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Int. J. Mech. Eng. & Rob. Res. 2014 Dharmendra Kumar Madhukar et al., 2014

ISSN 2278 – 0149 www.ijmerr.com

Vol. 3, No. 2, April, 2014

© 2014 IJMERR. All Rights Reserved

Research Paper

DESIGN AND CFD THERMAL ANALYSISOF SHIP’s RADAR FRAME

Dharmendra Kumar Madhukar1*, Jitendra Nath Mahto2 and S C Roy3

*Corresponding Author: Dharmendra Kumar Madhukar, � madhukardharmendra@gmail.com

As the electronic equipment is powered, heat is being developed and in increase of temperaturein components. Overheating can shorten the life expectancy of costly electrical components orlead to catastrophic failure. For safe functioning of component, the allowable temperature mustbe provided and if the temperature exceeds these limits, the component fails. In this paper,thermal design of an enclosure for ship's radar frame and its assembly is taken up and ensuringcomponent temperature within the limits. For CFD thermal analysis purpose ANSYS 11 hasbeen used.

Keywords: ANSYS, Design, Homodyne, Radar Frame, Temperature, etc

INTRODUCTION

Ship’s radar frame include radar antenna,transmitter, receiver and other electronic en-closure like homodyne, etc. which are usu-ally packaged as a single unit, enclosed ineither a radome or in housing with a rotating,bar-like antenna mounted on its top surface.As the electronic equipment is powered, heatis being developed and the effect of heatdeveloped is raising the temperature of thecomponents mounted on radar frame. If theradar frame assembly crossing the allowabletemperature specified by manufacturer willcause either malfunctioning of the compo-nents or permanent failure (R Parales Jr.1993); (R Ridley, M Reynell and S Kern,1993), i.e. in other word the accumulation of

1 M. Tech Scholar (Machine Design), Mechanical Engineering Deppt., BIT Sindri, Dhanbad, Jharkhand, India.2 Assitant Professor, Mechanical Engineering Deppt., BIT Sindri, Dhanbad, Jharkhand, India.3 Professor, Mechanical Engineering Deppt., BIT Sindri, Dhanbad, Jharkhand, India.

heat in an enclosure is potentially damagingto electrical and electronic devices. Overheat-ing can shorten the life expectancy of costlyelectrical components or lead to catastrophicfailure. For thermal analysis and modelingcomputational fluid dynamics (CFD) is accu-rate approach for calculating heat transfer co-efficient based on air flow condition and also,simulate and analyzed the component in theactual operating condition (G Groove, 1996).The maximum junction temperature of anelectronic component position on NRF struc-ture limited to 80°C with air inlet temperatureof 55°C i.e. the maximum allowable tempera-ture raise from air inlet to component hot spottemperature = 80-55= 25°C. The design offrame component is taken up in this work witha view to keep the temperature below 80°C.

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Int. J. Mech. Eng. & Rob. Res. 2014 Dharmendra Kumar Madhukar et al., 2014

CFD THERMAL ANALYSIS OF

SHIP’s RADAR FRAME

Finite Element Modeling

The geometry of 3D radar frame enclosureis built up in Unigraphics-NX as per providedby user in 2D. All the subsystem likehomodyne, card cage and other componentare considered for radar frame's Assemblymodeling and saved as parasolid. Thisparasolid is imported in ANSYS to performCFD Analysis to find out the temperature dis-tribution due to power dissipation of LBH,HBH, etc. The solid model of radar frame andexploded view is shown in Figure 1 & 2 re-spectively.

Figure 1: Solid Model of Radar Frame

Figure 2: Solid Model of Radar FrameEnclosure in Exploded View with LBH,

HBH, Card and Antenna

Material Properties

The radar frame and its enclosure are madeusing Aluminum HE 30 material. The analy-sis is done for air inlet temperature of 55°Cwithout the effect of radiation. For carryingout the steady state CFD thermal analysismaterial property as assigned as table no 1.

Table 1: Material Properties Used

Material Properties

1

2

3

4

Young's Modulus (N/mm2)

Poisson's Ratio

Density (kg/mm3)

Thermal Conductivity (in w/m2k)

7.0E+04

0.3

2700

235

To capture the thermal conductivity fromhomodyne to the bottom plate Solid 70 ele-ment is used. Description of Solid 70 elementused for thermal model of radar frame is givenbelow.

SOLID70 Element has a 3-D thermal con-duction capability. The element has eightnodes with a single degree of freedom, tem-perature, at each node. The element is ap-plicable to a 3-D, steady-state or transientthermal analysis. The element also can com-pensate for mass transport heat flow from aconstant velocity field. If the model contain-ing the conducting solid element is also tobe analyzed structurally, the element shouldbe replaced by an equivalent structural ele-ment. The solid 70 geometry is shown as inFigure 3.

Figure 3: The Solid 70 Geometry

A detailed Finite Element model was built withshell and mass elements to idealize all thecomponents of the Radar Frame. The FEmodel of radar frame is shown as in Figure4.

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Int. J. Mech. Eng. & Rob. Res. 2014 Dharmendra Kumar Madhukar et al., 2014

Figure 4: Finite Element Modelof the Radar Frame

Design Inputs

The thermal boundary condition applied onradar frame for CFD analysis. LBH, HBH andCard received a total heat generation load of42000 w/m3, 45000 w/m3 and 38000 w/m3

respectively. Next, there is heat transfer co-efficient boundary condition of 26.60 w/m2Kis applied is shown in the Figure 5 Followingare the equation use to determine the heattransfer coefficient of the fluid flow.

hplate = NuL

KL

Re = =pVL

µVLv

NuL = 0.664 * (Pr) ReL

13

Figure 5: Thermal Boundary ConditionsApplied for Thermal Analysis

RESULTS AND DISCUSSION

FOR CFD THERMAL ANALYSIS

The CFD model is solved for the tempera-ture distribution in order to show maximumtemperature developed on radar frame en-closure; more specifically on the homodynetemperature. The overall temperature distri-bution of entire assembly is shown in figures6, 7 & 8. The red and blue in color in fig.shows the maximum and minimum tempera-ture in the frame assembly.

Figure 6: Temperature Distributionon the Radar Frame

Figure 7: Temperature Distribution onthe Base Plate of Radar Frame

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Int. J. Mech. Eng. & Rob. Res. 2014 Dharmendra Kumar Madhukar et al., 2014

Figure 8: Temperature Distribution onthe Base Plate of Radar Frame

From the above CFD thermal analysisit is observed that maximum temperatureof 63°C is observed on the homodyneswhich is well below the maximum allow-able temperature of homodyne.

CONCLUSION

In the present paper a Ship’s of radar framehas been designed and studied for tempera-ture.

From Figure 6, Figure 7 and Figure 8, itwas found that the temperatures are wellbelow from the maximum allowable tempera-ture of homodynes i.e. 80°C.

Therefore it concluded that the radar frameis safe under the given operating conditions.

ACKNOWLEDGEMENT

I would like to thank Mr. H. Pradeep Reddy,Head Project Engineer at RAMTECH Engi-neering Service, Hyderabad. I am very grate-ful to Prof. (Dr.) B N Prasad, NIT Jamshedpur,for being incredibly supportive throughout thework and his exhaustive guidance for his im-mense support and encouragement. I ownmy greatest debt to my parents specially tomy father Sri Mahadev Modi, mother Smt.Shanti Devi, Mr. Upendra Kumar and ShrutiKumari for their constant support, encourage-ment and their moral support; without them Iwould not be what I am right now.

References

1. ANSYS 11 Help manuals.

2. G Groove (1996), “Thermal Analysis &optimization of small, high density depower system by FEA” proc IEEE Int.Telecommunication Energy conference,pp. 718-722.

3. R Parales Jr (1993), “Solving the ther-mal concerns of low voltages power sup-ply using CFD modeling”, Proceeding offlowtherm user's conference.

4. R Ridley, M Reynell and S Kern (1993),“Thermal consideration of distributedpower converters system” Proceeding ofIEEE applied power electronic confer-ence, pp. 866-872.