Simulation of noise in HVAC ducts Dr Karamjit Sandhu Climate Control Systems Jaguar Land Rover STAR Global Conference 19-21 March 2012 STAR Global Conference 19-21 March 2012
Overview • Introduction • Experimental Work • Modelling • Results • Summary & Conclusions STAR Global Conference 19-21 March 2012 STAR Global Conference 19-21 March 2012
Introduction • Noise in the HVAC system is generally an issue which has to be tackled • Aim is to predict up front the noise experienced by the customer • CAE methods are required to solve the problem • HVAC noise is a complex problem • Problem is broken down into smaller parts: - HVAC Unit - IP Ducting - Vents/Registers - Interior Cabin • A first step is to predict the interior and noise propagation from a simple duct STAR Global Conference 19-21 March 2012 STAR Global Conference 19-21 March 2012
Introduction • Joint project with CD-adapco, London, UK • Current CFD software supplier of STAR-CCM+ • CFD & aero-acoustics techniques simulated in one software • No data manipulation required between softwares • Aim of the work was to improve the CAE capability within Jaguar Land Rover STAR Global Conference 19-21 March 2012 STAR Global Conference 19-21 March 2012
Introduction • The project was developed as a two step process - Step 1: Determination of the inlet profile - Step 2: Aero-acoustic analysis of the duct Inlet profile Noise generated at Noise propagation duct surface from the duct outlet • The results were validated against experimental measurements • A CAE methodology was developed and procedure created to predict interior and noise propagation from a HVAC duct STAR Global Conference 19-21 March 2012 STAR Global Conference 19-21 March 2012
Experimental Work • Mean flow out of the duct was measured from the outlet of the straight portion of the duct • Transient pressure measurements were taken inside the duct and at the far field positions from the outlet Measurements on duct surface Far field measurements STAR Global Conference 19-21 March 2012 STAR Global Conference 19-21 March 2012
Modelling Domain for the LES Outlet Plenum Volume Source STAR Global Conference 19-21 March 2012 STAR Global Conference 19-21 March 2012
Modelling • 6 million cell mesh to capture the flow using an LES model • Computational time is 6 days on 64 CPU’s Computational Mesh STAR Global Conference 19-21 March 2012 STAR Global Conference 19-21 March 2012
Modelling • A recycling mass boundary model is run to determine the inlet profile for the full simulation • A Reynolds stress model is employed • Output from this model is used for input for the steady RANS solution STAR Global Conference 19-21 March 2012 STAR Global Conference 19-21 March 2012
Modelling • The recycling solution is run to provide the RANS/LES simulation with data • Parameters exported to the LES: - Flow direction - Mach Number - Pressure - Temperature • The RANS solution is run to provide a good initial guess and reduce simulation time • LES solution was run for 0.5 seconds • 2.5x10 -5 second time step is used STAR Global Conference 19-21 March 2012 STAR Global Conference 19-21 March 2012
Modelling Overall CAE process using STAR-CCM+ STAR Global Conference 19-21 March 2012 STAR Global Conference 19-21 March 2012
Results • The inlet profile to the main duct was modelled to establish the developed velocity profile • The comparison with experiment show good general agreement Comparison measured and predicted inlet velocity profile STAR Global Conference 19-21 March 2012 STAR Global Conference 19-21 March 2012
Results Velocity Streamline Plot STAR Global Conference 19-21 March 2012 STAR Global Conference 19-21 March 2012
Results Velocity Contour Plot through the Duct Velocity Contour Plot of the Flow from the Duct STAR Global Conference 19-21 March 2012 STAR Global Conference 19-21 March 2012
Results Pressure Contour Plot through the Duct Pressure Contour Plot of the Flow from the Duct STAR Global Conference 19-21 March 2012 STAR Global Conference 19-21 March 2012
Results Velocity fluctuations in the duct STAR Global Conference 19-21 March 2012 STAR Global Conference 19-21 March 2012
Results B1 B2 B3 B4 SPL(dB) for the internal probes STAR Global Conference 19-21 March 2012 STAR Global Conference 19-21 March 2012
Results F1 F3 F4 F5 SPL(dB) for the internal probes STAR Global Conference 19-21 March 2012 STAR Global Conference 19-21 March 2012
Results L1 L2 L3 L5 SPL(dB) for the internal probes STAR Global Conference 19-21 March 2012 STAR Global Conference 19-21 March 2012
Results R1 R3 R5 R8 SPL(dB) for the internal probes STAR Global Conference 19-21 March 2012 STAR Global Conference 19-21 March 2012
Results • The far field noise measurements were compared to the simulated data FF1 FF2 FF3 FF4 STAR Global Conference 19-21 March 2012 STAR Global Conference 19-21 March 2012
Results FF6 FF7 • Comparison of the measured and simulated noise spectra is very good • Good agreement of external measurements from 10Hz up to 5000Hz STAR Global Conference 19-21 March 2012 STAR Global Conference 19-21 March 2012
Summary & Conclusions • Summary - CAE method was developed to predict noise in HVAC ducts - Software STAR-CCM+ was employed for the CAE - The method was validated against experimental measurements - CAE procedure for the work was delivered - Method allows A-B comparisons to be made in the vehicle programmes - Allows early NVH issues to be highlighted so palliatives can be implemented early STAR Global Conference 19-21 March 2012 STAR Global Conference 19-21 March 2012
Acknowledgements I would like to thank Elisabeth Gren, CD-adapco, UK Mark Farrall, CD-adapco, UK Fred Mendonça, CD-adapco, UK for the work and support in developing this method for Jaguar Land Rover. STAR Global Conference 19-21 March 2012 STAR Global Conference 19-21 March 2012
Latest product designed using STAR-CCM+ Thank You For Listening The End Range Rover Evoque STAR Global Conference 19-21 March 2012 STAR Global Conference 19-21 March 2012
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