Control/CFD
Interdisciplinary Research

Background

There is an effort currently underway at NASA Glenn Research Center to develop technology that will facilitate the use of CFD (computational fluid dynamics) by engineers designing propulsion controls.

Objective

The program objective of the research is to develop technology which reduces the time and cost of the control design process by using CFD-based simulations to provide time accurate plant models for control design, testing, and validation. The motivation for this work stems from control design requirements for accurate models of high speed propulsion systems such as those being developed for the national High Speed Research (HSR) program. A more accurate initial model should shorten the design cycle and reduce experimental test time resulting in cost savings. Furthermore, as compute power increases, further savings might be obtained by using CFD rather than experiments for some control validation.

Approach

The design of any control requires some knowledge of the plant under consideration. For the design of propulsion controls, this knowledge is usually in the form of data derived from analytical models and experiments. The preferred method of obtaining this data is through analytical models as they are less costly and risky to run than experiments. Propulsion system models are based on one of two paradigms: large lumping techniques or CFD. The controls engineer has traditionally relied on lumped parameter models because they are simple and can operate at or near real-time. They are useful for generating low order linear models and for initial validation of the closed-loop control. However, they are unable to model the complex physics of mixed compression flows such as those found in mixed-compression inlets. Multidimensional CFD codes are more suitable for modeling complex high speed flows. Unfortunately, long execution times, computational resource requirements, and lack of time dependent control surfaces make CFD an impractical tool for controls engineers.

In most cases, detailed CFD modeling precedes the fabrication of high speed inlets. If the technology can be developed to address controls issues, then control design engineers could take advantage of these high fidelity models. This should shorten the control design cycle in two ways. It should provide a higher quality initial model reducing the number of iterations during the design cycle. And, by providing the higher quality model, it will eliminate the need to develop coarse lumped parameter models.

Control Technology
CFD Technology
Control/CFD Interface Technology

Publications

A. Chicatelli and T. Hartley, "A Method for Generating Reduced Order Linear Models of Supersonic Inlets," NASA Contractor Report 198538, January 1996.

K. Melcher and G. Cole, "An Overview of the Glenn Controls/CFD Interdisciplinary Research Program," Proceedings of the NASA Computational Aerosciences Workshop, March 7-9, 1995.

A. Chicatelli, T. Hartley, G. Cole, and K. Melcher, "Interdisciplinary Modeling Using Computational Fluid Dynamics and Control Theory," Proceedings of the American Control Conference, June 1994, pp. 3438-3443.

G. Cole, K. Melcher, A. Chicatelli, T. Hartley, and J.K. Chung, "Computational Methods for HSCT-Inlet Controls/CFD Interdisciplinary Research," NASA TM 106618 (ICOMP-94-10, AIAA- 94-3209), May 1994.

Participants

• NASA Glenn Research Center
  • 5530/Controls and Dynamics Technology Branch
  • 2620/Computational Technologies Branch
  • 2900/Interdisciplinary Technology Office
  
  
• The University of Akron
  • Department of Electrical Engineering
  
  
• ICOMP - Institute for Computational Mechanics in Propulsion

Personnel

• Project Manager: Controls Discipline
  Kevin J. Melcher
  NASA Glenn Research Center/77-1
  phone: (216) 433-3743
  email: kevin.melcher@grc.nasa.gov
  
  
• Project Manager: CFD Discipline
  Gary L. Cole
  NASA Glenn Research Center/5-99
  phone: (216) 433-3655
  email: glc@grc.nasa.gov
  
  
• Other key personnel:
  
  Tom T. Hartley, Ph.D.
  Principal Investigator for Grant NCC3-508
  Department of Electrical Engineering
  The University of Akron
  Akron, Ohio 44325-3904
  email: TomHartley@aol.com
  
  Amy Chicatelli
  Research Associate for Grant NCC3-508
  Department of Electrical Engineering
  The University of Akron
  Akron, Ohio 44325-3904
  email: chic@cntrld.grc.nasa.gov
  
  J.K. Chung, Ph.D.
  ICOMP Research Associate
  ICOMP
  NASA Glenn Research Center/MS 5-11
  Cleveland, Ohio 44135
  email: jkchung@scooby.grc.nasa.gov
  

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