An Approximation and CFD Validation in Dashboard Nozzles for Reviewing Demisting and Deicing Issues in Windshields

Özcan O., Ylldlz A. E., Coşkun A.

SAE Automotive Technical Papers, WONLYAUTO 2022, Pennsylvania, United States Of America, 01 January 2022 identifier

  • Publication Type: Conference Paper / Full Text
  • Doi Number: 10.4271/2022-01-5035
  • City: Pennsylvania
  • Country: United States Of America
  • Keywords: Cabin comfort, CFD, Dashboard nozzle, De-icing, De-misting, Fan boundary condition, HVAC, Windshield
  • Istanbul Technical University Affiliated: Yes


© ANADOLU ISUZU Otomotiv Sanayi A.Å .; Published by SAE International. This Open Access article is published under the terms of the Creative Commons Attribution Non-Commercial, No Derivatives License (, which permits use, distribution, and reproduction in any medium, provided that the use is non-commercial, that no modifications or adaptations are made, and that the original author(s) and the source are credited. Windshield visibility for passenger buses is a crucial matter since it is directly related to the safety of the drivers. The fog that forms on the windshield restricts the driver's visibility and adversely affects driving safety. Due to these concerns, there should be an effective demisting system in every passenger bus. In this study, the performance of the windshield demisting system was investigated in a passenger bus developed by Anadolu Isuzu. The demisting system in the vehicle was examined by performing CFD (computational fluid dynamics) analysis with the software Ansys FLUENT R20 version. Tests were performed on the vehicle with the existing system in order to measure air velocity values and temperatures on the nozzles. Fan boundary conditions in the CFD simulations are applied to entrance of blower, which is a radial fan placed in defroster unit to supply air to windshield. With this method, the flow rate values of the blower and the nozzle outlet velocity values are obtained as outputs of the analysis without modeling the blower in all cases. This method can decrease much more time consumption in these simulations and is used to improve system design with validation of vehicle test and CFD results. In addition, realizable k-ϵ, SST k-ω with PRESTO in pressure scheme, and SST k-ω turbulence models were compared in the calculations and SST k-ω was found to be the most consistent one.