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The present work is to computationally analyze side loads in a thrust-optimized parabolic nozzle during high-altitude testing. The engine startup and shutdown processes of the Korean Space Launch V...

In this study, a numerical analysis of pogo instability in liquid propulsion rockets was conducted and an optimization of the pogo suppressor was attempted. Pogo analysis was carried out using nume...

Shape optimization of modern three-dimensional hypersonic inlets requires many geometric design parameters. Because the flow physics is complex, a Reynolds-averaged Navier–Stokes (RANS) analysis is...

This paper details the numerical investigations of bleed effects on supersonic inlet performance and buzz under various bleed conditions, including location, width, plenum static pressure, and inle...

Lateral thrust jets exhibit better maneuverability performance than control surfaces such as conventional fins for attitude control or the orbital transfer of guided weapons. In the supersonic region, however, jet interaction phenomena occur due to the lateral thrust jet during flight and a complicated flow structure is exhibited by the interaction of the shock wave, boundary layer flow, and vortex flow. In particular, hit-to-kill interceptors require precise control and maneuvering; therefore, it is necessary to analyze the effect of the jet interaction flow. A number of conventional jet interaction analyses have been performed under low-altitude conditions; however, there are not many cases with respect to medium-altitude conditions. Unlike low-altitude conditions, jet interaction flows at medium-altitude conditions have different flow characteristics. In this study, a jet interaction flow analysis is performed on a lateral thrust jet controlled interceptor operating at medium altitudes. Based on the results, the characteristics of the flow structure and the changes in the aerodynamic coefficients are analyzed.

Despite their simple formulations, advection upstream splitting method (AUSM)-type flux schemes treat linear and nonlinear waves of complex flow fields in a robust and accurate manner. This paper presents the progress of AUSM-type fluxes augmented with pressure-based weight functions introduced by the authors and their colleagues. Starting from a flux designed for single-phase gas dynamics (AUSMPW+), its extensions to capture multi-phase flow physics with phase transition (AUSMPW+_N) have been carried out. The accuracy of the computed results by the AUSMPW+_N scheme for multi-phase flows is then further improved by introducing a simple phase interface-sharpening procedure, which scales the volume fraction in a mass-conserving manner. Various all-speed compressible tests ranging from interactions between a shock and phase interfaces, two- and three-dimensional interface-only problems, to a cryogenic three-component flow with phase change are computed to demonstrate the effectiveness of the proposed method.

‘e-Science’ represents the global collaborations of people and shared resources to solve new and challenging problems in science and engineering (Hey & Trefethen, 2003) on the basis of the IT infrastructure, typically referred to as the Grid (Foster & Kesselman, 1999). As we can easily infer, e-Science initially meant a virtual environment where a new and challengeable research can be accomplished using latest infrastructures. That virtual environment usually has a form of a web portal page or an independent application with a bunch of computer scientific components inside: high-end application researches include large-scale computations for complex multi-physical mechanisms, coupled works of computation and experiments for design-to-development processes, and/or data-intensive researches. The infrastructure consists of computational and experimental facilities, valuable datasets, knowledge, and so on. Researchers can be referred to as a core component of e-Science environment as their discussions and collaborations are promoted by, managed by and integrated to the environment. Meanwhile, the meaning of ‘e-Science’ is becoming broader nowadays. Though e-Science first intended to enrich high-end research activities, it is soon proven to be also effective on academic activities as a cyber education system. (On the other hand, use on inter-disciplinary collaborative researches is not much vitalized as expected, because of diverse preference on internal workflow, I/O and interface among research domains.) Thus, the term ‘e-Science’ is rather used to represent ‘all scientific activities on high performance computing and experimental facilities with the aid of user-friendly interface and system middleware’ these days. As a virtual academic system for aerospace engineering, ‘e-AIRS’ (e-Science Aerospace Integrated Research System) has been designed and developed since 2005. After three years’ development, e-AIRS educational system is finally open, where non-experts can intuitively conduct the full process of computational and experimental fluid dynamic study. Also, the

To understand cavity dynamics, many experimental and computational studies have been conducted for many decades. As computational methods, incompressible, isothermal compressible, and fully compressible flow solvers were used for the purpose. In the present study, to understand the compressibility effect on cavity dynamics, both incompressible and fully compressible flow solvers were developed, respectively. Experiments were also carried out in a cavitation tunnel to compare with the computational results. The cavity shedding dynamics, re-entrant jet, transition from bounded shear layer vortices to Karman vortices, and pressure and velocity contours behind the two-dimensional wedge by the two developed solvers were compared at various cavitation numbers.

The present paper deals with a new improvement of hierarchical multi-dimensional limiting process for resolving the subcell distribution of high-order methods on two-dimensional mixed meshes. From previous studies, the multi-dimensional limiting process (MLP) was hierarchically extended to the discontinuous Galerkin (DG) method and the flux reconstruction/correction procedure via reconstruction (FR/CPR) method on simplex meshes. It was reported that the hierarchical MLP (hMLP) shows several remarkable characteristics such as the preservation of the formal order-of-accuracy in smooth region and a sharp capturing of discontinuities in an efficient and accurate manner. At the same time, it was also surfaced that such characteristics are valid only on simplex meshes, and numerical Gibbs–Wilbraham oscillations are concealed in subcell distribution in the form of high-order polynomial modes. Subcell Gibbs–Wilbraham oscillations become potentially unstable near discontinuities and adversely affect numerical solutions in the sense of cell-averaged solutions as well as subcell distributions. In order to overcome the two issues, the behavior of the hMLP on mixed meshes is mathematically examined, and the simplex-decomposed P1-projected MLP condition and smooth extrema detector are derived. Secondly, a troubled-boundary detector is designed by analyzing the behavior of computed solutions across boundary-edges. Finally, hMLP_BD is proposed by combining the simplex-decomposed P1-projected MLP condition and smooth extrema detector with the troubled-boundary detector. Through extensive numerical tests, it is confirmed that the hMLP_BD scheme successfully eliminates subcell oscillations and provides reliable subcell distributions on two-dimensional triangular grids as well as mixed grids, while preserving the expected order-of-accuracy in smooth region.

Computations of all-speed multiphase real fluid flows for aerospace launch vehicles are known to be very demanding, owing to several issues that include robust capturing of two-phase shock/phase di...