Static Stress Analysis on Centrifugal Compressor Impeller

Transcription

1 Static Stress Analysis on Centrifugal Compressor Impeller Spoorthy Mary 1 B-Tech- Aerospace engineering Karunya Institute of Technology and Sciences, Coimbatore, spoorthymary@karunya.edu.in R Gayathri 2 Assistant Professor- Aerospace department Karunya Institute of Technology and Sciences, Coimbatore, gayathri@karunya.edu Abstract The key component that makes a compressor centrifugal is the centrifugal impeller which contains a set of rotating vanes (or blades) that gradually raises the energy of the working fluid. An impeller is a rotary component, therefore shape and strength of impeller plays an important role in the overall performance of the compressor. In the present paper, a centrifugal compressor impeller is optimized for better performance and to predict the structural integrity of the impeller for 50,000rpm. The investigation is done using Solid Works 2010 and ANSYS SolidWorks is used to model the impeller and structural analysis is carried out for three different materials namely Ti , Inconel alloy 740 and Aluminum 2618 alloy using ANSYS. The von-mises stress, von-mises strain and total deformation is investigated by structural analysis of the impeller for three different materials. From the analysis, Aluminum 2618 alloy is suggested as the compatible alloy for the impeller. Index Terms Impeller, Static structural analysis, ANSYS, Thermal analysis and Load compressor. 1 INTRODUCTION Centrifugal compressors are also termed as radial compressors [1]. The idealized radial flow roto-dynamic machine achieves pressure rise by adding kinetic energy or velocity to a continuous flow of fluid through the rotor or impeller [2]. The components of a centrifugal compressor are an inlet, impeller/rotor, and diffuser. These are used in gas turbines, auxiliary power units, automotive engine, diesel engine, turbochargers, and superchargers. small gas turbine application using solver I-DEAS 10NX and was analyzed to identify the location of maximum stresses. C.H. Satyasai et al. [7] had designed the turbocharger impeller and also carried out structural analysis of the impeller for different materials to achieve better life. From the literature survey, it is noticed that at higher loads the impeller had more stress at the hub and blade fixation nodes. In this paper, best material is suggested to withstand the high loads. The von-mises stress, total deformation and von-mises strain is investigated using thermal- static stress analysis of the centrifugal compressor impeller for three different materials. By comparing the results obtained for three different alloys from the FEM analysis the best material is identified. 2 MATERIAL SELECTION FOR OPTIMIZATION The Impeller has to withstand high centrifugal loads, high pressures and temperatures when working, so materials for the study of centrifugal compressor impeller is chosen on the basis of Young s Modulus, Density, Poisson s ratio and Ultimate Strength. Fig.1 Centrifugal Compressor impeller Meha Setiya et al. [3] carried out structural and thermal analysis on impeller blade of the load compressor aircraft APU 131-9A for four different materials to check the safe limit of stresses. V.R.S.M. Kishore et al. [4] designed the impeller of a turbocharger for a diesel engine to increase its power and efficiency. Structural, modal and thermal analysis of impeller for three different materials was investigated using ANSYS. Syam Prasad et al. [5] analyzed the centrifugal pump impeller which is made of three different alloy materials by conducting static and dynamic tests to estimate its performance. J B Chaudhari et al. [6] studied the stress acting on centrifugal compressor radial impeller blade which was designed for Alloy TABLE 1 MATERIAL PROPERTIES Young s Modulus (Pa) Density (Kg/m3) Ultimate Strength(Pa) Ti E E+9 Inconel alloy E E+9 Aluminum 2618 alloy 0.80E E+9 16

2 Pa= Pascal, Kg=kilogram, m=meter 3 MODELING SolidWorks 2010 software is used to model the impeller. The impeller model is then saved in IGS format which is imported to ANSYS geometry. 4.2 Boundary Conditions The boundary conditions given for static structural analysis are 1. Hub portion is fixed. 2. Rotational velocity of 50,000 rpm. The imported and meshed geometry is treated with boundary conditions for both thermal and static structural analysis to calculate the von-mises stress, Total deformation, and von-mises strain. Firstly, Thermal analysis is carried out and the solution is imported to static structural analysis. Each material is provided with inlet and exit temperatures and solution is evaluated. The obtained temperature load is then imported for static structural analysis. 5 ANALYSIS RESULTS Fig.2 Solid works modeling 4 F E M ANALYSIS Thermal- static structural analysis is executed using ANSYS R17.2 for different materials to investigate the von-mises stress, total deformation, and von-mises strain for the considered geometry. 4.1 Meshing The imported geometry is meshed by tetrahedrons method. To achieve fine mesh, element size is adjusted to 3.5x10-3 m using body sizing. A total of 1, 60,449 elements and 2, 38,696 nodes are obtained. Fig.4 From thermal analysis minimum temperature of 40 deg C is at the inlet and maximum temperature of 200deg C at the exit. Fig.3 Meshed Impeller 17

3 Fig.5 Maximum von-mises stress for TI is found at the hub i.e. 6.75E+8 Pa. Fig.8 Maximum von-mises stress for Inconel 740 alloy is found at the hub i.e. 1.18E+9 Pa. Fig.6 Maximum deformation for TI is found at inlet blade tip i.e m. Fig.9 Maximum deformation for Inconel 740 alloy is found at inlet blade tip i.e m. Fig.7 Maximum von-mises strain for TI is found at the hub i.e. 18

4 Fig.10 Maximum von-mises strain for Inconel 740 alloy is found at the hub i.e Fig.12 Maximum deformation for Aluminum 2618 alloy is found at inlet blade tip i.e m. Fig.11 Maximum von-mises stress for Aluminum 2618 alloy is found at the hub i.e. 3.92E+8 Pa. Fig.13 Maximum von-mises strain for aluminum 2618 alloy is found at the hub i.e Results from the analysis for von-mises stress, total deformation and von- mises strain is tabulated below TABLE 2 Alloy von-mises stress (Pa) Total Deformation (m) von-mises strain ANALYSIS RESULT Pa= Pascal, m=meter Ti E E E-3 Inconel alloy E E E-3 Aluminum 2618 alloy 3.92E E E-3 6 CONCLUSION This paper mainly concentrates on analyzing the structural integrity of the considered geometry. Static structural analysis is carried out to analyze the strength of the impeller for three different materials i.e. Ti , inconel 740 alloy and aluminum 2618 alloy using ANSYS. From table.2 it is clear that Ti has higher strength compared to inconel 740 and aluminum 2618 alloy. However, 19

5 Aluminum 2618 alloy has lower total deformation and von-mises strain than Ti and inconel 740 alloys. Furthermore, Aluminum 2618 alloy is cost effective and has low density which reduces engine weight. From the structural analysis, it can be concluded that Aluminum 2618 alloy is the best material for the considered centrifugal compressor impeller for 50,000rpm. ACKNOWLEDGMENT I would like to thank authors, mentioned in the references which are citied below for their valuable research works which helped me to gain more knowledge. And also I thank my guide for her precious guidance. REFERENCES [1] [2] machine/ui/course_home-lec6.htm [3] Meha Setiya, Dr. Beena D. Baloni, Dr. Salim A. Channiwala.. Structural analysis of load compressor blade of aircraft auxiliary power unit.international Journal of Scientific & Engineering Research, Volume 6, Issue 2, February [4] V. R. S. M. Kishore Ajjarapu, K. V.P.P.Chandu, D.M.Mohanthy Babu. Design and Analysis of the Impeller of a Turbocharger for a Diesel, International Journal of Advanced Engineering Research and Studies, Volume 2, Issue 1, Oct.-Dec., [5] A Syam Prasad, BVVV Lakshmipathi Rao, A. Babji, Dr P Kumar Babu. Static and Dynamic Analysis of a Centrifugal Pump Impeller, International Journal of Scientific & Engineering Research, Volume 4, Issue 10, October [6] J B Chaudhari, S A Channiwala.. Finite Element Analysis of Centrifugal Compressor, National Conference on Thermal, Fluid and Manufacturing Science, Paper No: 2014TFMSXXXX, January [7] CH.Satyasai Manikanta, S.D.V.V.S.B.Reddy, A.Sirishabhadrakali,. Design & Analysis of Turbocharger Impeller, International Journal & Magazine of Engineering, Technology, Management and Research, Volume 3, Issue 1, January