Improving Performance of a Heavy Duty Engine Cooling Drive Through Reduction of

Drag Losses

Design Recommendations & Future Analysis

CFD Analysis• It is recommended that the static pump be designed with an airfoil shape similar to that of the standard airfoil shape constructed by the team• Further CFD Analysis recommendations

- 2-D analysis on front view of the static pump- 3-D turbulent flow analysis- Data obtained should be run through Heeds, or a similar optimization program, to optimize the airfoil shape

Test FixtureIt is recommended that the static pump be designed with the airfoilshape due to its reduction in both drag and flow separation as compared to the current static pump design. Further testing on airfoil shaped static pumps should be conducted, including:

• Production airfoil design• Standard airfoil design as modeled for the CFD analysis

Project Background

BorgWarner Thermal Systems is known worldwide for its advancementsin automotive technology as the leading designer and supplier of engine thermal management components for global vehicle manufacturers. The Cool Logic heavy duty, multi-speed fan drives area breakthrough in engine cooling technology. These fan drives are electronically controlled and built to last, while improving fuel economyand meeting emission requirements.

Simplified views of the clutch fan assembly

Within the Cool Logic clutch fan assembly lays a rotating housing used to move the fan powered by the engine. This assembly acts as a clutch fan to control the rotation of the fan at variable operating speeds.

To ensure that the clutch fan assembly is cooled and lubricated properly,a static pump enclosed in the assembly is used to transfer AutomaticTransmission Fluid (ATF) into the assembly housing. The static pump protrudes into the clutch assembly housing. During operation, the assembly housing rotates between a range of 600 to 3600 rpm, whichforces ATF to flow over and around the static pump. This static pumpexperiences drag losses due to its interruption of the flow of the rotatingfluid. Two means of drag losses on the static pump are skin friction dragand pressure drag. By reducing these losses, a redesign of the static pump could ultimately reduce the drag on the entire Cool Logic clutchfan assembly, thus improving engine efficiency.

Design Constraints

Certain specifications and constraints needed to be followed as instructedby the project sponsor. The static pump needed to remain near its currentheight to fit in the existing clutch fan assembly. Also, it was to remain located in the nine-o’clock position when viewing the housing from thefront view. The width and shape of the part were allowed to be adjusted to achieve a more aerodynamic and efficient pump design. The 48 ounces of ATF used for the working fluid in the assembly remains at a level slightlybelow the halfway point of the entire housing, when the clutch is not engaged. The fluid can move at a maximum rotational speed of 3600 rpmaround the interior of the housing. The average operating speed of thefluid was 2000 rpm, which was analyzed to determine the nature of the flow was present. The drag losses on the original static pump design at 2000 rpm are approximately 5 horsepower.

Project Sponsor Information

Sponsor: BorgWarner Thermal SystemsLocation: Marshall, MichiganSponsor Representatives:

Mr. Dale Pickelman Mr. Don Buckley

Team Information

Team Members Evan DiMaggio George Elliott Kyle Jose John Sanburn Faculty Advisor

Dr. Oguzhan Guven

Approach

The drag loss problem on the static pump was approached using the the following tools:

• Fundamental principles of Aerodynamics and Fluid Mechanics• Computational Fluid Dynamics (CFD) Analysis - Modeling and meshing using Gambit - CFD Testing completed in Fluent - Three different cross-section profiles evaluated• Flow Visualization through Experimentation - Conducted using a window inserted in the cap of the clutch fan assembly to visualize the flow path of the ATF - Confirm the level of the rotating fluid inside the clutch housing - Observe the separation of the fluid flow as it intersects the static pump - Two different shaped static pumps tested and compared under a constant experiment conditions

CFD Analysis

Project Goals

• Improve the design of the static pump to minimize drag losses• Formulate design recommendations based on a comparative analysis with the current pump design• Reduce power losses on the Cool Logic clutch fan assembly through reduction of drag on the static pump• Understand the nature of the flow of the ATF as it rotates around the interior of the clutch fan housing and interacts with the static pump• Develop a visualization of the centrifugal forces acting on the fluid• Determine the level of fluid that the pump observes at varying speeds

Project Conclusions

CFD Analysis The drag force on the static pump was determined to be reducedby designing the pump with an airfoil shape. The drag force reduction percentages, as compared with the correlation of the current static pump design, are as follows:

• Production Airfoil…………………………………38.6% reduction• Standard Airfoil……..…….……………………...68.0% reduction

Test Fixture• Fluid flow level (from the housing outer diameter) measured as approximately 2.9 cm • The flow over the airfoil static pump caused much less separation of the boundary layers and less disruption of the flow• The drag force was reduced with use of the airfoil static pump design, compared to the original static pump design

Flow Visualization Through Experimentation

Special Thanks & Recognition

Automotive Research Experiment Station Dr. Harold Schock & Mr. Tom Steucken

Spartan Oil Corporation

Computational Fluid Dynamics Laboratory Srikanth Sridhar

BorgWarner Cool Logic Clutch Fan Assembly

Example of a 2-D Meshed Model in Gambit - Original Pump Design

Estimated correlation of Horsepower Loss based on Fluent data

Velocity Contour Plot – Original Pump Design

Velocity Contour Plot – Standard Airfoil

Design

Velocity Contour Plot – Production Airfoil Design

Testing Parameters:• Two different pumps designs• Testing Speeds: 600 & 1200 rpm

Testing Observations:• The fluid flow over the original static pump design led to more separation • The flow over the airfoil static pump was much more controlled & there was less separation• Much less separation in the airfoil pump compared to the original pump• Tests at 1200 rpm were similar in that the airfoil pump design affected the flow much less than the original pump design (i.e. less separation)

Original Static Pump

Airfoil Prototype

Pump

Flow Over Original Pump

(600 rpm)

Experiment Setup

5

3.07

1.6

0

1

2

3

4

5

6

Geometry

Ho

rsep

ow

er L

oss

Current Pump

Production Model

Ideal Airfoil

Flow Over Airfoil

Prototype Pump (600

rpm)