On the Pressure Losses Due to the Tip Clearance of Centrifugal Blowers

1981 ◽  
Vol 103 (2) ◽  
pp. 271-278 ◽  
Author(s):  
M. Ishida ◽  
Y. Senoo
Keyword(s):  
Pressure Gradient ◽  
Pressure Loss ◽  
Relative Velocity ◽  
Pressure Rise ◽  
Input Power ◽  
Tip Clearance ◽  
Centrifugal Impeller ◽  
Clearance Ratio ◽  
Local Pressure ◽  
Pressure Losses

The pressure distribution along the shroud is measured for three types of centrifugal impeller at seven different values of tip clearance each. The change of input power due to a change of tip clearance is related to the effective blockage at the impeller tip. Since the change of input power is little for the test cases, the variation of local pressure gradient along the shroud is mostly attributed to the change of local pressure loss. The local pressure loss is related to the local tip clearance ratio and to the local pressure gradient based on the deceleration of relative velocity in the impeller. Since the local pressure gradient is largest near the throat of the impeller, for many impellers the clearance ratio at the throat is used as the representative value. The tip clearance loss is related to the clearance ratio and the pressure rise based on the deceleration of relative velocity in the impeller. A good correlation is observed in all cases at various flow rate.

scholarly journals On the Pressure Losses due to the Tip Clearance of Centrifugal Blowers

1980 ◽  
Author(s):  
M. Ishida ◽  
Y. Senoo
Keyword(s):  
Pressure Gradient ◽  
Pressure Loss ◽  
Relative Velocity ◽  
Pressure Rise ◽  
Input Power ◽  
Tip Clearance ◽  
Centrifugal Impeller ◽  
Clearance Ratio ◽  
Local Pressure ◽  
Pressure Losses

The pressure distribution along the shroud is measured for three types of centrifugal impeller at seven different values of tip clearance each. The change of input power due to a change of tip clearance is related to the effective blockage at the impeller tip. Since the change of input power is little for the test cases, the variation of local pressure gradient along the shroud is mostly attributed to the change of local pressure loss. The local pressure loss is related to the local tip clearance ratio and to the local pressure gradient based on the decleration of relative velocity in the impeller. Since the local pressure gradient is largest near the throat of impeller is used as the representative value. The tip clearance loss is related to the clearance ratio and the pressure rise based on the deceleration of relative velocity in the impeller. A good correlation is observed in all cases at various flow rate.

Measurement and Analysis of an Efficient Turbine Rotor Pump Work Reduction System Incorporating Pre-Swirl Nozzles and a Free Vortex Pressure Augmentation Chamber

2004 ◽  
Author(s):  
V. Laurello ◽  
M. Yuri ◽  
K. Fujii ◽  
K. Ishizaka ◽  
T. Nakamura ◽  
...  
Keyword(s):  
Relative Velocity ◽  
Static Pressure ◽  
Tangential Velocity ◽  
Pressure Rise ◽  
Turbine Rotor ◽  
Vortex Chamber ◽  
Free Vortex ◽  
Pressure Losses ◽  
Cooling Air ◽  
Velocity Pressure

Measurements and analysis of an efficient turbine rotor pump work reduction system is presented. The system features; a “low” radius pre-swirl nozzle comprised of cascade vanes with a radial orientation, equal radius seals downstream of the nozzle, “jumper” tubes across the nozzle, and a free vortex chamber. A scaled experimental rig was utilized to measure and compare with predictions the following; rotor pump work, average tangential velocity exiting the nozzle, tangential velocity variation in the axial and radial direction, free vortex chamber static pressure rise, effect of relative velocity pressure losses, and effect of “pollution” by seal flow. The effort focused on measuring pump work reduction and the efficiency of the pressure augmentation system. In contrast to aero-engines where the main objective of pre-swirl is to reduce cooling air temperature to the blades, the main objective for this industrial gas turbine is to reduce pump work and increase output. An external pre-cooler is utilized to achieve the large cooling air temperature reduction required to maintain disk material limits. The analytical results and rig test data are presented and compared. The results substantiated the following: the level of reduced rotor pump work due to pre-swirl, the static pressure rise in the free vortex chamber, the effect of eliminating “pollution”, and relative velocity pressure losses. CFD analytical results are compared with the rig data.

scholarly journals Minor pressure losses for different connections of PP-R and PEX/Al/PEX installation pipes

2019 ◽  
Vol 100 ◽  
pp. 00045
Author(s):  
Kinga Ligaj ◽  
Marcin K. Widomski ◽  
Anna Musz-Pomorska
Keyword(s):  
Reynolds Number ◽  
Numerical Modeling ◽  
Pressure Loss ◽  
Flow Resistance ◽  
Direct Connection ◽  
Laboratory Measurements ◽  
Local Pressure ◽  
Pressure Losses ◽  
Numerical Research

This paper presents results of laboratory and numerical research concerning determination of water flow resistance through three types of two-way connection of polymer installation pipes: PP-R 20x3.4 mm and PEX/Al/PEX 16x2.0 mm. The following fittings were applied: the direct connection, pipe union and coupler, allowing to test six measurement variants. The laboratory measurements of pressure loss for the tested pipes connections were performed for variable Reynolds number, from approx. 5000 to 50000. The numerical modeling allowing to assess the distributions of velocity of flow and turbulence intensity were performed using FLUENT, Ansys Inc. modelling software. The relations between determined values of minor pressure loss and coefficients of local pressure losses and type of pipes connection, direction of flow as well as the value of Reynolds number were observed. The applied nonparametric statistics, combined with multi comparison, showed that in most cases of analyzed connections, besides the pipe union, the observed differences in pressure losses for various directions of flows are statistically significant for p = 0.05.

Effect of Blade Tip Configuration on Tip Clearance Loss of a Centrifugal Impeller

1990 ◽  
Vol 112 (1) ◽  
pp. 14-18 ◽  
Author(s):  
M. Ishida ◽  
H. Ueki ◽  
Y. Senoo
Keyword(s):  
Tip Clearance ◽  
Centrifugal Impeller ◽  
Meridional Plane ◽  
Leakage Flow ◽  
Clearance Ratio ◽  
Contraction Coefficient ◽  
Blade Tip ◽  
Flow Through ◽  
Annular Clearance ◽  
Blade Tip Clearance

According to the theory presented by the authors, the tip clearance loss of an un-shrouded centrifugal impeller mainly consists of two kinds of loss; one is the drag due to the leakage flow through the blade tip clearance and the other is the pressure loss to support the fluid in the thin annular clearance space between the shroud and the blade tip against the pressure gradient in the meridional plane without blades. The former is proportional to the leakage flow or the contraction coefficient of leakage flow. The authors have conducted performance tests using an impeller with 16 backward-leaning blades in three configurations of the blade tip: round edge, sharp square edge, and edge with an end-plate. The experimental tip clearance effects can be predicted by the theory assuming reasonable contraction coefficients. They are 0.91, 0.73, and 0.53 for the respective tip configurations. The impeller efficiency is improved by about 1.5 point by reducing the contraction coefficient from 0.91 to 0.53, providing that the tip clearance ratio at the exit of impeller is 0.1. More improvement is expected for an impeller with highly loaded blades where the leakage loss shares the major part of the tip clearance loss.

Effects of Air Induct Structure to Flow Uniformity and Resistance for Primary Surface Recuperator of a Micro Gas Turbine

2010 ◽  
Author(s):  
Wei Qu ◽  
Shan Gao
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Pressure Loss ◽  
Air Flow ◽  
Flow Distribution ◽  
Structure Design ◽  
Flow Uniformity ◽  
Local Pressure ◽  
Pressure Losses ◽  
Micro Gas Turbine

Primary surface recuperator is important for micro gas turbines, the flow distribution and pressure loss are sensitive to the induct structure design significantly. The air induct structure for one recuperator is modelled and simulated. Several flow fields and pressure losses are obtained for different designs of air induct structure. The air induct structure can affect the flow uniformity, further influence the pressure loss a lot. For several changes of air induct structure, the non-distribution of air flow can be decreased from 67% to 13%, and the pressure loss can be decreased to 50% of the original. Considering the recuperator design and the gas turbine, one optimized structure is recommended, which has less local pressure loss and better flow distribution.

scholarly journals Determination of the Local Pressure Loss Coefficient Experimentally and Using CFD Methods

2020 ◽  
Vol 328 ◽  
pp. 02019
Author(s):  
Šimon Kubas ◽  
Andrej Kapjor ◽  
Martin Vantúch ◽  
Marián Pafčuga
Keyword(s):  
Pressure Loss ◽  
Air Conditioning ◽  
Loss Coefficient ◽  
Cfd Model ◽  
Acoustic Attenuation ◽  
Local Pressure ◽  
High Noise ◽  
Pressure Losses ◽  
Pressure Loss Coefficient

When choosing silencers in air conditioning, it is necessary to pay attention not only to the acoustic attenuation, but also to the pressure loss of the silencer. If the pressure loss of the damper is too high, noise will occur directly in the damper. The pressure losses of the silencers are determined mainly experimentally. Based on the performed measurement, a CFD model of the selected silencer was constructed, where the influence of various parameters on the value of the pressure loss of the selected silencer was investigated.

Secondary Flow Due to the Tip Clearance at the Exit of Centrifugal Impellers

1990 ◽  
Vol 112 (1) ◽  
pp. 19-24 ◽  
Author(s):  
M. Ishida ◽  
Y. Senoo ◽  
H. Ueki
Keyword(s):  
Velocity Distribution ◽  
Secondary Flow ◽  
Shear Force ◽  
Input Power ◽  
Tip Clearance ◽  
The Other ◽  
Centrifugal Impeller ◽  
Meridional Plane ◽  
Flow Angle ◽  
Different Types

The velocity distribution was measured at the exit of two different types of un-shrouded centrifugal impeller under four different tip clearance conditions each; one with 20 radial blades and inducers and the other with 16 backward-leaning blades. The effect of tip clearance on input power was also measured. By increasing the tip clearance, the input power was hardly changed in the radial blade impeller and was reduced in the backward-leaning blade impeller. The velocity distribution normalized by the passage width between hub and shroud wall was hardly changed at the exit of the radial blade impeller by varying the tip clearance. On the other hand, the relative flow angle was reduced significantly and monotonously by an increase of tip clearance in the backward-leaning blade impeller. The change in input power due to the tip clearance was clearly related to the change of flow pattern at the exit of impeller due to the secondary flow. This is most likely caused by the component, normal to the blade, of the shear force to support the fluid in the clearance space against the pressure gradient in the meridional plane without blades.

End-Wall and Profile Losses in a Low-Speed Axial Flow Compressor Rotor

1986 ◽  
Vol 108 (1) ◽  
pp. 22-31 ◽  
Author(s):  
B. Lakshminarayana ◽  
N. Sitaram ◽  
J. Zhang
Keyword(s):  
Axial Flow ◽  
Pressure Rise ◽  
Tip Clearance ◽  
Blade Loading ◽  
Pressure Losses ◽  
Axial Flow Compressor ◽  
Compressor Rotor ◽  
Profile Losses ◽  
Flow Compressor ◽  
End Wall

The blade-to-blade variation of relative stagnation pressure losses in the tip region inside the rotor of a single-stage, axial-flow compressor is presented and interpreted in this paper. The losses are measured at two flow coefficients (one at the design point and the other at the near peak pressure rise point) to discern the effect of blade loading on the end-wall losses. The tip clearance losses are found to increase with an increase in the pressure rise coefficient. The losses away from the tip region and near the hub regions are measured downstream. The losses are integrated and interpreted in this paper.

Pressure Loss Due to the Tip Clearance of Impeller Blades in Centrifugal and Axial Blowers

1986 ◽  
Vol 108 (1) ◽  
pp. 32-37 ◽  
Author(s):  
Y. Senoo ◽  
M. Ishida
Keyword(s):  
Experimental Data ◽  
Pressure Gradient ◽  
Pressure Loss ◽  
Present Model ◽  
Tip Clearance ◽  
Fair Agreement ◽  
Leakage Flow ◽  
Flow Through ◽  
Annular Clearance ◽  
Special Case

The pressure loss based on the tip clearance of impeller blades consists of the pressure loss induced by the leakage flow through the clearance and the pressure loss for supporting fluid against the pressure gradient in the channels and in the thin annular clearance space between the shroud and the impeller. Equations to evaluate these losses are derived and the predicted efficiency drop is compared with experimental data for two types of centrifugal impellers. Furthermore, the equations are simplified for axial impellers as a special case, and the predicted efficiency drop is compared with the experimental data for seven cases in the literature. Fair agreement demonstrates plausibility of the present model.

Effect of Differential Tip Clearance on the Performance of a Tandem Rotor

2021 ◽  
Author(s):  
Amit Kumar ◽  
Hitesh Chhugani ◽  
Shubhali More ◽  
A. M. Pradeep
Keyword(s):  
Pressure Gradient ◽  
Total Pressure ◽  
Vortex Breakdown ◽  
Pressure Rise ◽  
Adverse Pressure Gradient ◽  
Tip Clearance ◽  
Tip Vortex ◽  
Sudden Expansion ◽  
Engine Operation ◽  
Operation Stability

Abstract Tandem blade is an interesting concept that promises a higher total pressure rise per stage. Owing to two separate tip leakage vortices and their interaction, losses are likely to increase particularly near the tip region. Although, rotors are designed with optimum tip clearance, the clearance changes during engine operation as well as during its service life. In the case of tandem rotors, the forward and the aft rotors can have different tip clearances. This will also impact the performance of the stage. Six different tip clearances have been investigated. ANSYS CFX is used for steady RANS computational analysis. The results suggest that the performance of the tandem rotor is highly sensitive to the forward rotor tip clearance. Higher tip clearance adversely affects the total pressure rise and operation stability of the tandem rotor. At design mass flow rate, the performance degradation for tandem configuration with the higher tip clearance (Case2, Case 3, Case 5, and Case 6), is attributed to the vortex breakdown of TLV1, which leads to the sudden expansion of the blockage region near the rotor tip. Vortex breakdown primarily depends upon the swirling strength of TLV1 and TLV2 as well as on the adverse pressure gradient. Near the stall point, the role of the adverse pressure gradient becomes more dominant in the vortex breakdown.

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