Adam Huang

Vortex Shift Control of Delta Wings by MEMS

     This is one of the first artificial demonstrations that the physical understanding and manipulation of the microscale can create a significant and immediate physical change in the macro scale. The overlying concept is to take advantage of existing physical mechanisms that has inherent gain amplification in its spatial dimensions. In this case, we take advantage of the fact that most aerodynamic bodies manifest separated vortices that originated from very small spatial domains (micron to millimeter scale). Thus, in this example we seek to control the separated primary vortex pair of a delta wing aircraft by utilizing MEMS sensors and actuators to affect the global vortex structures. We call this concept the Vortex Shift Control (VSC). The above movie shows the effect of a single strip of MEMS actuator on the starboard side. The delta wing model is mounted on a low friction bearing in the roll axis with the freestream at 15m/s. The actuation height is less than 2mm, which translates to 0.8% of the mean aerodynamic chord (MAC). The picture on the right side shows the equivalent delta wing model mounted with conventional flap/aileron surfaces of 19.4% MAC and +20/-25 degree deflections. The following figure shows the plot of rolling moment coefficient generated by the MEMS actuator and the conventional aileron (outboard only). Notice that the MEMS actuator was able to generate over 50% of the rolling moment at high angles of attacks when compared to the conventional effectors.

     The following picture shows the final integration (both for on the wind tunnel model and a full scale UAV research vehicle built by AeroVironment, Inc) of the MEMS shear stress sensors and actuators used for detecting the leading edge separation line and actuation control. The windtunnel model has 60 shear stress sensors fabricated on 2 flexible strips (30 each) and 12 linear actuator arrays. The 6ft long jet-powered UAV has 5 flexible strips of sensors (96 sensors total) and 24 linear actuators in 4 sigments. The project was sponsored by DARPA-MTO and NASA Dryden.

Active Control of Turbulent Boundary Layers by MEMS Sensors and Actuators

     Through simple scaling law of the spatial dimensions, we know that surface effects would gain dominance over body effects as the length scale decreases. Hence, it is often advantageous to use distributed MEMS devices to couple with microscale phenomena and effects that are highly dependent on surfaces in order to achieve macroscale consequences. It is known that the surface shear stress contribute a significant amount of the overall drag of an aerodyanmic vehicle. Also, in the viscous sublayer of the turbulent boundary layers, the presence of innumerable shear streaks that transport high-momentum flow to the surface contributes 30-40% of the total viscous drag. Therefore, it is not hard to envision the usage of MEMS shear stress sensors to sense and MEMS actuators to interact with these shear streaks. It is exactly through this modus operandi that we seek to exploit in this research. The movie above is the MEMS flap developed for this project. It is a 3x1mm rectangular cantilever design with a thickness of ~50um. Underneath the flap is a RTV-11 silicone membrane that acts as the piston actuator to articulate the flap. The membrane is inflated by an offboard pnuematic system driven by pressurized helium gas and a high speed solenoid valve. The actuator system lag time is ~1ms while the actuation height is ~110um at 200Hz. There are faster repetition, higher actuation height, lower lag time, more robust, or high actuation force MEMS/miniature flap actuator designs, however, a single acutator design with all the above characteristics, like the ones used in this research, is extremely rare. The MEMS shear stress sensor used (right side figure above) is also an unique design that lend itself to high sensitivity, spatial and temporal resolution, and sensor density.

     The left side figure above shows the MEMS shear stress sensor array and actuator module mounted in the 2D turbulent wind tunnel. In this research, only the sensor rows closest to the flap actuator is used since this minimizes the dissipative effects between the sensors and the actuator. The right side figure above shows the shear stress image formed by the off-line ensemble average of the shear stress arrays triggered by the corresponding actuator response. Notice that the actuator does induce a initial high stress region, but a significantly larger low stress region trails the actuation event. Also note that the actuator does not induce any shear stress forward enough to be detectable by the upstream shear stress sensor array. This setup was used to perform on-line, off-line, feed-backed, and feed-forward (via neural network training) shear stress reduction experiments. This project was funded by the AFOSR and DARPA-MTO. The lead graduate student with this project was James Lew. The MEMS shear stress sensor is fabricated by Caltech Micromachining Lab.

MEMS Based Pulse Combustor (Research in Progress)

     Combustion is a rapidly oxididating chemical reaction involving chemical species at the molecular level and propagates to spatial dimensions that can reach into stellar magnitudes. Naturally, this process can incorporate a multitude of characteristics depending on the spatial domains of the ensuing flame sizes. The goal of this project is to create a small scale combustion engine design (with the combustion chamber length scales in the order of millimeters) that can produce meaningful work in the form of a thrusting jet. Thus, the crucial components in this research are the ignition of the flame kernels, the flame propagation, and the quenching characteristics of the MEMS based combustor. In addition, the mode of combustion pursued here is based on the acoustically coupled pulse combustors. Pulse combustors are characterized by unsteady and resonating combustions that form its cyclical characteristics. This may prove to be the enabling mode of a stable small scale combustor due to the large inertial energy of typical resonant systems.

Nanoparticle Based Conductive Polymers (Research in Progress)

     This section is currently still under construction. Please see the corresponding section in my colleague's page ( Tak-Sing Wong ).

Education

• Ph.D. UCLA School of Engineering and Applied Science, Major in Aerospace Engineering, Expected 2005
• M.S. UCLA School of Engineering and Applied Science, Major in Aerospace Engineering, 2003
• B.S. UCLA School of Engineering and Applied Science, Major in Aerospace Engineering, 1998

Publications (UCLA Only)

Journal Publications

1. J. Lew, P-H. A. Huang, Y-C. Tai, and C-M. Ho, “Active Control of Surface Streak in Turbulent Flow,” in preparation for Journal of Fluid Mechanics.
2. A. Huang, V.T.S. Wong, and C-M. Ho, “Silicone Polymer Chemical Vapor Sensors Fabricated by Direct Polymer Patterning On Substrate Technique (DPPOST),” submitted to Sensors and Actuators B, July 2005.
3. A. Huang, J. Lew, Y. Xu, Y-C. Tai, C-M. Ho, “Micro Sensors and Actuators for Macro Fluidic Control,” IEEE Sensors Journal, Vol. 4, No. 4, pp. 494-502, Aug 2004.
4. Y. Xu, Y-C. Tai, A. Huang, C-M. Ho, “IC-Integrated Flexible Shear-Stress Sensor Skin,” Journal of Microelectromechanical Systems, Vol. 12, No. 5, pp.740-747, October 2003.
5. Y. Xu, F. Jiang, S. Newbern, A. Huang, C-M. Ho, Y-C. Tai, “Flexible shear-stress sensor skin and its application to unmanned aerial vehicles,” Sensors and Actuators A: Physical. Vol. A105, No. 3, pp. 321-329, August 2003.
6. G.B., Lee, C. Shih, Y.-C. Tai, T. Tsao, C. Liu, A. Huang, and C.-M. Ho, “Robust Vortex Control of a Delta Wing by Distributed Microelectromechanical-Systems Actuators,” AIAA Journal of Aircraft, Vol. 37, No. 4, pp. 697-706, July-August 2000.
7. G.B. Lee., A. Huang, C-M. Ho, F. Jiang, C. Grosjean, Y.C. Tai, “Sensing And Control of Aerodynamic Separation by MEMS,” The Chinese Journal of Mechanics, Vol. 16, No. 1, pp. 45-52, March 2000.

Conferences

1. A. Huang, V.T.S. Wong, C.M. Ho, “Conductive Silicone Based MEMS Sensor and Actuator,” Proceedings, The 13th International Conference on Solid-State Sensors, Actuators, and Microsystems (Transducers’05), Seoul, Korea, June 5-9, 2005.
2. V.T.S. Wong, A. Huang, and C.M. Ho, “Toward High Density Silicone Polymeric Chemical Vapor Sensor Arrays,” in Proc. 11th Intl. Symp. on Olaf. and Elect. Nose (ISOEN), pp. 398-401, Barcelona, Spain, Apr. 13-15, 2005.
3. V.T.S. Wong, A. Huang, and C.M. Ho, “SU-8 Lift-off Patterned Silicone Chemical Vapor Sensing Arrays”, in Proc. 18th IEEE Intl. Conf. on Micro-Electro-Mechanical Systems (MEMS2005), pp. 754-7, Miami Beach, Florida, Jan. 30-Feb. 3, 2005.
4. A. Huang, P-J. Chen, J. Boland, D. Alberer, T.S. Wong, H.Q. Yang, Y-C. Tai, and C-M. Ho, "Liquid Rotor Electret Power Generator Array Energized by a MEMS-Based Pulsed Combustor," The Fourth International Workshop on Micro and Nanotechnology for Power Generation and Energy Conversion Applications(PowerMEMS 2004), Kyoto, Japan, Nov. 28-30, pp. 171-174, 2004.
5. J. Lew, A. Huang, F. Jiang, Y-C. Tai, and C-M. Ho, “Surface Shear Stress Reduction with MEMS Sensors/Actuators in Turbulent Boundary Layers,” 42nd AIAA Aerospace Sciences Meeting and Exhibit, AIAA-2004-424, Reno, Nevada, Jan. 5-8, 2004.
6. A. Huang, J.J. Gau, J.M. Yang, Y-C. Tai, C.-M. Ho, “Miniaturized real-time airborne bio-agents detector for expendable-UAVs,” 2nd AIAA "Unmanned Unlimited" Systems, Technologies, and Operations - Aerospace, Land, and Sea Conference, Workshop and Exhibition, San Diego, CA; Sep. 15-18, 2003.
7. Y. Xu, Y.-C. Tai, A. Huang, and C.-M. Ho, "IC-Integrated Flexible Shear-Stress Sensor Skin," Solid-State Sensor, Actuator, and Microsystems Workshop (Hilton Head), Hilton Head Island, South Carolina, 2002.
8. A. Huang, C. Folk, C.-M. Ho, Z. Liu, W.W. Chu, Y. Xu, Y.-C. Tai., "Gryphon M3 system: integration of MEMS for flight control," MEMS Components and Applications for Industry, Automobiles, Aerospace, and Communication, Proceedings of SPIE (The Int'l Society for Optical Engineering), vol. 4559, pp. 85-94, San Francisco, CA, October, 2001.
9. Z. Liu, W.W. Chu, A. Huang, C. Folk, and C.M. Ho, “Mining Sequence Patterns from Wind Tunnel Experimental Data for Flight Control”, in Proc. 5th Pacific-Asia Conf. on Knowledge Discovery and Data Mining (PAKDD), Hong Kong, China, April, 2001.
10. A. Huang, C. Folk, C. Silva, B. Christensen, Y.F. Chen, G.B. Lee, M. Chen, S. Newbern, F. Jiang, C. Grosjean, C.M. Ho, and Y.C. Tai, “Application of MEMS Devices to Delta Wing Aircraft: From Concept Development to Transonic Flight Test,” 39th AIAA Aerospace Sciences Meeting, 01-0124, Reno, NV, January, 2001.
11. C. Folk, A. Huang, C. Silva, C-M. Ho, H. Suzuki, Y-C. Tai, and S. Newbern, "Aero-MEMS Transducers for UAV and Jet Flight Tests" International conference on Heat Transfer, Tsukuba, Japan, September 25-26, 2000.
12. F. Jiang, Y. Xu, T. Weng, Z. Han, Y.C. Tai, A. Huang, C.M. Ho, and S. Newbern, “Flexible Sensor Skin for Aerodynamics Applications,” in Proc. 13th IEEE Intl. Conf. on Micro-Electro-Mechanical Systems (MEMS2000), pp. 465-470, Miyazaki, Japan, 2000.
13. A. Huang, C-M. Ho, F. Jiang, and Y.C. Tai, “MEMS Transducers for Aerodynamics-A Paradigm Shift,” 38th AIAA Aerospace Sciences Meeting, 00-0249, Reno, NV, January, 2000.
14. C.M. Ho, P.H. Huang, J. M. Yang, G.B. Lee, and Y.C. Tai, “Active Flow Control by MicroSystems,” FLOWCON, International Union of Theoretical and Applied Mechanics (IUTAM) Symposium on Mechanics of Passive and Active Flow Control, Gottingen, Germany, pp. 18-19, September, 1998.
15. C.M. Ho, P.H. Huang, J. Lew, J.D. Mai, V. Lee, Y.C. Tai, “Intelligent System Capable of Sensing-Computing-Actuating,” Keynote Address, 4th International Conference on Intelligent Materials, Society of Non-Traditional Technology, Tokyo, Japan, October 1998.

Talks and Seminars

1. A. Huang and C.M. Ho, “An Integrated Bio-Spy UAV,” NASA Flight Systems Research Center, 2003 Annual Research Review Meeting, NASA Dryden, April, 2003.
2. A. Huang and C.M. Ho, “MEMS Shear Stress Sensor Array with Integrated On-Chip Circuitry,” NASA Flight Systems Research Center, 2002 Annual Research Review Meeting, NASA Dryden, May 24, 2002.
3. A. Huang and C.M. Ho, “MEMS for Aero Control,” U.S. Army, Picatinny, Sponsored MEMS workshop, Picatinny Arsenal, NJ, October 31-November 2, 2000.
4. A. Huang, G.B. Lee, C. Folk, C.M. Ho, C. Grosjean, F. Jiang, T. Weng, Y.C. Tai, S. Newbern, and M. Cowley, “Control of an Aircraft by M3 Microsystems,” 51th Annual meeting of APS Division of Fluid Dynamics, November 22-24, Philadelphia, PA, 1998.

Work Experience

• 2000-present, Member of Technical Staff, Center for Microtechnology, The Aerospace Corporation, El Segundo, California
• 1998-present, Graduate Student Researcher,AERO-MEMS Laboratory, Mechanical and Aerospace Engineering Department University of California, Los Angeles
• 1995-1998, Undergraduate Student Helper, Center for Microsciences, Mechanical and Aerospace Engineering Department University of California, Los Angeles
• 1994-1995, Undergraduate Student Helper, Experimental Elementary Particle Physics, Department of Physics and Astronomy, University of California, Los Angeles

Contact Info

Mailing Address:
48-121 Engineering IV
420 Westwood Plaza
Los Angeles, CA 90095

Phone: 310-825-8275
E-Mail: pohao@ucla.seas.edu