This paper presents a lumped element model of a piezoelectric-driven synthetic jet actuator. A synthetic jet, also known as a zero net mass-flux device, uses a vibrating diaphragm to generate an oscillatory flow through a small orifice or slot. In lumped element modeling (LEM), the individual components of a synthetic jet are modeled as elements of an equivalent electrical circuit using conjugate power variables. The frequency response function of the circuit is derived to obtain an expression for outAC QV, the volume flow rate per applied voltage. The circuit is analyzed to provide physical insight into the dependence of the device behavior on geometry and material properties. Methods to estimate the model parameters are discussed, and experimental verification is presented. In addition, the model is used to estimate the performance of two prototypical synthetic jets, and the results are compared with experiment. IntroductionSynthetic jet actuators have been the focus of significant research activity for the past decade (Smith and Glezer 1998). The interest in synthetic jets is primarily due to their utility in flow control applications, such as separation control, mixing enhancement, etc. Chen et al. 1999;Honohan et al. 2000;Chatlynne et al. 2001).A schematic of a synthetic jet actuator is shown in Figure 1. A typical synthetic jet, also known as a zero net mass-flux device, uses a vibrating diaphragm to drive oscillatory flow through a small orifice or slot. Although there is no source, a mean jet flow is established a few diameters from the orifice due to In addition to studies that emphasize applications, there are numerous others that have concentrated on the design, visualization, and/or measurements of synthetic jets (Crook et al. 1999;Chen et al. 2000;Crook and Wood, 2001;Gilarranz and Rediniotis, 2001).Furthermore, several computational studies also have focused on fundamental aspects of these devices (Kral et al. 1997; Rizzeta et al. 1998;Mallinson et al. 2000;Utturkar et al. 2002). Crook and Wood (2001) emphasize the importance of understanding the scaling and operational characteristics of a synthetic jet. Clearly, this information is required for a user to design an appropriate device for a particular application.In addition, feedback control applications require the actuator transfer function that relates the input voltage to the output property of interest (e.g., volumetric flow rate) in the control system.The design itself represents an electromechanical-acoustic coupled system with frequency dependent properties determined by device dimensions and material properties. The analysis and design of coupled-domain transducer systems are commonly performed using lumped element models (Fisher 1955;Hunt 1982;Rossi 1988).The main assumption employed in LEM is that the characteristic length scales of the governing AIAA-2002-0125Lumped Public reporting burden for the collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching exis...

This paper presents a lumped element model of a piezoelectric-driven synthetic jet actuator. A synthetic jet, also known as a zero net mass-flux device, uses a vibrating diaphragm to generate an oscillatory flow through a small orifice or slot. In lumped element modeling (LEM), the individual components of a synthetic jet are modeled as elements of an equivalent electrical circuit using conjugate power variables. The frequency response function of the circuit is derived to obtain an expression for outAC QV, the volume flow rate per applied voltage. The circuit is analyzed to provide physical insight into the dependence of the device behavior on geometry and material properties. Methods to estimate the model parameters are discussed, and experimental verification is presented. In addition, the model is used to estimate the performance of two prototypical synthetic jets, and the results are compared with experiment. IntroductionSynthetic jet actuators have been the focus of significant research activity for the past decade (Smith and Glezer 1998). The interest in synthetic jets is primarily due to their utility in flow control applications, such as separation control, mixing enhancement, etc. Chen et al. 1999;Honohan et al. 2000;Chatlynne et al. 2001).A schematic of a synthetic jet actuator is shown in Figure 1. A typical synthetic jet, also known as a zero net mass-flux device, uses a vibrating diaphragm to drive oscillatory flow through a small orifice or slot. Although there is no source, a mean jet flow is established a few diameters from the orifice due to In addition to studies that emphasize applications, there are numerous others that have concentrated on the design, visualization, and/or measurements of synthetic jets (Crook et al. 1999;Chen et al. 2000;Crook and Wood, 2001;Gilarranz and Rediniotis, 2001).Furthermore, several computational studies also have focused on fundamental aspects of these devices (Kral et al. 1997; Rizzeta et al. 1998;Mallinson et al. 2000;Utturkar et al. 2002). Crook and Wood (2001) emphasize the importance of understanding the scaling and operational characteristics of a synthetic jet. Clearly, this information is required for a user to design an appropriate device for a particular application.In addition, feedback control applications require the actuator transfer function that relates the input voltage to the output property of interest (e.g., volumetric flow rate) in the control system.The design itself represents an electromechanical-acoustic coupled system with frequency dependent properties determined by device dimensions and material properties. The analysis and design of coupled-domain transducer systems are commonly performed using lumped element models (Fisher 1955;Hunt 1982;Rossi 1988).The main assumption employed in LEM is that the characteristic length scales of the governing AIAA-2002-0125Lumped Public reporting burden for the collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching exis...

[Excerpt] Electronic-distribution-channel options constitute a complex web of choices through which suppliers and buyers of hospitality services must carefully navigate to ensure favorable financial results. The firms that compete in electronic distribution are internet-based companies, GDSs, DSPs, travel agents, and the hotel chains themselves. Individual properties face two major challenges from electronic distribution: 1. control over price and availability and 2. the management of web site content. To maintain price control, properties and the chains that operate them must structure rates effectively, apply terms and conditions to avoid dilution and arbitrage, monitor competitiveness, and manage rate accuracy and availability.

A new luminescent oxygen and temperature sensor has been developed that utilizes two luminescent dyes, 5,10,15,20-tetrakis(pentafluorophenyl)porphyrin platinum(II) (PtTFPP, the oxygen sensor) and tris(1,10-phenanthroline)ruthenium(II) dichloride (Ruphen, the temperature sensor). The two dyes are dispersed in an oxygen-permeable polymer binder consisting of a copolymer of 4-tert-butylstyrene (tBS) and 2,2,2-trifluoroethyl methacrylate (p-tBS-co-TFEM). To alleviate energy transfer and other quenching interactions between the two luminescent dyes in the p-tBS-co-TFEM binder, the Ruphen temperature sensor is encapsulated in polyacrylonitrile (PAN) polymer nanospheres that are prepared by coprecipitation of PAN and Ruphen from N,N-dimethylformamide solution. The temperature and air-pressure response of the emission from the sensor film is fully characterized by using emission spectroscopy. The emission from the two luminescent dyes is spectrally well-separated. The intensity of the Ruphen emission varies strongly with temperature (approximately 1.4% degrees C(-1)), whereas the intensity of the PtTFPP emission varies with temperature and air pressure. The two-dye luminescent coating is useful as a pressure-sensitive paint (PSP), where the emission from the Ruphen temperature sensor is used to correct for the temperature dependence of the pressure response of the PtTFPP sensor. To demonstrate the PSP application, a coupon coated with the sensor was imaged using a CCD camera, and the CCD images were analyzed by intensity ratio methods. Spectroscopic studies were also carried out on a sensor that contains three dyes in order to demonstrate the feasibility of including an intensity reference dye along with the temperature and pressure dyes into the sensor.

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