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DESIGN AND THERMAL ANALYSIS ON A PISTON OF AN ENGINE

 

 

 

 

 

 

 

NEETU SHARMA

B.tech Student, Department of mechanical engineering

                                                 Dronacharya College of Engineering,Gurgaon

                                                 E-mail:Sharmaneetu507@gmail.com

ABSTRACT:

Piston is the Backbone of an I.C. engine. It is one of the stressed component which defines the life and performance of the engine. Also this comes under influence of the thermal load during the working time.so it is important to carry out the thermal analysis of the engine. Thus Thermal analysis of a piston plays an important role in understanding the behavior of the component under thermal loading conditions. Therefore the main objectives of this paper is to investigate and analyze the thermal analysis of piston at the real time conditions during combustion process. The model of the piston is developed by using Solidworks and imported into ANSYS for preprocessing, solution and post-processing. This is done by using Finite Element Analysis shortly called FEA and the numerical method used for the same is called Finite Element Method (FEM).

Keywords: Piston, Critical, Engine, Stress, Performance, Influence, Thermal, Solidworks, ANSYS, Preprocessing, Post-processing, FEA, FEM etc.

 

 

INTRODUCTION

As we know that Internal  combustion  engines  produce  power  by converting  chemical  energy  of  the  fuel  into  heat energy. This produces the useful mechanical work by converting the heat energy.  In  the  process  of converting this thermal energy into mechanical work, which  is  performed  by  increase  in  pressure  which generates  forces  to  move  piston connected  to  crankshaft  by  piton  connecting  rod.Thus Piston plays an important role in order to convert chemical energy into thermal energy and thermal energy into mechanical energy.This part is responsible for the reciprocating movement of the engine. The reciprocating movement is to be done with the help of working fluid. The main function of a piston is to convert reciprocating motion of expanding gases in the combustion chamber into rotatory motion. Thus a piston transfer energy from expanding gases to crankshaft through the connecting rods and gudgeon pin.

FINITE ELEMENT ANALYSIS

The Finite Element Analysis is a computing technique that is used to obtain approximate solution of Boundary Value Problem. It uses a computer based numerical method called as Finite Element Method used for calculating the nature of engineering structures. FEA involves a computer model of a design that is loaded and analyzed for specific results. FEA involves three basic step in order to analyzed any problem, Preprocessing, solution and post-processing. It can be used to calculate stress analysis, thermal analysis, vibrational analysis, deflection and deformation in the engineering structure. It also help in the optimization of a design. It helps us in order to make a more reliable, high quality and competitive design. The main advantage of is that it reduces the amount of prototype testing, thereby saving the cost and time. During performing the FEA we must be considered some key assumptions.

  1. Initial temperature before combustion is to be 220C.
  2. The system is to be water cooled.

The following steps are required to complete the task of thermal analysis of piston:

  1. Import the existing Model.
  2. Generate mesh for the Model.
  3. Change the unit and generate the mesh.
  4. Apply thermal boundary conditions.
  5. Analyze the results.

 

THERMAL ANALYSIS

Thermal analysis is a kind of analysis which is used to determine the temperature distribution and related thermal quantities in the model. In this analysis all heat transfer modes, namely conduction, convection and radiation are analyzed

STEPS OF THERMAL ANALYSIS:

  1. IMPORTING

 

  1. Importing is the first step of analysis.
  2. Import the existing model from design location.

 

  1. GENERATING MESH FOR THE MODEL

 

  1. Mesh generation is the next step in modal Analysis.
  2. Before Mesh Generation process make sure that Metric (mm, kg, N,s,mV,mA) is select from the units menu in the Menu bar.
  3. In the tree outline, right click on mesh to display a shortcut menu.
  4. After this choose Generate Mesh option from the shortcut menu.
  5. The mesh with default setting is generated as shown in fig.
  6. Calculate the number of mesh.
  7. In my model number of elements generated are 3707.
  8. If we required more accuracy than we apply refined mesh.
  9. After refined mesh number of elements generated are 28000.

 

  1. APPLY THE BOUNDARY CONDITION
  2. After the piston is meshed, we need to apply the suitable boundary condition under which the thermal analysis will be performed.
  3. Right click on the transient thermal node in the tree outline and then choose INSERT>>TEMPERATURE from the shortcut menu displayed.
  4. Now select Temperature under the Transient Thermal node, the details of "Temperature" window is displayed.
  5. In the details of "Temperature" window, click on the geometry selection box to display the Apply and Cancel Buttons, if they are not already displayed.
  6. Select the head of the piston as shown in fig. and then choose the Apply button from the Geometry selection box in the "Detailsof Temperature" window to specify the dome face of the model for applying the Temperature load.
  7.  Apply temperature value 20000C.
  8. Next step is to apply convection by selecting all the outer faces.
  9. Now choose the right arrow displayed next to the Film Coefficient edit Box in the "Details of Convection" window; a flyout is displayed.
  10. In the flyout, choose the Import option, as shown in fig.
  11. Import Convection Data box is displayed.

In this dialogue box, select the Stagnant Water-simplified Case radio button. Then choose OK button to close the dialogue box.

  1. SETTING ANALYSIS RESULTS
  1. After the temperature and convection loads are applied,we need to specify the parameters which we want to evaluate.
  2. Drag Temperature from the Transient Thermal node in tree Outline and drop it in the Solution node,as shown in fig. Reaction Probe is added to the Solution Node.
  3. Now from the Details of "Reaction Probe" right click on the Boundary Condition. In drop list Temperature options is selected by Default. We can also select Convection in this illustration.
  4. Right click on the solution node in the Tree Outline, a shortcut menu is displayed.
  5. In this shortcut menu choose Insert>>Thermal>>Temperature; Temperature is added under the Solution node.

 

Fig 5: Reaction Probe

 

  1. Similarly choose Insert>>Thermal>>Total Heat Flux; Total Heat Flux is added under the Solution node.
  2. Choose the Solve tool from the Standard toolbar; the ANSYS Workbench Solution Status window is displayed. After sometime, the ANSYS Workbench Solution Status window is closed and a green tick mark is displayed before the Result in the Solution node in the Tree Outline indicating that the analysis has been solved.
  3. Select Temperature under the Solution node in the Tree Outline; the Details of "Temperature" window is displayed. The Temperature Contours are displayed in the Graphics screen.
  4. Click on the Total Heat Flus under the Solution node in the Tree Outline; the Details of "Total Heat Flux" window is displayed. Fig 6 & 7: Graph and Tabular data window of temperature distribution .

CONCLUSION:

Design of piston is analyzed by applying temperature and convection tools. From the above thermal analysis we concluded that maximum temperature on the piston is 20000C and minimum temperature is 220C. Also the maximum Total Heat Flux is 35.277 W/mm2 and minimum value of Total Heat Flux is 1.0309e-009. The corresponding graphs and contours provides us further details. The above concluded analysis is performed on Ansys 14.5 analysis software. These results are based on Finite Element Method.

 

REFERENCES:

  1. International Journal of Advanced Trends in Computer Science and Engineering, Vol.2, No.1, Pages: 596 - 601 (2013) Special Issue of ICACSE 2013 - Held on 7-8 January, 2013 in Lords Institute of Engineering and Technology, Hyderabad
  2. A Reference Guide of Ansys Workbench( CADD CENTRE)
  3. DESIGN AND WEIGHT OPTIMIZATION OF IC ENGINE Sasi Kiran Prabhala1, K. Sunil Ratna Kumar2  ,Prabhala et al, International Journal of Advanced Engineering Research and Studies E-ISSN2249–8974IJAERS/Vol. II/ Issue I/Oct.-Dec.,2012/56-58
  4. www.em.Wikipedia.org
  5. Vinay V. Kuppast, Dr.S.N.Kurbet, H.D Umeshkumar, Adarsh B.C / International Journal of

Engineering Research and Applications (IJERA) ISSN: 2248-9622

www.ijera.com Vol. 3, Issue 3, May-Jun 2013, pp.1402-1407