Simulation and Testing on Performance of the Woven Brush Seal in Vacuum Environment

2016 ◽  
Author(s):  
Farong Du ◽  
Zheng Xu ◽  
Fenzhu Ji ◽  
Yu Zhou
Keyword(s):  
Porous Medium ◽  
Boundary Conditions ◽  
Finite Volume ◽  
Calculation Method ◽  
Rotational Speed ◽  
Labyrinth Seal ◽  
Experimental Results ◽  
Actual Situation ◽  
Brush Seal

The liquid lubrication is one of the most common lubrication modes in long-term space equipment, the sealing for liquid lubricants is thus important. Woven brush seal is motived by contact, which is able to achieve zero gap and thus have better performance than others. In this paper, we propose a woven brush seal system based on the model of porous medium with deformation of woven brush wire in anisotropic. For estimating the leakage and verifying availability of our system, we build calculation models by employing finite volume k-epsilon model and SIMPSON calculation method. Additionally, we run both simulation and experiments to evaluate our system, the calculation and experimental results show that: the leakage is much lower than traditional labyrinth seal, the amount of leakage increases gradually with the increase of rotational speed. The calculation method and boundary conditions are consistent with the actual situation. Namely, woven brush is able to satisfy the requirements in vacuum environment and thus considered as the corresponding seal component.

Numerical Comparison of Leakage Flow and Rotordynamic Characteristics for Two Types of Labyrinth Seals With Baffles

2020 ◽  
Vol 142 (9) ◽  
Author(s):  
Yuanqiao Zhang ◽  
Jun Li ◽  
Zhigang Li ◽  
Xin Yan
Keyword(s):  
Rotational Speed ◽  
Flow Resistance ◽  
Labyrinth Seal ◽  
Leakage Flow ◽  
Numerical Comparison ◽  
Vibration Frequencies ◽  
Labyrinth Seals ◽  
Rotordynamic Coefficients ◽  
Brush Seal ◽  
Swirl Intensity

Abstract Cavity separation baffles can decrease the circumferential swirl intensity of labyrinth seals and increase the seals' rotordynamic characteristics. Compared with conventional baffles, the bristle packs of brush seal baffles can contact the rotor directly, thereby further reducing the swirl intensity of the seal cavity. This paper, using the numerical model combining a multifrequency elliptical whirling orbit model, a porous medium model, and transient Reynolds-averaged Navier–Stokes (RANS) solutions, compares the leakage flow and rotordynamic characteristics of a labyrinth seal with brush-seal baffles (LSBSB) and a labyrinth seal with conventional baffles (LSCB). Ideal air flows into the seal at an inlet preswirl velocity of 0 m/s (or 60 m/s or 100 m/s), total pressure of 690 kPa, and temperature of 14 °C. The outlet static pressure is 100 kPa and the rotational speed is 7500 r/min (surface speed of 66.8 m/s) or 15,000 r/min (surface speed of 133.5 m/s). Numerical results show that the LSBSB possesses the slightly less leakage flow rate than the LSCB due to the flow resistance of the bristle pack to the fluid. Compared with the LSCB, the LSBSB shows a higher positive effective stiffness (Keff) at all considered vibration frequencies and a higher effective damping (Ceff) for most vibration frequencies. What is more, the crossover frequency (fc0) of the LSBSB is significantly lower than that of the LSCB, which means that the LSBSB has a wider frequency range offering positive effective damping. The increasing inlet preswirl velocity and rotational speed only slightly affect the Keff for both seals. The Ceff of two seals decreases as the inlet preswirl velocity rises, especially for the LSCB. The Ceff of the LSCB slightly decreases because of the increasing rotational speed. In contrast, the Ceff of the LSBSB is not sensitive to the changes in rotational speed. In a word, the LSBSB possesses superior rotordynamic performance to the LSCB. Note that this work also investigates the leakage flow and rotordynamic characteristics a labyrinth seal with inclined baffles (LSIB) under the condition of u0 = 60 m/s and n = 15,000 r/min. The inclined baffles of the LSIB are same as the backing plates of LSBSB baffles. The LSIB has rotordynamic coefficients almost equal to the LSCB. Hence, the reason why the LSBSB possesses better rotordynamic performance than that of the LSCB is the flow resistance of bristle packs of brush seal baffles, not the inclination direction variation of baffles.

scholarly journals Leakage performance predictions of a brush seal based on fluid–solid coupling method

2020 ◽  
Vol 103 (1) ◽  
pp. 003685041989722
Author(s):  
Chang Yue ◽  
Sun Bitian ◽  
Zhang Lanzhu
Keyword(s):  
Porous Medium ◽  
Porous Media ◽  
Boundary Conditions ◽  
Coupling Model ◽  
Calculation Model ◽  
Brush Seal ◽  
Sealing Performance ◽  
Performance Predictions ◽  
Porous Media Model ◽  
Porous Medium Model

The sealing performance of a brush seal is studied in this article. At present, the mostly used model to analyze the performance of a brush seal is porous medium model in which the effect of bristle deformation is not considered. Here, a combined numerical method is proposed. First, the deformation of bristle is calculated in a fluid–solid coupling model with a simplified bristle model, and then the results of the bristle deformation is imported to a porous media model as the boundary conditions. More accurate media flow and leakage variation law of the brush seal are obtained with this calculation model.

CFD Prediction and Test Results of Stiffness and Damping Coefficients for Brush-Labyrinth Gas Seals

2010 ◽  
Author(s):  
Alexander O. Pugachev ◽  
Martin Deckner
Keyword(s):  
Porous Medium ◽  
Three Dimensional ◽  
Great Influence ◽  
Dynamic Test ◽  
Labyrinth Seal ◽  
Rotordynamic Coefficients ◽  
Damping Coefficients ◽  
Brush Seal ◽  
Gas Seals ◽  
Stiffness And Damping

This paper presents ongoing investigations on calculation and measurement of rotordynamic coefficients for brush-labyrinth gas seals. The seals are tested on static and dynamic test rigs to measure leakage, pressure distribution, and seal specific forces. To predict seal performance a full three-dimensional eccentric CFD model is considered. Rotordynamic coefficients are calculated using the whirling rotor method. The bristle pack of the brush seal is modeled using the porous medium approach. The prediction results show some deviations in absolute values of stiffness and damping coefficients in comparison with the experimental values, but the trends are similar. Comparing with a staggered labyrinth seal, the brush seal improves rotordynamic characteristics in most cases. Position of the brush seal in sealing configuration has a great influence on the stiffness and damping coefficients, while leakage performance remains relatively unaffected. The capability of the brush seal model based on the porous medium approach to predict rotordynamic coefficients is discussed.

scholarly journals Calculation Method for Plates with Discrete Variable Thickness Under Uniform Loading or Hydrostatic Pressure

2018 ◽  
Vol 23 (4) ◽  
pp. 835-853
Author(s):  
G. Aryassov ◽  
D. Gornostajev ◽  
I. Penkov
Keyword(s):  
Hydrostatic Pressure ◽  
Boundary Conditions ◽  
Variable Thickness ◽  
Analytical Method ◽  
Calculation Method ◽  
Theoretical Calculations ◽  
Complex Loading ◽  
Experimental Results ◽  
Test Machine ◽  
Special Equipment

Abstract The article proposes a new analytical method for the calculation of plates with constant and variable rigidity parameters. This method renders it possible to decrease the weight of the plates working under hydrostatic pressure by using variable thicknesses. Firs, a short overview of existing calculation methods and their results are compared. It is shown that all existing methods depend on boundary conditions. Then is given the theory of the proposed calculation method is described and calculations for plates with constant and variable thickness worked under uniformly loaded forces and hydrostatic pressure are made. The results are compared to the FEM calculations and experimental results obtained by a tensile test machine and special equipment. Calculation results obtained by the proposed analytical method and FEM results are very close. Deviations are not more than 11%. Deviations between theoretical calculations and experimental results depend on loading type and design of the test specimens but maximum values are not more than 17%. The proposed calculation method does not depend on the boundary conditions and can be used for plate calculations. Especially for plates with difficult design and complex loading.

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

2010 ◽  
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.

scholarly journals Experimental and Analytical Study on Creep Characteristics of Box Section Bamboo-Steel Composite Columns under Long-Term Loading

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 983
Author(s):  
Shixu Wu ◽  
Keting Tong ◽  
Jianmin Wang ◽  
Yushun Li
Keyword(s):  
Load Level ◽  
Experimental Results ◽  
Creep Model ◽  
Composite Column ◽  
Composite Columns ◽  
Creep Coefficient ◽  
Creep Characteristics ◽  
Section Size ◽  
Steel Composite

To expand the application of bamboo as a building material, a new type of box section composite column that combined bamboo and steel was considered in this paper. The creep characteristics of eight bamboo-steel composite columns with different parameters were tested to evaluate the effects of load level, section size and interface type under long-term loading. Then, the deformation development of the composite column under long-term loading was observed and analyzed. In addition, the creep-time relationship curve and the creep coefficient were created. Furthermore, the creep model of the composite column was proposed based on the relationship between the creep of the composite column and the creep of bamboo, and the calculated value of creep was compared with the experimental value. The experimental results showed that the creep development of the composite column was fast at first, and then became stable after about 90 days. The creep characteristics were mainly affected by long-term load level and section size. The creep coefficient was between 0.160 and 0.190. Moreover, the creep model proposed in this paper was applicable to predict the creep development of bamboo-steel composite columns. The calculation results were in good agreement with the experimental results.

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