Local Mass/Heat Transfer on Turbine Blade Near-Tip Surfaces

2002 ◽  
Author(s):  
P. Jin ◽  
R. J. Goldstein
Keyword(s):  
Mass Transfer ◽  
Reynolds Number ◽  
Turbine Blade ◽  
Turbulence Intensity ◽  
Tip Clearance ◽  
Suction Surface ◽  
Transfer Rates ◽  
Local Mass ◽  
Pressure Surface ◽  
Local Mass Transfer

Local mass transfer measurements on a simulated high pressure turbine blade are conducted in a linear cascade with tip clearance, using a naphthalene sublimation technique. The effects of tip clearance (0.86%–6.90% of chord), are investigated at an exit Reynolds number of 5.8 × 105 and a low turbulence intensity of 0.2%. The effects of the exit Reynolds number (4–7 × 105) and the turbulence intensity (0.2% and 12.0%) are also measured for the smallest tip clearance. The effect of tip clearance on the mass transfer on the pressure surface is limited to 10% of the blade height from the tip at smaller tip clearances. At the largest tip clearance high mass transfer rates are induced at 15% of curvilinear distance (Sp/C) by the strong acceleration of the fluid on the pressure side into the clearance. The effect of tip clearance on the mass transfer is not very evident on the suction surface for curvilinear distance of Ss/C < 0.21. However, much higher mass transfer rates are caused downstream of Ss/C ≈ 0.50 by the tip leakage vortex atthe smallest tip clearance, while at the largest tip clearance, the average mass transfer is lower than that with zero tip clearance, probably because the strong leakage vortex pushes the passage vortex away from the suction surface. A high mainstream turbulence level (12.0%) increases the local mass transfer rates on the pressure surface, while a higher mainstream Reynolds number generates higher local mass transfer rates on both near-tip surfaces.

Local Mass/Heat Transfer on Turbine Blade Near-Tip Surfaces

2003 ◽  
Vol 125 (3) ◽  
pp. 521-528 ◽  
Author(s):  
P. Jin ◽  
R. J. Goldstein
Keyword(s):  
Mass Transfer ◽  
Reynolds Number ◽  
Turbine Blade ◽  
Turbulence Intensity ◽  
Tip Clearance ◽  
Suction Surface ◽  
Transfer Rates ◽  
Local Mass ◽  
Pressure Surface ◽  
Local Mass Transfer

Local mass transfer measurements on a simulated high-pressure turbine blade are conducted in a linear cascade with tip clearance, using a naphthalene sublimation technique. The effects of tip clearance (0.86–6.90% of chord) are investigated at an exit Reynolds number of 5.8×105 and a low turbulence intensity of 0.2%. The effects of the exit Reynolds number 4−7×105 and the turbulence intensity (0.2 and 12.0%) are also measured for the smallest tip clearance. The effect of tip clearance on the mass transfer on the pressure surface is limited to 10% of the blade height from the tip at smaller tip clearances. At the largest tip clearance high mass transfer rates are induced at 15% of curvilinear distance Sp/C by the strong acceleration of the fluid on the pressure side into the clearance. The effect of tip clearance on the mass transfer is not very evident on the suction surface for curvilinear distance of Ss/C<0.21. However, much higher mass transfer rates are caused downstream of Ss/C≈0.50 by the tip leakage vortex at the smallest tip clearance, while at the largest tip clearance, the average mass transfer is lower than that with zero tip clearance, probably because the strong leakage vortex pushes the passage vortex away from the suction surface. High mainstream turbulence level (12.0%) increases the local mass transfer rates on the pressure surface, while a higher mainstream Reynolds number generates higher local mass transfer rates on both near-tip surfaces.

An Experimental Investigation of the Effect of Freestream Turbulence on the Wake of a Separated Low-Pressure Turbine Blade at Low Reynolds Numbers

1999 ◽  
Vol 122 (2) ◽  
pp. 431-433 ◽  
Author(s):  
C. G. Murawski ◽  
K. Vafai
Keyword(s):  
Reynolds Number ◽  
Turbine Blade ◽  
Turbulence Intensity ◽  
Reynolds Numbers ◽  
Low Pressure ◽  
Freestream Turbulence ◽  
Suction Surface ◽  
Low Reynolds Numbers ◽  
Low Pressure Turbine ◽  
Flow Reynolds Number

An experimental study was conducted in a two-dimensional linear cascade, focusing on the suction surface of a low pressure turbine blade. Flow Reynolds numbers, based on exit velocity and suction length, have been varied from 50,000 to 300,000. The freestream turbulence intensity was varied from 1.1 to 8.1 percent. Separation was observed at all test Reynolds numbers. Increasing the flow Reynolds number, without changing freestream turbulence, resulted in a rearward movement of the onset of separation and shrinkage of the separation zone. Increasing the freestream turbulence intensity, without changing Reynolds number, resulted in shrinkage of the separation region on the suction surface. The influences on the blade’s wake from altering freestream turbulence and Reynolds number are also documented. It is shown that width of the wake and velocity defect rise with a decrease in either turbulence level or chord Reynolds number. [S0098-2202(00)00202-9]

Effect of Inlet Skew on Heat/Mass Transfer From a Simulated Turbine Blade

2012 ◽  
Vol 134 (5) ◽  
Author(s):  
Kalyanjit Ghosh ◽  
R. J. Goldstein
Keyword(s):  
Mass Transfer ◽  
Turbine Blade ◽  
Sherwood Number ◽  
Heat Mass Transfer ◽  
Velocity Ratio ◽  
Transition To Turbulence ◽  
Suction Surface ◽  
Freestream Velocity ◽  
Pressure Surface ◽  
Passage Vortex

Heat (mass) transfer experiments are conducted to study the effect of an inlet skew on a simulated gas-turbine blade placed in a linear cascade. The inlet skew simulates the relative motion between rotor and stator endwalls in a single turbine stage. The transverse motion of a belt, placed parallel to and upstream of the turbine cascade, generates the inlet skew. With the freestream velocity constant at approximately 16 m/s, which results in a Reynolds number (based on the blade chord length of 0.184 m) of 1.8 × 105, a parametric study was conducted for three belt-to-freestream velocity ratios. The distribution of the Sherwood number on the suction surface of the blade shows that the inlet skew intensifies the generation of the horseshoe vortex close to the endwall region. This is associated with the development of a stronger passage vortex for a higher velocity ratio, which causes an earlier transition to turbulence. Corresponding higher mass transfer coefficients are measured between the midheight of the blade and the endwall, at a midchord downstream location. However, a negligible variation in transport properties is measured above the two-dimensional region of the blade at the higher velocity ratios. In contrast, the inlet skew has a negligible effect on the distribution of the Sherwood number on the entire pressure surface of the blade. This is mainly because the skew is directed along the passage vortex, which is from the pressure surface of the airfoil to the suction surface of the adjacent airfoil.

The Effect of Naturally Developing Roughness on the Mass Transfer in Pipes Under Different Reynolds Numbers

2017 ◽  
Vol 139 (10) ◽  
Author(s):  
D. Wang ◽  
D. Ewing ◽  
C. Y. Ching
Keyword(s):  
Mass Transfer ◽  
Reynolds Number ◽  
Initial Period ◽  
Reynolds Numbers ◽  
Multiple Time ◽  
Transfer Enhancement ◽  
Flow Loop ◽  
Local Mass ◽  
Mass Transfer Enhancement ◽  
Local Mass Transfer

The local mass transfer over dissolving surfaces was measured at pipe Reynolds number of 50,000, 100,000, and 200,000. Tests were run at multiple time periods for each Reynolds number using 203 mm diameter test sections that had gypsum linings dissolving to water in a closed flow loop at a Schmidt number of 1200. The local mass transfer was calculated from the decrease in thickness of the gypsum lining that was measured using X-ray-computed tomography (CT) scans. The range of Sherwood numbers for the developing roughness in the pipe was in good agreement with the previous studies. The mass transfer enhancement (Sh/Shs) was dependent on both the height (ep−v) and spacing (λstr) of the roughness scallops. For the developing roughness, two periods of mass transfer were present: (i) an initial period of rapid increase in enhancement when the density of scallops increases till the surface is spatially saturated with the scallops and (ii) a slower period of increase in enhancement beyond this point, where the streamwise spacing is approximately constant, and the roughness height grows more rapidly. The mass transfer enhancement was found to correlate well with the parameter (ep−v/λstr)0.2, with a weak dependence on Reynolds number.

Effect of Wake-Disturbed Flow on Heat (Mass) Transfer to a Turbine Blade

2010 ◽  
Vol 133 (1) ◽  
Author(s):  
S. Olson ◽  
S. Sanitjai ◽  
K. Ghosh ◽  
R. J. Goldstein
Keyword(s):  
Mass Transfer ◽  
Reynolds Number ◽  
Turbine Blade ◽  
Heat Mass Transfer ◽  
Turbine Blades ◽  
Freestream Turbulence ◽  
Suction Surface ◽  
Disturbed Flow ◽  
Linear Cascade ◽  
Naphthalene Sublimation Technique

This study investigates the effect of wakes in the presence of varying levels of background freestream turbulence on the heat (mass) transfer from gas turbine blades. Measurements using the naphthalene sublimation technique provide local values of the mass transfer coefficient on the pressure and suction surfaces of a simulated turbine blade in a linear cascade. Experimental parameters studied include the pitch of the wake-generating blades (vanes), blade-row separation, Reynolds number, and the freestream turbulence level. The disturbed flow strongly affects the mass transfer Stanton number on both sides of the blade, particularly along the suction surface. An earlier transition to a turbulent boundary layer occurs with increased background turbulence, higher Reynolds number, and from wakes shed from vanes placed upstream of the linear cascade. Note that once the effects on mass transfer are known, similar variation on heat transfer can be inferred from the heat/mass transfer analogy.

scholarly journals The Local Mass Transfer Rates inside a Single Liquid Drop

1968 ◽  
Vol 32 (1) ◽  
pp. 68-74,a1
Author(s):  
Tadashi Shirotsuka ◽  
Akihiko Murakami ◽  
Akira Hirata ◽  
Sukehiro Gotoh
Keyword(s):  
Mass Transfer ◽  
Liquid Drop ◽  
Transfer Rates ◽  
Local Mass ◽  
Local Mass Transfer
Sign in / Sign up

Export Citation Format

Share Document