Full vehicle aero-thermal cooling drag sensitivity analysis for various radiator pressure drops

Nicholas Simmonds, Panagiotis Tsoutsanis, Dimitris Drikakis, Adrian Gaylard, Wilko Jansen

Research output: Chapter in Book/Report/Conference proceedingConference contribution book

5 Citations (Scopus)

Abstract

Simulations are presented which fully couple both the aerodynamics and cooling flow for a model of a fully engineered production saloon car (Jaguar XJ) with a two-tier cooling pack. This allows for the investigation of the overall aerodynamic impact of the under-hood cooling flow, which is difficult to predict experimentally. The simulations use a 100 million-element mesh, surface wrapped and solved to convergence using a commercially available RANS solver (STARCCM+). The methodology employs representative boundary conditions, such as rotating wheels and a moving ground plane. A review is provided of the effect of cooling flows on the vehicle aerodynamics, compared to published data, which suggest cooling flow accounts for 26 drag counts (0.026 Cd). Further, a sensitivity analysis of the pressure drop curves used in the porous media model of the heat exchangers is made, allowing for an initial understanding of the effect on the overall aerodynamics. An analysis is made of the various pressure drops on the overall vehicle drag with a breakdown of the most affected components. Simulations suggest that at 50 kph, containing fan driven cooling flow, a linear relationship can be obtained where a variation of 1% in the pressure drop can result in the drag count changing by 0.02 drag counts (0.00002 Cd). An increase in the pressure drop is predicated increase heat exchangers drag, but a combination of the higher momentum loss in the heat exchangers and consequently lower flow velocities downstream at the engine and firewall, along with cooling outflow re-attaching to the under body of the vehicle combine for an overall predicted drag reduction. Further the system is studied without the radiator resulting in an increase of drag over the baseline case of 5 drag counts (0.048 Cd), indicating the need to reduce airflow downstream of the radiator. When blanking the radiator itself a drag difference of 18 drag counts (0.018 Cd) was obtained, further emphasizing the importance of the downstream region.

LanguageEnglish
Title of host publicationSAE Technical Papers
Number of pages9
Volume2016
EditionApril
DOIs
Publication statusPublished - 5 Apr 2016
EventSAE 2016 World Congress and Exhibition - Detroit, United States
Duration: 12 Apr 201614 Apr 2016

Conference

ConferenceSAE 2016 World Congress and Exhibition
CountryUnited States
CityDetroit
Period12/04/1614/04/16

Fingerprint

Radiators
Sensitivity analysis
Pressure drop
Drag
Cooling
Aerodynamics
Heat exchangers
Hot Temperature
Drag reduction
Flow velocity
Fans
Porous materials
Wheels
Momentum
Railroad cars
Boundary conditions
Engines

Keywords

  • aerodynamics
  • cooling flow
  • vehicle aerodynamics
  • drag sensitivity

Cite this

Simmonds, N., Tsoutsanis, P., Drikakis, D., Gaylard, A., & Jansen, W. (2016). Full vehicle aero-thermal cooling drag sensitivity analysis for various radiator pressure drops. In SAE Technical Papers (April ed., Vol. 2016). [2016-01-1578] https://doi.org/10.4271/2016-01-1578
Simmonds, Nicholas ; Tsoutsanis, Panagiotis ; Drikakis, Dimitris ; Gaylard, Adrian ; Jansen, Wilko. / Full vehicle aero-thermal cooling drag sensitivity analysis for various radiator pressure drops. SAE Technical Papers. Vol. 2016 April. ed. 2016.
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abstract = "Simulations are presented which fully couple both the aerodynamics and cooling flow for a model of a fully engineered production saloon car (Jaguar XJ) with a two-tier cooling pack. This allows for the investigation of the overall aerodynamic impact of the under-hood cooling flow, which is difficult to predict experimentally. The simulations use a 100 million-element mesh, surface wrapped and solved to convergence using a commercially available RANS solver (STARCCM+). The methodology employs representative boundary conditions, such as rotating wheels and a moving ground plane. A review is provided of the effect of cooling flows on the vehicle aerodynamics, compared to published data, which suggest cooling flow accounts for 26 drag counts (0.026 Cd). Further, a sensitivity analysis of the pressure drop curves used in the porous media model of the heat exchangers is made, allowing for an initial understanding of the effect on the overall aerodynamics. An analysis is made of the various pressure drops on the overall vehicle drag with a breakdown of the most affected components. Simulations suggest that at 50 kph, containing fan driven cooling flow, a linear relationship can be obtained where a variation of 1{\%} in the pressure drop can result in the drag count changing by 0.02 drag counts (0.00002 Cd). An increase in the pressure drop is predicated increase heat exchangers drag, but a combination of the higher momentum loss in the heat exchangers and consequently lower flow velocities downstream at the engine and firewall, along with cooling outflow re-attaching to the under body of the vehicle combine for an overall predicted drag reduction. Further the system is studied without the radiator resulting in an increase of drag over the baseline case of 5 drag counts (0.048 Cd), indicating the need to reduce airflow downstream of the radiator. When blanking the radiator itself a drag difference of 18 drag counts (0.018 Cd) was obtained, further emphasizing the importance of the downstream region.",
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Simmonds, N, Tsoutsanis, P, Drikakis, D, Gaylard, A & Jansen, W 2016, Full vehicle aero-thermal cooling drag sensitivity analysis for various radiator pressure drops. in SAE Technical Papers. April edn, vol. 2016, 2016-01-1578, SAE 2016 World Congress and Exhibition, Detroit, United States, 12/04/16. https://doi.org/10.4271/2016-01-1578

Full vehicle aero-thermal cooling drag sensitivity analysis for various radiator pressure drops. / Simmonds, Nicholas; Tsoutsanis, Panagiotis; Drikakis, Dimitris; Gaylard, Adrian; Jansen, Wilko.

SAE Technical Papers. Vol. 2016 April. ed. 2016. 2016-01-1578.

Research output: Chapter in Book/Report/Conference proceedingConference contribution book

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Simmonds N, Tsoutsanis P, Drikakis D, Gaylard A, Jansen W. Full vehicle aero-thermal cooling drag sensitivity analysis for various radiator pressure drops. In SAE Technical Papers. April ed. Vol. 2016. 2016. 2016-01-1578 https://doi.org/10.4271/2016-01-1578