scholarly journals Analysis of the impact of the labyrinth seal geometric parameters on the leakage

2021 ◽  
Vol 323 ◽  
pp. 00015
Author(s):  
Damian Joachimiak ◽  
Piotr Krzyślak
Keyword(s):  
Experimental Research ◽  
Gas Flow ◽  
Labyrinth Seal ◽  
Gas Pressure ◽  
Geometric Parameters ◽  
Labyrinth Seals ◽  
Flow Parameters ◽  
Number Of Teeth ◽  
The Impact ◽  
Size Data

This paper includes results of experimental research and CFD calculations concerning gas flow in segments of straight through labyrinth seals of fixed length and varying number of teeth. Relation between the number of teeth and the leakage is analyzed in this paper. Authors determined the range of teeth number for which the minimum leakage was achieved. They focused particularly on the analysis of geometry with maximum number of teeth which fell within the range of the minimum leakage. For this geometry they examined the relation between the thickness of the teeth and the distribution of gas pressure and velocity along the seal and the leakage size. Data presented in this paper indicate that the teeth thickness has a significant impact on the flow parameters.

scholarly journals Experimental Research of Gaseous Emissions Impact on the Performance of New-Design Cylindrical Multi-Channel Cyclone with Adjustable Half-Rings

2022 ◽  
Vol 14 (2) ◽  
pp. 902
Author(s):  
Aleksandras Chlebnikovas ◽  
Dainius Paliulis ◽  
Kristina Kilikevičienė ◽  
Artūras Kilikevičius
Keyword(s):  
Experimental Research ◽  
Gas Flow ◽  
Collection Efficiency ◽  
Fine Particulate Matter ◽  
Air Flow ◽  
Gaseous Emissions ◽  
Channel System ◽  
Flow Parameters ◽  
The Impact ◽  
Channel Type

Cyclones are widely used for separating particles from gas in energy production objects. The efficiency of conventional centrifugal air cleaning devices ranges from 85 to 90%, but the weakness of many cyclones is the low collection efficiency of particles less than 10 μm in diameter. The novelty of this work is the research of the channel-type treatment device, with few levels adapted for precipitation of fine particulate matter, acting by a centrifugal and filtration principle. Many factors have an impact on cyclone efficiency—humidity, temperature, gas (air) composition, airflow velocity and etc. Many scientists evaluated only the effect of origin and size of PM on cyclone efficiency. The effect of gas (air) composition and temperature, and humidity on the multi-channel cyclone-separator efficiency still demands contributions. Complex theoretical and experimental research on air flow parameters and the efficiency of a cylindrical eight-channel system with adjustable half-rings for removing fine-dispersive particles (<20 μm) was carried out. The impact of air humidity and temperature on air flow, and gaseous smoke components on the removal of wood ashes was analyzed. The dusty gas flow was regulated. During the experiment, the average velocity of the cyclone was 16 m/s, and the temperature was 20–50 °C. The current paper presents experimental research results of wood ash removal in an eight-channel cyclone and theoretical methodology for the calculation of airflow parameters and cyclone effectiveness.

scholarly journals Experimental Research and CFD Calculations Based Investigations Into Gas Flow in a Short Segment of a Heavily Worn Straight Through Labyrinth Seal

2017 ◽  
Vol 24 (2) ◽  
pp. 83-88 ◽  
Author(s):  
Damian Joachimiak ◽  
Piotr Krzyślak
Keyword(s):  
Experimental Research ◽  
Power Plants ◽  
Gas Flow ◽  
Labyrinth Seal ◽  
Steam Turbines ◽  
Static Pressure Distribution ◽  
Flow Parameters ◽  
Working Medium ◽  
Theoretical Assumptions ◽  
Flow Phenomena

Abstract Steam turbines are used as propulsion components in not only power plants but also on merchant and naval ships. The geometry of the steam turbine seals changes throughout the machine life cycle. The rate of deterioration of these seals, in turn, affects heavily the efficiency of the thermal machine. However, the literature overview does not provide any research reports on flow phenomena occurring in heavily deteriorated seals. The paper describes the course and results of investigations into a model straight through labyrinth seal composed of 4 discs, each with the slot height of 2 mm. The investigations have been conducted with air as the working medium. Changes of gas flow parameters due to wear were analysed. Based on the experimental data, more intensive leakage was observed as the result of the increased slot height. The static pressure distribution along the examined segment was measured. The experimentally recorded distribution differed remarkably from the theoretical assumptions. Another part of the experimental research focused on comparing the gas velocities at points situated upstream of the first and second seal disc. The velocity measurements were carried out using a constant temperature wire probe. This part of the investigations provided opportunities for analysing the influence of seal wear on gas flow conditions in the seal segment. The paper compares the results of the experimental research with those obtained using the CFX software. The presented results of velocity distributions provide a clear picture of the nature of the gas flow in the seal, which enables its analysis.

Study on Dynamic Behavior of a Gas Pressure Relief Valve for a Big Flow Rate

2013 ◽  
Author(s):  
Victor Sverbilov ◽  
Dmitry Stadnick ◽  
Georgy Makaryants
Keyword(s):  
Flow Rate ◽  
Gas Flow ◽  
Dynamic Properties ◽  
Gas Pressure ◽  
Pressure Relief Valve ◽  
Relief Valve ◽  
Pressure Relief ◽  
Wide Range ◽  
The Impact ◽  
Pilot Valve

The paper investigates instable behavior of a poppet-type gas pressure relief valve operating at a big flow rate (more than 2 kg/s) under super critical pressure drop. Instability is experienced as noise and vibration and leads to severe damage of a seat and other elements. Significant and unsteady flow forces coupled with small inherent damping make it difficult to stabilize the system. In previous works, the analytical and experimental research was carried out to reveal the most essential factors influencing stability and dynamic properties of the valve. The impact of the pilot valve dynamics on the system behavior was studied for the purpose of obtaining required accuracy and stability in a wide range of flow rate. It was shown in some testing that unstable behavior of the main valve occurred when the pilot valve was stable. This paper considers inherent stability of the main valve in the gas flow. CFD software ANSYS FLUENT is employed to study the effect of the poppet geometry on aerodynamic lifting force and valve stability in axial and lateral direction. The results have been verified through comparison with experimental data.

scholarly journals Experimental research and CFD analysis of flow parameters in a SCR system for the original part and WALKER’s replacement

2019 ◽  
Vol 179 (4) ◽  
pp. 13-20
Author(s):  
Damian KURZYDYM ◽  
Adam KLIMANEK ◽  
Zbigniew ŻMUDKA
Keyword(s):  
Reverse Engineering ◽  
Experimental Research ◽  
Gas Flow ◽  
Catalytic Reduction ◽  
Ansys Fluent ◽  
Flow Parameters ◽  
3D Geometry ◽  
Flow Through ◽  
Original Part ◽  
Scr System

The article presents the results of experimental research and their comparison with CFD simulations for the original selective catalytic reduction system and WALKER replacement. The research was performed to develop the WALKER universal mixer. The SCR prototype without mixer and with the proposed mixer were tested and compared with the original VW part. The next step was reverse engineering, which consisted in scanning the tested parts with a laser and processing their point cloud in Leios2 program. Reverse engineering has allowed the reconstruction of 3D geometry of the tested parts in the Catia v5 program and then preparation their models for computational fluid dynamics. Numerical simulations were carried out in the Ansys Fluent program, thanks to which several quantities were determined e.g. uniformity index of gas flow through the monolith and coefficient of variation as a measure of mixing degree, which have a significant impact on the design of the mixer and the SCR system.

Effective Clearance And Differential Gapping Impact on Seal Flutter Modelling and Validation

2021 ◽  
Author(s):  
Roque Corral ◽  
Michele Greco ◽  
Almudena Vega
Keyword(s):  
Labyrinth Seal ◽  
Analytical Models ◽  
Navier Stokes ◽  
Labyrinth Seals ◽  
Theoretical Support ◽  
Gap Ratio ◽  
Flutter Analysis ◽  
The Impact ◽  
Cv Model ◽  
Additional Loss

Abstract This paper presents an update of the model derived by Corral and Vega (2018, “Conceptual Flutter Analysis of Labyrinth Seal Using Analytical Models. Part I - Theoretical Support”, ASME J. of Turbomach., 140 (12), pp. 121006) for labyrinth seal flutter stability, providing a method of accounting for the effect of dissimilar gaps. The original CV model was intended as a conceptual model for understanding the effect of different geometric parameters on the seal stability comprehensively, providing qualitative trends for seal flutter stability. However, the quantitative evaluation of seal flutter, and the comparison of the CV model with detailed unsteady numerical simulations or experimental data, require including additional physics. The kinetic energy generated in the inlet gap is not dissipated entirely in the inter-fin cavity of straight-through labyrinth seals, and part is recovered in the downstream knife. This mechanism needs to be retained in the seal flutter model. It is concluded that when the theoretical gaps are identical, the impact of the recovery factor on the seal stability can be high. The sensitivity of the seal stability to large changes in the outlet to inlet gap ratio is high as well. It is concluded that fin variations due to rubbing or wearing inducing inlet gaps more open than the exit gaps lead to an additional loss of stability concerning the case of identical gaps. The agreement between the updated model and 3D linearized Navier-Stokes simulations is excellent when the model is informed with data coming from steady RANS simulations of the seal.

An Experimental Study of Labyrinth Seal Flow

2003 ◽  
Author(s):  
Mike Michaud ◽  
Ahmad Vakili ◽  
Abraham Meganathan ◽  
Robert Zielke ◽  
Lewis Shuster ◽  
...  
Keyword(s):  
Flow Visualization ◽  
Field Measurements ◽  
Labyrinth Seal ◽  
Scale Model ◽  
Labyrinth Seals ◽  
Turbine Generators ◽  
Flow Parameters ◽  
Flow Stagnation ◽  
Viscous Losses ◽  
Pressure And Velocity Measurements

The leakage flow in a 2-D stationary stepped labyrinth seal is investigated by means of flow visualization, pressure field measurements, and Particle Image Velocimetry. The basis of investigation is a generic stepped labyrinth seal currently used by the industry in steam turbine generators. Geometric and flow parameters were varied in order to examine their influence on leakage through seals. Flow visualization results revealed inter-related mechanisms of energy loss in labyrinth seals to include turbulence induced viscous losses, chamber vortex generation, flow stagnation, and increased flow streamline curvature. A five times scale model was constructed and tested over a range of seal pressure ratios from 1:1 to 10:1. Model configurations included a baseline and six variants of the basic design that were conceptually devised to be superior and by varying step height and knife angle. Detail pressure and velocity measurements were carried out. Results show that with relatively minor changes in geometry, determined based on our understanding of the physics of the flow, leakage reductions of up to 17% were accomplished.

Flexible Seal Strip Design for Advanced Labyrinth Seals in Turbines

2013 ◽  
Author(s):  
N. Herrmann ◽  
K. Dullenkopf ◽  
H.-J. Bauer
Keyword(s):  
High Speed ◽  
Discharge Coefficient ◽  
Life Time ◽  
Labyrinth Seal ◽  
Labyrinth Seals ◽  
Seal Design ◽  
Discharge Rates ◽  
Balanced Designs ◽  
Cooling Effects ◽  
The Impact

The paper discusses the potential benefit of flexible seal strips in labyrinth seals for turbines. By reducing the radial stiffness compared to a standard straight and stiff knife, seal clearance could be reduced without significantly reducing the seal durability and long-term performance. As contact between the seal strips and the rotor can occur especially during transient operating phases, a more flexible design of the seal strips can prevent damage and wear, keeping the discharge rates constantly low. However, the pressure difference across the fin will cause a deflection of the seal strip due to the increased flexibility and thus creating an additional possible risk for an unwanted contact. Pressure balanced designs and supports on the low pressure side are used on the investigated seal designs to eliminate that risk. To give evidence of possible performance gain a standard labyrinth seal configuration is compared to two configurations with segmented and curved seal strips. In a first step, the discharge coefficient and the leakage rates for the nominal seal design are calculated using two-dimensional CFD. In order to investigate the impact of a worn seal tip on the leakage flow, the geometry change due to a rubbing event is simulated with FEA tools. Therefore, a specific high-speed wear model is implemented and calibrated by experimental data, enabling the correct cooling effects and plastic deformation. The discharge coefficient and the leakage mass flow rates of the worn geometry are then again modeled with CFD for the various seal configurations and compared to the unworn state. The study shows that a wise combination of the advantages of flexible curved seal strips can be used to reduce the leakage rates significantly, improving the life time of seal elements at the same time.

scholarly journals The Impact of Non-Parallelism of Toothed Gear Shafts Axes and Method of Gear Fixing on Gearbox Components Vibrations

2018 ◽  
Vol 12 (2) ◽  
pp. 165-171 ◽  
Author(s):  
Grzegorz Wojnar ◽  
Michał Juzek
Keyword(s):  
Mechanical System ◽  
Experimental Research ◽  
Ball Bearing ◽  
Angular Position ◽  
Test Stand ◽  
Number Of Teeth ◽  
The Subject ◽  
The Impact

Abstract The subject of the experimental research was a modified back-to-back test stand. During the test, the driven gear with a number of teeth z1=16 was fixed on stationary axis. The tested gearbox worked without load and the closing gearbox was dismantled to avoid any additional vibration and noise. A mechanical system was also used which, during the tests, allowed to change the position of the above mentioned stationary axis. Gear with number of teeth z1 was fixed on a stationary axis with the arrangement of two self-aligning ball bear-ings which prevented significant changes in the angular position of axis of gear in regard of stationary axis; or fixed on a stationary axis with the arrangement of one self-aligning ball bearing which allowed significant changes in the angular position of axis of gear in regard of stationary axis. On the basis of the conducted studies, it can be stated that only in some of the analyzed cases fixing of gear with the arrangement of one self-aligning ball bearing reduces the vibration of the gearbox elements.

Tip-Shroud Labyrinth Seal Effect on the Flutter Stability of Turbine Rotor Blades

2019 ◽  
Vol 141 (10) ◽  
Author(s):  
Roque Corral ◽  
Michele Greco ◽  
Almudena Vega
Keyword(s):  
Rotor Blade ◽  
Labyrinth Seal ◽  
Turbine Rotor ◽  
Rotor Blades ◽  
Labyrinth Seals ◽  
Turbine Rotor Blade ◽  
The Stability ◽  
Shrouded Rotor ◽  
Tip Shroud ◽  
The Impact

Abstract The effect of the tip-shroud seal on the flutter onset of a shrouded turbine rotor blade, representative of a modern gas turbine, is numerically tested, and the contributions to the work per cycle of the aerofoil and the tip shroud are clearly identified. The numerical simulations are conducted using a linearized frequency-domain solver. The flutter stability of the shrouded rotor blade is evaluated for an edgewise mode and compared with the standard industrial approach of not including the tip-shroud cavity. It turns out that including the tip shroud significantly changes the stability prediction of the rotor blade. This is due to two facts. First, the amplitude of the unsteady pressure created in the inter-fin cavity due to the motion of the airfoil is much greater than that of the airfoil. The impact of this contribution increases with the frequency. Second, the effect of the outer shroud of the rotor blade, which usually is not included either in the simulations, has an opposite trend with the nodal diameter than the airfoil reducing the maximum and minimum damping. It is concluded that the combined effect of the seal and its platform tends to stabilize the edgewise mode of the rotor blade for all the examined nodal diameters and reduced frequencies. Finally, the numerical results are shown to be consistent with those obtained using an analytical simplified model to account for the effect of the labyrinth seals.

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