Pressure Loss Coefficient of Impingement Cooled Leading Edge System of a Turbine Blade

1976 ◽  
Vol 98 (4) ◽  
pp. 554-556
Author(s):  
D. K. Mukherjee
Keyword(s):  
Reynolds Number ◽  
Turbine Blade ◽  
Model Test ◽  
Pressure Loss ◽  
Leading Edge ◽  
Loss Coefficient ◽  
Relative Distance ◽  
Pressure Loss Coefficient

The pressure loss coefficient of an impingement cooled system similar to that often used to cool the leading edge of a turbine blade has been determined from model test. The influence of Reynolds number in the range tested is negligible. However, the influence of relative distance of the jet holes from the surface to be cooled is very significant.

A Study of the Fabrication and Analysis of Micro Diffuser/Nozzles

2003 ◽  
Author(s):  
Kai-Shing Yang ◽  
Ing-Young Chen ◽  
Bor-Yuan Shew ◽  
Chi-Chuan Wang
Keyword(s):  
Reynolds Number ◽  
Friction Factor ◽  
Pressure Loss ◽  
Measured Data ◽  
Loss Coefficient ◽  
Opening Angle ◽  
Velocity Change ◽  
Pressure Loss Coefficient ◽  
Micro Nozzle ◽  
Volumetric Flowrate

In this study, an analysis of the performance of micro nozzle/diffusers is performed and fabrication of the micro nozzle/diffuser is conducted and tested. It is found that the pressure loss coefficient for the nozzle/diffuser decreases with the Reynolds number. At a given Reynolds number, the pressure loss coefficient for nozzle is higher than that of the diffuser due to considerable difference in the momentum change. For the effect of nozzle/diffuser length on the pressure loss coefficient, it is found that the influence is rather small. At a fixed volumetric flowrate, a “minimum” phenomenon of the pressure loss coefficient vs. nozzle/diffuser depth is encountered. This is related to the interactions of velocity change and friction factor. Good agreements of the measured data with the predicted results are found in this study except at a diffuser having an opening angle of 20° . It is likely that the departure of this case to the prediction is due to the separation phenomenon in a larger angle of the diffuser.

scholarly journals Improved Vane-Island Diffusers at High Swirl

1982 ◽  
Author(s):  
Tong Jiang ◽  
Tah-teh Yang
Keyword(s):  
Experimental Investigation ◽  
Pressure Loss ◽  
Previous Investigation ◽  
Pressure Rise ◽  
Leading Edge ◽  
Loss Coefficient ◽  
Flow Coefficient ◽  
Percent Reduction ◽  
Pressure Loss Coefficient ◽  
Coefficient Versus

The results of an experimental investigation of the performance of vane-island diffusers at high swirl [λ = 9] are presented in this paper. These results show the advantage of the 14-vane versus several 8-vane configurations. Four sets of 14 straight vanes are used in this study as compared to five sets of eight vanes in a previous investigation. The 14-vane configuration results in a 40 percent reduction in pressure loss coefficient below that obtained with eight vane configurations. The lowest loss coefficient obtained in the present investigation is achieved when the vane leading edge is at a radius approximately equal to 1.2 times the diffuser inlet radius. The experimental results are presented in the form of pressure rise versus radial location along the diffuser, diffuser effectiveness versus flow coefficient, and minimum pressure loss coefficient versus flow coefficient.

Laminar Pressure Loss Coefficient in Close Coupled Fittings

2006 ◽  
Author(s):  
Murthy Lakshmiraju ◽  
Jie Cui
Keyword(s):  
Reynolds Number ◽  
Pressure Loss ◽  
Total Pressure ◽  
Laminar Flows ◽  
Loss Coefficient ◽  
Piping System ◽  
Duct System ◽  
Pressure Loss Coefficient ◽  
Intermediate Distance ◽  
Loss Coefficients

Close-coupled fittings are widely used in piping system to change the direction of the fluid and to connect pipes. These fittings cause losses and these losses play a significant role in the total pressure loss in a duct system. Numerical simulations were performed using Fluent on laminar flows in a circular pipe to obtain pressure loss coefficients associated with different fittings of two elbows and three elbows. Each configuration was studied with different intermediate distances between fittings of 0, 1, 3, 5, and 10 pipe diameters. It was observed that for a Reynolds number of 100 and for an intermediate distance less than 5 pipe diameters, the pressure loss coefficient for the coupled fittings was less than that of the uncoupled fittings. While the fittings become uncoupled when the intermediate distance was greater than 5 pipe diameters. Variation of velocity along the axis of the pipe was analyzed to understand the mechanism of the pressure loss for various fitting configurations with different intermediate distances.

Analysis of microdiffuser/nozzles

2006 ◽  
Vol 220 (8) ◽  
pp. 1289-1296 ◽  
Author(s):  
K-S Yang ◽  
M-S Liu ◽  
I-Y Chen ◽  
C-C Wang
Keyword(s):  
Reynolds Number ◽  
Flow Separation ◽  
Pressure Loss ◽  
Three Dimensional ◽  
Side Wall ◽  
Loss Coefficient ◽  
Opening Angle ◽  
Three Dimensional Model ◽  
Velocity Change ◽  
Pressure Loss Coefficient

In this study, an analysis of the performance of micronozzle/diffusers is performed and fabrication of the micronozzle/diffuser is conducted and tested. It is found that the ratio of the loss coefficient of nozzle and diffuser increases with the Reynolds number and with the opening angle. At a given Reynolds number, the pressure loss coefficient for nozzle is higher than that of the diffuser due to considerable difference in the momentum change. At a fixed volumetric flowrate, a ‘minimum’ phenomenon of the pressure loss coefficient versus nozzle/diffuser depth is encountered. This is related to the interactions of velocity change and friction factor. Good agreements of the measured data with the predicted results are found in this study except at a diffuser having an opening angle of 20°. This is because of the presence of flow separation. The departure of this case to the prediction is due to the separation phenomenon in a larger angle of the diffuser. Hence, a more complicated two- and three-dimensional model is adopted to verify this flow separation inside the diffuser. For the simulation of the two-dimensional case, asymmetry flow field is seen for low Reynolds number region, whereas this phenomenon is not seen under three-dimensional simulation due to the confinement of the side wall.

Development of High-Efficiency Half-Ducted Propeller Fan for Air-Conditioners by Blade Tip Shape Modification

2019 ◽  
Author(s):  
Masashi Yoshikawa ◽  
Hiroyuki Toyoda ◽  
Hisashi Daisaka
Keyword(s):  
Pressure Loss ◽  
Total Pressure ◽  
Static Pressure ◽  
Leading Edge ◽  
Loss Coefficient ◽  
Total Pressure Loss ◽  
Trailing Edge ◽  
Pressure Loss Coefficient ◽  
Blade Tip ◽  
Total Pressure Loss Coefficient

Abstract We developed a high-efficiency half-ducted propeller fan to reduce the electric power consumption of the outdoor unit of air conditioner by using computational fluid dynamics (CFD). Total pressure loss coefficient on the cylindrical surface of blade tip started increasing at the middle of the blade, and the region of high total pressure loss coefficient was formed after trailing edge. Therefore, we assumed that decreasing this region helped increasing static pressure efficiency. Limiting stream lines on the pressure surface showed that the flow from leading edge leaked at the middle of the blade tip, so it was assumed that the region of the high total pressure loss coefficient arose from the leakage at the middle of the blade tip. We confirmed that static pressure at the middle of blade tip, which was the leakage point, was low. We assumed that low inward force to the flow caused the leakage. On the other hand, static pressure at trailing edge of the blade tip was high. Therefore, it was found that the inward force could be increased by making the static pressure higher at the meddle of the blade tip. In order to make the static pressure higher at the middle of the blade tip, we attempted to move the maximum camber position of the blade tip from trailing edge side to leading edge side. Calculation results showed leakage at the blade tip decreased and the static pressure efficiency increased by 0.5%. Experimental results showed that the static pressure efficiency increased by 1.7 % and sound pressure level was almost the same. For the above reasons, we found leakage of flow from leading edge could be decreased by adjusting the maximum camber position of the blade tip. Decreasing leakage contributed to increasing static pressure efficiency and decreasing electric power consumption.

Simulation of Compressible and Incompressible Flows Through Planar and Axisymmetric Abrupt Expansions

2019 ◽  
Vol 141 (11) ◽  
Author(s):  
Ali Nouri-Borujerdi ◽  
Ardalan Shafiei Ghazani
Keyword(s):  
Reynolds Number ◽  
Mach Number ◽  
Pressure Loss ◽  
Incompressible Flows ◽  
Splitting Method ◽  
Expansion Ratio ◽  
Loss Coefficient ◽  
Turbulent Regime ◽  
Reattachment Length ◽  
Pressure Loss Coefficient

In this paper, compressible and incompressible flows through planar and axisymmetric sudden expansion channels are investigated numerically. Both laminar and turbulent flows are taken into consideration. Proper preconditioning in conjunction with a second-order accurate advection upstream splitting method (AUSM+-up) is employed. General equations for the loss coefficient and pressure ratio as a function of expansion ratio, Reynolds number, and the inlet Mach number are obtained. It is found that the reattachment length increases by increasing the Reynolds number. Changing the flow regime to turbulent results in a decreased reattachment length. Reattachment length increases slightly with a further increase in Reynolds number. At a given inlet Mach number, the maximum value of the ratio of the reattachment length to step height occurs at the expansion ratio of about two. Moreover, the pressure loss coefficient is a monotonic increasing function of expansion ratio and increases drastically by increasing Mach number. Increasing inlet Mach number from 0.1 to 0.2 results in an increase in pressure loss coefficient by less than 5%. However, increasing inlet Mach number from 0.4 to 0.6 results in an increase in loss coefficient by 70–100%, depending on the expansion ratio. It is revealed that increasing Reynolds number beyond a critical value results in the loss of symmetry for planar expansions. Critical Reynolds numbers change adversely to expansion ratio. The flow regains symmetry when the flow becomes turbulent. Similar bifurcating phenomena are observed beyond a certain Reynolds number in the turbulent regime.

An Experimental Investigation of Contoured Leading Edges for Secondary Flow Loss Reduction

2004 ◽  
Author(s):  
Sandor Becz ◽  
Mark S. Majewski ◽  
Lee S. Langston
Keyword(s):  
Secondary Flow ◽  
Pressure Loss ◽  
Total Pressure ◽  
Leading Edge ◽  
Loss Coefficient ◽  
Total Pressure Loss ◽  
Loss Reduction ◽  
Pressure Loss Coefficient ◽  
Flow Loss ◽  
Total Pressure Loss Coefficient

Experimental results are presented which provide mass averaged total pressure loss coefficient measurements for three different turbine airfoil leading edge configurations. A baseline (Langston) configuration, a leading edge bulb, and a leading edge fillet were tested in a large-scale, low aspect ratio, high turning linear cascade. Results show that while the fillet geometry reduced overall loss by approximately 7%, the bulb did not exhibit a loss reduction. For the fillet, overall turning was slightly reduced, while for the bulb turning increased slightly. Thus, the bulb shows potential for increasing airfoil loading without an associated loss penalty. Contour plots of total pressure loss coefficient and vorticity are presented for all geometries and the major differences between each are discussed. Through investigation of pitch averaged loss profiles it is found that the area of greatest reduction differs between the bulb and fillet, leading to the possibility that the mechanisms through which each is affecting the flow may be different. This provides hope that the best features of each may potentially be combined to determine an optimum shape for secondary flow loss reduction.

The Comparative Study Between Swirl and Impingement of Mist/Air Cooling on Blade Leading Edge

2015 ◽  
Author(s):  
Yuting Jiang ◽  
Qun Zheng ◽  
Bo Liu ◽  
Jie Gao ◽  
Hai Zhang
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Comparative Study ◽  
Pressure Loss ◽  
Leading Edge ◽  
Swirl Flow ◽  
Air Cooling ◽  
Impingement Cooling ◽  
Pressure Loss Coefficient ◽  
Blade Leading Edge

A comparative study of the flow field and heat transfer characteristics between swirl and impingement of mist/air cooling on blade leading edge is carried out to find better cooling configuration for phase transition cooling. The Eulerian-Lagrangian particle tracking technique is used to investigate the mist/air cooling. Comparisons are made between these two cooling forms in such aspects as vortex structure, heat transfer enhancement, pressure loss, and thermal uniformity with and without mist injection. The influences of mist ratio and Reynolds numbers on these parameters are studied in this paper. Results show that the heat transfer is enhanced, pressure loss and the thermal uniformity is improved by the swirl flow created by vortex impingement. The heat transfer performance increases by about 46.2% and 51.9% for impingement and swirl cooling with 8% mist injection, and the pressure loss coefficient increases by 19%. The difference of heat transfer coefficient between swirl and impingement cooling with and without mist injection at high Reynolds number is larger than that at low Reynolds number. In addition, heat transfer non-uniform coefficient of swirl cooling is about 15% lower than impingement cooling.

scholarly journals Effect of Incidence on Secondary Flows in a Linear Turbine Cascade

1994 ◽  
Author(s):  
G. V. Ramana Murty ◽  
N. Venkatrayulu
Keyword(s):  
Pressure Loss ◽  
Total Pressure ◽  
Leading Edge ◽  
Loss Coefficient ◽  
Secondary Flows ◽  
Total Pressure Loss ◽  
Turbine Cascade ◽  
Local Loss ◽  
Pressure Loss Coefficient ◽  
Total Pressure Loss Coefficient

The effect of incidence on the generation and growth of secondary flows in a linear turbine cascade was studied in the present investigations using a Variable Density Cascade Tunnel at an exit Mach number of 0.43 and a Reynolds number of 8 × 105. The angles of incidence chosen were +15°, +50, 0°, −5° and −8.5°. The flow field was surveyed at five axial stations from cascade inlet to exit with a view to understanding the development of the secondary flow with the help of the variation of mass averaged total pressure loss coefficient and the contours of local loss coefficients in the pitch and spanwise directions. The total pressure loss coefficient and the net secondary loss coefficient have shown a steady growth along the cascade upto about 74 of the axial chord from the leading edge and thereafter rose very rapidly. The incidence is found to have an effect on the passage vortex and the loss cores due to the inlet boundary layer.

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