements ◽  
Navier Stokes ◽  
Eddy Simulation ◽  
River Bed ◽  
Hydrodynamic Evolution ◽  
Spur Dikes ◽  
Potential Damage

A 3D numerical model is developed to study the flow characteristics of a double-spur dikes field on Yangtze River during a flood process, which was presented by the variation of the flow condition. The model is based on Navier–Stokes (NS) equations, the porous medium method (PMM) is employed to treat the solid structures including the river bed surface, the volume of fluid (VOF) method is applied to track the motion of the water surface during the flood process, and large eddy simulation (LES) is adopted to capture the turbulence transport and dissipation. Using this model, the target reach’s flow field before the construction of double-spur dikes is simulated first, while the numerical results are compared to the field measurements on flow velocity and water surface level, and fairly good agreements are shown. Then, the model is applied to reproduce the hydrodynamic evolution during a flood process after double-spur dikes’ constructions, while the detailed 3D flow fields are obtained under some certain states with different submergence rates of the spur dikes; finally, the potential damage positions around these spur dikes are analyzed accordingly.

scholarly journals Numerical study of unsteady flow and exciting force for swept turbomachinery blades

2016 ◽  
Vol 20 (suppl. 3) ◽  
pp. 669-676
Author(s):  
Di Zhang ◽  
Ma Jiao-Bin ◽  
Qi Jing
Keyword(s):  
Boundary Layer ◽  
Unsteady Flow ◽  
Pressure Fluctuation ◽  
Numerical Study ◽  
Flow Characteristics ◽  
Aerodynamic Performance ◽  
Rotor Blades ◽  
Stable Operation ◽  
Straight Blade ◽  
Excitation Force

The aerodynamic performance of blade affects the vibration characteristics and stable operation of turbomachinery closely. The aerodynamic performance of turbine stage can be improved by using swept blade. In this paper, the RANS method and the RNG k-? turbulence mode were adopted to investigate the unsteady flow characteristics and excitation force of swept blade stage. According to the results, for the swept blade, the fluid of boundary layer shifts in radial direction due to the influence of geometric construction. It is observed that there is similar wake development for several kinds of stators, and the wake has a notable effect on the boundary layer of the rotor blades. When compared with straight blade, pressure fluctuation of forward-swept blade is decreased while the pressure fluctuation of backward-swept blade is increased. The axial and tangential fundamental frequency excitation force factors of 15?forward-swept blade are 0.139 and 0.052 respectively, which are the least, and all excitation force factors are in the normal range. The excitation factor of the forward-swept blade is decreased compared with straight blade, and the decreasing percentage is closely related to the swept angle. As for backward-swept blades, the situation is the other way around. Additionally, the change of axial excitation factor is more obvious. So the vibration reduction performance of forward-swept blade is better.

scholarly journals Numerical Study of Bleed Slot Flow Characteristics Using Magneto-Aerodynamics

2021 ◽  
Author(s):  
Szym on Buhajczuk
Keyword(s):  
Magnetic Field ◽  
Boundary Layer ◽  
High Speed ◽  
Numerical Study ◽  
Flow Characteristics ◽  
Past Research ◽  
Charge Generation ◽  
High Speed Engine ◽  
Displacement Thickness ◽  
Sonic Flow

A numerical study into magneto-aerodynamic bleed control systems has been undertaken with the intent of improving the shock swallowing ability of high speed engine intakes. Past research has shown that bleed slots effectively remove sufficient mass flow of air from the system to permit shocks to be swallowed. A magnetic field's influence on a charged boundary layer creates a possibility of sealing a bleed slot when not needed. 2D bleed slots were modeled using structured grids for use with the FLUENT CFD solver. User defined functions were written to simulate charge generation and magnetic field forces. Solutions revealed that bleed slot angles, free stream Mach numbers, pressure ratios, boundary layer displacement thickness, field strength and field position all affect how the system performs. Results have shown that a properly positioned magnetic field can reduce sonic flow coefficients up to 88%, thus justifying further research and investment in wind tunnel experiments.

Numerical Study on Supersonic Combustor with an Allotype Cavity

2014 ◽  
Vol 694 ◽  
pp. 187-192
Author(s):  
Jin Xiang Wu ◽  
Jian Sun ◽  
Xiang Gou ◽  
Lian Sheng Liu
Keyword(s):  
Alternative Model ◽  
Numerical Study ◽  
Reverse Flow ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Experimental Result ◽  
Navier Stokes ◽  
Cold Flow ◽  
Hypersonic Inlet ◽  
Good Agreement

The three-dimensional coupled explicit Reynolds Averaged Navier–Stokes (RANS) equations and the two equation shear-stress transport k-w (SST k-w) model has been employed to numerically simulate the cold flow field in a special-shaped cavity-based supersonic combustor. In a cross-section shaped rectangular, hypersonic inlet with airflow at Mach 2.0 chamber, shock structures and flow characteristics of a herringbone-shaped boss and a herringbone-shaped cavity models were discussed, respectively. The results indicate: Firstly, according to the similarities of bevel-cutting shock characteristics between the boss case and the cavity case, the boss structure can serve as an ideal alternative model for shear-layer. Secondly, the eddies within cavity are composed of herringbone-spanwise vortexes, columnar vortices in the front and main-spanwise vortexes in the rear, featuring tilting, twisting and stretching. Thirdly, the simulated bottom-flow of cavity is in good agreement with experimental result, while the reverse flow-entrainment resulting from herringbone geometry and pressure gradient. However, the herringbone-shaped cavity has a better performance in fuel-mixing.

Flow Characteristics in a Three-Dimensional Rectangular Channel With a Pair of Ribs Placed Symmetrically at the Channel Walls

2000 ◽  
Author(s):  
M. Singh ◽  
P. K. Panigrahi ◽  
G. Biswas
Keyword(s):  
Heat Transfer ◽  
Large Scale ◽  
Numerical Study ◽  
Rectangular Channel ◽  
Turbine Blades ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Navier Stokes ◽  
Complex Flow ◽  
Energy Equations

Abstract A numerical study of rib augmented cooling of turbine blades is reported in this paper. The time-dependent velocity field around a pair of symmetrically placed ribs on the walls of a three-dimensional rectangular channel was studied by use of a modified version of Marker-And-Cell algorithm to solve the unsteady incompressible Navier-Stokes and energy equations. The flow structures are presented with the help of instantaneous velocity vector and vorticity fields, FFT and time averaged and rms values of components of velocity. The spanwise averaged Nusselt number is found to increase at the locations of reattachment. The numerical results are compared with available numerical and experimental results. The presence of ribs leads to complex flow fields with regions of flow separation before and after the ribs. Each interruption in the flow field due to the surface mounted rib enables the velocity distribution to be more homogeneous and a new boundary layer starts developing downstream of the rib. The heat transfer is primarily enhanced due to the decrease in the thermal resistance owing to the thinner boundary layers on the interrupted surfaces. Another reason for heat transfer enhancement can be attributed to the mixing induced by large-scale structures present downstream of the separation point.

Numerical Study on Film Foam Flow Characteristics in a Straight Duct

2013 ◽  
Vol 561 ◽  
pp. 472-477 ◽  
Author(s):  
Dong Xing Du ◽  
Fa Hu Zhang ◽  
Dian Cai Geng ◽  
Ying Ge Li
Keyword(s):  
Drag Force ◽  
Pressure Difference ◽  
Numerical Study ◽  
Flow Behavior ◽  
Petroleum Industry ◽  
Flow Characteristics ◽  
Viscous Force ◽  
Ideal Condition ◽  
Surface Evolver ◽  
The Mathematical Model

Straight ducts capture some essential features of the motion of foam in porous media in petroleum industry. In this paper, Surface Evolver was employed to build the mathematical model to study the flow behavior of lamellas in the duct with different models. Numerical results show good agreement with experiments and some important features of lamella flow behavior in straight ducts are obtained. It is concluded that, the physical model with viscous force can adequately describe the flow characteristics of reality foam in the experiment. The actual pressure difference consists of the pressure difference caused by the curvature of the lamellas and the drag force on the boundary wall. Under the ideal condition of without drag force along the wall, the pressure drop for lamella flow in the duct is zero, and the shape and the velocity of the lamellas will maintain constant.

Numerical Performance of Transition Models in Different Turbomachinery Flow Conditions: A Comparative Study

2000 ◽  
Author(s):  
Jiasen Hu ◽  
Torsten H. Fransson
Keyword(s):  
Reynolds Number ◽  
Pressure Gradient ◽  
Numerical Study ◽  
Adverse Pressure Gradient ◽  
Navier Stokes ◽  
Test Cases ◽  
Pressure Gradients ◽  
Flow Conditions ◽  
Transition Models ◽  
High Reynolds

A numerical study has been performed to compare the overall performance of three transition models when used with an industrial Navier-Stokes solver. The three models investigated include two experimental correlations and an integrated eN method. Twelve test cases in realistic turbomachinery flow conditions have been calculated. The study reveals that all the three models can work numerically well with an industrial Navier-Stokes code, but the prediction accuracy of the models depends on flow conditions. In general, all the three models perform comparably well to predict the transition in weak or moderate adverse pressure-gradient regions. The two correlations have the merit if the transition starts in strong favorable pressure-gradient region under high Reynolds number condition. But only the eN method works well to predict the transition controlled by strong adverse pressure gradients. The three models also demonstrate different capabilities to model the effects of turbulence intensity and Reynolds number.

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