Download or read book DNS of Reacting Hypersonic Turbulent Boundary Layers written by M. Pino Martin and published by . This book was released on 1998 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book DNS and the LES Closure of Reacting Turbulence in Hypersonic Flows written by María del Pino Martín Aguirre and published by . This book was released on 1999 with total page 216 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book DNS of Hypersonic Turbulent Boundary Layers written by Junji Huang and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Understanding the physics of the pressure fluctuations induced by high-speed turbulent boundary layers (TBLs) is of major practical importance. The fluctuating pressure on aerodynamic surfaces of flight vehicles determines the vibrational loading of the vehicles and often leads to damaging effects as fatigue and flutter. The freestream pressure fluctuations radiated from the tunnel-wall TBLs are responsible for the genesis of freestream acoustic noise in conventional (i.e., noisy) supersonic and hypersonic wind tunnels. In this manuscript, wall and freestream pressure fluctuations induced by high-speed TBLs were characterized by direct numerical simulations (DNS). The DNS database covered a broad range of flow conditions (Mach number of $M_\infty = 2.5-14$, wall-to-recovery temperature ratio of $T_w/T_r = 0.18-1.0$, Reynolds number of $Re_\tau=450-1172$) and geometric configurations (flat plate, sharp circular cone, two dimensional channel, realistic wind-tunnel nozzle). The DNS overcame multiple experimental difficulties and provided access to wall and freestream pressure statistics that were difficulty to obtain otherwise, including the root-mean-square fluctuations and higher order moments (skewness and flatness) , probability density function , two-point correlation, convection speed, and coherence function. The study yielded useful insights into the physics of the boundary-layer-induced pressure field and provided critical assessment to reduced-order models such as the Corcos theory for modeling the wall pressure and the eddy-Mach-wave radiation theory for predicting the freestream acoustic pressure.

Download or read book DNS Studies of Transitional Hypersonic Reacting Flows Over 3 D Hypersonic Vehicles written by Xiaolin Zhong and published by . This book was released on 2003 with total page 56 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Viscous Hypersonic Flow written by William H. Dorrance and published by Courier Dover Publications. This book was released on 2017-05-22 with total page 353 pages. Available in PDF, EPUB and Kindle. Book excerpt: Designed for advanced undergraduate and graduate courses in modern boundary-layer theory, this frequently cited work offers a self-contained treatment of theories for treating laminar and turbulent boundary layers of reacting gas mixtures. 1962 edition.

Download or read book DNS and Linear Stability Analyses of Unsteady 3 D Hypersonic Wall Bounded Flows with Real Gas Effects written by and published by . This book was released on 2000 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The goal of this research project is to develop new advanced numerical methods and to perform DNS studies of transient hypersonic reacting flows over full 3-D maneuvering vehicles. The DNS tools and supporting theoretical approaches are used to gain new fundamental understanding of transition phenomena of 3-D chemically-reacting hypersonic boundary layers. In the three-year period, significant progress has been made in the DNS of hypersonic boundary-layer flow instabilities in the following areas: (1) receptivity of 3-D hypersonic flows over blunt elliptical cones, (2) nonlinear breakdown of 3-D Gortler vortices, and (3) reacting hypersonic flow receptivities and stabilities. We have also finished the development of linear stability codes for hypersonic flow and have started the work on developing new parallel implicit algorithms for DNS of reacting hypersonic flows. So far, we have developed new methodologies and have demonstrated the feasibility of our approach as a practical DNS tool to explore transient hypersonic reacting flow physics. The focus of future work is on the DNS studies of the hypersonic flow physics related to the hypersonic boundary layer transition, and to extend these DNS and theoretical studies to 3-D transient hypersonic flows with complex real-gas models and complex geometries, and the DNS of nonlinear breakdown and interactions of instability modes in hypersonic boundary layers.

Download or read book DNS Studies of Transitional Hypersonic Reacting Flows Over 3 D Hypersonic Vehicles written by and published by . This book was released on 2003 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The objectives of this research project are to develop CFD techniques and to conduct DNS studies of fundamental flow physics leading to boundary-layer instability and transition in hypersonic flows During the three-year period, we have conducted extensive DNS studies on the receptivity of a supersonic boundary layer over a blunt cone, and over both sharp and blunt leading edge; and on the receptivity of the Goertler vortices. DNS studies were also compared with Stetson's 1984 stability experiment on Mach 7.99 flow over a blunt cone. Our studies have led to new understanding of a number of hypersonic boundary layer receptivity mechanisms. Such understanding can lead to better tool for the prediction and control of high-speed boundary layer transition.

Download or read book Simulation of Turbulent Hypersonic Flows written by Graham V. Candler and published by . This book was released on 1997 with total page 70 pages. Available in PDF, EPUB and Kindle. Book excerpt: Direct numerical simulations of turbulent reacting flows were performed to study the interaction between chemical heat release and turbulent fluid motion. A portion of the energy released by exothermic reactions is placed in the compressible mode of turbulent kinetic energy, with very little energy disposed to the incompressible mode. This process results in a positive feedback mechanism, whereby temperature fluctuations are amplified by the chemical reactions. In the case of endothermic reactions, the feedback is negative, resulting in decreased turbulent motion. The results of the simulations were used to develop a model for temperature fluctuations under conditions typical of a hypersonic boundary layer. This model has been validated and is suitable for use in the large eddy simulation of hypersonic turbulent boundary layers.

Download or read book Direct Numerical Simulation and Linear Analysis of Stability of Nonequilibrium Hypersonic Boundary Layers written by Xiaolin Zhong and published by . This book was released on 1998 with total page 31 pages. Available in PDF, EPUB and Kindle. Book excerpt: The goal of this research project is to develop new advanced numerical methods and to perform direct numerical simulation (DNS) studies of transient hypersonic reacting flows over full 3-D maneuvering vehicles. The DNS tools and supporting theoretical approaches are used to gain new fundamental understanding of transition phenomena of 3-D chemically-reacting hypersonic boundary layers. Our research accomplishments in the report period can be classified into three areas. First, we have developed and validated new efficient and high-order accurate numerical methods for the DNS of 3-D hypersonic reacting boundary layers. The new methods include high-order semi-implicit Runge-Kutta schemes and new upwind high-order finite-difference shock-fitting schemes. These new methods were developed in order to overcome the difficulties associated with the DNS of hypersonic reacting flows with shock waves. Second, we have conducted extensive studies on the stability and receptivity phenomena of hypersonic boundary layers over blunt leading edges and elliptical cross-section blunt cones both by direct numerical simulation and by linear stability analyses. Third, the effects of using Burnett equations for rarefied hypersonic flow computations were investigated.

Download or read book Numerical Studies of Low Density Two Dimensional Hypersonic Flows by Using the Navier Stokes and Burnett Equations with Nonequilibrium Real Gas Effects written by and published by . This book was released on 1997 with total page 33 pages. Available in PDF, EPUB and Kindle. Book excerpt: The goal of this research is to study the laminar turbulent transition and other transient flow phenomena of 3-D chemically reacting hypersonic boundary layers by direct numerical simulation (DNS) and by linear stability analysis. The research in the report period was focused on developing new numerical methods for such studies and studying several fundamental transient hypersonic flow phenomena. First, several new efficient and high-order accurate numerical methods for DNS of 3-D hypersonic reacting boundary layers and for computing unsteady hypersonic flows with complex shock interactions were developed. These new methods were developed in order to overcome difficulties associated with the direct numerical simulation of hypersonic flows. Second, several studies on the stability phenomena of hypersonic boundary layers over blunt leading edges both by direct numerical simulation and by linear stability analyses were performed. Also completed were extensive numerical studies on real gas effects on a steady shock/boundary layer interaction and a self-sustained unsteady shock-shock interference heating flows. Third, the effects of using Burnett equations for rarefied hypersonic flow computations were investigated. With the completion of the bulk of work on the development of new numerical methods for complex hypersonic flow simulation, the DNS studies are currently being extended to 3-D hypersonic boundary layer transition over elliptic cross section cones.

Download or read book DNS of Hypersonic Boundary Layer Stability and Transition Using High Order Nonuniform Grid Schemes written by Xiaolin Zhong and published by . This book was released on 2001 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: High-order schemes are necessary for the DNS of stability and transition of hypersonic boundary layers because lower-order schemes do not have a sufficient accuracy level to compute small flow details. Currently, the main limiting factor in the application of high-order schemes is the numerical instability of high-order boundary closure schemes. In a previous AIAA paper (2001-0437), we presented a family of high-order nonuniform-grid finite-difference schemes with stable boundary closures for multi-dimensional flow simulations. In this paper, the high-order nominiform-grid schemes (up to 11th order) are applied to the numerical simulation of the receptivity of hypersonic boundary layers to freestream disturbances over a blunt leading edge. The stability and numerical accuracy of the new high-order nonuniform-grid schemes are evaluated for computing the nonlinear 2-D Navier-Stokes equations for hypersonic flow simulations.

Download or read book Hypersonic Shock Wave Turbulent Boundahb written by KNIGHT and published by IOP ebooks. This book was released on 2023-06-29 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides a comprehensive exposition of hypersonic turbulent boundary layers including the fundamental mathematical theory, structure of equilibrium boundary layers, and extensive surveys of Direct Numerical Simulation (DNS), Large Eddy Simulation (LES) and experiments.

Download or read book Analysis of the Three dimensional Compressible Turbulent Boundary Layer on a Sharp Cone at Incidence in Supersonic and Hypersonic Flow written by John C. Adams and published by . This book was released on 1972 with total page 98 pages. Available in PDF, EPUB and Kindle. Book excerpt: An analytical approach toward numerical calculation of the three-dimensional turbulent boundary layer on a sharp cone at incidence under supersonic and hypersonic flow conditions is presented. The theoretical model is based on implicit finite-difference integration of the governing three-dimensional turbulent boundary-layer equations in conjunction with a three-dimensional scalar eddy-viscosity model of turbulence. Comparison is made of present theory with detailed experimental measurements of the three-dimensional turbulent boundary-layer structure (velocity and temperature profiles), the surface streamline direction (obtained via an oil-flow technique) and surface heat-transfer rate.

Download or read book Recent Advances in DNS and LES written by Doyle Knight and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 516 pages. Available in PDF, EPUB and Kindle. Book excerpt: This collection of papers presents a broad range of topics in DNS and LES, from new developments in LES modeling to DNS and LES for supersonic and hypersonic boundary layers. The book provides an extensive view of the state of the art in the field.

Download or read book Understanding and Predicting Shockwave and Turbulent Boundary Layer Interactions written by M. Pino Martin and published by . This book was released on 2009 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt: Shockwave and turbulent boundary layer interactions produce intense localized pressure loads and heating rates that can have a dramatic influence on the drag and heating experienced by a high-speed vehicle, and can significantly impact fuel mixing and combustion in propulsion systems. The lack of standardized and traceable databases prevents the calibration of computational fluid dynamic models to accurately represent these critical flow phenomena. In this work we accomplished the development and validation against experiments at the same flow and boundary conditions of direct numerical simulations of shock and turbulent boundary layer interactions. We pioneered the development of a unique numerical capability that allows the accurate and detailed three-dimensional turbulence data at a reasonable turn-around time. In turn, parametric studies of fundamental flow physics are feasible, for the first time. By accurate, it is meant that the numerical uncertainty is within the experimental error.

Download or read book Linear and Nonlinear Processes in Hypersonic Boundary Layer Transition to Turbulence written by Kenneth Joseph Franko and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The design of vehicles which travel at hypersonic speeds is strongly determined by drag characteristics and heat transfer. A portion of this drag and heating is due to the boundary layer where viscosity and thermal conductivity are most important. The level of drag and heating depends on whether the boundary layer is laminar or turbulent with the latter leading to higher levels of drag and heating. In addition, as high speed boundary layers transition from laminar to turbulent flow, an overshoot of the heat transfer beyond that of turbulent flow has been observed in experiments. In low disturbance environments, transition to turbulence follows the path of receptivity, linear growth, nonlinear interaction, and finally breakdown to turbulence. The linear growth of disturbances can be determined by linear stability theory. An analysis of the predicted growth rates and integrated growth of linear disturbances for hypersonic boundary layers including thermal and chemical non-equilibrium is undertaken. The sensitivity to different chemical assumptions, transport models and thermal boundary conditions is investigated. A disturbance energy norm is proposed and its corresponding balance equation is derived. This energy norm is then to determine the effect of different terms of the linear stability equations and to compute transient growth for hypersonic laminar boundary layers. DNS (Direct Numerical Simulation) is used to simulate the nonlinear breakdown to turbulence for a variety of transition scenarios for both zero pressure gradient and adverse pressure gradient high-speed flat plate boundary layers in order to investigate the mechanism for the overshoot of heat transfer in transitional hypersonic boundary layers. The initial disturbances are excited through suction and blowing at the wall and their frequencies are chosen based on linear stability theory. Different transition mechanisms are investigated including a pair of oblique waves and 2D and 3D instabilities at higher frequencies which are unique to high speed boundary layers. Oblique breakdown shows a clear overshoot in heat transfer and skin friction and leads to a fully turbulent boundary layer. The alternative scenarios also lead to transition but further downstream and without large overshoots in heat transfer. A detailed analysis of the transitional and turbulent regions is undertaken.

Download or read book Examining A Hypersonic Turbulent Boundary Layer at Low Reynolds Number written by Michael Thomas Semper and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The purpose of the current study was to answer several questions related to hypersonic, low Reynolds number, turbulent boundary layers, of which available data related to turbulence quantities is scarce. To that end, a unique research facility was created, instrumentation was developed to acquire data in the challenging low Reynolds number (low density) domain, and meaningful data was collected and analyzed. The low Reynolds number nature of the boundary layer (Re_theta = 3700) allows for tangible DNS computations/validations using the current geometry and conditions. The boundary layer examined in this experiment resembled other, higher Reynolds number boundary layers, but also exhibited its own unique characteristics. The Van Driest equivalent velocity scaling method was found to perform well, and the log layer of the law of the wall plot matched expected theory. Noticeably absent from the data was an overlap region between the two layers, which suggests a different profile for the velocity profiles at these low Reynolds number, hypersonic conditions. The low density effects near the wall may be having an effect on the turbulence that modifies this region in a manner not currently anticipated. The Crocco-Busemann relation was found to provide satisfactory results under its general assumptions. When compared to available data, the Morkovin scaled velocity fluctuations fell almost an order of magnitude short. Currently, it is not known if this deficit is due to inadequacies with the Strong Reynolds Analogy, or the Morkovin scaling parameters. The trips seem to promote uniformity across the span of the model, and the data seems to generally be in agreement across the spanwise stations. However, additional information is needed to determine if two-dimensional simulations are sufficient for these boundary layers. When the turbulent boundary layer power spectra is analyzed, the result is found to follow the traditional power law. This result verifies that even at low Reynolds numbers, the length scales still follow the behavior described by Kolmogorov. Moving downstream of the trips, the peak RMS disturbance value grows in amplitude until it reaches a critical value. After this point, the peak begins to decrease in amplitude, but the affected region spreads throughout the boundary layer. Once the influenced region covers a significant portion of the boundary layer, transition occurs. The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/150983