Verification Of Numerical Method Research Articles

Powder fuel transport process and mixing characteristics in cavity-based supersonic combustor with different injection schemes

The transport process and mixing characteristics of powder fuel in the supersonic airflow are essential for the working performance of a powder fueled scramjet. In the current investigation, the effect of different injection schemes on the powder fuel jet flow field and mixing characteristics are numerically studied in the cavity-based supersonic combustion chamber. The simulation is employed by the Eulerian-Lagrangian scheme coupling with the gas-solid two-phase Reynolds-average Navier-Stokes (RANS) method. Verification of numerical method and grid-independent is conducted firstly, which demonstrated the correctness and credibility of the method in this research. The results show that the powder fuel injection into the combustor induces typical gas-solid two-phase jet flow characteristics. With respect to the fuel injection schemes upstream of the cavity, the powder fuel moves across the cavity section and is continuously mixed with the mainstream along the flow direction. The mixing intensity in the combustion chamber is associated with the motion and distribution patterns of the particles. For the cavity internal fuel injection scheme, the particles are mainly distributed inside the cavity. Some of the particles can be coiled and sucked into the supersonic mainstream. The cavity shear layer and expansion section near the bottom wall is the main region with better mixing performance.

Rayleigh--Bénard convection in strong vertical magnetic field: flow structure and verification of numerical method

Direct numerical simulations are performed to study turbulent Rayleigh-Benard convection in a vertical cylindrical cavity with uniform axial magnetic field. Flows at high Hartmann and Rayleigh numbers are considered. The calculations reveal that, similarly to the behavior observed in Rayleigh-Benard convection with strong rotation, flows at strong magnetic field develop a central vortex, while the heat transfer is suppressed.

A study of performance parameters on drag and heat flux reduction efficiency of combinational novel cavity and opposing jet concept in hypersonic flows

The drag reduction and thermal protection system applied to hypersonic re-entry vehicles have attracted an increasing attention, and several novel concepts have been proposed by researchers. In the current study, the influences of performance parameters on drag and heat reduction efficiency of combinational novel cavity and opposing jet concept has been investigated numerically. The Reynolds-average Navier-Stokes (RANS) equations coupled with the SST k-ω turbulence model have been employed to calculate its surrounding flowfields, and the first-order spatially accurate upwind scheme appears to be more suitable for three-dimensional flowfields after grid independent analysis. Different cases of performance parameters, namely jet operating conditions, freestream angle of attack and physical dimensions, are simulated based on the verification of numerical method, and the effects on shock stand-off distance, drag force coefficient, surface pressure and heat flux distributions have been analyzed. This is the basic study for drag reduction and thermal protection by multi-objective optimization of the combinational novel cavity and opposing jet concept in hypersonic flows in the future.

Modal Analysis as the Base of Dynamic Analysis

The article deals with the modal analysis as a tool for specification of natural frequencies and the mode shapes of the turning tool. This type of analysis is the first step that is necessary to do at the dynamic analysis of technical components. At the beginning, the verification of numerical method was realized in laboratory conditions, where the fixed beam substituted the turning tool. Vibrodiagnostics of the real cutting tool in the workshop and the modal analysis using FEM in the software PTC Creo followed. It can be said that the results of the numerical method based on FEM were comparable with the data achieved by means of experimental measurements. The work described in this paper can be considered as a foundation for the dynamic tool life analysis.

Computational aerodynamic analysis on perimeter reinforced (PR)-compliant wing

Implementing the morphing technique on a micro air vehicle (MAV) wing is a very challenging task, due to the MAV’s wing size limitation and the complex morphing mechanism. As a result, understanding aerodynamic characteristics and flow configurations, subject to wing structure deformation of a morphing wing MAV has remained obstructed. Thus, this paper presents the investigation of structural deformation, aerodynamics performance and flow formation on a proposed twist morphing MAV wing design named perimeter reinforced (PR)-compliant wing. The numerical simulation of two-way fluid structure interaction (FSI) investigation consist of a quasi-static aeroelastic structural analysis coupled with 3D incompressible Reynolds-averaged Navier–Stokes and shear-stress-transport (RANS–SST) solver utilized throughout this study. Verification of numerical method on a rigid rectangular wing achieves a good correlation with available experimental results. A comparative aeroelastic study between PR-compliant to PR and rigid wing performance is organized to elucidate the morphing wing performances. Structural deformation results show that PR-compliant wing is able to alter the wing’s geometric twist characteristic, which has directly influenced both the overall aerodynamic performance and flow structure behavior. Despite the superior lift performance result, PR-compliant wing also suffers from massive drag penalty, which has consequently affected the wing efficiency in general. Based on vortices investigation, the results reveal the connection between these aerodynamic performances with vortices formation on PR-compliant wing.