solid cfd simulations

8/12/2019 Solid Cfd Simulations

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Overview

This paper relaes wo hea sinks, a medical sucion device, a household oven, and an indusrial conrol valve as examplesha illusrae how SolidWorksFlow Simulaion can help design engineers creae he bes possible produc designswhen dealing wih hea ranser and fluid flow problems. SolidWorks Flow Simulaion is an inelligen, easy-o-usecompuaional fluid dynamics (CFD) program ha will aciliae he work o design engineers who use SolidWorks 3DCAD sofware or design creaion.

THE ROLE OF CFD

IN REAL LIFE DESIGNS

W H I T E P A P E


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The SolidWorks Flow Simulation approach

Hea ranser problems always crop up when design engineers work on elecronicproducs ha can be damaged easily by overheaing. Hea sinks solve heoverheaing problembu whas he bes hea sink design and placemen or agiven elecronic device? And how can a design engineer choose he bes, moscos-effecive hea sink or his purpose wihou building and breaking many coslyprooypes?

Compleely differen kinds o problems occur when designing a medical suciondevice or an applicaion ha needs he highes possible flow rae or a givenpressure drop (sucion), wih limied recirculaion wihin he device, and he mosuniorm velociy profile possible a he sucion head. Again, he quesion arises ohow o choose he bes design in he mos cos- and ime-effecive way.

And he same principles hold rue or consumer producs, such as baking ovens, andor indusrial equipmen ha includes conrol valves.

The examples menioned above are problems ha design engineers may ace inheir day-o-day work, and are also highly represenaive o he everyday problemsencounered by designers o many differen producs.

Compuaional fluid dynamics (CFD) is a simulaion ool ha can be o greaassisance in solving such problems. Very ofen, however, CFD programs arevery complex and difficul o use, especially by design engineers who have nohad a grea deal o advanced educaion in he physics o fluid flows. SolidWorksFlow Simulaion offers inelligen, easy-o-use CFD o design engineers who useSolidWorks 3D CAD sofware or design creaion.

Design 1: Heat sink for external electronic deviceThe firs hea sink is mean or a piece o elecronic equipmensay a surveillancecameraha will be used on he exerior o buildings. To proec i rom heelemens, he device has o be well sealedbu wih no vening, mos o he hearanser will ake place hrough one side o he enclosure only. The hea sink in his

case has o aid in removing he hea. The manuacurer o he device has decided onan off-he-shel hea sink, and is design can be changed.

How can he design engineer find cos-effecive ways o increase he cooling wihinsuch circumscribed parameers?

Saring wih a SolidWorks sofware model o he commercial hea sink (Figure 1),he designer can see ha, as he orce o graviy acs downwards, he hea romhe enclosure will be conduced o he hea sinks fins, and removed by ligher airrisingha is, naural convecion. To es a shield design, he designer places acover over he hea sink and hen needs o deermine wheher ha will generaea chimney effeccreaing more air flow, and hus cooling he elecronic producmore effecively.

The Role of CFD in Real Life Designs 2

Very ofen, CFD programs are very complex

and difficul o use, especially by design

engineers who have no had a grea deal o

advanced educaion in he physics o fluid flows

SolidWorks Flow Simulaion offers inelligen,

easy-o-use CFD o design engineers who

use SolidWorks 3D CAD sofware or design

creaion.


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Wih SolidWorks Flow Simulaion, he design

engineer uses he programs Projec Wizard o

se up he flow analysis.


Figure 1: Mandaed Hea Sink

Wih SolidWorks Flow Simulaion, he design engineer uses he programs ProjecWizard o se up he flow analysis. The Projec Wizard les he designer definehe uni sysem o be used, he fluid as air, and he ype o analysis as an exernalconjugae hea ranser problem; apply graviy o drive he flow or he reeconvecion; inpu he ambien emperaure and pressure condiions; and selec hedesired resul resoluion auomaic meshing levelall wihin a single, easy-o-useinerace.

The nex sep akes he engineer o he SolidWorks Flow Simulaion analysis ree,where he can apply he hea power load on he hea sink wih a simple righ-clickmenu opion ha also walks him hrough seting he locaion or he load and powerinpu.

Finally, he design engineer defines he overall design objecives o he analysis,maximum hea sink emperaure, and maximum air velociy as goals, making ipossible or him o monior hose values during he calculaion and creae a able ohe compued values when he analysis has been compleed.

Figure 2: Hea sink wihou shield Hea sink wih shield

To deermine wheher he hea sink will perorm beter wih or wihou he shield,he design engineer runs a SolidWorks Flow Simulaion CFD analysis.

Table 1: Compued average emperaure or each version o he design

Parameer Wihou Shield Wih Shield

Temperaure (C) 62.0 55.9


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Figure 3: Analysis resuls, showing velociy cus. Warmer colors indicae higher verical velociy.

The design wih he shield has greaer velociy around he hea sink fins.

Figure 4: Velociy cus hrough a verical secion. Resuls show ha he version wih he shielddemonsraes ar greaer velociy wihin he model.

Figure 5: Temperaure cus hrough a cross-secion. This resul proves ha he model wih he

shield ransers more hea o he air.

Figure 6: Solid emperaure cus hrough a cross-secion. These resuls show ha he model wih

he shield is dramaically cooler, wih emperaures in a range rom 55 C o 57 C. The hea sink

wihou he shield has emperaures enirely above he 55 C o 57 C range.

The SolidWorks Flow Simulaion sudies show ha he addiion o a shield o averically mouned hea sink produces a significan increase in coolingwih a 10.9percen decrease in average emperaure when he wo designs are compared.


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To define he an in his orced flow analysis,

he designer can choose he appropriae an

profile rom a lis available in he Engineering

Daabase buil ino SolidWorks Flow Simulaion.

Design 2: Heat sink for the main chip in an electronic enclosure

The second hea sink needs o proec he main chip, insalled wih oher elecroniccomponens, in an elecronic enclosure. In his case, he design engineer needs oideniy and selec he bes hea sink shape or he purpose.

Figure 7: Elecronic enclosure model

The design shown in Figure 7 is a SolidWorks soware assembly model o heelecronic enclosure, including he main hea sink. An insalled an blows air ino heenclosure, hrough he hea sink, and ou hrough he oule slos o cool he heaedelecronic componens by orced convecion. Which o wo dierenly shapedcommercially available hea sinks resuls in he lowes main chip emperaure?

The design engineer can deermine his wih SolidWorks Flow Simulaion in a verysraighorward way. As in he previous analysis, he design engineer uses heProjec Wizard o se up he inernal conjugae hea ranser problem. To deinehe an in his orced low analysis, he designer can choose he appropriae anproile rom a lis available in he Engineering Daabase buil ino SolidWorks FlowSimulaion.

Nex, he designer uses volumeric hea sources o represen he componensheaed during use sofware and ses goals o maximum and average emperaureso boh he main chip and hea sink. When he analysis has been compleed, he canview he resuling emperaures boh as surace plos on he elecrical componens,and as cu plos hrough he fluid and solids. The design engineer can also creae

velociy vecors ha make i easier o visualize flow paterns hrough which he anblows air over he hea sink and around he enire enclosure.

Figure 8: Compeing shapes o he hea sink SolidWorks Flow Simulaion helps engineers compue

he emperaure o he elecronic enclosure.

Table 2: Compued maximum and average emperaures o he main chip wih each o he wo

hea sinks


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Figure 9: Analysis resuls in a emperaure cu plo, showing he ron view, as obained or hea

sink No. 1. The 30-color palee shows emperaures in he 50 F o 100 F range.

Figure 10: Temperaure cu plo, showing he opview, as obained or hea sink No. 1

Figure 11: Temperaure cu plo, showing he side view, as obained or hea sink No. 1

Figure 12: The velociy vecors, showing a side view, as obained or hea sink No. 1

Figure 13: Analysis resuls in a emperaure cu plo, showing he ron view, as obained or hea

sink No. 2


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The goal o he SolidWorks Flow Simulaion

analysis is o deermine he flow rae a a given

pressure drop or each o wo screen designs.

Figure 14: Temperaure cu plo, showing he op view, as obained or hea sink No. 2

Figure 15: Temperaure cu plo, showing he side view, as obained or hea sink No. 2.

As he purpose o he SolidWorks Flow Simulaion analysis was o enable hechoice o he beter hea sink shape or a main chip insalled wih oher elecroniccomponens in an elecronic enclosure, and he resuls show 17.5 percen reducion insolid emperaures in hea sink No. 2, ha shape proved o be beter.

Design 3: Medical suction device screen

In his design, he design engineer needs o ideniy he bes screen shape ora medical sucion device, o allow he highes flow rae or a given sucion, limirecirculaion wihin he device, and also creae he mos uniorm velociy profile ahe sucion head.

Figure 16 shows he SolidWorks sofware assembly model o he device, including

a screen wih riangular cus. Flow eners he device hrough a conical head, flowshrough he screen, and down he ube. The designer ses up he inernal flow in heProjec Wizard, and defines he inle and oule pressure condiions. The goal o heSolidWorks Flow Simulaion analysis is o deermine he flow rae a a given pressuredrop or each o wo screen designsone wih riangular cus as shown in he model,and one wih circular cuswhen insalled in he sucion device. Here, in addiiono he compued volume flow rae, he engineer uses flow rajecories o show hepahs aken by represenaive air molecules hrough he device. He can also creae ananimaion o he flow rajecories o produce a beter visualizaion o flow paternsand areas o recirculaion.

Figure 16


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Figure17:: The wo screen shapes under sudy

Table 3: Compued volumeric low raes o each screen shape

Figure 18: Pressure cu plos or each design. Boh designs have similar pressure proiles.

Figure 19: Velociy cu plos wih velociy vecors or each design. Boh designs have similar

velociy proiles a he sucion head.

Figure 20: Trajecory plos showing recirculaion zone

Figure 21: Trajecory plos in a recirculaion zone or each design. While boh designs have some

recirculaion, he zone or he riangular design is larger.


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The objecive o he SolidWorks Flow Simulaion

analysis is o learn which ray design will provide

he opimal flow o heaed air by sudying he

naural convecion wihin he oven.

As saed above, he purpose o his analysis was o selec he bes perormingscreen head or he medical sucion device. The resuls show a 7.8 percen higherlow rae when using he screen wih circular cus, and boh designs have reasonablyequal velociy proiles a he sucion head. The circular cu design, however, has asmaller recirculaion zonemaking i clear ha he circular cu design will providesuperior perormance, based upon he original design crieria.

Design 4: Household Oven

In his design o a household baking oven, he design engineer can use SolidWorksFlow Simulaion o sudy he air flow patern and emperaure disribuion, andopimize he design o achieve he uniorm ho air circulaion required or uniormbaking. The CFD program enables sudy o hea ranser by conducion, convecion,and radiaion wihin he oven.

Figure 22 shows he SolidWorks sofware model o he oven, wih hree bakingrays and cakes on each. The objecive o he SolidWorks Flow Simulaion analysisis o opimize he flow o heaed air, by sudying he naural convecion wihin heoven and checking he final surace emperaure o he objec being baked. To dohis, he designer inroduces ho air a 120 C ino he oven chamber, raising hehea rom an iniial emperaure o 20 C.

Figure 22: SolidWorks soware model o oven wih hree baking rays and cakes

Figure 23: Temperaure a he surace o he cakes or Design 1


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Because ho air is ligher han cooler air, he

ho air rises o he op, and he emperaure

decreases a lower heighs.

SolidWorks Flow Simulaion can also deermine

wheher he perormance o he oven will be

more efficien i he designer adds air flow

deflecors.

Figure 21 shows he surace emperaure resuls, wih uneven heaing o he objecplaced on he sack o rays. Because ho air is ligher han cooler air, he ho airrises o he op, and he emperaure decreases a lower heighs.

The design engineer uses he wizard o se up a simulaion o inernal low byenering he iniial oven emperaure. He deines he velociy o he ho air alongwih is emperaure a he six inles, as well as he pressure condiion a he oule.To visualize he resuls, he engineer can plo he emperaure disribuion aroundhe baking objec, and or beer visualizaion o air low disribuion, he can plo

low rajecories and velociy conour plos a muliple secions.

SolidWorks Flow Simulaion can also deermine wheher he perormance o heoven will be more eicien i he designer adds air low delecors. And o opimizehe design, he engineer can sudy boh he ideal locaion and number o inles hainroduce ho air ino he oven.

Figure 24: Air velociy and disribuion a he op ray around he cake wih Design 2

Figure 25: Air velociy and disribuion a he boom ray around he cake wih he second design

Figure 26: Flow rajecories in he oven or he ive-cuou ray, wih emperaures


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SolidWorks Flow Simulaion makes i easy

o calculae he pressures a he openings

and hrough he enire modela level o

comprehensive inormaion ha canno easily

be obained hrough physical esing.

In addiion o plos, SolidWorks Flow Simulaion

can also produce a able showing he flow

values a any poin, surace, or volume wihin

he model.

Design 5: Control valve

In his design, he engineer needs o opimize he design o a conrol valve orminimum pressure loss, and also o predic possible caviaion problems.The engineer uses CFD o perorm an inernal air flow simulaion hrough he valve.CFD resuls give he engineer a deailed undersanding o he flow patern in sucha valve by means o analysis resuls showing flow velociy, pressure, and pariclerajecories. SolidWorks Flow Simulaion makes i easy o calculae he pressures ahe openings and hrough he enire modela level o comprehensive inormaionha canno easily be obained hrough physical esing because o he difficuly inplacing insrumenaion o provide sufficien inormaion abou whas happeninginside he valve.

Figure 27 shows he 3D SolidWorks sofware model o he valve. The designengineer ses up he simulaion wih he help o he SolidWorks Flow SimulaionWizard. He defines he velociy a which air eners he valve a he inle, and appliessaic pressure equivalen o he amosphere a he oule.

Figure 27: SolidWorks 3D valve model

Figure 28: Velociy disribuion wih gradien vecors shown hroughou he model

Figure 29: Velociy rajecories help in he sudy o he low paern.


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Figure 30: Pressure disribuion plo wih isobars shows he possibiliy o caviaionwhich proves

no o be a problem in he case o his conrol valve.

The pressure resul plo shows minimum loss o pressure or his valve design. Thepressure a he region where caviaion could occur became negaive, indicaingha he valve would no experience caviaion. In addiion o plos, SolidWorks FlowSimulaion can also produce a able showing he flow values a any poin, surace, orvolume wihin he model.

Conclusion

Wheher designing hea sinks or elecronic producs, medical sucion devices,consumer producs, or indusrial conrol valves, design engineers need o knowwhich design is bes, while avoiding he exra coss and ime involved in buildingoo many prooypes in order o achieve heir goals. Compuaional fluid dynamicssimulaion ools can help mee his challenge. SolidWorks Flow Simulaion is aninelligen, easy-o-use ool ha allows you o es muliple designs and scenarios osudy hea ranser and fluid flow problems so you can opimize your design wihouspending excess ime and money in he process.

S lidW k i i d d k D l S S lidW k C All h d d d k

Dassaul SysmesSolidWorks Corp.300 Baker AvenueConcord, MA 01742 USAPhone: 1 800 693 9000Ouside he US: +1 978 371 5011Email: [email protected]

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