Simulation of noise in HVAC ducts Dr Karamjit Sandhu Climate - - PowerPoint PPT Presentation

STAR Global Conference 19-21 March 2012 STAR Global Conference 19-21 March 2012

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
• 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

Inlet profile Noise generated at duct surface Noise propagation from the duct outlet

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 of the Flow from the Duct Velocity Contour Plot through the Duct

STAR Global Conference 19-21 March 2012 STAR Global Conference 19-21 March 2012

Results

Pressure Contour Plot of the Flow from the Duct Pressure Contour Plot through 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

SPL(dB) for the internal probes B1 B2 B3 B4

STAR Global Conference 19-21 March 2012 STAR Global Conference 19-21 March 2012

Results

SPL(dB) for the internal probes F1 F3 F4 F5

STAR Global Conference 19-21 March 2012 STAR Global Conference 19-21 March 2012

Results

SPL(dB) for the internal probes L1 L2 L3 L5

STAR Global Conference 19-21 March 2012 STAR Global Conference 19-21 March 2012

Results

SPL(dB) for the internal probes R1 R3 R5 R8

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

• Comparison of the measured and simulated noise spectra is very good
• Good agreement of external measurements from 10Hz up to 5000Hz

FF6 FF7

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

Range Rover Evoque

Latest product designed using STAR-CCM+

Thank You For Listening The End