Showing papers on "Supersonic speed published in 2021"
TL;DR: In this article, a computational method is applied to examine the impacts of coaxial hybrid air and fuel jets on fuel mixing at the supersonic cross-flow of Mach = 4.
67 citations
TL;DR: In this paper, the impact of step height on the jet features and circulation of jets in different sections of the combustor at downstream of the multi-injectors was analyzed.
65 citations
TL;DR: In this article, a trapezoidal strut was used to inject fuel jet into a coaxial supersonic air stream to augment fuel mixing and diffusion downstream by intensifying vortices inside the domain.
65 citations
TL;DR: In this article, a SST k − ω model is used to explore the mixing characteristics of a transverse jet injection into a supersonic airstream, and a novel shock generator is introduced and placed at different locations of the combustor.
49 citations
TL;DR: In this paper, a cleaner approach for removing CO2 and H2S from highly acid natural gas by supersonic separation technology was proposed, and the effects of nozzle structure, swirl angle of static vanes and inlet parameters on the refrigeration performance of the nozzle and the separation characteristics of the swirl device were systematically investigated.
43 citations
TL;DR: In this article, a semi-analytical method is proposed to determine the acoustic power, radiation efficiency, source location and far-field acoustic pressure of annular acoustic black holes (ABHs) shells and compare them with those of uniform thickness shells.
36 citations
TL;DR: In this paper, the flutter analysis of a rotating pre-twisted GPLRC blade under supersonic airflow is investigated, and the performance of the IMLS-Ritz method for this problem is validated by comprehensive convergence studies and careful comparison studies.
Abstract: In this study, the flutter analysis of a rotating pre-twisted functionally graded graphene nanoplatelets reinforced composite (FG GPLRC) blade under supersonic airflow is investigated. The pre-twisted blade is multi-layered and reinforced with graphene nanoplatelets (GPLs) evenly distributed in each layer while the GPL weight fraction changes from layer to layer through the thickness direction. The effective Young's modulus is determined by Halpin-Tsai micromechanical model while the Poisson's ratio and mass density are predicted by Voigt's rule for GPLRC layers. According to assumptions of the first-order shear deformation theory (FSDT), the first-order piston theory and shell theory, the dynamic model of rotating pre-twisted GPLRC blades subjected to supersonic flow is developed. Meshless the improved moving least-square Ritz method (IMLS-Ritz) is used to derive the discrete dynamic equations of rotating pre-twisted GPLRC blades under aerodynamic load. The accuracy of the IMLS-Ritz method for this problem is validated by comprehensive convergence studies and careful comparison studies. A detailed parameter investigation of the effects of GPL distribution configuration, rotation velocity and geometrical parameters on flutter behavior characteristics of GPLRC blades is systematically conducted.
36 citations
TL;DR: In this paper, a high order shear deformable computational framework is developed with inclusion of the trapezoidal shape factor to eliminate the errors introduced by the curvature of the panels and the standard Lagrange processing in conjunction with the Navier-solution technique, with the help of the first-order piston theory, is applied to derive the equations of motion related to the vibration and flutter characteristics of the cylindrical panel with simple-supported boundary condition.
34 citations
TL;DR: In this article, a hybrid Lattice Boltzmann Method (HLBM) is proposed for the simulation of both compressible subsonic and supersonic flows, which is an extension of the model of Feng et al.
34 citations
TL;DR: The flow and heat transfer characteristics of a film jet inclined to different supersonic situations with a varying Mach number of the main flow were numerically investigated to observe multi-interfacial layered structures caused by the film jet under the complicated effect of shock waves.
Abstract: The flow and heat transfer characteristics of a film jet inclined to different supersonic situations with a varying Mach number of the main flow were numerically investigated. In supersonic situations, complicated waves are generated by the obstacle of the film jet. In this work, extra pressure is exerted onto the film jet, causing better film attachment to the wall. The strengthening of attachment decreases mixing between the main flow and film jet, causing better film cooling. We observed multi-interfacial layered structures caused by the film jet under the complicated effect of shock waves. At the interfaces of the film jet and shock waves, additional pressure is exerted on the film towards the wall. The pressure increases as the Mach number of the main flow increases and contributes to the increased adhesion of the gas film, which causes the cooling enhancement under a supersonic condition. In the vicinity of the film hole exit, a local low pressure region is formed under the influence of the supersonic main flow. An aerodynamic convergent–divergent state was formed in the film hole, devastating the state of supersonic congestion of the film hole and further enhancing the film cooling effect.
33 citations
TL;DR: In this paper, the effect of wall transverse fuel injection system in addition with parallel fuel injection approach have been found suitable for stable flame and combustion performance for supersonic combustor observation.
TL;DR: In this article, the mean flowfield and mixing characteristics of free supersonic jets from twin and triple converging-diverging nozzles placed in close proximity are studied experimentally.
TL;DR: In this paper, the potential of clean natural gas dehydration using nonequilibrium condensations in high-pressure supersonic flows was evaluated using a computational fluid dynamics model to study the formation of massive nanodroplets due to the phase change process.
TL;DR: In this article, the effects of wedge shock generator on co-flow of air and hydrogen jet are studied by the computational method, and the main emphasis of this work is to disclose the structure of the fuel jet in presence of wedge shocks produced in the middle of the air and fuel injector.
TL;DR: Several verification and validation cases show the excellent performance of the proposed framework and set the stage for its deployment on more advanced applications.
Abstract: A stabilized finite element framework for high-speed compressible flows is presented. The Streamline-Upwind/Petrov–Galerkin formulation augmented with discontinuity-capturing (DC) are the main constituents of the framework that enable accurate, efficient, and stable simulations in this flow regime. Full- and reduced-energy formulations are employed for this class of flow problems and their relative accuracy is assessed. In addition, a recently developed DC formulation is presented and is shown to be particularly well suited for hypersonic flows. Several verification and validation cases, ranging from 1D to 3D flows and supersonic to the hypersonic regimes, show the excellent performance of the proposed framework and set the stage for its deployment on more advanced applications.
TL;DR: In this paper, a comprehensive review of all relevant experimental data was completed, including recent data for the drag coefficient for a sphere in supersonic and hypersonic flows, and the primary characterization was performed.
Abstract: A comprehensive review of all relevant experimental data was completed, including recent data for the drag coefficient for a sphere in supersonic and hypersonic flows. The primary characterization ...
TL;DR: In this paper, the influence of a primary nozzle on steam ejector performance considering phase change processes is analyzed and validated in detail against experimental data of supersonic nozzles and steam ejectors available in the literature.
TL;DR: In this article, different series of micro vortex generators were investigated as a passive control method (with the ability to increase the flow momentum), affecting the structure of a compressible flow at the Mach number of 2.05 in a low-aspect-ratio duct.
TL;DR: In this article, the needle jet propagates at supersonic speed through the gas phase toward the solid and reaches average velocities of more than 850 ms−1 and thus is an order of magnitude faster than the regular jets that have frequently been observed in cavitation bubbles.
Abstract: Collapsing cavitation bubbles produce intense microscopic flows Here, in an aqueous environment, we seed single laser-induced bubbles (diameter about one millimeter) in proximity to a solid surface, in a regime that has not been well explored before in order to generate a “needle jet” The needle jet propagates at supersonic speed through the gas phase toward the solid It reaches average velocities of more than 850 ms−1 and thus is an order of magnitude faster than the regular jets that have frequently been observed in cavitation bubbles The dynamics leading to the needle jet formation are studied with high speed imaging at five million frames per second with femtosecond illumination This highly repeatable, localized flow phenomenon may be exploited for injection purposes or material processing, and it is expected to generate significantly larger water hammer pressures and may also play a role in cavitation erosion and peening
TL;DR: In this article, a unified analytical model is developed to investigate the nonlinear aeroelastic behaviors of a supersonic functionally graded piezoelectric material (FGPM) plate with general boundary conditions under electro-thermo-mechanical loads.
TL;DR: In this article, an innovative strut fuel injector with a wavy wall surface and double strut has been investigated for possible mixing enhancement of fuel and air in a scramjet engine.
TL;DR: In this article, the influence of the vacuum degree on the flow field around a train capsule running in an evacuated tube with circular section was numerically studied, revealing that lowering the nominal pressure can have a significantly beneficial effect on the aerodynamic performance of the train capsule.
TL;DR: In this paper, the authors present high-fidelity reacting simulations of a supersonic cavity flame-holder configuration, showing that fuel injection closer to the ramp at the aft end of the cavity allows for greater mixing and lower peak temperatures compared to fuel injection upstream that is closer to backward facing step.
TL;DR: In this paper, an innovative fuel injection strut has been designed to develop mixing enhancement by elevating multiple interactions between the shock wave and shear mixing layer, which leads to an increase in mixing enhancement.
TL;DR: In this article, the impact of the jet pressure ratio and length-to-diameter ratio (L / D ) on the flow field and the aerodynamic characteristics of a double-cone missile was investigated.
01 Jan 2021
TL;DR: In this paper, the combustion instabilities of supersonic combustion were investigated experimentally in a laboratory-scale scramjet combustor with a cavity flame holder, and the results indicated that two combustion instability were observed for cavity shear-layer stabilized combustion and the oscillation between jet-wake stabilized and cavity shearslayer ram combustions for the power spectral density of pressure.
Abstract: The combustion instabilities of supersonic combustion were investigated experimentally in a laboratory-scale scramjet combustor with a cavity flame holder. Ethylene was injected transversely from an orifice to the supersonic flow of Mach 2 with a stagnation temperature of 1900 K and a total pressure of 0.37 MPa. The dynamic pressure, CH* chemiluminescence and shadowgraph images were measured with a pressure sensor and a high-speed video camera. Dynamic pressure was analyzed by fast Fourier transform, and time-resolved CH* chemiluminescence images were modally decomposed by the sparsity-promoting dynamic mode decomposition (SP-DMD). The results indicated that two combustion instabilities were observed for cavity shear-layer stabilized combustion and the oscillation between jet-wake stabilized and cavity shear-layer ram combustions for the power spectral density (PSD) of pressure. In the case of the combustion instability of cavity shear-layer stabilized combustion, a dominant peak of approximately 128 Hz was observed for the PSD of pressure. This instability corresponded to an entire flame oscillation of the cavity shear-layer stabilized combustion, which was validated by the SP-DMD and a low rank reproduction with 10 modes. This was driven by a fuel injection oscillation in the injection orifice. In the case of oscillation between the jet-wake stabilized and the cavity shear-layer ram combustions, peaks around 1600 Hz were observed for the PSD of pressure. This mechanism was also explained by the SP-DMD modes and a low rank reproduction using within 10 modes. The DMD and shadowgraph images indicated that the vortex formed by a separation of the boundary layer induced a strong jet-wake flame, resulting in the temporal thermal choke followed by cavity shear-layer stabilized ram combustion. The data-driven approach with SP-DMD clarified the combustion instability mechanisms of the supersonic combustion in detail.
TL;DR: In this paper, the impinging shock of varying strengths on the free shear layer in a confined supersonic cavity flow is studied numerically using the detached-eddy simulation, and the resulting spatiotemporal variations are analyzed between the different cases using unsteady statistics, spectral analysis, and modal decomposition.
Abstract: The impinging shock of varying strengths on the free shear layer in a confined supersonic cavity flow is studied numerically using the detached-eddy simulation. The resulting spatiotemporal variations are analyzed between the different cases using unsteady statistics, $x-t$ diagrams, spectral analysis, and modal decomposition. A cavity of length to depth ratio $[L/D]=2$ at a freestream Mach number of $M_\infty = 1.71$ is considered to be in a confined passage. Impinging shock strength is controlled by changing the ramp angle ($\theta$) on the top-wall. The static pressure ratio across the impinging shock ($p_2/p_1$) is used to quantify the impinging shock strength. Five different impinging shock strengths are studied by changing the pressure ratio: $1.0,1.2,1.5,1.7$ and $2.0$. As the pressure ratio increases from 1.0 to 2.0, the cavity wall experiences a maximum pressure of 25% due to shock loading. At [$p_2/p_1]=1.5$, fundamental fluidic mode or Rossiter's frequency corresponding to $n=1$ mode vanishes whereas frequencies correspond to higher modes ($n=2$ and $4$) resonate. Wavefronts interaction from the longitudinal reflections inside the cavity with the transverse disturbances from the shock-shear layer interactions is identified to drive the strong resonant behavior. Due to Mach-reflections inside the confined passage at $[p_2/p_1]=2.0$, shock-cavity resonance is lost. Based on the present findings, an idea to use a shock-laden confined cavity flow in an enclosed supersonic wall-jet configuration as passive flow control or a fluidic device is also demonstrated.
TL;DR: In this article, the impinging shock of varying strengths on the free shear layer in a confined supersonic cavity flow is studied numerically using the detached eddy simulation, and the resulting spatiotemporal variations are analyzed between the different cases using unsteady statistics, x-t diagrams, spectral analysis, and modal decomposition.
Abstract: The impinging shock of varying strengths on the free shear layer in a confined supersonic cavity flow is studied numerically using the detached eddy simulation. The resulting spatiotemporal variations are analyzed between the different cases using unsteady statistics, x–t diagrams, spectral analysis, and modal decomposition. A cavity of length to depth ratio [ L / D ] = 2 at a freestream Mach number of M ∞ = 1.71 is considered to be in a confined passage. Impinging shock strength is controlled by changing the ramp angle (θ) on the top wall. The static-pressure ratio across the impinging shock ( p 2 / p 1) is used to quantify the impinging shock strength. Five different impinging shock strengths are studied by changing the pressure ratio: 1.0 , 1.2 , 1.5 , 1.7, and 2.0. As the pressure ratio increases from 1.0 to 2.0, the cavity wall experiences a maximum pressure of 25% due to shock loading. At [ p 2 / p 1 ] = 1.5, fundamental fluidic mode or Rossiter's frequency corresponding to n = 1 mode vanishes whereas frequencies correspond to higher modes (n = 2 and 4) resonate. Wavefronts interaction from the longitudinal reflections inside the cavity with the transverse disturbances from the shock-shear layer interactions is identified to drive the strong resonant behavior. Due to Mach reflections inside the confined passage at [ p 2 / p 1 ] = 2.0, shock-cavity resonance is lost. Based on the present findings, an idea to use a shock-laden confined cavity flow in an enclosed supersonic wall-jet configuration as passive flow control or a fluidic device is also demonstrated.
TL;DR: In this article, the mixing and distribution of multi hydrogen cross jets are investigated under the impacts of downstream sinusoidal wall, and the results indicate that the fuel distribution in the downstream is substantially limited by increasing the frequency of downstream wavy wall.