PERFORMANCE OF EXHAUST PORT CFD SIMULATION WITH AN TEMPERATURE VARIATIONS AND BASIC CONCEPT RELATING TO SIMILAR RESULT

Ans 1) Conjugate heat transfer allows the simulation of the heat transfer between solid and fluid domains , by exchanging thermal energy at the interfaces between them.It requires a multiregion mesh to have a clear defination of the interfaces in the computational domain.

As In our case we are simulating exhaust port model with including all flow takes place inside it. Here in this example we have Fluid volume and the Solid volume . When the hot air is flowing through the four inlets, THe air containing fluid volume will heat up the internal surface of solid volume.and this is due to convection heat transfer. Again the heat is transfered from lower surface of a solid volume to the upper surface by conduction method and Again the heat is transfered to outside envitonmenyal air/ Atmospheric air,by convection method.

So, HEre there are different mediums are included and to Conduct heat transfer analysis Conjugate heat transfer analysis is the only convinient method.

APPLICATION:-

The CHT used in -Heat exchangers simulations.

- Cooling of an electronic component/equiepments.

- Also, the general purpose cooling and heating system.

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Ans 2) Objective :- In this challenge We have to perform conjugate heat transfer analyisis on a exhaust port and observe the temprature variation of hot air flowing though it, Also the variation of heat transfer coefficent across the internal surface of solid geometry.

Basic-set up and pre-processing for the analyisis:-

The fluent was draged into the main window,then the geometry was uploded in the space claim,also the units are changed to meters.The solis model imported is having extra edges in the geometry so that should be cleaned by th tool extra edges (it deletes the extra edges and allow us to select the single edge selection for the volume extraction procedure).

After that both the geometry are shared with topology option ,The the concept behind the sharing of topologies is to create the conformal meshing between the solid and fluid volume.

After the geometry preperation the meshing modeule is open up.

In the meshing module. the base line mesh is used for the first simulation and for second case there is slight refinement (such as the inflation leyers are added)

The mesh Quality was displayed above Also the named selection was mentiond on the above listing.

After that the Fluent processing was done, HEre the basic boundary conditions and the energy equations are incorporated for the solution to initiate.

1) Firstly the mesh checking operation was performed , and the type /configuration of analysis is set.

2) Steady state analysis was preformed with the pressure based and velocity formulation is absolute Also the energy equation is on.And the turbulent model was selected as K-epsilon model.

3)material selected as air For a working fluid,And for the solid volume Aluminium material was selected.

4) The inlet is air velocity ia set to 5m/s and the temperature is kept to 700 k. Also the outerwall convection surface is having a heat transfer coefficent of 20 W/mdeg.k.

5) After all of this setting the calculation running set-up is configured. before that the hybrid intiailization is done with 10 points.

the analysis is ran for 150 itterations.

In this challenge i perfomed two case one with base line meshing and another one is refinement in the meshing .

Case 1 ) REsults.

residual plot temperature variation.

By observing the above result that when the air is flowing fron the inlet the heat transfer fron the fluid to the solid body is less but as the all inlets are merging at one point there is increment in the outer wall temperature , It means that when the hot air coming out fron cylinder lesser amount of heat is get transfered to the outer pipe but as the hot air is flowing at a distance there is some sort of turbulance and that may result is high heat transfer fron fluid to solid pipe,Also the four hot inlets was combining to form one outlet and the volumetric flow rate is also higher at that point or path.

The upper temperature profile was generated is totally depending on the simple fluid physics,Because of the higher volumetric flow rate and high velocity the reynold\'s number is getting higher and that increases the heat transfer coefficent,As the heat transfer coefficent increases At the surface of fluid volume ,more amount of heat is get convected from the solid pipe.That\'s why the temperature is higher at the outlet section.

Other results from CFX-post.

In this cas the heat transfer coefficent is not isplayed properly because we do not have a finer mesh at the inner wall thats why we see the disturbed colour coding. This issue was resolved

creating the inflation layers at that point .

2)case results:-

meshing for case 2

The temp. variation is similar as first case but there is slight refinements because of the meshing modification. here also we see the temperature ate the outlet bend is higher as compared to the four pipe connecting region. And why this phenomenon is there is explained above in the case 1 result listing.

Other results from CFX-post.

here the wall heat transfer coefficent is around at wall with smooth curvature.at the inflation layers.

In this way i performed the analysis and carried out results and i understood the basic concept of temperature change in the exhaust port.

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Ans 3) After adding up of volumetric flow rate from four inlets it increases the reyonld\'s number of air also, The heat transfer coefficent also increased across the walls. To verify that whether the (HTC) is correct or not we have to Extract the result from CFX (post) That ,What kind os varrying values we found across the section plane . Where the temperature is low, Exactly we get lesser HTC value or where the temperature is higher, the HTC will be of bigger value.

The total Accuracy is exactly depend upon the meshing done on the external profile of fluid domain. We added an inflation layer while meshing ,so we got a greater accuracy. As the (HTC) is boundary function we get the smoother colour coding/result across the interfering region of Fluid volume and the internal surface of solid volume.

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