Inlet total pressure non-uniformities in axial flow fans and compressors can contribute to the loss of component structural integrity through high cycle fatigue (HCF) induced by the excitation of blade vibratory modes. As previous research has shown total pressure distortion to be the dominant HCF driver in aero engines [Manwaring et al, 1997], an understanding of its transfer through, and impact on, subsequent turbomachine stages and engine components is an important topic for assessment. Since current modeling techniques allow for total pressure distortion magnitudes to be directly related to blade vibratory response, the prediction of downstream distortion patterns from an upstream measurement would allow for the inference of the vibratory response of downstream blade rows to an inlet total pressure distortion. Nonlinear Volterra theory can be used to model any periodic nonlinear system as an infinite sum of multidimensional convolution integrals. A semi-empirical model has been developed using this theory by assuming that a distortion waveform is a periodic signal that is being presented to a nonlinear system, the compressor being the system. The use of Volterra theory in nonlinear system modeling relies on the proper identification of the Volterra kernels, which make up the transfer function that defines the system's impulse response characteristics. Once the kernels of a system are properly identified, the system's response can be calculated for any arbitrary input. This model extracts these kernels from upstream and downstream total pressure distortion measurements of a transonic rotor of modern design. The resulting transfer function is then applied to predict distortion transfer at new operating points on the same rotor and compared with the measured data. The judicious choice of distortion measurement data allows predictions of the downstream distortion content based on a measured non-uniform inlet flow at conditions different from those at which the transfer function was derived. This allows for the determination of downstream total pressure distortion that has the potential to excite blade vibratory modes that could lead to HCF under operating conditions other than those at which the data was taken, such as varying inlet distortion patterns, mass flow settings, rotational speeds, and inlet geometry. This report presents the creation of a Volterra model in order to predict distortion transfer in axial flow fans and compressors. This model, in three variations, is applied to a variety of distortions and compressor operating conditions as measured in the ADLARF tests at the Compressor Research Facility. Predictions are compared with data from the test and final results are also compared with two previous studies conducted at Virginia Tech using the same experimental data. Using the Volterra model it is shown that, with appropriate limitations, distortion transfer can be predicted for flow conditions different from those used for calibration. The model is considered useful for both performance and HCF investigations. / Master of Science

The rising interest in fan performance in the presence of total pressure distortion, a topic of fundamental interest for integrated airframe/engine architectures, has led to increased research in ground based testing environments. Included in these studies is the generation of simulated total pressure distortion profiles using wire mesh screens. Although the inlet duct development of total pressure distortion patterns has been studied in a historical context when distortion effects on engine performance were first of interest, these were typically simplified experimental studies for low-speed flows. To aid in the understanding of total pressure distortion development approaching a transonic fan face, a series of experiments were conducted to detail the development of such a profile downstream of the screen plane in the absence and presence of fan effects. Presented is an extensive experimental set to detail (1) the evolution of a screen-generated total pressure distortion profile as it develops in a constant diameter inlet duct and (2) the effect that a single stage transonic fan has on the distortion development. Included is a detailed analysis of the distortion profile characteristics for increasing development length, and the behavioral changes of the profile when fan blockage is present near the screen plane. Recommendations are made regarding the placement of total pressure distortion screens relative to the fan face, and insights are given into the expected profile evolution. This work is a contributing part of an ongoing systematic investigation of fan performance when subjected to screen-generated total pressure inlet distortion. / Master of Science

Les balances manométriques sont utilisées en métrologie des pressions statiques.Des projets européens tel qu'Euromet 463 ont mis en évidence des écarts systématiques entreles mesures expérimentales et les calculs des paramètres nécessaires à la caractérisation desbalances de référence. La vitesse de chute du piston est l'un d'eux pourtant essentiel dans laprocédure d'étalonnage. L'objectif des travaux de thèse est l'ajustement des méthodesd'estimation de cette vitesse de chute. Cela permettra d'améliorer la caractérisation du jeuinterne de la balance, de déterminer plus précisément la section effective de ce jeu et parconséquent d'améliorer l'incertitude portant sur le coefficient de déformation, paramètre clé del'étalonnage par comparaison. Jusqu'à présent le modèle de calcul de l'écoulement du fluidedans la balance était quasi unidimensionnel. Il assimilait le jeu entre le piston et le cylindre àdeux parois parallèles. Dans cette étude, les équations de l'écoulement du flu ide sont modifiéespour évaluer l'influence du modèle dans un jeu annulaire. Les corrections dues à la vitesse dechute du piston sont également prises en compte. Les calculs des déformations des structuressont réalisés en utilisant la méthode des éléments finis. Les travaux expérimentaux portent surdes ensembles piston-cylindre 50, 200 et 1000 MPa du Laboratoire National de Métrologie etd'Essais (LNE). Une confrontation calcul-expérience est réalisée en prenant en compte lesparamètres de variabilités tels que la géométrie ou les propriétés du fluide. / The pressure balances are utilized in the metrology of the static pressure. TheEuropean project as "Euromet 463" has underlined the lack of agreement between experimentalmeasurements and calculations of the parameters necessary for the pressure balance. Thepiston fall rate is, in particular, an essential parameter in the calibration procedure. The aim ofthe thesis is the adjustment of methods for estimating the piston fall rate. This will improve thecharacterization of the gap, determine the effective area more precisely and consequentlyimprove the uncertainty on the pressure distortion coefficient, a key parameter for the calibrationby comparison. lndeed, the former quasi one-dimensional madel assimilates the gap betweenpiston and cylinder as formed by two parallel walls, which is an approximation. ln this study, theequations of the fluid flow are modified to evaluate the influence of the model in an annular gapmadel. ln addition, corrections due to the velocity of the piston wall are taken into account. Thisresearch work is applied on the piston-cylinder units 50, 200 and 1000 MPa of the Laboratoirenational de métrologie et d'essais (LNE). Taking into consideration the variability of parameterssuch as geometry or fluid properties, a comparison between the experiment and the calculationis carried out.

No description available.

This master thesis deals with design of a subsonic intake which is used to supply small jet engine integrate into the fuselage of agile small unmanned aerial vehicle (UAV). Some kinds of these intakes are listed in order to inspire and introduce future designers into this part of jet plane design. This thesis contains a small amount of theory about compressible flow, and necessary knowledge which are important to know before the very first attempt to design an intake. Two models were designed in order to prove that the theory listed in this thesis is useful and can be used as a guide in design process of subsonic intakes. Both designs have the same layout. S-duct design with one intake placed on the belly of fuselage was chosen. After CFD analysis of first model it was found that there are huge area with separated flow and vortex. Separated flow leads to big total pressure loss and pressure distortion. While designing the second model the emphasis was to avoid this vortex and improve flow conditions. This optimization was success and the second design have smaller pressure loss in compare to the first design. The difference is more than 50% at fly speed M=0,8.

<p>The purpose of this research was to determine what components of a complex centrifugal  compression system inlet needed to be modelled to accurately predict the swirl and total pressure  distortions at the compressor face. Two computational models were developed. A full-fidelity case  where all the inlet geometry was modelled and a reduced model where a small portion of the inlet  was considered. Both the numerical cases were compared with experimental data from a research  compressor rig developed by Honeywell Aerospace. The test apparatus was designed with a  modular inlet system to develop swirl distortion patterns. The modular inlet system utilized  transposable baffles within the radial-to-axial section of the inlet and blockage plates of varying  sizes and geometries at the inlet to this section.  Discerning the dominant inlet component that dictates distortion behavior at the compressor  face would allow the reduced modelling of inlet components for compression systems and would  allow coupling with more tortuous systems. Furthermore, it would reduce the design iteration and  simulation time of the inlet systems. Several investigations utilizing a reduced model only  considering a radial-to-axial inlet are available in literature, but no comprehensive justification has  been presented as to the impact this has on the distortion behavior.   Experimental surveys of flow conditions just upstream of the inducer of the centrifugal  compressor were conducted at several operating conditions. The highest and lowest mass flow  rates of these operating points were simulated using ANSYS CFX 2020R1 for both the  computational models. Multiple inlet configurations were simulated to test the robustness of the  reduced model in comparison to the full fidelity. The numerical simulations highlighted  shortcomings of the instrumentation used to characterize the experimental flow field at the inducer,  particularly with respect to total pressure distortion. Furthermore, transient pressure data were  measured in experiment and indicated unsteady fluctuations in the inlet that would not be captured  by steady computational fluid dynamic simulations. These data matched locations of disagreement  with swirl distortion behavior at high mass flow rates. This suggested that transient vortex  movement occured at the aerodynamic interface plane in certain configurations.   The total pressure distortion metrics between the two models were remarkably comparable.  Furthermore, the simplified model accurately predicted the mixing losses associated with the  blockage plates at the inlet to the radial-to-axial inlet using a simple inlet extension. Swirl  18  distortion was dictated by the radial-to-axial inlet. The reduced model data trends were comparable  with experiment for both the baffle and blocker plate configurations. The swirl intensities for all  configurations were comparable between the two models. The reduced model swirl directivity  trends matched those of experiment. The most notable deviations between the full-fidelity model  and the reduced model were observed with swirl directivity numerics. </p>

Efficient analysis and storage of data is an integral but often challenging task when working with computation fluid dynamics mainly due to the amount of data it can output. Methods centered around the proper orthogonal decomposition were used to analyze, compress, and model various simulation cases. Two different high-fidelity, time-accurate turbomachinery simulations were investigated to show various applications of the analysis techniques. The first turbomachinery example was used to illustrate the extraction of turbulent coherent structures such as traversing shocks, vortex shedding, and wake variation from deswirler and rotor blade passages. Using only the most dominant modes, flow fields were reconstructed and analyzed for error. The reconstructions reproduced the general dynamics within the flow well, but failed to fully resolve shock fronts and smaller vortices. By decomposing the domain into smaller, independent pieces, reconstruction error was reduced by up to 63 percent. A new method of data compression that combined an image compression algorithm and the proper orthogonal decomposition was used to store the reconstructions of the flow field, increasing data compression ratios by a factor of 40.The second turbomachinery simulation studied was a three-stage fan with inlet total pressure distortion. Both the snapshot and repeating geometry methods were used to characterize structures of static pressure fluctuation within the blade passages of the third rotor blade row. Modal coefficients filtered by frequencies relating to the inlet distortion pattern were used to produce reconstructions of the pressure field solely dependent on the inlet boundary condition. A hybrid proper orthogonal decomposition method was proposed to limit burdens on computational resources while providing high temporal resolution analysis.Parametric reduced order models were created from large databases of transient and steady conjugate heat transfer and airfoil simulations. Performance of the models were found to depend heavily on the range of the parameters varied as well as the number of simulations used to traverse that range. The heat transfer models gave excellent predictions for temperature profiles in heated solids for ambitious parameter ranges. Model development for the airfoil case showed that accuracy was highly dependent on modal truncation. The flow fields were predicted very well, especially outside the boundary layer region of the flow.