639 Numerical Investigations on Leakage Flow Characteristics of Labyrinth Brush Seals at the Turbine Blade Shroud

Abstract This paper numerically investigates the leakage flow characteristics of two types of HLBSs (bristle pack installed upstream or downstream of helical-labyrinth tooth named as HLBS-U and HLBS-D, respectively) at various pressure ratios (1-1.3) and rotational speeds (0-10000r/min). In parallel, the leakage flow characteristics of the HLBS-D with the constant cb of 1.0 mm are experimentally measured at the pressure ratio up to 1.3 and rotational speed up to 2000 r/min. The effective clearance of the HLBS-U is smaller than that of the HLBS-D in the case of cb=0.5mm and rotational speed n<10000r/min, and the case of cb=1.0mm. However, for the case of cb=0.5mm and n=10000r/min, and the case of cb=0.1mm, the situation is opposite. The brush seal sections of the HLBS-U and the HLBS-D offer over 55% and 65% total static pressure drop in the case of cb=1.0 mm, respectively; The brush seal sections of two HLBSs bear almost the same static pressure drop of the over 97% total static pressure drop as cb equals to 0.1 mm. The HLBS-U has lower turbulent kinetic energy upstream of the bristle pack than the HLBS-D does, which means that intensity of bristles flutter of the HLBS-U is lower. The HLBS-U possesses significantly lower absolute value of aerodynamic forces than the HLBS-D does as cb=1.0 mm.

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Unsteady Tip Leakage Flow Characteristics and Heat Transfer on Turbine Blade Tip and Casing

41st AIAA Thermophysics Conference ◽

10.2514/6.2009-3929 ◽

2009 ◽

Author(s):

Md Rahman ◽

Sung In Kim ◽

Ibrahim Hassan

Keyword(s):

Heat Transfer ◽

Turbine Blade ◽

Flow Characteristics ◽

Leakage Flow ◽

Tip Leakage Flow ◽

Tip Leakage ◽

Blade Tip

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Characteristics of Tip Leakage Flow of the Turbine Blade With Cutback Squealer and Coolant Injection

Volume 7: Turbomachinery, Parts A, B, and C ◽

10.1115/gt2010-22566 ◽

2010 ◽

Cited By ~ 2

Author(s):

Jianhua Wang ◽

Yalin Liu ◽

Xiaochun Wang ◽

Zhineng Du ◽

Shijie Yang

Keyword(s):

Turbine Blade ◽

Film Cooling ◽

Flow Characteristics ◽

Leakage Flow ◽

Tip Leakage Flow ◽

Tip Leakage ◽

Coolant Injection ◽

Blade Tip ◽

Film Cooling Holes ◽

Numerical Program

Experimental and numerical investigations of the tip leakage flow characteristics between turbine blade tip and stator wall (shroud) were conducted by a particle image velocimetry (PIV) system and the commercially available software CFX 11.0. A three-time scaled profile of the GE-E3 blade was used as specimen. Two rows of cylindrical film-cooling holes with 1.5mm diameter were arranged in the blade tip. One row with 5 holes was placed in pressure side just below the groove floor, and the other with 11 holes was equidistantly arranged on the tip along the mid camber line. To exhibit the generation and movement of leakage vortex, and to compare the coolant injection effects from different rows, several typical velocity profiles were captured by the PIV system. The experimental results were used as a data source to validate the turbulence model and numerical program. To better understand the mixing characteristics of the coolant injected from different rows with the leakage flow, the fluid fields of the leakage vortex and coolant flow were simulated, and the leakage mass rates from the blade tip in different coolant injection cases and different gaps were quantitatively estimated by the validated numerical program.

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A Three-Dimensional Tube Bundle Model Analysis for Leakage Flow Characteristics of Variable Bristle Diameter Brush Seals With Bristle Pack Stratification

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.4050065 ◽

2021 ◽

Vol 143 (5) ◽

Author(s):

Dengqian Ma ◽

Zhigang Li ◽

Jun Li

Keyword(s):

Tube Bundle ◽

Pressure Ratio ◽

Large Diameter ◽

Three Dimensional ◽

Flow Characteristics ◽

Leakage Flow ◽

Sealing Performance ◽

Leakage Flow Rate ◽

Brush Seals ◽

Resistance Coefficients

Abstract The leakage flow characteristics of the variable bristle diameter (VBD) brush seals are numerically investigated using the three-dimensional (3D) tube bundle model with consideration of bristle pack stratification. The discretization of the computational domain applies the multiblock structured mesh, which ensures that there is no need to set interfaces between the fluid domains of the bristle pack and the cavities to eliminate interpolation errors. The bristle pack stratification is achieved by using mesh motion technique from the point of cause-effect. The effects of pressure ratio (Rp=1.5, 2.5, 3.5), axial rows of bristles (Nx=9–21), sealing clearance (c=0, 0.1 mm), bristle pack arrangements, and bristles gapping (gi=0, 0.005, 0.010, 0.015 mm) on the leakage flow characteristics and aerodynamic forces are conducted. The recorded leakage flow of the 3D tube bundle model is multiplied by circumferential loop number (Ncl) to determine total leakage flow rate of the brush seal. The numerical results agreed well with the experimental data, which verifies the reliability of the numerical method. The numerical results indicate that the leakage flow rate increases linearly with the pressure ratio. The increase of Nx has a distinctly different effect on the relative rate of leakage flow for the contacting and clearance brush seals. The use of large diameter bristles weakens the sealing performance of the brush seals, particularly in the rear region. Bristle pack stratification can improve the sealing performance of the brush seals. The large diameter bristles increase the porosity and reduce the flow resistance coefficients. On the contrary, the bristle pack stratification decreases the porosity and rises the flow resistance coefficients in the rear region. The results of this article indicate when designing VBD brush seals, the effects of bristle diameter and bristle density on the sealing performance and pressure loading capacity of the brush seals should be fully considered.

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Numerical investigations on the leakage flow characteristics of pocket damper labyrinth seals

Proceedings of the Institution of Mechanical Engineers Part A Journal of Power and Energy ◽

10.1177/0957650912451410 ◽

2012 ◽

Vol 226 (7) ◽

pp. 932-948 ◽

Cited By ~ 6

Author(s):

Zhigang Li ◽

Jun Li ◽

Xin Yan ◽

Zhenping Feng

Keyword(s):

Flow Characteristics ◽

Leakage Flow ◽

Labyrinth Seals ◽

Numerical Investigations

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Experimental and Numerical Investigations on the Leakage Flow Characteristics of the Labyrinth Brush Seal

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.4007062 ◽

2012 ◽

Vol 134 (10) ◽

Cited By ~ 13

Author(s):

Jun Li ◽

Bo Qiu ◽

Zhenping Feng

Keyword(s):

Experimental Data ◽

Pressure Ratio ◽

Flow Characteristics ◽

Leakage Rate ◽

Navier Stokes ◽

Leakage Flow ◽

Blow Down ◽

Pressure Distributions ◽

Brush Seal ◽

Brush Seals

The leakage rate of the labyrinth brush seal was experimentally measured and numerically investigated in this paper. Four different rotational speeds of 0, 1500, 2400 and 3000 rpm were utilized to investigate the effects on the leakage rate of the labyrinth brush seal. In addition, five different pressure ratios and two initial clearances were also adopted to study the influences of pressure ratio and clearance size on the leakage rate of the labyrinth brush seal. The leakage rates of the experimental labyrinth brush seal at different rotational speeds, pressure ratios, and initial clearances were also predicted using Reynolds-averaged Navier-Stokes (RANS) solutions coupling with a non-Darcian porous medium model. The rotor centrifugal growth and bristle blow-down effects were considered in the present numerical research. The rotor centrifugal growth at different rotational speeds was calculated using the finite element method (FEM). The variation of the sealing clearance size with rotor centrifugal growth and bristle blow-down was analyzed. The numerical leakage rate was in good agreement with the experimental data. The effects of rotational speeds, pressure ratios, and clearance sizes on the leakage flow characteristics of brush seals were also investigated based on the experimental data and numerical results. The detailed leakage flow fields and pressure distributions of the brush seals were also presented.

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Numerical Investigations on the Leakage Flow Characteristics of Brush Seal Based on the 3D Staggered Tube Bundle Model

10.1115/1.0002783v ◽

2021 ◽

Author(s):

Dengqian Ma ◽

Yuanqiao Zhang ◽

Zhigang Li ◽

Jun Li ◽

Xin Yan

Keyword(s):

Tube Bundle ◽

Flow Characteristics ◽

Leakage Flow ◽

Numerical Investigations ◽

Brush Seal

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Effects of Clearances on the Leakage Flow Characteristics of Two Kinds of Brush Seals and Referenced Labyrinth Seal

Volume 4: Heat Transfer, Parts A and B ◽

10.1115/gt2010-22877 ◽

2010 ◽

Cited By ~ 2

Author(s):

Jun Li ◽

Yangzi Huang ◽

Zhigang Li ◽

Zhenping Feng ◽

Hong Yang ◽

...

Keyword(s):

Porous Medium ◽

Flow Characteristics ◽

Numerical Approach ◽

Labyrinth Seal ◽

Leakage Flow ◽

Medium Model ◽

Multi Stage ◽

Brush Seal ◽

Brush Seals ◽

Porous Medium Model

Numerical investigations of leakage flow fields of two kinds of brush seals with four sealing clearances were conducted in this paper. The Reynolds-Averaged Navier-Stokes (RANS) and non-Darcian porous medium model solutions were applied as the numerical approach to analyze the flow characteristics of brush seal. The reliability and accuracy of the RANS and non-Darcian porous medium model for leakage flow in brush seals were established by comparison with the experimental data. The referenced labyrinth seal was changed into a multi-stage brush seal which has two configurations. One configuration had a traditional geometrical structure. The other had a shim structure installed between the front plate and brush bristle pack. The leakage flow rates of the brush seal with two different configurations were calculated for four bristle pack tip clearances (0mm, 0.1mm, 0.3mm, 0.5mm) which were compared with the results for the referenced labyrinth seal. The numerical results show that the leakage flow rate increases rapidly with the increasing of clearance between the bristle pack tip and the rotor surface for two kinds of brush seals. The sealing performance of the brush seal with shim structure is similar to that of the traditional design with the same sealing clearance and flow conditions. In addition, as compared with the traditional brush seal, the brush seal with shim structure can reduce the pressure difference between the bristle free and fence height at 0.3mm and 0.5mm sealing clearance. The leakage flow patterns in brush seals with two different configurations were also illustrated.

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