Gas turbine has many merits, such as good flexibility, compact structure, reliable and stable operation, high efficiency and so on. However, leakage between rotor and static parts of the engine is the enemy of power and efficiency. Several mechanisms have been used to reduce the leakage, among them brush seals, labyrinth seals are predominating. Review of literature indicates that increasing stiffness can decrease the hysteresis and leakage of finger seal (FS). In this paper an attempt is made to increase the stiffness of seals. V thread and V and square threads are provided to finger seals. Analysis of static pressure loading using ANSYS fluent is carried out and presented. It is found that providing V thread and combination of V and square thread to finger seals is worth

., Sudhakar

Hebbal, Dr. Ompraksh

International Journal of Innovative Technology and Research (IJITR)

Sudhakar * et al. (IJITR) INTERNATIONAL JOURNAL OF INNOVATIVE TECHNOLOGY AND RESEARCH Volume No.5, Issue No.4, June – July 2017, 6607-6611.  2320 –5547 @ 2013-2017 http://www.ijitr.com All rights Reserved.  Page | 6607 Design of Hybrid Seals for Gas Turbines SUDHAKAR Dept. of Mechanical engineering (Thermal power ENGG) PDA College of engineering kalburgi District, Karnataka, India Dr. OMPRAKSH HEBBAL Professor and Voice principal of PDA College of engineering kalburgi District, Karnataka, India. Abstract: Gas turbine has many merits, such as good flexibility, compact structure, reliable and stable operation, high efficiency and so on. However, leakage between rotor and static parts of the engine is the enemy of power and efficiency. Several mechanisms have been used to reduce the leakage, among them brush seals, labyrinth seals are predominating. Review of literature indicates that increasing stiffness can decrease the hysteresis and leakage of finger seal (FS). In this paper an attempt is made to increase the stiffness of seals. V thread and V and square threads are provided to finger seals. Analysis of static pressure loading using ANSYS fluent is carried out and presented. It is found that providing V thread and combination of V and square thread to finger seals is worth.  I. INTRODUCTION In a gas turbine power plant, gas turbine has many merits, such as good flexibility, compact structure, reliable and stable operation, high efficiency and so on. Gas turbine is widely used in departments like space, navigation, land transportation and electric energy sector. The efficiency of gas turbine is mainly depends on pressure ratio, inlet air temperature and temperature after combustion. In high pressure ratio gas turbine leakage of air/gas through the seals is more predominate [1]. Gas turbines are constantly driven to higher pressure ratios, bypass ratios and turbine inlet temperatures. Because of these airflows in the internal air system and resultant thermodynamic cycle losses increase. Reducing internal airflows while increasing thermodynamic efficiency puts greater emphasis on improvements to the internal flow system [2]. It can be achieved by modifying the cooling procedure of compressor casing to avoid non uniform temperature distribution and consequently decrease in the clearance to avoid damage [3]. The control of clearances in the seals requires a material with the proper combination of rub tolerance and erosion resistance [3]. Leakage through the tip seals can be reduced by providing honeycomb land [4]. Structural optimization indicates that increasing the finger stiffness can reduce the leakage. These finger seals allow radial displacements while under operation. With the run out of shaft, the fingers move out radially but do not recover to their original position, since the friction between the aft cover plate and fingers is greater than the restoring force in the fingers [5].Finger seals has better performance ratio than labyrinth seals and brush seals [6]. Research indicates that increasing stiffness can decrease the hysteresis and leakage of finger seal (FS). In this paper an attempt is made to increase the stiffness of seals by providing V thread and V and square thread to finger seals. Static pressure loading analysis using ANSYS fluent is carried out and results are presented.  II. METHODOLOGY  The flow chart for designing, fabrication and analysing for combine of labyrinth seals and finger seals are presented as shown in Fig.1. Methodology details as follows.  Fig.1 Flow chart of seals methodology.  Studying types of seals.  Comparing performance parameters.  Designing of hybrid seal.  Analysis of design using software tools.  Production of prototype. Seals Seals are devices used to prevent or limit leakage of fluids or particulates. Seals are widely used for applications where components do not move significantly relative to each other and also for applications where there is significant movement between components as a result of rotation or reciprocation. Seals fall into two general categories  Static seals, where sealing takes place between two surfaces that do not move relative to each other.  Dynamic seals, where sealing takes place between two surfaces that move relative to each other for example, rotary or reciprocating motion. Sudhakar * et al. (IJITR) INTERNATIONAL JOURNAL OF INNOVATIVE TECHNOLOGY AND RESEARCH Volume No.5, Issue No.4, June – July 2017, 6607-6611.  2320 –5547 @ 2013-2017 http://www.ijitr.com All rights Reserved.  Page | 6608 Geometry of hybrid seals for gas turbine: The detail geometry of hybrid seals for gas turbine is as shown in Fig.2   Fig.2: Geometry of hybrid seals for gas turbine Meshing: The detailed meshing product of hybrid seals is as shown in Fig.3.  Fig.3: detailed meshing product of hybrid Boundary conditions:   Model specifications.   Material Used for Seal: INCONEL 625. Types of Seals Analysed  Finger seals.  Labyrinth seals.  Hybrid seals (V Thread Only).  Hybrid seals (V and Sq. Thread Combined).  Single strip of hybrid seals. Properties of Material  Density =8440 kg/m3.  Young’s modulus =2.058*1011   Poisson’s ratio =0.33  Shear modulus=7.7368*1010 pa.  Bulk modulus=2.0176*1011 pa.  III. RESULTS Introduction: Deformation, stress and strain for plane finger seal, hybrid combination of labyrinth and finger seals with V thread and hybrid seals combination of labyrinth and finger seals with V and square thread are modelled using CATIA and this values are determine using ANSYS fluent and presented in this chapter. Stiffness calculation:𝑆𝑡𝑖𝑓𝑓𝑛𝑒𝑠𝑠 =𝐹𝑜𝑟𝑐𝑒𝐷𝑒𝑓𝑙𝑒𝑐𝑡𝑖𝑜𝑛        𝐹𝑜𝑟𝑐𝑒 = 𝑃𝑟𝑒𝑠𝑠𝑢𝑟𝑒 ∗  𝐴𝑟𝑒𝑎 Finger seal: Deformation, stress and strain of finger seals Fig.4, 5, 6 and 7 shows CATIA model, deformation, stress and strains respectively of finger seals. When 10MPa pressure applied. The maximum deflection is found to be 0.0199mm. The respective maximum stress and strains are determined to be 7.5938GPa and 3.7366*10-02 respectively. From the Table 1. We can observe that a pressure of fluid increases respective deformation, stress and strain increases. The minimum deformation, stress and strain. The minimum deformation, stress and strain are minimum at end of the finger seals.  Fig.4: Finger seals  Fig.5: Deflection in finger seals  Fig.6: Stress in finger seals  Fig.7: strain in finger seals   Sudhakar * et al. (IJITR) INTERNATIONAL JOURNAL OF INNOVATIVE TECHNOLOGY AND RESEARCH Volume No.5, Issue No.4, June – July 2017, 6607-6611.  2320 –5547 @ 2013-2017 http://www.ijitr.com All rights Reserved.  Page | 6609 Table.1: Finger seals Pressure (Pa.) Deflection (mm) Max Von. Stress (Pa) Max Von. Strain 1x106 0.00199 7.5938 x 105 3.7366 x 105 10x106 0. 0199 7.5938 x 109 3.7366 x 10-2 100x106 0. 199 7.5938 x 1010 0.37366 500x106 0.99643 3.7969 x 1011 1.8683 Hybrid seals (V thread design): CATIA model, deformation, maximum stress and maximum strain of the Hybrid Seal (V Thread Design) are as shown in Fig.8, 9, 10and  11 respectively. The maximum value of deformation, stress and strain are respectively 0.01312mm, 5.468GPa and 2.6763 at pressure 10MPa applied over the internal periphery. Compare to plane finger seals is V thread deflection is lowered by 34%. This means there is consider reduction in leakage losses.  Fig.8: Hybrid Seals (V thread design)  Fig.9: Deformation in hybrid Seals V thread  Fig.10: Stress in hybrid seals (V thread design).  Fig.11: Strain in hybrid seals with V thread.     Table.2: Hybrid seals (V thread design) Pressure (Pa.) Deflection (mm) Max Von. Stress (Pa) Max Von. Strain (Pa) 1x106 0.001312 5.468 x 105 2.6783 x 10-6 10x106 0.01312 5.468 x 109 2.6783 x 10-2 100x106 0.1312 5.468 x 1010 0.26783 500x106 0.6562 2.734 x 1011 1.3392 Hybrid seals (V and square. thread combined): In this model at the internal periphery square threads are prepared by square thread followed by gradual V-thread with square ate the end as shown in the Fig.12. The maximum deflections, stress and strains for V and square thread for finger seal at 10MPa periphery in pressure is respectively 0.01309, 6.26GPa and 3.0544*10-02 respectively. From Table.3. One can observe that deflection compared with plane and a square threaded finger seals are lower by34.07 %and 34.23% respectively. The respective stress and strains are also lower in V and square threaded. The respective maximum stress and strains are 6.26GPa and 3.0544*10-02.  Fig.12: Hybrid seals V and Sq. thread combined.    Fig.13: Deformation in hybrid seals V and Sq. thread  Fig.14: stress in hybrid seals V and square thread          Fig.15: Strain in hybrid seals V and square thread   Sudhakar * et al. (IJITR) INTERNATIONAL JOURNAL OF INNOVATIVE TECHNOLOGY AND RESEARCH Volume No.5, Issue No.4, June – July 2017, 6607-6611.  2320 –5547 @ 2013-2017 http://www.ijitr.com All rights Reserved.  Page | 6610 Table.3: V and Square thread combined Pressure (Pa.) Deflection (mm) Max Von. Stress (Pa) Max Von. Strain 1x106 0.0013109 2.734 x 105 3.0544 x 10-4 10x106 0.013109 6.260 x 109 3.0544 x 10-2 100x106 0.13109 6.260 x 1010 0.30544 500x106 0.6554 3.130 x 1011 1.5272 Deflection and stiffness calculation of single strip: The stiffness for finger seals, hybrid seals combination of labyrinth seals and finger seals with V thread and hybrid seals combination of labyrinth seals and finger seals with V and square combined are calculated and presented in Fig.16. The stiffness of finger seals, Hybrid seal with V thread and Hybrid seal with V and square thread are respectively 65326.63 N/m and 99085.36 N/m and 99312.63 N/m respectively. The stiffness of hybrid seals combination of finger and labyrinth seals with V and square thread has better flexibility and most preferred. Arc Length= 70*10-3 m. Thickness of the strip face = 10mm Width of the Strip = 13 mm  Area of the Strip Face = 130 mm2  Fig.16 Single strip of hybrid seals. For 10 MPa. Pressure. Stiffness[k] =   𝐹𝑜𝑟𝑐𝑒𝐷𝑒𝑓𝑙𝑐𝑡𝑖𝑜𝑛  =   𝐹𝛿   =   𝑃∗𝐴𝛿. Case No. 1  Only finger seals. K=10∗106∗130∗10−60.0199 K= 65326.63 N/m Case No. 2 Hybrid seals (V thread design) K=  K= 99085.36 N/m Case No. 3 Hybrid seals (V and Square thread combined) K=  K= 99312.63 N/m IV. CONCLUSION The conclusion of this work as are follows. The models in the all cases are prepared using CATIA and analysed using ANSYS fluent work bench results are discussed for 10MPa.  Deflections of hybrid seals combinations of labyrinth and finger seals with V and square thread are respectively are lowered by 34.3% and 0.08% respectively. In comparison with plane finger seals. Hence leakage losses are minimum in hybrid seals combinations of labyrinth and finger seals with V and square thread. The increasing the pressure of fluid at inner periphery increases deflection/deformation and respective stress and strain. The stiffness hybrid seals combinations of labyrinth and finger seals with V and square thread are respectively higher by 34.07% and 34.23% in comparison with plane finger seals and hybrid seals combinations of labyrinth and finger seals with V thread seals. V. REFERENCES [1]  Xiong-fei Zhao, Yong-boa Liu, Xing He “Fault Diagnosis of Gas Turbine based on Fuzzy Matrix and the Principle of Maximum Membership Degree” [2]  DrInz. KrzyzsztofJozwik and Ao .univ. prof. dip- ing .Dr. Techn. Reinhard willinger “CFD Simulations for Advanced Turbo Machinery Sealing Technologies Brush Seals”, Vienna, December 2004. [3]  L. P. Ludwig and R. L. Johnson Lewis Research Canter Cleveland, ohio “sealing technology for aircraft gas turbine engines”.  [4]  włodzimierz wróblewski, et al. “optimization of tip seal with honeycomb land in lp counter rotating gas turbine engine”. Received 26 August 2010.  [5]  Zhang Yancho, Liu Kai, Cui Yahui,ZhouChunguo School Of Mechanical Instrumental Engineering Xi An University Kof Technology Xian, 710048,China“The Performance Of Optimization Of Finger Seal ”,2011.  [6]  Chen Guoding,WangLi’na a, Yu Qiangpeng b, Su Hua a Dynamic analysis of C/C composite finger seal”16 June 2013; revised 20 August 2013  [7]  R. Rajendran “gas turbine coatings – an overview”. [8]  Dara W. Child’s. Leland T. Jordan Professor and John M. Vance. Professor Texas A&M Sudhakar * et al. (IJITR) INTERNATIONAL JOURNAL OF INNOVATIVE TECHNOLOGY AND RESEARCH Volume No.5, Issue No.4, June – July 2017, 6607-6611.  2320 –5547 @ 2013-2017 http://www.ijitr.com All rights Reserved.  Page | 6611 University “Annular Gas Seals and Rotor Dynamics of Compressors and Turbines”  [9]  Sinha S K .Dynamic characteristics of a flexible bladed rotor with Coulombdampingduetotip-rub.JSoundVib2004; 273(4–5):875–919. [10]  Xiao X,McCarterAA, Lakshminarayana B. Tip clearance effects in a turbine rotor: part pressurefieldandloss.JTurbomach2000; 123(2):296–304. [11]  Margaret P. Proctor, Irebert R. Delgado, “Leakage and Power Loss Test Results for Competing Turbine Engine Seals”. June 2004  [12]  www.IEEE.com. [13]  Source: stein seals. [14]  M.J.braun professor, H.M Pierson graduate Student University of Akron OH 44325, V.V kudriavtsev Canada“Finger Seal Solid Modeming Design and Some Solid/Fluid Interaction Considerations”. [15]  Source: seals ESDU (2009) [16]  E. Poursaeidia, H.Ghaemia,nM.Charmchb “effects of temperature gradient on compressor casing in an industrial gas turbine”. AUTHOR BIOGRAPHY  SUDHAKAR was born in kalburgi District, KARNATAKA India, in 1992. He received the BE degree in Mechanical engineering from BMS college of engineering Bangalore, pursuing M. Tech degree in Thermal power engineering in PDA college of engineering kalburgi district, Karnataka, India in 2017.  Dr. Ompraksh hebbal M. Tech from IIT Bombay, PhD from JNTU Hyderabad. As present working as professor and Voice principal of PDA College of engineering kalburgi District, Karnataka, India. 

DESIGN OF HYBRID SEALS FOR GAS TURBINES

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DESIGN OF HYBRID SEALS FOR GAS TURBINES

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International Journal of Innovative Technology and Research (IJITR)