Tip Leakage Flow and Heat Transfer Characteristics on Rotor Casing and Blade Tip in an Axial Gas Turbine Engine: Steady Analysis

2008 ◽  
Author(s):  
Md Hamidur Rahman ◽  
Sung In Kim ◽  
Ibrahim Hassan
Keyword(s):  
Heat Transfer ◽  
Rotor Blade ◽  
Leakage Flow ◽  
Tip Leakage Flow ◽  
Heat Transfer Characteristics ◽  
Turbine Engine ◽  
Tip Leakage ◽  
Transfer Characteristics ◽  
Flow And Heat Transfer ◽  
Blade Tip

Steady simulations have been performed to investigate tip leakage flow and heat transfer characteristics on the casing and rotor blade tip in a single stage turbine engine. A turbine stage of stator and rotor was modeled with a pressure ratio of 3.2. The predicted isentropic Mach number and adiabatic wall temperature on the casing showed good agreement with available experimental data. The effects of tip clearance height and rotor rotational speed on the blade tip and casing heat transfer characteristics are mainly considered. It is observed that the tip leakage flow structure is highly dependent on the height of the tip gap as well as speeds of the rotor blade. In all cases, flow separates just around the corner of the pressure side of the blade tip. The region of recirculating flow increases with the increase of the clearance height. Then the flow reattaches on the tip surface near the suction side beyond the flow separation. This flow reattachment enhances surface heat transfer. The leakage flow interaction with the reverse cross flow, induced by relative casing motion, is found to have significant effect on the blade tip and casing heat transfer distribution. Critical region of high heat transfer on the casing exists near the blade tip leading edge and along the pressure side edge at all clearance height. Whereas, at high speed rotation, it tends to move towards the trailing edge due to the change of inflow angle.

Aerothermal Investigations of Tip Leakage Flow in Axial Flow Turbines—Part I: Effect of Tip Geometry and Tip Clearance Gap

2008 ◽  
Vol 131 (1) ◽  
Author(s):  
S. K. Krishnababu ◽  
P. J. Newton ◽  
W. N. Dawes ◽  
G. D. Lock ◽  
H. P. Hodson ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Mass Flow ◽  
Axial Flow ◽  
Tip Clearance ◽  
Leakage Flow ◽  
Tip Leakage Flow ◽  
Heat Transfer Characteristics ◽  
Tip Leakage ◽  
Transfer Characteristics ◽  
Flow And Heat Transfer

A numerical study has been performed to investigate the effect of tip geometry on the tip leakage flow and heat transfer characteristics in unshrouded axial flow turbines. Base line flat tip geometry and squealer type geometries, namely, double squealer or cavity and suction-side squealer, were considered. The performances of the squealer geometries, in terms of the leakage mass flow and heat transfer to the tip, were compared with the flat tip at two different tip clearance gaps. The computations were performed using a single blade with periodic boundary conditions imposed along the boundaries in the pitchwise direction. Turbulence was modeled using three different models, namely, standard k-ε, low Re k-ω, and shear stress transport (SST) k-ω, in order to assess the capability of the models in correctly predicting the blade heat transfer. The heat transfer and static pressure distributions obtained using the SST k-ω model were found to be in close agreement with the experimental data. It was observed that compared to the other two geometries considered, the cavity tip is advantageous both from the aerodynamic and from the heat transfer perspectives by providing a decrease in the amount of leakage, and hence losses, and average heat transfer to the tip. In general, for a given geometry, the leakage mass flow and the heat transfer to the tip increased with increase in tip clearance gap. Part II of this paper examines the effect of relative casing motion on the flow and heat transfer characteristics of tip leakage flow. In Part III of this paper the effect of coolant injection on the flow and heat transfer characteristics of tip leakage flow is presented.

scholarly journals Effect of Tip Clearance on Flow Field and Heat Transfer Characteristics in a Large Meridional Expansion Turbine

Energies ◽  
2019 ◽  
Vol 12 (1) ◽  
pp. 162 ◽  
Author(s):  
Fusheng Meng ◽  
Qun Zheng ◽  
Jie Gao ◽  
Weiliang Fu
Keyword(s):  
Heat Transfer ◽  
Tip Clearance ◽  
Leakage Flow ◽  
Tip Leakage Flow ◽  
Heat Transfer Characteristics ◽  
Tip Leakage ◽  
Turbine Stator ◽  
Transfer Characteristics ◽  
Flow And Heat Transfer ◽  
Expansion Turbine

The large meridional expansion turbine stator leads to complex secondary flows and heat transfer characteristics in the blade endwall region, while the upstream tip clearance leakage flow of the rotor makes it more complex in flow and heat transfer. The influence of the upstream rotor tip clearance on the large meridian expansion stator is worth studying. The flow and heat transfer characteristics of the downstream large meridional expansion turbine stator were studied by comparing the tip leakage flow of 1.5-stage shrouded and unshrouded turbines using a three-dimensional Reynolds-Averaged Navier-Stokes (RANS) solver for viscous turbulent flows. Validation studies were performed to investigate the aerodynamics and heat transfer prediction ability of the shear stress transport (SST) turbulence model. The influence of different tip clearances of the rotor including unshrouded blade heights of 0%, 1% and 5% and a 1% shrouded blade height were investigated through numerical simulation. The results showed that the upper passage vortex separation was more serious and the separation, and attachment point of horseshoe vortex in the pressure side were significantly more advanced than that of non-expansion turbines. The tip leakage vortex obviously increased the negative incidence angle at the downstream inlet. Furthermore, the strength of the high heat transfer zone on the suction surface of the downstream stator was significantly increased, while that of the shrouded rotor decreased.

Aero-Thermal Investigations of Tip Leakage Flow In Axial Flow Turbines: Part I — Effect of Tip Geometry and Tip Clearance Gap

2007 ◽  
Author(s):  
S. K. Krishnababu ◽  
P. J. Newton ◽  
W. N. Dawes ◽  
G. D. Lock ◽  
H. P. Hodson ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Mass Flow ◽  
Axial Flow ◽  
Tip Clearance ◽  
Leakage Flow ◽  
Tip Leakage Flow ◽  
Heat Transfer Characteristics ◽  
Tip Leakage ◽  
Transfer Characteristics ◽  
Flow And Heat Transfer

A numerical study has been performed to investigate the effect of tip geometry on the tip leakage flow and heat transfer characteristics in unshrouded axial flow turbines. Baseline flat tip geometry and squealer type geometries namely double squealer or cavity and suction side squealer were considered. The performances of the squealer geometries, in terms of the leakage mass flow and heat transfer to the tip, were compared with the flat tip at two different tip clearance gaps. The computations were performed using a single blade with periodic boundary conditions imposed along the boundaries in the pitchwise direction. Turbulence was modelled using three different models namely standard k-ε, low Re k-ω and SST k-ω, in order to assess the capability of the models in correctly predicting the blade heat transfer. The heat transfer and static pressure distributions obtained using the SST k-ω model was found to be in close agreement with the experimental data. It was observed that compared to the other two geometries considered, the cavity tip is advantageous both from the aerodynamic and from the heat transfer perspectives by providing a decrease in the amount of leakage, and hence losses, and average heat transfer to the tip. In general, for a given geometry, the leakage mass flow and the heat transfer to the tip increased with increase in tip clearance gap. Part II of this paper examines the effect of relative casing motion on the flow and heat transfer characteristics of tip leakage flow. In Part III of this paper the effect of coolant injection on the flow and heat transfer characteristics of tip leakage flow is presented.

Investigation of Leakage Flow and Heat Transfer in a Gas Turbine Blade Tip With Emphasis on the Effect of Rotation

2008 ◽  
Author(s):  
Dianliang Yang ◽  
Xiaobing Yu ◽  
Zhenping Feng
Keyword(s):  
Heat Transfer ◽  
Relative Motion ◽  
Turbulence Models ◽  
Leakage Flow ◽  
Tip Leakage Flow ◽  
Blade Height ◽  
Tip Leakage ◽  
Flow And Heat Transfer ◽  
Blade Rotation ◽  
Blade Tip

In this paper, numerical methods have been applied to the investigation of the effect of rotation on the blade tip leakage flow and heat transfer. Using the first stage rotor blade of GE-E3 engine high pressure turbine, both flat tip and squealer tip have been studied. The tip gap height is 1% of the blade height, and the groove depth of the squealer tip is 2% of the blade height. Heat transfer coefficient on tip surface obtained by using different turbulence models was compared with experimental results. And the grid independence study was carried out by using the Richardson extrapolation method. The effect of the blade rotation was studied in the following cases: 1) blade domain is rotating and shroud is stationary; 2) blade domain is stationary and shroud is rotating; and 3) both blade domain and shroud are stationary. In this approach, the effects of the relative motion of the endwall, the centrifugal force and the Coriolis force can be investigated respectively. By comparing the results of the three cases discussed, the effects of the blade rotation on tip leakage flow and heat transfer are revealed. It indicated that the main effect of the rotation on the tip leakage flow and heat transfer is resulted from the relative motion of the shroud, especially for the squealer tip blade.

scholarly journals TIP LEAKAGE FLOW AND HEAT TRANSFER ON TURBINE STAGE TIP AND CASING: EFFECT OF UNSTEADY STATOR–ROTOR INTERACTIONS

2014 ◽  
Vol 11 (04) ◽  
pp. 1350058 ◽  
Author(s):  
MD HAMIDUR RAHMAN ◽  
SUNG IN KIM ◽  
IBRAHIM HASSAN
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Flow Structures ◽  
Leakage Flow ◽  
Tip Leakage Flow ◽  
Trailing Edge ◽  
Tip Leakage ◽  
Flow And Heat Transfer ◽  
Blade Tip

Unsteady simulations were performed to investigate time dependent behaviors of the leakage flow structures and heat transfer on the rotor blade tip and casing in a single stage gas turbine engine. This paper mainly illustrates the unsteady nature of the leakage flow and heat transfer, particularly, that caused by the stator–rotor interactions. In order to obtain time-accurate results, the effects of varying the number of time steps, sub iterations, and the number of vane passing periods was firstly examined. The effect of tip clearance height and rotor speeds was also examined. The results showed periodic patterns of the tip leakage flow and heat transfer rate distribution for each vane passing. The relative position of the vane and vane trailing edge shock with respect to time alters the flow conditions in the rotor domain, and results in significant variations in the tip leakage flow structures and heat transfer rate distributions. It is observed that the trailing edge shock phenomenon results in a critical heat transfer region on the blade tip and casing. Consequently, the turbine blade tip and casing are subjected to large fluctuations of Nusselt number (about Nu = 2000 to 6000 and about Nu = 1000 to 10000, respectively) at a high frequency (coinciding with the rotor speed).

Investigation of Leakage Flow and Heat Transfer in a Gas Turbine Blade Tip With Emphasis on the Effect of Rotation

2010 ◽  
Vol 132 (4) ◽  
Author(s):  
Dianliang Yang ◽  
Xiaobing Yu ◽  
Zhenping Feng
Keyword(s):  
Heat Transfer ◽  
Relative Motion ◽  
Turbulence Models ◽  
Groove Depth ◽  
Leakage Flow ◽  
Tip Leakage Flow ◽  
Tip Leakage ◽  
Flow And Heat Transfer ◽  
Blade Tip ◽  
Richardson Extrapolation Method

Numerical analysis was applied to investigate the effect of rotation on the blade tip leakage flow and heat transfer. Flows around both flat and squealer tips at the first stage rotor blade of GE E3 high-pressure turbine were studied. The tip gap and squealer groove depth were specified as 1% and 2% of the blade height, respectively. The heat transfer coefficient on the tip surface was obtained by using different turbulence models and compared with the experimental data. The grid independence study was also carried out by using the Richardson extrapolation method. The effect of the blade rotation was studied in the following cases: (1) the blade domain is rotating and the shroud is stationary; (2) the blade domain is stationary and the shroud is rotating; and (3) both blade domain and shroud are stationary. In this approach, the effects of the relative motion of the endwall, the centrifugal force, and the Coriolis force can be investigated, respectively. By comparing the results of the three cases discussed, it is concluded that the main effect of the rotation on the tip leakage flow and heat transfer resulted from the relative motion of the shroud, especially for the squealer tip blade.

Effects of Inlet Temperature Uniformity and Nonuniformity on the Tip Leakage Flow and Rotor Blade Tip and Casing Heat Transfer Characteristics

2011 ◽  
Vol 134 (2) ◽  
Author(s):  
Md. Hamidur Rahman ◽  
Sung In Kim ◽  
Ibrahim Hassan
Keyword(s):  
Heat Transfer ◽  
Operating Conditions ◽  
Inlet Temperature ◽  
Leakage Flow ◽  
Tip Leakage Flow ◽  
Turbine Inlet Temperature ◽  
Turbine Engine ◽  
Tip Leakage ◽  
Turbine Inlet ◽  
Blade Tip

High thermal load appears at the blade tip and casing of a gas turbine engine. It becomes a significant design challenge to protect the turbine materials from this severe situation. As a result of geometric complexity and experimental limitations, computational fluid dynamics tools have been used to predict blade tip leakage flow aerodynamics and heat transfer at typical engine operating conditions. In this paper, the effect of turbine inlet temperature on the tip leakage flow structure and heat transfer has been studied numerically. Uniform low (444 K) and high (800 K) inlet temperatures and nonuniform (parabolic) temperature profiles have been considered at a fixed rotor rotation speed (9500 rpm). The results showed that the change of flow properties at a higher inlet temperature yields significant variations in the leakage flow aerodynamics and heat transfer relative to the lower inlet temperature condition. Aerodynamic behavior of the tip leakage flow varies significantly with the distortion of turbine inlet temperature. For more realistic inlet condition, the velocity range is insignificant at all time instants. At a high inlet temperature, reverse secondary flow is strongly opposed by the tip leakage flow and the heat transfer fluctuations are reduced greatly.

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