Thrust performance of micromachined synthetic jets

Mueller, Michael; Bernal, Luis P.; Moran, Robert P.; Washabaugh, Peter D.; Parviz, Babak A.; Chou, T.-K.; Zhang, Chunbo; Najafi, K.

doi:10.2514/6.2000-2404

Cited by 16 publications

(10 citation statements)

References 4 publications

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“…The resonance frequency of the device can be found by plotting the ratio of the third to the first harmonic (Parviz et al 2001;Muller et al 2000). Figure 4 shows the first resonance point of a design#1 device.…”

Section: Electrical Characterizationmentioning

confidence: 99%

Electrostatically driven synthetic microjet arrays as a propulsion method for micro flight

et al. 2005

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A propulsion system based on acoustic streaming generated by Helmholtz resonators is presented. High frequency (>60 kHz) electrostatically driven micromachined Helmholtz resonators constitute the basic unit of the system. Microjets produced at the exit of these resonators can be combined to form a distributed propulsion system. A high yield (>85%) fabrication process is introduced for fabrication of individual as well as arrays of resonators. The fabrication results for ten different designs are presented. About 1000 resonators of similar design cover the surface of a 4-in. wafer, effectively converting it to a distributed propulsion system. A number of characterization methods such as monitoring the harmonics of the drive current, laser interferometry, hot-wire anemometry, acoustic spectrum measurement and video particle imaging are used to determine the structural and fluidic behavior of different resonator designs. Collapse and recovery times of the diaphragm in the electrostatic actuator of the resonator are characterized and reduced to less than 10 ls by optimizing the perforation design. The occurrence of acoustic streaming in the micron-scale is verified via video particle imaging. The jet streams produced with pulse drive at low frequencies ($1 kHz) are spatially profiled and jet velocities exceeding 1 m/s are measured at the exit of the resonators. It has been verified that the resonance frequencies of the device at 50 and 175 kHz can be closely predicted by modeling.

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Section: Electrical Characterizationmentioning

confidence: 99%

Electrostatically driven synthetic microjet arrays as a propulsion method for micro flight

et al. 2005

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“…Compression pumping can maximize its flow transfer efficiency by utilizing fluidic resonance, which is observed as a sudden peak in flow rate at a certain gas compression frequency [41], as depicted in Fig. 2.2.…”

Section: Mechanical Compression Pumpsmentioning

confidence: 99%

A scalable, modular, multi-stage, peristaltic, electrostatic gas micro-pump

Besharatian

Kumar

Peterson

et al. 2012

2012 IEEE 25th International Conference on Micro Electro Mechanical Systems (MEMS)

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Professor Khalil Najafi for his all-time support, encouragement and advice. If it was not for his deep understanding and patience, as well as respectful and humane attitude towards his students, going through hardships of the research would totally be impossible for me. My sincere acknowledgement goes to Dr. Rebecca Peterson, my supervisor and mentor, for all her unbelievably responsible, respectful and kind support of my research over the past years. I would also like to thank my other thesis committee members, Professor Luis Bernal, Professor Kensall Wise, Professor Edward Zellers and Professor Yogesh Gianchandani for their guidance and support. I would like to acknowledge my former and present group-mates and colleagues from Najafi Research Group and from Wireless Integrated MicroSensing and Systems (WIMS) Center, for their help, friendship and useful discussions. My special thanks goes to my colleague Karthik Kumar from Aerospace Engineering for his help and assistance in device testing and modeling. I would like to thank the staff and students of the Solid-State Electronics Laboratory (SSEL) and Luire Nanofabrication Facility (LNF) at the University of Michigan for all their help, in particular, sharing their expertise with me. I would also like to thank Professor Karl Grosh research group at Mechanical Engineering and the staff of Polytec facility at Dexter, MI, for their help with laser vibration analysis. My Ann Arbor experience remains a great chapter in my life thanks to all wonderful friends I made, or I enjoyed the company of, here. I would like to recognize and thank them all. In particular, I would like to thank Ms. Mahta Mousavi for all her support, love and encouragement over the past several months. This dissertation has been dedicated to my parents and my sister, who disserve the biggest appreciation of all. If it was not for their all-time love, sacrifice, support and encouragement, I would not be where I am now. iv TABLE OF CONTENTS DEDICATION ii ACKNOWLEDGMENTS iii LIST OF FIGURES vii

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“…Muller et a/. 2 ' 4 describe a reduced order model of synthetic jets driven by an acoustic resonator. The model was developed to predict the performance of the micromachined acoustic ejectors.…”

Section: American Institute Of Aeronautics and Astronauticsmentioning

confidence: 99%

“…The data for L/D < ~3 departs significantly from this trend line. In this region the thrust coefficient is proportional to (L/D) 4 . The dashed line in the figure identifies this trend…”

Section: Synthetic Jet Performancementioning

confidence: 99%

Flow structure and performance of axisymmetric synthetic jets

Mueller¹,

Bernal²,

Miska³

et al. 2001

39th Aerospace Sciences Meeting and Exhibit

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Experimental analysis is presented of the flow structure and performance of axisymmetric synthetic jets. We report direct thrust and Particle Image Velocimetry (PIV) measurements at varying amplitude and frequency for Reynolds numbers in the range 200-2200. It is shown that the jet performance is determined by the flow length, L, defined as the length of fluid ejected during the output stroke of the synthetic jet. Two flow regimes are identified. At small flow lengths L/D < ~3, the thrust is less than the momentum flux ejected during the output stroke, and increases proportional to L 4. This reduced thrust is due to reingestion of vorticity during the intake stroke. At large flow lengths L/D >-3, the thrust equals the momentum flux ejected during the output stroke, and is proportional to L 2. The entrainment rate of the synthetic jet was measured and found comparable to that of conventional axisymmetric turbulent jets. The mean and time-resolved flow structure in the near field of the synthetic jet varies with flow length. At small flow lengths, vortex rings form close to the orifice and loose some of the vorticity during the input stroke. At large flow lengths, vortex rings with some trailing vorticity form and move away from the orifice thus avoiding re-ingestion of vorticity during the input stroke. The amount of trailing vorticity does not affect the thrust produced by the synthetic jet.

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Thrust performance of micromachined synthetic jets

Cited by 16 publications

References 4 publications

Electrostatically driven synthetic microjet arrays as a propulsion method for micro flight

Electrostatically driven synthetic microjet arrays as a propulsion method for micro flight

A scalable, modular, multi-stage, peristaltic, electrostatic gas micro-pump

Flow structure and performance of axisymmetric synthetic jets

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