No-moving-part hybrid-synthetic jet actuator

In contrast to usual synthetic jets, the “hybrid-synthetic jets” of non-zero timemean nozzle mass flow rate are increasingly often considered for control of flow separation and/or transition to turbulence as well as heat and mass transfer. The paper describes tests of a scaled-up laboratory model of a new actuator version, generating the hybrid-synthetic jets without any moving components. Self-excited flow oscillation is produced by aerodynamic instability in fixed-wall cavities. The return flow in the exit nozzles is generated by jet-pumping effect. Elimination of the delicate and easily damaged moving parts in the actuator simplifies its manufacture and assembly. Operating frequency is adjusted by the length of feedback loop path. Laboratory investigations concentrated on the propagation processes taking place in the loop

Spectral proper orthogonal decomposition

The identification of coherent structures from experimental or numerical data is an essential task when conducting research in fluid dynamics. This typically involves the construction of an empirical mode base that appropriately captures the dominant flow structures. The most prominent candidates are the energy-ranked proper orthogonal decomposition (POD) and the frequency ranked Fourier decomposition and dynamic mode decomposition (DMD). However, these methods fail when the relevant coherent structures occur at low energies or at multiple frequencies, which is often the case. To overcome the deficit of these "rigid" approaches, we propose a new method termed Spectral Proper Orthogonal Decomposition (SPOD). It is based on classical POD and it can be applied to spatially and temporally resolved data. The new method involves an additional temporal constraint that enables a clear separation of phenomena that occur at multiple frequencies and energies. SPOD allows for a continuous shifting from the energetically optimal POD to the spectrally pure Fourier decomposition by changing a single parameter. In this article, SPOD is motivated from phenomenological considerations of the POD autocorrelation matrix and justified from dynamical system theory. The new method is further applied to three sets of PIV measurements of flows from very different engineering problems. We consider the flow of a swirl-stabilized combustor, the wake of an airfoil with a Gurney flap, and the flow field of the sweeping jet behind a fluidic oscillator. For these examples, the commonly used methods fail to assign the relevant coherent structures to single modes. The SPOD, however, achieves a proper separation of spatially and temporally coherent structures, which are either hidden in stochastic turbulent fluctuations or spread over a wide frequency range

Comparison of Hybrid Multi-dimensional Models of a Bi-Stable Load-Switched Supersonic Fluidic Oscillator Application

Fluidic oscillators are devices capable of superimposing large pressure and velocity fluctuations on the flow through a device without the necessity of having any moving parts. The lack of moving parts makes these devices superior to conventional moving-part valves in high temperature applications. The specific application of interest in the current study is the super-plastic forming (SPF) process in which large sheets of aluminum at very high temperature are formed into the desired shape by pressurizing one side inside the SPF chamber. It is known that the introduction of pressure fluctuations onto the increasing pressure in the SPF chamber reduces the chances of the metal tearing. The use of a Bi-Stable Load-Switched Supersonic Fluidic Oscillator to create the large pressure fluctuation amplitudes is ideal for this application. A numerical investigation of a Bi-Stable Load-Switched Supersonic Fluidic Oscillator is performed to understand the performance of the device under a variety of operating conditions consistent with this application. The commercial CFD code ANSYS Fluent 17.0 is used in the present work. The computational time and memory required to complete a full three-dimensional (3D) model of the device are excessive and hence simplifications are made. This research includes a comparison of the results obtained from two such simplifications. These models are used to monitor the volume average pressure and temperature changes inside the feedback tanks and exhaust chambers during the filling process. This information is used to determine the frequency and amplitude of the pressure oscillation as well as the operational conditions at which the oscillations begin and end. The numerical simulations are also validated by comparing them with experimental results

Active flow control methods for aerodynamic applications

The cylinder in cross flow has been the subject of many numerical and experimental studies since it provides a deep insight of the physical phenomena occurring in a wide range of flow regimes. Despite a number of investigations at Reynolds number (Re = 3900), there has been a constant debate on the important aspects of the flow such as spanwise resolutions, lateral domain extent, convergence of turbulent statistics in the near wake, the so called U-V streamwise velocity profiles at x = 1D, where D is the cylinder diameter, and the critical Re for the onset of shear layer instability together with its characterization. In this thesis, an attempt has been made to address some of these issues and report new results through Direct numerical simulations (DNS) by employing spanwise domain extents i.e. Lz = 1.5D; 2D; 2.5D; pD at the moderate flow regime i.e. Re = 2000, where boundary layer is still laminar while the near wake has gone fully turbulent. Intermittent bursts of shear layer instability have been spotted at this Re indicating the signs of the incipient laminar to turbulent transition in the separating shear layer. It is further confirmed that the secondary instability develops in the regions between the opposite sign large scale spanwise vortices and features a phase lag of 135 degree. Pseudo-Floquet analysis gives a good prediction of fastest growing mode consistent with the reported numerical and experimental measurements. In the second part of the thesis, active flow control (AFC) past circular cylinder has been thoroughly investigated with the aid of parametric analysis at the same Re. We applied spanwise-dependent fluidic actuation, both steady and time-dependent, on the flow past a circular cylinder at Re = 2000. The actuation takes place in two configurations: in-phase blowing and suction from the slits located at ±90 degree (top and bottom) with respect to the upstream stagnation point for both steady and time periodic actuation, and blowing and suction from the top and bottom slits traveling oppositely with respect to each other in the spanwise direction. Optimal forcing amplitude and wavelength are obtained by sweeping across the parametric space. Spanwise-dependent time-independent forcing with wavelength ¿z = 2D has been found the optimal one in terms of drag reduction and attenuation in lift fluctuations. The time-dependent forcing with sinusoids travelling oppositely with respect to each other along the span produced significant reduction in drag force and lift fluctuations, however, the in-phase time periodic actuation with forcing frequency four times the natural vortex shedding frequency resulted in significant increased drag and lift fluctuation, signalling to a potential candidate for the energy harvesting applications. Finally, in the last part of the thesis, time-dependence of flow inside novel laminar-fluidic-oscillator has been analyzed using DNS. Again, pseudoFloquet stability analysis has been utilized to predict the fastest growing Fourier modes along the homogeneous direction. Supplementary three-dimensional numerical study has also been conducted for the suitable cases at various Re. It has been found that steady flow inside fluidic oscillator’s cavity bifurcates from steady state to time-periodic state through supercritical Hopf bifurcation. The secondary transition inside fluidic oscillator’s cavity occurs through the breaking of flow symmetry about the cavity axis by pitchfork supercritical bifurcation.El cilindro en flujo cruzado ha sido objeto de muchos estudios numéricos y experimentales, ya que proporciona una visión profunda de los fenómenos físicos que ocurren en una amplia gama de regímenes. A pesar de una serie de investigaciones en el número de Reynolds (Re = 3900), ha habido un debate constante sobre los aspectos importantes del flujo, como las resoluciones en el span, la extensión del dominio lateral, la convergencia de estadísticas turbulentas en la estela cercana, el tipo de perfil (U o V) en la estela a x = 1D, donde D es el diámetro del cilindro, y el Re crítico para el inicio de la inestabilidad de la capa de cizalla y su caracterización. En esta tesis, se han intentado abordar algunos de estos problemas e informar nuevos resultados a través de simulaciones numéricas directas (DNS) mediante el uso de extensiones de dominio spanwise de Lz = 1.5D; 2D; 2.5D; pD en un régimen de flujo transicional a Re = 2000, donde la capa límite todavía es laminar mientras que la estela cercana se ha vuelto completamente turbulenta. A este Re h sido detectada inestabilidad intermitente, lo que indicando una transición incipiente laminar-turbulenta de la capa de cizalla. Se confirma además que la inestabilidad secundaria se desarrolla en las regiones entre los vórtices a gran escala del signo opuesto y presenta un desfase de 135 grados. El análisis de pseudo-Floquet da una buena predicción del modo de crecimiento más rápido consistente con las mediciones numéricas y experimentales reportadas. En la segunda parte de la tesis, el control de flujo activo (AFC) sobre el cilindro circular se ha investigado a fondo con la ayuda de análisis paramétrico al mismo Re. Aplicamos una actuación fluídica dependiente de la envergadura, tanto constante como dependiente del tiempo, en el flujo alrededor de un cilindro circular a Re = 2000. La actuación se realiza en dos configuraciones: soplado y succión en fase desde las ranuras ubicadas a ± 90 grados (arriba y abajo) con respecto al punto de estancamiento aguas arriba (tanto para la actuación periódica constante como dependiente del tiempo), y para el soplado y la succión con dependencia temporal tal que viajan en sentido opuesto a lo largo de las ranuras superior e inferior. La amplitud y la longitud de onda de forzado óptimas se obtienen barriendo el espacio paramétrico. Se ha encontrado que el forzado independiente del tiempo pero de amplitud variable en la envergadura con longitud de onda ¿z = 2D es el óptimo en términos de reducción de la resistencia y atenuación en las fluctuaciones de sustentación. El forzado dependiente del tiempo con sinusoides que viajan en sentido opuesto entre sí a lo largo del tramo produce una reducción significativa en la fuerza de resistencia aerodinámica y la fluctuación de la sustentación, sin embargo, la actuación periódica en el tiempo en fase con una frecuencia de forzado cuatro veces mayor que la frecuencia natura de desprendimiento de vórtices resultó en un aumento significativo de la resistencia y fluctuaciones de sustentación, lo cual lo coloca como potencial candidato para aplicaciones de recolección de energía. Finalmente, en la última parte de la tesis, la dependencia temporal del flujo dentro de un nuevo oscilador fluídico laminar se ha analizado utilizando DNS. Nuevamente, el análisis de estabilidad pseudoFloquet se ha utilizado para predecir los modos de Fourier de más rápido crecimiento en la dirección homogénea. También se ha realizado un estudio numérico tridimensional suplementario para varios de los Re considerados. Se ha encontrado que el flujo constante dentro de la cavidad del oscilador fluídico bifurca del estado estacionario al estado periódico en el tiempo mediante una bifurcación supercrítica de Hopf. La transición secundaria dentro de la cavidad del oscilador fluídico ocurre a través de la ruptura de la simetría del flujo en relación al eje de simetría de la cavidad por bifurcación supercrítica pitchfork

Etude et développement de micro-oscillateurs fluidiques pour le refroidissement de systèmes électroniques embarqués

Dans le domaine aéronautique, les contraintes sur le refroidissement sont multiples. L'efficacité d'un système de refroidissement ne se résume plus au simple taux de chaleur dissipée, mais englobe d'autres facteurs comme la compacité, le poids, la robustesse, le coût de maintenance ainsi que la durabilité. Une conception du système de refroidissement qui intègre ces aspects pourrait diminuer les coûts de fonctionnement, notamment la consommation de kérosène, et donc réduire l'impact environnemental du vol. La multiplication de systèmes embarqués dans l'aéronautique amène des contraintes supplémentaires pour leur refroidissement. Dans ce contexte, les actionneurs fluidiques présentent un fort potentiel. Ces travaux portent plus précisément, sur l'utilisation de jets pulsés produits par des oscillateurs fluidiques pour refroidir une surface chauffée. Plusieurs travaux sur les jets d'impact ont montré qu'il était possible d'améliorer la dissipation thermique en introduisant des pulsations dans l'écoulement. Il manque cependant un consensus dans la littérature autour de l'ensemble des conditions opératoires propices à l'amélioration des performances. D'où la nécessité de mener une étude sur l'écoulement produit par ces dispositifs fluidiques et le refroidissement qui en résulte. En amont de cela, il est nécessaire de se pencher sur l'effet de certains paramètres liés à la géométrie du l'oscillateur sur son mode de fonctionnement, en commençant par la caractérisation de l'écoulement pulsé produit par l'oscillateur. AK cette fin, un prototype d'oscillateur est réalisé en fabrication additive puis caractérisé via une reconstruction spatiale 2D et 3D du champ de vitesse à l'aide d'un seul fil-chaud et d'une sonde de pression placée au niveau des canaux de retours. Cette méthode de mesure nous permet de mettre en évidence des structures cohérentes et suivre leur évolution. En marge de cette étude, un réseau de neurones artificiels profond, ayant des fonctions d'activations sinusoïdales atypiques, est utilisé pour créer une représentation implicite du champ de vitesse. L'oscillateur ainsi caractérisé a alors été utilisé pour refroidir une plaque en verre chauffé. Des tests sont pratiqués sur des jets stationnaires et des jets pulsés de même débit massique moyen. Une amélioration considérable des performances est observée pour des faibles distances d'impact et des hautes fréquences de pulsation. Des simulations numériques sont ensuite réalisées en utilisant des méthodes statistiques en un point (dites RANS) et des modèles hybrides LES/RANS. En vue de concevoir un système de refroidissement compact et capable de cibler des composants de tailles submillimétriques, des versions micrométriques de ces mêmes oscillateurs ont été conçues et fabriquées ainsi qu'une instrumentation électronique à même de les caractériser. Rares sont les études menées sur les microjets d'impact alors qu'aucune étude n'a pu être recensée à ce jour sur les microjets d'impact pulsés ni sur les micro-oscillateurs fluidiques gazeux. Le défi est donc double : de montrer que les micro-oscillateurs à gaz peuvent fonctionner à cette échelle et de les utiliser pour refroidir des composants dissipateurs de chaleur. À cela vient s'ajouter un problème non moins ambitieux, celui d'instrumenter l'oscillateur ainsi que la surface d'impact chauffée. Étant donné que la fréquence d'oscillation à cette échelle-là se mesure en kilohertz et que les fluctuations de température sont relativement faibles, des capteurs thermiques à base de couches de polysilicium fortement dopé ont donc été produits. Bien que leur haute sensibilité thermique ait été déjà démontrée, il est question ici d'améliorer leur temps de réponse. Pour ce faire, les capteurs ont été partiellement désolidarisés du substrat en silicium. Cette amélioration de la dynamique du capteur a été obtenue au prix d'une structure fragilisée qu'il a fallu prendre en compte dans les étapes technologiques suivantes.Thermal management in the aerospace industry is subject to a number of constraints. The suitability of a cooling system does not only depend on the heat flux that it can evacuate, but also includes such aspects as compactness, weight, sturdiness, cost of maintenance and durability. Taking these factors into consideration contributes to reducing fuel consumption, thus reducing the carbon footprint of the airplane. With this in mind, fluidic actuators were developed for electronics cooling applications on-board airplanes. In other words, the aim is to cool heated surfaces using the periodic unsteady flow produced by no-moving-parts fluidic oscillators. Previous studies had shown the possibility of enhancing jet impingement heat transfer by introducing a periodic perturbation in the flow. Nevertheless, the exact experimental conditions that lead to this improvement remain somewhat inconsistent across different studies. For this reason, this study tackles both the flow features of the pulsed impinging jet as well as their effects on heat transfer. In preparation, the oscillator is characterized by assessing its response to changes in design parameters and experimental conditions. This was followed by a two- and three-dimensional reconstructions of the velocity field outside the device using a hot-wire and a pressure transducer mounted onto one of the feedback loops. Using this technique, it was possible to deduce certain flow characteristics as well as detect and track the evolution of large coherent vortices produced by the pulsed jet. The data from these exhaustive measurements was then used to train a deep neural network that uses sinusoidal activation functions. The result is an implicit representation of the flow that could be useful to designers when the oscillator is only part of a larger system. The oscillators were then used to cool a heated plate whose temperature was measured using an infrared camera. Both steady and pulsed jets were studied for a large range of frequencies, impact distances and flow rates. Remarkable enhancement was observed for small impact distances and high frequencies. Simulations where then performed using both RANS and hybrid LES/RANS approaches. In the second part of this work, a miniaturized version of the oscillator was produced that can efficiently target small electronic components. Impinging microjets have rarely been studied, while little to no works could be found on pulsed microjets of air or no-moving-parts microfluidic oscillators. The goal of the present study is then twofold, to prove that functional microfluidic oscillators with air as working fluid can be produced and that they can efficiently cool a heated surface. From an experimental standpoint, this requires proper instrumentation capable of acquiring measurements at the spatial and temporal scales of the system. For this end, high-sensitivity thermal sensors were implemented inside the microfluidic device as well as on the heated target surface. The current iteration of these sensing elements involves partially suspending them over the substrate on which they were built in order to reduce their thermal inertia. The carefully suspended structures were shown to withstand the subsequent fabrication steps despite undergoing high temperatures and pressures

Process development using oscillatory baffled mesoreactors

PhD ThesisThe mesoscale oscillatory baffled reactor (meso-OBR) is a flow chemistry platform whose niche is the ability to convert long residence time batch processes to continuous processes. This reactor can rapidly screen reaction kinetics or optimise a reaction in flow with minimal waste. In this work, several areas were identified that could be addressed to broaden the applicability of this platform. Four main research themes were subsequently formulated and explored: (I) development of deeper understanding of the fluid mechanics in meso-OBRs, (II) development of a new hybrid heat pipe meso-OBR for improved thermal management, (III) further improvement of continuous screening using meso-OBRs by removing the solvent and employing better experiment design methodologies, and (IV) exploration of 3D printing for rapid reactor development. I. The flow structures in a meso-OBR containing different helical baffle geometries were studied using computational fluid dynamics simulations, validated by particle image velocimetry (PIV) experiments for the first time. It was demonstrated, using new quantification methods for the meso-OBR, that when using helical baffles swirling is responsible for providing a wider operating window for plug flow than other baffle designs. Further, a new flow regime resembling a Taylor-Couette flow was discovered that further improved the plug flow response. This new double vortex regime could conceivably improve multiphase mixing and enable flow measurements (e.g. using thermocouples inside the reactor) to be conducted without degrading the mixing condition. This work also provides a new framework for validating simulated OBR flows using PIV, by quantitatively comparing turbulent flow features instead of qualitatively comparing average velocity fields. II. A new hybrid heat pipe meso-OBR (HPOBR) was prototyped to provide better thermal control of the meso-OBR by exploiting the rapid and isothermal properties of the heat pipe. This new HPOBR was compared with a jacketed meso-OBR (JOBR) for the thermal control of an exothermic imination reaction conducted without a solvent. Without a solvent or thermal control scheme, this reaction exceeded the boiling point of one of the reactants. A central composite experiment design explored the effects of reactant net flow rate, oscillation intensity and cooling capacity on the thermal and chemical response of the reaction. The HPOBR was able to passively control the temperature below the boiling point of the reactant at all conditions through heat spreading. Overall, a combined 260-fold improvement in throughput was demonstrated compared to a reactor requiring the use of a solvent. Thus, this ii wholly new reactor design provides a new approach to achieving green chemistry that could be theoretically easily adapted to other reactions. III. Analysis of in situ Fourier transform infrared (FTIR) spectroscopic data also suggested that the reaction kinetics of this solventless imination case study could be screened for the first time using the HPOBR and JOBR. This was tested by applying flow-screening protocols that adjusted the reactant molar ratio, residence time, and temperature in a single flow experiment. Both reactor configurations were able to screen the Arrhenius kinetics parameters (pre-exponential factors, activation energies, and equilibrium constants) of both steps of the imination reaction. By defining experiment conditions using design of experiments (DoE) methodologies, a theoretical 70+% reduction in material usage/time requirement for screening was achieved compared to the previous state-of-the-art screening using meso-OBRs in the literature. Additionally, it was discovered that thermal effects on the reaction could be inferred by changing other operating conditions such as molar ratio and residence time. This further simplifies the screening protocols by eliminating the need for active temperature control strategies (such as a jacket). IV. Finally, potential application areas for further development of the meso-OBR platform using 3D printing were devised. These areas conformed to different “hierarchies” of complexity, from new baffle structures (simplest) to entirely new methods for achieving mixing (most complex). This latter option was adopted as a case study, where the passively generated pulsatile flows of fluidic oscillators were tested for the first time as a means for improving plug flow. Improved plug flow behaviour was indeed demonstrated in three different standard reactor geometries (plain, baffled and coiled tubes), where it could be inferred that axial dispersion was decoupled from the secondary flows in an analogous manner to the OBR. The results indicate that these devices could be the basis for a new flow chemistry platform that requires no moving parts, which would be appealing for various industrial applications. It is concluded that, for the meso-OBR platform to remain relevant in the next era of tailor-made reactors (with rapid uptake of 3D printing), the identified areas where 3D printing could benefit the meso-OBR should be further explored

Numerical study of fluidic oscillators with compressible flow

Se estudiará el fllujo en el interior de osciladores fluídicos mediante el uso de un código abierto de Mecánica de Fluidos Computacional, prestando especial atención al comportamiento con flujo compresible.1. Documentación y estudio del estado del arte. 2. Aprendizaje de los conceptos básicos de la Mecánica de Fluidos Computacional. 3. Aprendizaje del software OpenFOAM. 4. Mallado del oscilador fluídico de referencia. 5. Lanzamiento de las simulaciones. 7. Extracción y análisis de resultados, comparándolos con los resultados obtenidos en simulaciones con flujo incompresible. 8. Conclusiones

Computational analysis of sweeping jet actuator using dynamic mode decomposition

A sweeping jet actuator (SJA) is a self-sustaining, periodically oscillating device without involving any moving parts. SJA requires only pressurized fluid at the inlet to transfer momentum via the Coanda effect. As an active flow control device, SJA is a reliable option for suppressing aerodynamic flow separation. SJAs are integrated into series which eject bi-stable harmonic oscillation to suppress the separation bubble created downstream of the aerodynamic components. In this thesis, we analyzed the geometric variations of the SJA to combine with aerodynamic wings, and stabilizers using computational fluid dynamics (CFD). Based on high-fidelity CFD data, we further developed a reduced order model (ROM) using dynamic mode decomposition (DMD). The ROM solutions have been demonstrated to be successful in decreasing computational costs greatly with negligible loss in physical accuracy and therefore a proven alternative to existing methodologies for cost reduction. DMD algorithm provides the output of the SJA device that can be utilized as a boundary condition to decrease the numerical burden of simulating micro-scale structure in macro-scale models

Fluidic Nozzles for Automotive Washer Systems: Computational Fluid Dynamics and Experimental Analysis

One of the main goals of this project was to cultivate an understanding of fluidic nozzle geometries and characteristic flow. Through this knowledge, three new fluidic nozzle concepts were developed to be used as components in several windscreen washer systems for an automotive part supplier, Kautex Textron CVS Ltd.Accurate and conclusive visualisation of flow through fluidic nozzles was vital in understanding how they can be best utilised for different applications. Over the past century, the specific needs of automotive cleaning systems have greatly developed with new technological discoveries, these advances allow the driver further knowledge of their surroundings. These specialised systems each require a different type of maintenance and cleaning system depending on their usage and the different size and shape of the vehicle. By completing this project, it is hoped to allow manufacturers to accurately identify what sort of fluidic nozzles are best for windscreen cleaning systems for a vehicle and how to design a nozzle to suit their specification. Fluidic nozzles have been researched experimentally and computationally to ensure an accurate comparison of results. By guaranteeing a precise comparison it will negate the need for high volume testing of nozzles in experimental situations, greatly reducing time and resources required to analyse a fluidic nozzle.The fluidic nozzles that are investigated and developed in this project were modelled and examined both experimentally and computationally, this ensured valid and accurate results were achieved by both the computational modelling and experimental testing. The development of the nozzles within this project was conducted using several experimental and computational setups to analyse the spray distribution, angle and oscillatory frequency amongst other parameters significant to the nozzle usage on a vehicle. Through this it was possible to tailor nozzle dimensions to allow for a streamlined design approach, this increased efficiency in fluidic nozzle development for any specification given by a vehicle manufacturing company customer. In addition to this the water flow emitted from the outlet was experimentally tested and modelled with both stationary and high surrounding velocities to examine how external variables affect the flow of the water from the nozzle.iiiThis project has been useful in the design manufacturing process of fluidic nozzles, by utilising computational modelling it has allowed a faster and cheaper method of analysing the effect of design alterations to fluidic nozzles. There is a greatly reduced frequency required for rapid prototyping of an array of fluidic chips with minimal dimensional differences to be used in the experimental stages of design, as once the inlet boundary conditions are established the nozzle can be redesigned completely within reason without the need for additional material wastage. This ensures a more easy and precise method of testing the manufacturing tolerances of a fluidic nozzle with a target of reaching customer specifications are always achieved.Three nozzles were aimed developed to satisfy conditions set by the customers, the vehicle manufacturers at which the new nozzle designs are aimed at are Honda, Nissan and Toyota. The nozzles to be established were designed for use on windscreen washer systems with a varying number of nozzles and with diverse windscreen sizes for different vehicles, resulting in a wide variety of specifications that must be met for each vehicle manufacturer. This meant that a single nozzle could not be utilised for all vehicles, instead a base model of fluidic chip was developed for the Nissan vehicle which was then dimensionally changed to suit the other vehicles.Throughout this project there were design specifications changes and ambiguities from the automotive company customers, leading to redesigns of the fluidic chips designed in this project. This means that although only two of the three fluidic nozzle designs are successfully in production, a much greater understanding of the mechanics of the fluid flow within the fluidic nozzle was achieved