Structural Analysis Of Compressor Impeller Of Turbocharger By Changing .

International Journal of Mechanical and Production Engineering, ISSN(p): 2320-2092, ISSN(e): 2321-2071 Volume- 7, Issue-9, Sep.-2019, http://iraj.in STRUCTURAL ANALYSIS OF COMPRESSOR IMPELLER OF TURBOCHARGER BY CHANGING THE BLADE’S THICKNESS 1 NI NIHLAING, 2HTAYHTAY WIN, 3MYINTTHEIN 1,2,3 Mandalay Technological University, Myanmar Email: 1ninihlaing@mtu.edu.mm, 2, htayhtayw@gmail.com Abstract - In this paper, it is presented that the stress analysis of the compressor impeller of turbocharger in locomotive diesel engine. The centrifugal compressor is the key component of turbochargers. The main aim of this paper is to analyze the stress variation on the blades of compressor impeller by changing the blade’s thickness. Air is used as working fluid and aluminium alloy material is used for impeller. The model of the impeller is drawn by using SolidWorks2016 and is analyzed by using ANSYS14.5. The design of the impeller, 68000 rpm is considered for this research. By changing the blade’s thickness from 2mm or 3mm or 4mm, the stress is increased for thicker blades. The maximum von-Mises stress and effective strain of the blade’s thickness (2mm)are found better results than other two thicknesses. Keywords - Analysis, Blade’s Thickness, Impeller, Stress, Strain, Turbocharger. (YWAHTAUNG), Sagaing Division,Myanmar’. The centrifugal compressor of the station has the following parameter; Power 810kW Outlet Temperature, T2 408 K Capacity, Q 0.19 m3/sec Outlet Pressure, P2 500 kPa Air mass flow rate, m 1.6 kg/sec Slip factor, σ 0.85 Ambient pressure and ambient temperature is 1.2 bars and 30 C. Figure 2 shows entry and exit velocity triangles for impeller. I. INTRODUCTION A turbocharger consists of a compressor and turbine operating on a single common shaft. These are often designed for use on automobile internal combustion engines. When installed, the hot exhaust gases exiting the cylinders pass through the turbine side of the turbocharger, spinning the turbine blades, and thus the shaft. The shaft then transmits power to drive the compressor. The exhaust gases then continue out to the exhaust manifold and continue as usual. As the compressor spins, it raises the pressure of the incoming air from the air intake. The high pressure air is often directed through a charged air cooler (also known as an intercooler) to further raise the density of the air [1]. Turbochargers are a class of turbo machinery intended to increase the power of internal combustion engines. This is accomplished by increasing the pressure of intake air, allowing more fuel to be combusted [2]. Figure 1 shows the operation of turbocharger. (b). Inlet Velocity Component (a) Absolute Velocity as Sum of (c) Outlet Velocity Velocity Relative to Blade Component Fig 2. Entry and Exit Velocity Triangles for Impeller[8] Design calculation can be divided into five main parts for turbocharged compressor. These are (i) Calculation of Impeller Inlet Dimensions (ii) Calculation of Impeller Outlet Dimensions (iii) Efficiency of Compressor (iv) Calculation ofStress on Compressor Impeller,and (v) Calculation of Strain on Compressor Impeller 2.2. Calculation of Impeller Inlet Dimensions The fluid moves through the impeller where work is done on it to increase its staticpressure from P1 to P2. Impeller inlet and outlet pressure ratio, Fig 1. Operation of Turbocharger[2] II. DESIGN OF COMPRESSOR IMPELLER FOR TURBOCHARGER P rp 2 P1 2.1. Design Procedure for Compressor Impeller In this research, the design parameter of impeller is collected at ‘Diesel Locomotive Workshop (1) Shaft Diameter, Ds (Aluminum Alloy (7050-T7651)) Ds 3 16T π Ss Structural Analysis of Compressor Impeller of Turbocharger by Changing The Blade’s Thickness 18 (2)

International Journal of Mechanical and Production Engineering, ISSN(p): 2320-2092, ISSN(e): 2321-2071 Volume- 7, Issue-9, Sep.-2019, http://iraj.in Hub Diameter, Dh The hub diameter is 12.5% increased of standard shaft diameter. (3) D h 1.125 Ds 2.5. Calculation of Stress on Compressor Impeller There are two forces on the compressor impeller. There are as follows: The centrifugal force, Fc 2 (14) Fc m r ω Inlet Absolute Velocity, V0 The impeller inlet hub Mach number is 0.2 to 1 for compressible fluid. The value of Mach number is 0.3 (assumed)[8]. The gas bending force, Fb Fb m Vω (15) The most important components of static stresses are centrifugal stress and gas bending stress. The centrifugal stress can be determined as follows: The centrifugal stress, σc 2 (4) D1 1.025 D0 Impeller Inlet Velocity and Inlet Blade Angle The air enters the impeller eye to tip in the axial direction. The prewirl angle is zero so that V1 Vf1. Inlet Absolute Velocity, U1 πD1N (5) U1 60 Inlet Blade Angle, β1 β1 tan V1 σc (7) 60 H p g ' πN K (8) σ 1 x σy 2 4 τ xy 2 (18) 2 2 The von-Mises stress is calculated by the following equation; 1 σv K’ is the pressure coefficient which has a value between 0.5 and 0.65 depending on the type of impeller [8]. The Outlet Peripheral Velocity, U2 πD 2 N (10) U2 60 2 σ1 σ2 2 2 2 σ 2 σ3 σ3 σ1 (19) 2.6. Calculation of Strain on Compressor Impeller If three principal stresses are applied simultaneously, each causes Poisson strains in the directions and the three dimensional form of Hook’s law shows that, 1 ε1 σ1 υ σ 2 σ 3 (20) E 1 ε 2 σ 2 υ σ1 σ 3 (21) E Outlet blade angle, β2 The compressor industry commonly uses a backward leading blade with angle, of between about 55-75 deg[8]. Choose: β2 65 deg. The impeller outlet width, b2 Q2 b2 (11) π D 2 V2 ε 2 2.4. Efficiency of Compressor Input power of the compressor can be calculated the following equations. Compressor Efficiency, ηc Output ρgQH ηc Input m C p (T02 - T01 ) σx σy σ1 ,σ 2 (9) Input Power m Cp (T02 - T01 ) (17) In the principle stress theory failure will occur when the principle stress in the complex system reaches the value of the maximum stress at the elastic limit in simple tension. The principal stresses are determined by the following equation. 2.3. Calculation of Impeller Outlet Dimensions Impeller outlet dimensions can be found out the following equations.Assume K’ 0.55 D2 m Cw-in Cw-out h R 2 n R z c3R σgb U1 Number of Blades, n Impeller Inlet Width, b1 Q b1 πD1V1ε1 (16) The gas bending stress can be calculated as follows; (6) 0.63π n 1- σ ρ ω2 2 2 rt rr 2 σ 3 υ σ1 σ 2 E For the von-Mises criterion, the effective given by; 1/2 2 2 2 2 ε 3 ε1 ε 2 ε 3 N Name Value o. 1 Pressure ratio, rp 4.167 2 Shaft Diameter, Ds 0.016 ε3 1 (12) (13) strain is Structural Analysis of Compressor Impeller of Turbocharger by Changing The Blade’s Thickness 19 (22) (23) Units m

International Journal of Mechanical and Production Engineering, ISSN(p): 2320-2092, ISSN(e): 2321-2071 Volume- 7, Issue-9, Sep.-2019, http://iraj.in 1 Inlet Blade Angle,β1 Outlet Blade Angle, β2 Number of blades, n Impeller Inlet Diameter, D1 Impeller Outlet Diameter, D2 Impeller Inlet Width, b1 Impeller Outlet Width, b2 Compressor Efficiency, ηc Centrifugal Force, Fc 1 Gas Bending Force, Fgb 1 The Centrifugal Stress, σc The Gas Bending Stress, σgb 3 4 5 6 7 8 9 1 0 1 2 3 1 4 33 65 14 0.052 0.169 m 0.016 0.007 m m 92.58 % 1049 1.3 790.5 40 62.27 0 3.486 Figure 3 shows the 3D model of compressor impeller for turbocharger in locomotive. Tetrahedron mesh generation method with element size 0.005m is used for meshing as shown in Figure 4. This mesh model has 54891 nodes and 30049 elements. degree degree m N (a) (b) N MPa MPa Table 1.Resulting Data of Compressor Table 1 describes the resulting data of compressor for Aluminum Alloy (7050-T7651). (c) Fig.4. Mesh Model of Compressor (a) t 2mm, (b) t 3mm and t 4mm III. STRUCTURAL ANALYSIS OF COMPRESSORIMPELLER 3.2. Static Structural Analysis of Compressor In the static structural analysis, the boundary condition is regarded. The locations of fixed support are the tip of compressor wheel. The values of gas bending force (790.54N) and the centrifugal force (10491.30N) are affected on the compressor blades. Figure 5 shows the boundary condition of impeller. Structural analysis is the most common application of the finite element analysis. The term structural implies civil engineering structure like bridge, building and also naval, aeronautical and mechanical structure like ship hulls, aircraft bodies and machine housing such as mechanical components like piston, machine parts and tools [3]. 3.1. Model and Mesh of Compressor The model is created using SolidWorks (2016 and analyzed using ANSYS 14.5 for compressor impeller with different the blades’ thickness. Fig.5.Boundary Condition of Compressor (a) (b) (c) Fig.3. Model of Compressor (a) t 2mm, (b) t 3mm and (c) t 4mm Fig.6. Equivalent (von-Mises) Stress for (t 2mm) Structural Analysis of Compressor Impeller of Turbocharger by Changing The Blade’s Thickness 20

International Journal of Mechanical and Production Engineering, ISSN(p): 2320-2092, ISSN(e): 2321-2071 Volume- 7, Issue-9, Sep.-2019, http://iraj.in Structural analysis results of von-Mises stress and effective strain for compressor blade’s thickness, (2mm) are shown in figures 6 and 7. Maximum vonMises stress is 65.05 MPa while the yield strength of the Aluminum Alloy is 490 MPa. Maximum effective strain is obtained as 9.02 10-4. Fig.10. Equivalent (von-Mises) Stress for t 4mm Fig.7. Equivalent Elastic Strain for t 2mm Fig.11. Equivalent Elastic Strain for t 4mm Structural analysis results of von-Mises stress and of effective strain for compressor blade’s thickness, (4mm) are shown in figures 10 and 11. Maximum von-Mises stress is 138.40MPa while the yield strength of the Aluminum Alloy is 490MPa. Maximum effective strain is obtained as 19.26 10-4. Fig.8. Equivalent (von-Mises) Stress for t 3mm Structural analysis results of von-Mises stress and effective strain for compressor blade’s thickness, (3mm) are shown in figures 8 and 9. Maximum vonMises stress is 85.35 MPa while the yield strength of the Aluminum Alloy is 490 MPa. Maximum effective strain is obtained as 11.88 10-4. 3.3. Results and Discussion In this result, it is found that Aluminum Alloy was the minimum von-Mises stress than other two materials. Tables 2 and 3 show theoretical and numerical results of von-Mises stress and effective strain.Figures 12 and 13 describe comparison of theoretical and numerical results for von- Mises stresses. Thickness Results Theoretical Numerical t 2 (mm) t 3 (mm) t 4 (mm) 60.60 65.05 84.96 85.35 137.04 MPa 138.40 MPa Units Table 2 Theoretical and Numerical Results of von-Mises Stress. Fig.9. Equivalent Elastic Strain for t 3mm Structural Analysis of Compressor Impeller of Turbocharger by Changing The Blade’s Thickness 21