Gary Steven Strumolo

Method and system for predicting sound pressure levels within a vehicle due to wind noise

A programmable digital computer system is utilized for predicting sound pressure levels (SPLs) within a vehicle due to wind noise by utilizing data representing pressure spectra for vortex, reattached and turbulent boundary layer flows over a glass side window of the vehicle. The method and system preferably utilize data representing physical properties of at least one door seal of the vehicle. A set of pressure coefficients is determined so that a vortex area in turn can be determined and utilized during computation of the SPLs. Plots of the SPLs over a predetermined frequency range can be displayed for a drivers ear position as well as for a passengers ear position within the vehicle.

VAWT: The virtual aerodynamic/aeroacoustic wind tunnel

Ever since computational fluid dynamics (CFD) arose as a tool for predicting fluid motions engineers have looked to the day when it could be used reliably to supplement wind tunnel tests. Limits on computer speed and algorithm accuracy have prevented the development of a virtual wind tunnel. But now, a team from Ford Research has developed the capability that allows engineers to evaluate vehicle designs both aerodynamically and aeroacoustically in a virtual environment. Starting with a CAD surface description of the vehicle, a CFD simulation can be constructed and executed with little user intervention in only a few days. This information can be used to estimate interior sound due to wind noise, which can then be played through speakers for a comparison of alternate vehicle designs. The technology that makes this possible combines a new method for CFD called PowerFlowTM (from the Exa Corporation) with an enhanced Wind Noise Modeller©. To illustrate this new capability, we will consider an analysis of the Taurus line. Aerodynamic information regarding flow around the side mirror and windshield wipers will be provided, and aeroacoustic wind-noise predictions will be made and compared to actual wind tunnel tests.

Obstacle State Estimation For Imminent Crash Prediction & Countermeasure Deployment Decision-Making

This paper describes how predictive crash sensing and deployment control of safety systems require reliable and accurate kinematic information about potential obstacles in the host vehicle environment. The projected trajectories of obstacles in the path of the vehicle assist in activation of safety systems either before, or just after collision, for improved occupant protection. An analysis of filtering and estimation techniques applied to imminent crash conditions are presented in this paper. Optimization of design criteria used to achieve required response performance, and noise minimization, are evaluated based on the safety system to be activated. The predicted target information is applied in the coordinated deployment of injury mitigation safety systems.

Supervisory vehicle impact anticipation and control of safety systems

Occupant safety systems are incorporated in vehicles to meet the requirements of occupant protection. For optimum performance safety devices require tailored activation. This paper presents a supervisory control approach using predictive collision sensor information to augment the performance of safety systems. The supervisory approach determines the potential for a collision to occur, and assists in deployment decision-making. Decision-making is based on the obstacle range, and closing velocity information obtained from the anticipatory sensor, and a reference signal indicative of the host-vehicle deceleration. The multi-input supervisory control system consists of a fuzzy rule-based system, which determines the potential for a collision to occur, and deployment command generation for activation of respective safety devices.

Enhancing Vehicle Ingress/Egress Ergonomics with Digital Human Models

The ease of getting in and out of a vehicle (or ingress/egress) is one of the most important ergonomic issues for automotive manufacturers. It represents the first physical contact of a customer with a vehicle. A pleasant sensation while interfacing with the vehicle plays a vital role in vehicle purchasing decisions. Understanding and being able to assess vehicle ingress/egress performance early in a design process is therefore critical to a successful vehicle design. Conventional method relies on clinic research with physical bucks, which is a time consuming and pure subjective process. A new hardware-in-the-loop motion analysis system has been developed, which uses the latest motion capture, biomechanical and digital human modelling technologies to capture and analyse human motions as the driver or passenger interacts with a vehicle. The design assessment is provided in both subjective ratings and, for the first time, the physical data (e.g., swept volumes in CAD). The use of the system avoids costly seating buck builds and reduces engineering time and cost associated with both buck build and conducting the tests. Most importantly, it enables engineers to assess a vehicle’s ingress/egress performances early in its design process, which will lead to better vehicle packages and better customer satisfaction.

SOUND GENERATION BY UNSTEADY FLOW ABOUT A RECTANGULAR CUBOID

Flow past a rectangular brick yawed at 30 degrees to the streamwise direction is simulated using a hybrid lattice gas - lattice Boltznann computational fluid dynamics code. This simple geometric shape generates vortex shedding similar to that found on a vehicle greenhouse, or upper, glass-containing portion of an automobile. This simulation computes the time-accurate flow field in order to capture the unsteady surface pressure which is the primary source of vehicle aerodynamic noise. The timeaveraged flow field closely matches the experimentally observed steady-state field. The surface pressure spectra for locations on the top surface of the brick are computed for frequencies between 50 and 5000 Hz. The shapes of the computed sound spectra compare well with the experimental data for locations clearly inside the two vortex regions or in the reattached flow region, but need a 15 dB shift to match the sound pressure level absolutely. The spectra for monitoring locations in the flow reattachment region compare less closely to experimental data.

The Vortex-Boundary Element Method - New pressure methods for application to the external flow noise problem

Three new methods to compute pressure within a vortex method are developed and presented. Although demonstrated in a Vortex-Boundary Element Method, these pressure methods are suitable for any vortex method. They have computational savings of 2-3 orders of magnitude over a standard Poisson pressure method when surface pressure at a small set of locations is desired. This savings is significant as the computational time needed to solve for the pressure field using a Poisson method exceeds that of the VBEM. for cases similar to those studied here.. These methods are validated for flow on the front face of a cube set orthogonal to a uniform freestream flow. Flow about a cube yawed at 30” to the streamwise direction is simulated. Timeaveraged ‘flow field data and surface pressure spectra are presented for Reynolds numbers of 500 and 1500. The results of the calculations correctly predict an overall sound pressure level increase with increasing Reynolds numbers. The VBEM also captures the different levels of pressure fluctuations associated with different flow regions. This work also serves as a successful first step in demonstrating the potential of the VBEM for use in computing unsteady flows to predict the pressure spectrum associated with the unsteady surface pressure fluctuations.

Prediction of sound inside an automobile due to wind noise

A mathematical model and computer program has been developed to predict the sound inside an automotive passenger compartment due to wind noise. Using steady‐state information on pressure distributions along the glass surfaces, the program computes the impact of vortices on the vibrational characteristics of the glass and the radiated sound from it. It also accounts for the sound radiated through the door seals and combines them for a composite sound‐pressure level (SPL) estimate at the driver’s ear location. This SPL spectrum is computed at the 1/3‐oct frequencies from 25 Hz to 10 kHz. The program also computes the overall SPL, loudness, and % speech intelligibility. Using optimization techniques, the model allows for a desired SPL spectrum to be specified along with a set of design variables. It then automatically computes the values needed by these variables to come as close as possible to the desired spectrum. The model has been validated over a wide range of cars and trucks. Typical accuracy is ± 3 dB...

Computational Fluid Dynamics Analysis of the Flow in an APCVD Applicator System

Application of Atmospheric Pressure Chemical Vapor Deposition (APCVD) to the production of coated glass is addressed in this study. Several layers of thin films are deposited on the surface of the glass as it moves underneath the APCVD applicator system at high temperature. A memory effect in the form of film thickness streaks, corresponding to the location of the inlet holes located upstream in the upper manifold feed channel, is evident on the glass. This nonuniform film across the glass causes a color variation of the coating. Effective mixing of the gas streams is required to treat the hole memory problem. However, a premature reaction is to be avoided. Optimum design parameters to correct this problem include the geometry of the applicator and the sensitivity of the flow field to boundary conditions is of major interest. The Computational Fluid Dynamics (CFD) simulation and analysis package FIRE is used to predict the flow. The flow of gases involved is treated as that of a steady, viscous, incompressible fluid. Results for both two- and three-dimensional cases demonstrate that the deposition process can be improved by injecting the flow at an angle counter to the direction of glass motion, and that CFD techniques can be successfully used to predict the flow behavior of an APCVD applicator system and help optimize its design.