Data processing: structural design – modeling – simulation – and em – Simulating nonelectrical device or system – Mechanical
Reexamination Certificate
1998-10-19
2001-07-17
Teska, Kevin J. (Department: 2825)
Data processing: structural design, modeling, simulation, and em
Simulating nonelectrical device or system
Mechanical
C703S006000, C703S007000, C703S009000, C703S012000
Reexamination Certificate
active
06263300
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to computer aided vehicle design in general, and more specifically to a particle trajectory analysis system for computer aided vehicle design.
BACKGROUND OF THE INVENTION
There are numerous computer related tools which can facilitate the design and testing of automotive vehicles, including generalized software programs such as computer aided engineering (CAE), computer aided design (CAD), and computational fluid dynamics (CFD). These tools are typically used to investigate many issues related to vehicle design, including vehicle durability, vehicle performance, and vehicle aerodynamics. Heretofore, limitations on computer speed and algorithm accuracy have inhibited the development of a particle trajectory analysis tool in which several exterior aerodynamic design issues can be studied. For example, while the depression of the windshield washer spray at high vehicle speeds is a well-known problem, currently there are no predictive CAE tools to analyze this extremely complex phenomenon, which involves the breakup of a liquid jet into droplets, the interaction between the droplets and the external three-dimensional flow field, inertia and gravity effects, and surface tension effects. A major obstacle in the past in investigating this, as well as other exterior aerodynamic issues, has been the inability to accurately calculate an external flow field around the vehicle.
However, with the advent of new and improved CFD technology, an accurate external flow field can now be calculated, thus making a particle trajectory analysis tool technically possible. A further need exists, nonetheless, for a method and system which utilizes available computer related technology to provide a user accessible particle trajectory analysis tool to aid in vehicle design. Additionally, a method and system is needed to provide a comparison between results from physical aerodynamic tests and a particle trajectory analysis tool, and to compare alternate vehicle designs.
SUMMARY OF THE INVENTION
The present invention addresses the deficiency in the field by providing a method and system for aiding in vehicle design by enabling dynamic placement of an array of particle injection points into a flow domain to permit visual observation and alteration of resulting particle trajectories under a computed flow solution. The method and system may be used, for example, to determine wiper spray trajectories and windshield impact at highway speed and parked, water droplet trajectories on window surfaces, paint particles from spray guns, soil deposition along the bottom of vehicles, as well as other flows that involve particle trajectories to aid in vehicle design.
The system of the present invention preferably comprises particle injector placement code operable with the user input means, such as a mouse, to effect a desired placement of at least one particle injector on the display with respect to a desired portion of a CAD model of the vehicle. Trajectory determination code means are included for computing at least one trajectory for a particle stream emanating from the at least one particle injector relative to the desired portion of the CAD model for a predetermined set of particle characteristics in a predetermined set of particle external conditions. The system also includes trajectory display code means for affecting display of the at least one trajectory with respect to the desired portion of the CAD model.
A method of the present invention comprises the steps of preparing a CAD model of the desired portion of the vehicle, placing a particle injector at a desired location with respect to the desired portion of the vehicle, specifying a set of particle information describing particles to be ejected from the particle injector, computing a stationary trajectory for a particle stream emanating from the particle injector, displaying the stationary trajectory relative to the desired portion of the vehicle on a display means to permit visual observation thereof, and repositioning the particle injector if necessary to achieve a desired stationary trajectory. In one embodiment, the particle injector is a windshield washer spray nozzle, and the method further includes the steps of creating a computational mesh over the desired portion of the vehicle designed from the CAD model, computing a transient flow field over the desired portion using the computational mesh, computing a depressed trajectory for a particle stream emanating from the particle injector due to the transient flow field, and displaying the stationary trajectory and the depressed trajectory on the display means to permit visual observation of resulting particle trajectories under a computed flow solution over the desired portion of the CAD model.
An advantage of the present invention is a method and system which permits modification of vehicle design based upon computed particle trajectories with respect to a CAD model of the vehicle.
Another advantage of the present invention is a method and system for aiding in vehicle design by enabling dynamic placement of particle injection points into a flow domain to permit visual observation and alteration of resulting particle trajectories with respect to a CAD model representative of the vehicle.
Still another advantage of the method and system of the present invention is a software program which allows a user to specify various characteristics of a wiper spray nozzle including visually placing it near the hood of a vehicle, prescribing droplet size and density, injection angle and velocity, and then computing and displaying spray trajectories which result under both parked and driving conditions.
Still yet another advantage of the present invention is a method and system for analyzing windshield wiper spray depression at highway speeds.
Another advantage is a software program for evaluating hood design and windshield washer spray nozzle placement relative to a vehicle design.
Yet another advantage of the present invention is a method and system which provides a software program which can predict streaking along the bottom sides of a vehicle design caused by soil thrown from the tires.
Yes still another advantage is a software program which can predict soil deposition patterns from a vehicle tire and evaluate modifications to a vehicle design to minimize such streak patterns.
Yet another advantage of the present invention is a method and system providing a software program to simulate movement of water droplets along a vehicle surface, such as along a windshield or side glass to aid in modifications to vehicle design in order to achieve a desired water management goal.
A further advantage is a software program which permits visual observation of both stream lines and water droplet trajectories along a vehicle surface.
In a preferred embodiment, the present invention includes arithmatic logic circuit configured to retrieve information from a specific file, display that information in a form of a vehicle design on a display screen, compute particle trajectories relative to the vehicle design based on specific input, display the trajectories relative to the vehicle design, and allow the user to modify the specific input in order to produce trajectories which meet the desired design criteria.
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Web article, “CFD Solutions for Automotive Design”, 1997, Fluent, Inc. http://www.fluent.com/solutions/automotive/applications.html.*
Ghannam, M, et al, “A model for automotive windshield washer spray delivered by a fluidic nozzle”, IMechE D, Journal of Automotile
Babu Viswanathan
Strumolo Gary Steven
Ford Global Technologies Inc.
Kelley David B.
Speight Jibreel
Teska Kevin J.
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