Numerical Simulation of 3D Flow Field Structure in Turbine Cascade With Bowed Blades

2001 ◽  
Author(s):  
Songtao Wang ◽  
Zhongqi Wang ◽  
Guotai Feng
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Pressure Gradient ◽  
Pressure Distribution ◽  
Great Influence ◽  
Horseshoe Vortex ◽  
Suction Surface ◽  
Blade Cascade ◽  
Passage Vortex ◽  
Type Pressure

The differences of flow field in bowed blade cascade and that in straight blade cascade are systematically studied in this paper. To bow a blade means to change its geometric boundary condition. This change not only affect the pressure distribution along the blade profile exit Mach number but also has great effect on the original position and development of the passage vertex. All of the changes mentioned above have great influence on the loss. Numerical simulation result showed that blade bowing can decrease the cross-pressure gradient near the end wall. This trend will be more obvious with the increase of the bow angle. The pressure gradient decrease is beneficial to weaken the passage vortex strength and reduces the secondary loss near the endwalls. In addition, Pressure gradient from endwalls to midspan can be established near suction surface in positively bowed blade. With the increase of bow angle, this C-type pressure distribution is remarkable. It is also found that this C-type pressure distribution will influence the position of corner vortex near the suction surface and will also influence the position and size of the passage vortex. Blade bowing also has great influence on the position of the saddle point near the leading edge and the separated line of the horseshoe vortex. It is found that the position of the saddle point and the separated line of both legs of the horseshoe vortex move forward in a positively bowed blade. The passage vortex structure in bowed cascade is also presented. It can be concluded that a bowed blade can make the passage vortex stable and helps change its structure from loose to compact. Blade bowing is also beneficial to limit the influence domain of the unstable passage vortex core by the stable limit cycle.

Swept Blade Aerodynamics Numerical Simulation of Super-Critical HP Stage Static Cascade

2010 ◽  
Vol 29-32 ◽  
pp. 554-559
Author(s):  
Zi Ming Feng ◽  
Zhen Xu Sun ◽  
De Shi Zhang ◽  
Guang Ling Zhou ◽  
Chun Hong Li
Keyword(s):  
Numerical Simulation ◽  
Pressure Distribution ◽  
Secondary Flow ◽  
Low Energy ◽  
Sweep Angle ◽  
Blade Cascade ◽  
Flow Loss ◽  
Simulation Results ◽  
End Wall ◽  
Type Pressure

Super-critical HP steam stage static blade cascade is as the prototype blade to numerical simulations. Different swept blades are made by changing the sweep angle and sweep height in order to study the effect of swept blade on aerodynamics characteristics of turbine static cascade. The numerical simulation sweep angle are made of ±10° and 0°,swept heights are 30% blade height. The turbine aerodynamics characteristics are analyzed by NUMECA software. The numerical simulation results indicate: that aft-sweep blades negative C-type pressure distribution increase the low energy fluid centralizing in end-wall corner and the end-wall secondary flow loss, but the loss is decreased at mid-span, depending on the baseline. But fore-sweep blades C-type pressure distribution decrease the low energy fluid centralizing in endwall corner and the endwall secondary flow loss, but the loss is increased at mid-span, depending on the baseline.

Numerical Simulation of Endwall Fence on the Secondary Flow in Compressor Cascade

2008 ◽  
Author(s):  
Jingjun Zhong ◽  
Ji-Ang Han ◽  
Yanming Liu ◽  
Fu Tian
Keyword(s):  
Numerical Simulation ◽  
Secondary Flow ◽  
Horseshoe Vortex ◽  
Side Branch ◽  
Compressor Cascade ◽  
Suction Surface ◽  
Rotation Direction ◽  
Pressure Surface ◽  
Passage Vortex ◽  
Blockage Effect

In this paper, based on the experimental data, a detailed numerical simulation has been carried out for the compressor cascade composed of CDA blades with fences on the endwall. There are several different configurations of the endwall fences, such as length, height, and pitch-wise location for the endwall fence. The optimum lengths, height, pitch-wise or span-wise location of the fences on the cascade end walls are obtained. The process of endwall fence’s controlling secondary flow in the compressor cascade mainly lies in two ways: hindering crosswise flow from pressure surface to suction surface near the endwall of the cascade; forming and developing of fence vortex, in which the fence blockage effect is more important. Endwall fences has a significant effect on the vortices distribution, in which the formation and development of fence vortex is important. Its formation has a close relationship with the strength of the crossflow at the region between the pressure surface and fence, which is mainly due to the relative airflow movement when the pressure side branch of the horseshoe vortex rolls up and lift along the fence. For the fence vortex and passage vortex have the different rotation direction, it plays an important role in decreasing the secondary flow loss, furthermore, reducing the strength of the passage vortex. In general, stronger crosswise flow induces stronger fence vortex. As height and length of the fence increased, the blockage effect is more obvious, but the additional fence losses increased at the same time. Numerical results show that the fences, with one third of height of the inlet boundary layer thickness and the length of 75 percent axial chord, are most effective when they are located 30 percent of pitch far from the pressure surface of the blade. For all the computational cases, they reduce the cascade loss furthest respectively.

scholarly journals The Effect of the Pressure Distribution in a Three-Dimensional Flow Field of a Cascade on the Type of Curved Blade

1994 ◽  
Author(s):  
Zhongqi Wang ◽  
Jiexian Su ◽  
Jingjun Zhong
Keyword(s):  
Flow Field ◽  
Pressure Distribution ◽  
Three Dimensional ◽  
Suction Surface ◽  
Three Dimensional Flow ◽  
Blade Height ◽  
Dimensional Flow ◽  
Cascade Energy ◽  
Curved Blade ◽  
Type Pressure

The effect of the pressure distribution in a three-dimensional flow field of a cascade on the type of curved blade is discussed in this paper through analysing the experimental results and numerical calculative results. Using curved blades, we can obtain “C” type pressure distribution along the blade height in the passage. For the expansion cascade, energy loss in the cascade can be reduced if positive curved blades are used. For guide vanes and compressor cascades, the choice of using positive curved blades or negative curved blades relies on the pressure gradient on the blade midspan suction surface along the direction of flow and whether there exists a separation of the boundary layer there. However, all of these need further studies and discussions.

Contrast Study on the Radial Velocity of the Flow Field of the Hydrocyclones with Different Inlet Structures

2011 ◽  
Vol 339 ◽  
pp. 624-629
Author(s):  
Lian Cheng Ren ◽  
Zheng Liang ◽  
Jiang Meng ◽  
Lin Yang ◽  
Jia Lin Tian
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Radial Velocity ◽  
Axial Symmetry ◽  
Separation Efficiency ◽  
Great Influence ◽  
The Other ◽  
Contrast Study ◽  
The One ◽  
Tangential Inlet

On the base of numerical simulation and theoretical analysis, the flow field of a conventional single-tangential-inlet Hydrocyclone and a newly put forward axial-symmetry double-tangential-inlet hydrocyclone were contrasted. The study shows that the inlet structure of the Hydrocylone has a great influence on the radial velocity of the flow field in the hydrocyclone and that the radial velocity in the hydrocyclone with single-tangential-inlet is not symmetry about the axis of the hydrocyclone; and on the other hand the radial velocity in the hydrocyclone with axial-symmetry double-tangential-inlet is symmetry about the axis of the hydrocyclone. The magnitude of the radial velocity of the flow in the hydrocyclone with single-tangential-inlet is greater than that in the hydrocyclone with axial-symmetry double-tangential-inlet hydrocyclone, which means the hydrocyclone with axial-symmetry double-tangential-inlet has greater capability than the rival one with single-tangential inlet. The symmetry about the axis of the hydrocyclone of the radial velocity means the radial velocities in the place where the radio is the same are constant, which means the hydrocyclone has a great separation efficiency. The conclusion is that changing the conventional hydrocyclone into the one with axial-symmetry double-tangential-inlet structure can offer greater separation capability and efficiency.

Computational Design and Experimental Evaluation of Using a Leading Edge Fillet on a Gas Turbine Vane

2001 ◽  
Author(s):  
G. A. Zess ◽  
K. A. Thole
Keyword(s):  
Boundary Layer ◽  
Flow Field ◽  
Pressure Gradient ◽  
Gas Turbine ◽  
Total Pressure ◽  
Guide Vane ◽  
Leading Edge ◽  
Field Measurements ◽  
Computational Design ◽  
Horseshoe Vortex

With the desire for increased power output for a gas turbine engine comes the continual push to achieve higher turbine inlet temperatures. Higher temperatures result in large thermal and mechanical stresses particularly along the nozzle guide vane. One critical region along a vane is the leading edge-endwall juncture. Based on the assumption that the approaching flow to this juncture is similar to a two-dimensional boundary layer, previous studies have shown that a horseshoe vortex forms. This vortex forms because of a radial total pressure gradient from the approaching boundary layer. This paper documents the computational design and experimental validation of a fillet placed at the leading edge-endwall juncture of a guide vane to eliminate the horseshoe vortex. The fillet design effectively accelerated the incoming boundary layer thereby mitigating the effect of the total pressure gradient. To verify the CFD studies used to design the leading edge fillet, flow field measurements were performed in a large-scale, linear, vane cascade. The flow field measurements were performed with a laser Doppler velocimeter in four planes orientated orthogonal to the vane. Good agreement between the CFD predictions and the experimental measurements verified the effectiveness of the leading edge fillet at eliminating the horseshoe vortex. The flowfield results showed that the turbulent kinetic energy levels were significantly reduced in the endwall region because of the absence of the unsteady horseshoe vortex.

Numerical Investigation on Unsteady Characteristics in Different Rim Seal Geometries: Part A

2020 ◽  
Author(s):  
Xie Lei ◽  
Wang RuoNan ◽  
Liu Guang ◽  
Lian ZengYan ◽  
Du Qiang
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Pressure Distribution ◽  
Engine Efficiency ◽  
Ansys Cfx ◽  
Geometry Configuration ◽  
Numerical Simulation Methods ◽  
Unsteady Simulation ◽  
Unsteady Characteristics ◽  
Cooling Air

Abstract Secondary sealing flow is of great importance in the turbine disk cooling and sealing system. The amount of cooling air extracted from the compressor is crucial to engine efficiency. To determine a minimum amount of cooling air, the flow characteristic of the rim seal should be investigated. Numerical simulation is carried out to investigate the flow field near the rim seal region. Both RANS and URANS numerical simulation methods are used in the commercial CFD code ANSYS CFX to analyze axial and radial rim seals. In the simulation, a 1/33 sector is selected as computing region to simulate the flow field and the SST turbulent model is used. The steady and unsteady simulation results of pressure distribution and seal efficiency are analyzed and compared. The computed results show that due to the different geometry configuration, the pressure distribution also shows inconsistency. Unsteady phenomena are observed in both axial and radial type of rim seals. Radial sealing lip can suppress the inherent unsteadiness and interaction between main flow and sealing flow, thus showing higher sealing efficiency. Comparing to steady results using the RANS method; unsteady simulation, using the URANS method, can capture the pressure difference and seal efficiency fluctuation at the disk rim more efficiently. Also, the interaction between the rotor and stator is considered in unsteady simulation, so the unsteady simulation is recommended. The results obtained in the current paper are useful to the investigation and design of turbine rim seals.

The compound bowing design in a highly loaded linear cascade with large turning angle

2020 ◽  
Vol 234 (16) ◽  
pp. 2323-2336
Author(s):  
Xingxu Xue ◽  
Songtao Wang ◽  
Lei Luo ◽  
Xun Zhou
Keyword(s):  
Numerical Simulation ◽  
Reynolds Number ◽  
Pressure Gradient ◽  
Side Effect ◽  
Adverse Pressure Gradient ◽  
Suction Surface ◽  
Turning Angle ◽  
Linear Cascade ◽  
Velocity Triangle ◽  
Highly Loaded

Numerical simulation was carried out to study the influences of blade-bowing designs based on a highly loaded cascade with large turning angle, while the compound bowing design showed much lower endwall loss than the conventional design in this study. Generally, it showed that the increased turning angle would strengthen the adverse pressure gradient on the suction surface, so the side effect of negative blade bowing angle would be enhanced because of the reduced flow filed stability near suction–endwall corner. However, the positive corner bowing angle that applied in the compound bowing design would enhance the flow field stability near the suction–endwall corner by adjusting spanwise pressure gradient and velocity triangle, so the side effect of negative blade bowing angle would be suppressed and lead to weaker secondary flow. In detail, the blade bowing angle (as well as the corner bowing angle in the conventional bowed cascades) was varied from −5° to −30° in this study, while the reductions of the loss coefficient in the compound bowed cascades were about 0.662.16 times higher (the absolute differences were about 0.0067 0.0097) than the corresponding conventional bowed cascades. Moreover, the Reynolds number and Mach number at the outlet plane were kept at 2.4 × 105 and 0.6, respectively, during the bowing design to ensure the comparability.

Effect of Turbulence Parameters on Numerical Simulation of Complex Automotive External Flow Field

2011 ◽  
Vol 52-54 ◽  
pp. 1062-1067 ◽  
Author(s):  
Xing Jun Hu ◽  
Peng Qin ◽  
Peng Guo ◽  
Yang An
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Numerical Simulations ◽  
Drag Coefficient ◽  
Pressure Distribution ◽  
Viscosity Ratio ◽  
External Flow ◽  
Length Scale ◽  
Slant Angle ◽  
Turbulence Parameters

Numerical simulations for the Ahmed model with 25° slant angle are performed under three different turbulent parameters, intensity and length scale, intensity and viscosity ratio, k and epsilon. The external flow field of ahmed model with 25° slant angle is got, and all the velocity vectors, pressure distribution and the drag coefficient of the flow field are obtained as well. The comparison between the numerical simulations and the experimental statistics shows that intensity and viscosity and k and epsilon characterized by higher computation accuracy are more suitable for numerical simulation of automotive external flow field.

Three-Dimensional Flow Near the Blade/Endwall Junction of a Gas Turbine: Application of a Boundary Layer Fence

1991 ◽  
Author(s):  
J. T. Chung ◽  
T. W. Simon ◽  
J. Buddhavarapu
Keyword(s):  
Boundary Layer ◽  
Gas Turbine ◽  
Film Cooling ◽  
Three Dimensional ◽  
Horseshoe Vortex ◽  
Management Technique ◽  
Suction Surface ◽  
Cooling Flow ◽  
Passage Vortex ◽  
Cooling Function

A flow management technique designed to reduce some harmful effects of secondary flow in the endwall region of a turbine passage is introduced. A boundary layer fence in the gas turbine passage is shown to improve the likelihood of efficient film cooling on the suction surface near the endwall. The fence prevents the pressure side leg of the horseshoe vortex from crossing to the suction surface and impinging on the wall. The vortex is weakened and decreased in size after being deflected by the fence. Such diversion of the vortex will prevent it from removing the film cooling flow allowing the flow to perform its cooling function. Flow visualization on the suction surface and through the passage shows the behavior of the passage vortex with and without the fence. Laser Doppler velocimetry is employed to quantify these observations.

Numerical Simulation of Atmospheric Flow Field around Bridge

2013 ◽  
Vol 368-370 ◽  
pp. 1379-1382
Author(s):  
Ying Jia ◽  
Li Zhang ◽  
Sheng Zhang
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Pressure Distribution ◽  
Cross Section ◽  
Horizontal Plane ◽  
Atmospheric Flow ◽  
Airflow Field ◽  
Distribution Laws ◽  
The Cross

This paper carries out a numerical simulation of the atmospheric flow field around bridge. The variation law of airflow field around bridge is studied. Velocity and pressure distribution laws of flow field in horizontal plane and the cross-section are discussed, and influence range of flow field around bridge area is identified.

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