Effect of a Jet Control Device on the Process of Missile and Internal Weapons Bay Separation

To ensure that the missile is safely separated from the internal weapons bay, the jet is used to control the process of missile separation, which is mounted on the front edge of the bay. The length-to-depth ratio of the bay was L/D=8, the diameter of the missile was d1 =0.178 m, the diameter of the jet was d2 =0.05 m . The FLUENT software was combined with our group-developed code under the platform of a user-defined function (UDF) to solve the flow field and the six-degrees-of-freedom (6DOF) of missile. The detached eddy simulation method and dynamic mesh technology were used in the numerical calculations. The boundary condition of missile, bay, and aircraft was no-slip wall condition. The boundary condition of the jet was the pressure-inlet. The pressure far-field boundary was selected as other boundaries. The constraint of the ejection device on the missile was considered. It was found that the jet control device thickens the shear layer, so the shear layer with more gradual velocity gradients, which is beneficial to the separation of missile. The distance between the internal weapons bay and the missile in the positive z-direction with the jet is 1.74 times that without the jet at t=0.5 s. In the case of the jet control device, the pitching angle of the missile ranged from 0.93° to -3.94° , the angular motion range of the missile with the jet is smaller than that without. The jet can make the characteristics of the flow field friendly, and enable the missile to separate from the bay quickly, stably, and safely.

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A numerical investigation of flow-induced cavity noise control

INTER-NOISE and NOISE-CON Congress and Conference Proceedings ◽

10.3397/in-2021-1410 ◽

2021 ◽

Vol 263 (6) ◽

pp. 298-306

Author(s):

Zhenan Song ◽

Daoqing Chang ◽

Hongling Sun

Keyword(s):

Flow Field ◽

Large Eddy Simulation ◽

Shear Layer ◽

Numerical Investigation ◽

Leading Edge ◽

Simulation Method ◽

Peak Amplitude ◽

Flow Rates ◽

Eddy Simulation ◽

Large Eddy

The influence of the multiple ultrasound transmitting units and the steady injecting water or suck-ing water on the shear layer oscillation and noise by flow-induced cavity is numerically investi-gated in this paper. The ultrasound transmitting units and the steady injecting water or sucking water are located upstream of the leading edge of the cavity. The flow field near the cavity is com-puted based on the large eddy simulation method (LES). The calculation and analysis results show that the peak amplitude of noise can be reduced by the steady injecting water at the leading edge of the opening. And within a specific range of flow rates, the greater the injecting rate is, the more obvious the peak amplitude of noise decreases

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Numerical Investigation of Intermittent Corner Separation in a Linear Compressor Cascade

Volume 2A: Turbomachinery ◽

10.1115/gt2016-57311 ◽

2016 ◽

Cited By ~ 1

Author(s):

Wei Ma ◽

Feng Gao ◽

Xavier Ottavy ◽

Lipeng Lu ◽

A. J. Wang

Keyword(s):

Flow Field ◽

Large Scale ◽

Leading Edge ◽

Suction Side ◽

Detached Eddy Simulation ◽

Compressor Cascade ◽

Linear Compressor ◽

Corner Separation ◽

Eddy Simulation ◽

Linear Compressor Cascade

Recently bimodal phenomenon in corner separation has been found by Ma et al. (Experiments in Fluids, 2013, doi:10.1007/s00348-013-1546-y). Through detailed and accurate experimental results of the velocity flow field in a linear compressor cascade, they discovered two aperiodic modes exist in the corner separation of the compressor cascade. This phenomenon reflects the flow in corner separation is high intermittent, and large-scale coherent structures corresponding to two modes exist in the flow field of corner separation. However the generation mechanism of the bimodal phenomenon in corner separation is still unclear and thus needs to be studied further. In order to obtain instantaneous flow field with different unsteadiness and thus to analyse the mechanisms of bimodal phenomenon in corner separation, in this paper detached-eddy simulation (DES) is used to simulate the flow field in the linear compressor cascade where bimodal phenomenon has been found in previous experiment. DES in this paper successfully captures the bimodal phenomenon in the linear compressor cascade found in experiment, including the locations of bimodal points and the development of bimodal points along a line that normal to the blade suction side. We infer that the bimodal phenomenon in the corner separation is induced by the strong interaction between the following two facts. The first is the unsteady upstream flow nearby the leading edge whose angle and magnitude fluctuate simultaneously and significantly. The second is the high unsteady separation in the corner region.

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Implementation of Delayed Detached Eddy Simulation method to a high order spectral difference solver

Computers & Fluids ◽

10.1016/j.compfluid.2017.05.035 ◽

2017 ◽

Vol 154 ◽

pp. 90-101 ◽

Cited By ~ 5

Author(s):

Junhui Gao ◽

Xiaodong Li

Keyword(s):

Simulation Method ◽

High Order ◽

Detached Eddy Simulation ◽

Spectral Difference ◽

Eddy Simulation ◽

Delayed Detached Eddy Simulation

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Comparative Study on CFD Turbulence Models for the Flow Field in Air Cooled Radiator

Processes ◽

10.3390/pr8121687 ◽

2020 ◽

Vol 8 (12) ◽

pp. 1687

Author(s):

Chao Yu ◽

Xiangyao Xue ◽

Kui Shi ◽

Mingzhen Shao ◽

Yang Liu

Keyword(s):

Flow Field ◽

Transient Flow ◽

Three Dimensional ◽

Turbulence Models ◽

Compartment Model ◽

Navier Stokes ◽

Engine Compartment ◽

Detached Eddy Simulation ◽

Eddy Simulation ◽

Relevant Calculation

This paper compares the performances of three Computational Fluid Dynamics (CFD) turbulence models, Reynolds Average Navier-Stokes (RANS), Detached Eddy Simulation (DES), and Large Eddy Simulation (LES), for simulating the flow field of a wheel loader engine compartment. The distributions of pressure fields, velocity fields, and vortex structures in a hybrid-grided engine compartment model are analyzed. The result reveals that the LES and DES can capture the detachment and breakage of the trailing edge more abundantly and meticulously than RANS. Additionally, by comparing the relevant calculation time, the feasibility of the DES model is proved to simulate the three-dimensional unsteady flow of engine compartment efficiently and accurately. This paper aims to provide a guiding idea for simulating the transient flow field in the engine compartment, which could serve as a theoretical basis for optimizing and improving the layout of the components of the engine compartment.

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Detached Eddy Simulation for Model Hydro Turbine

Volume 1: Symposia, Parts A and B ◽

10.1115/fedsm2006-98081 ◽

2006 ◽

Cited By ~ 1

Author(s):

Xiaojing Wu ◽

Shuhong Liu ◽

Yulin Wu

Keyword(s):

Vortex Motion ◽

Internal Flow ◽

Simulation Method ◽

Navier Stokes ◽

Detached Eddy Simulation ◽

Complex Flow ◽

Hydro Turbine ◽

Eddy Simulation ◽

Mesh Density ◽

Flow Vortex

In this paper, detached eddy simulation method is applied to the numerical simulation for whole passage of a model hydro turbine. The method combines the strong points of Reynolds-averaged Navier-Stokes and Large eddy simulation. In this model, Spalart–Allmaras turbulent model is improved, which reduces to a RANS formulation near a solid surface and to a subgrid model away from the wall. The hexahedron type mesh is used to divide the model, which can decrease the mesh scale and computation cost. In this paper, a unsteady turbulent simulation is done for model hydro turbine with this viscous model. The internal flow, vortex motion and pressure fluctuation inside hydro turbine can be studied from the result, which are also compared with the experiment data. It can be seen that this method can describe the complex flow of the turbine well while the mesh density is not very high.

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Hybrid Numerical Simulation of Jet Blast Distance of a Departing Aircraft

Mathematical Problems in Engineering ◽

10.1155/2021/5597414 ◽

2021 ◽

Vol 2021 ◽

pp. 1-11

Author(s):

Xin He ◽

Yaqing Chen ◽

Yilong Ma ◽

Dengfeng Hu ◽

Haoran Gao

Keyword(s):

Numerical Simulation ◽

Numerical Simulations ◽

Turbulence Model ◽

Internal Flow ◽

Aircraft Engine ◽

Simulation Method ◽

Detached Eddy Simulation ◽

Eddy Simulation ◽

Numerical Simulation Method

A hybrid numerical simulation method was established by combining the Spalart-Allmaras (SA) turbulence model and detached eddy simulation (DES). Numerical simulations were carried out to model cold and hot spray conditions of a nozzle without considering the internal flow of an engine to determine jet conditions. Analysis results show that the calculated hot spray results more in line with the reality. The jet effect of a typical aircraft engine was simulated numerically to determine the distance influenced by the jet blast from a departing aircraft engine.

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Wind turbines in atmospheric flow – FSI simulations with hybrid LES-IDDES turbulence modelling

10.5194/wes-2020-122 ◽

2020 ◽

Author(s):

Christian Grinderslev ◽

Niels Nørmark Sørensen ◽

Sergio González Horcas ◽

Niels Troldborg ◽

Frederik Zahle

Keyword(s):

Turbulence Model ◽

Wind Turbines ◽

Separated Flow ◽

Simulation Method ◽

Turbine Rotor ◽

Detached Eddy Simulation ◽

Atmospheric Flow ◽

Eddy Simulation ◽

Significant Difference ◽

The Impact

Abstract. In order to design future large wind turbines, knowledge is needed about the impact of aero-elasticity on the rotor loads and performance, and about the physics of the atmospheric flow surrounding the turbines. The objective of the present work is to study both effects by means of high fidelity rotor-resolved numerical simulations. In particular, unsteady computational fluid dynamics (CFD) simulations of a 2.3 MW wind turbine rotor are conducted, this rotor being the largest design with relevant experimental data available to the authors. Turbulence is modeled with two different approaches. On one hand, the well established improved delayed detached eddy simulation (IDDES) model is employed. An additional set of simulations relies on a novel hybrid turbulence model, developed within the framework of the present work. It consists on the blending of a large eddy simulation (LES) model for atmospheric flow by Deardorff with an IDDES model for the separated flow near the rotor geometry. In the same way, the assessment of the influence of the blade flexibility is performed by comparing two different sets of computations. A first group accounts for a structural multi body dynamic (MBD) model of the blades. The MBD solver was coupled to the CFD solver during run time with a staggered fluid structure interaction (FSI) scheme. The second set of simulations uses the original rotor geometry, without accounting for any structural deflection. The results of the present work show no significant difference between the IDDES and the hybrid turbulence model. However, it is expected that future simulations of more complex stratification and longer domains will benefit from the developed hybrid model. In a similar manner, and due to the fact that the considered rotor was relatively stiff, the loading variation introduced by the blade flexibility was found to be negligible when compared to the influence of inflow turbulence. The simulation method validated here is considered highly relevant for future turbine designs, where the impact of blade elasticity will be significant and the detailed structure of the atmospheric inflow will be important.

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Computational investigation and passive control of vehicle sunroof buffeting

Journal of Vibration and Control ◽

10.1177/1077546319889784 ◽

2019 ◽

Vol 26 (9-10) ◽

pp. 747-756

Author(s):

Yansong He ◽

Quanzhou Zhang ◽

Changfa An ◽

Yong Wang ◽

Zhongming Xu ◽

...

Keyword(s):

Flow Field ◽

Passive Control ◽

Pressure Fluctuations ◽

Leading Edge ◽

Simulation Method ◽

Dynamics Simulation ◽

The Road ◽

Eddy Simulation ◽

Large Eddy ◽

Utility Vehicle

A computational fluid dynamics simulation method based on large eddy simulation is presented and applied to compute the sunroof buffeting of a sport utility vehicle. The simulation result, i.e. the buffeting level curve, coincides well with the road test. The simulation method is then employed to investigate the sunroof buffeting of a vehicle during the development process in the range of 30 km/h–90 km/h. The results show that the most severe sunroof buffeting occurs at 70 km/h, which corresponds to the resonant frequency of the cabin. Flow field visualizations reveal that strong pressure fluctuations are generated inside the cabin due to vortex shedding from the leading edge and impinging onto the trailing edge of the sunroof opening, which explains the mechanism of sunroof buffeting. A new deflector with a gap and a notched upper edge is designed to replace the original castle type deflector. The simulation results show that the newly designed deflector can reduce the buffeting level to 97.9 dB; that is, the sunroof buffeting is completely eliminated. Moreover, the phenomenon of sunroof buffeting reduction is explained by comparing and analyzing the flow field between the newly designed deflector and the original deflector.

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