scholarly journals Flow Simulation over a Bulbous Heat Shield of a Typical Launch Vehicle

2019 ◽  
Vol 8 (2S11) ◽  
pp. 2944-2948

Numerical Simulation of flow field over a sharp and blunt nose cone bulbous heat shield are carried out. Software used for the simulation is ANSYS 19.2 student version. The Simulations are carried out in the Mach no. range 0.8 to 1.2 (transonic regime). Simulation results are analyzed in detail. Besides, Shock Strength on the heat shield for all the simulation results are obtained. Based on the studies, bulbous heat shield which gives least shock strength is recommended for the payload fairing configuration.

2016 ◽  
Vol 680 ◽  
pp. 82-85
Author(s):  
Jian Cai ◽  
Lan Chen ◽  
Umezuruike Linus Opara

OBJECTIVE To investigate the influence of mesh type on numerical simulating the dispersion performance of micro-powders through a home-made tube. METHODS With the computational fluid dynamics (CFD) method, a powder dispersion tube was meshed in three different types, namely, tetrahedral, unstructured hexahedral and prismatic-tetrahedral hybrid meshes. The inner flow field and the kinetic characteristics of the particles were investigated. Results of the numerical simulation were compared with literature evidences. RESULTS The results showed that using tetrahedral mesh had the highest computational efficiency, while employing the unstructured hexahedral mesh obtained more accurate outlet velocity. The simulation results of the inner flow field and the kinetic characteristics of the particles were slightly different among the three mesh types. The calculated particle velocity using the tetrahedral mesh had the best correlation with the changing trend of the fine particle mass in the first 4 stages of the new generation impactor (NGI) (R2 = 0.91 and 0.89 for powder A and B, respectively). Conclusions Mesh type affected computational time, accuracy of simulation results and the prediction abilities of fine particle deposition.


2014 ◽  
Vol 6 ◽  
pp. 853069 ◽  
Author(s):  
Dong Liu ◽  
Ying-ze Wang ◽  
Hyoung-Bum Kim ◽  
Fang-neng Zhu ◽  
Chun-lin Wang

The wavy vortex flow in the plain model was studied by experimental measurement; the preliminary feature of wavy vortex flow was obtained. This flow field in the plain model was also studied by numerical simulation. The reliability of numerical simulation was verified by comparing with the experimental and numerical simulation results. To study the slit wall effect on the wavy vortex flow regime, another two models with different slit number were considered; the slit number was 6 and 12. By comparing the wavy vortex flow field in different models, the axial fluctuation of Taylor vortices was found to be different, which was increased with the increasing of slit number. The maximum radial velocity from the inner cylinder to the outer one in the 6-slit number was increased by 12.7% compared to that of plain model. From the results of different circumferential position in the same slit model, it can be found that the maximum radial velocity in slit plane is significantly greater than that in other planes. The size of Taylor vortices in different models was also calculated, which was found to be increased in the 6-slit model but was not changed as the slit number increased further.


2019 ◽  
Vol 33 (24) ◽  
pp. 1950279
Author(s):  
Xinhua Song ◽  
Xiaojie Li ◽  
Yang Wang ◽  
Honghao Yan

In this paper, a computational fluid dynamics–discrete element method (CFD–DEM) coupling method is established to simulate the starch granule injection by coupling CFD and DEM. Then a gas–solid two-phase pulsed jet system is designed to capture the flow field trajectory of particle injection (colored starch with a mean diameter of 10.67 [Formula: see text]m), and the image is processed by color moment and histogram. Finally, the simulation results are compared with the experimental results, and the following conclusions are drawn. The numerical simulation results show that with the increase of injection pressure, the injection height increases gradually. When the injection pressure reaches above 0.4 MPa, the increase of injection height decreases. The experimental images show that the larger the pressure (i.e., the greater the initial velocity), the faster the velocity of particle distribution in the space, and the injection heights with the injection pressures of 0.4 MPa and 0.5 MPa are close, which is consistent with the result from the FLUENT numerical simulation based on CFD–DEM.


2012 ◽  
Vol 588-589 ◽  
pp. 1355-1358
Author(s):  
Xiao Xing ◽  
Guo Ming Ye

During the splicing process of pneumatic splicer, the principle of yarn splicing is closely related to the flow field inside the splicing chamber. This paper presents a numerical simulation of the flow char-acteristics inside the splicing chamber of the pneumatic splicer. A three-dimensional grid and the realizable tur¬bulence model are used in this simulation. The numerical results of veloc¬ity vectors distribution inside the chamber are shown. Streamlines starting from the two air injectors are also acquired. Based on the simulation, the principle of yarn splicing of the pneumatic splicer is discussed. The airflow in the splicing chamber can be divided into three regions. In addition, the simulation results have well sup¬ported the principle of yarn splicing of pneumatic splicer claimed by the splicing chamber makers.


2010 ◽  
Vol 139-141 ◽  
pp. 1048-1051 ◽  
Author(s):  
Qin Li ◽  
Hui Lin Wang ◽  
Fu Bao Li

The pressure distributions in cavitations nozzle of three different structures were studied by Hydromechanics theory, the models and mashes were completed by using Gambit software, for the conditions of the inlet pressure to 20MPa and the outlet pressure to 0.1MPa, the flow field within cavitations nozzles is simulated based on the standard k-ε model and the SIMPLE algorithm with Fluent. The result of numerical simulation is consistent with that of analytical calculation. Simulation results show that the flow has a strong shear effect with the surrounding medium in the diffuser, resulting in significant negative pressure, which is conducive to the formation of cavitations bubbles. The angle nozzle is best selected for impinging streams cavitations reactor on this basis in the paper.


2020 ◽  
Author(s):  
atsuhiro yorozuya

<p>A flood risk assessment has implemented with an inundation map or with other simulated results; e.g., a rainfall-runoff simulation. In order to conduct the flood risk assessment, it is usual that the case with maximum floods are subject for discussion. At the same time, it is usual that observed data of the maximum floods are not available, since the maximum floods has not experienced, or observation have not conducted. Estimation of the discharge values are not simple, since the river flow at the targeted cross section are affected by river shape, or roughness changes. Both of them are sensitive with different flow stage.</p><p>The present study discusses about constructing the stage discharge relationship with numerical simulation. For this purpose, the author implements the 2-D depth integrated flow simulation including the flow resistance. The flow resistance is one of the traditional studies of the sediment hydraulics. It deals with the changing of resistance with different micro-scale bed forms as the bed shear stress changes. Similar with the one by Engelund (1966), the relationship with grain shear stress and total shear stress are constructed in qualitative manner by Kishi and Kuroki (1973). It is useful to obtain the bed roughness with different flow stage. The author implements the changes of the roughness in the 2-D depth integrated flow simulation and obtains the flow field in actual river flow in order to obtain the discharge values.</p><p>The authors conducted the numerical simulation in steady flow condition. In order to construct the stage-discharge relationship based on the results, 10 different cases with appropriate ranges of stage were conducted. The domain of the simulation is 5 times longer than the width of the targeted section. In order to construct the initial condition, bathymetry data in the one point in 5 m with the laser technique, and sediment size distribution at the different location; e.g., at center of flow, top of the dune and etc., were obtained. The calculated results were compared with observed flow field by float measurements and other non-contact current meter. The results indicate that the numerical stage-discharge relationship shows some good agreements and few disagreements with the one created based on observation. For example, at the water stage which represents the dune I, the simulated results are similar with observed. However, at the stage of dune II, simulated velocity shows smaller velocity than observed. As Hirai (2015) suggested, shape of micro-bed form classified as Dune II is unstably changes between Dune and flat bed. Therefore, velocity at the stage is sensitively changes as well. From this aspect, the authors concluded that not only the numerical simulation but also field measurement are necessary in order to construct good stage-discharge relationships, in particular if the shear stress at the targeted discharge involves the Dune II.</p>


2013 ◽  
Vol 341-342 ◽  
pp. 333-336
Author(s):  
Ming Zhen Hu ◽  
Bo Zeng Wu ◽  
Jin Quan Chen ◽  
Ji Shu Zeng

For flotation characteristics of complex sulfide mineral of low-tin in Guangxi Dachang mine, fluid dynamics software FLUENT was applied to simulate the turbulence intensity of slurry fluid in flotation machine at different inflation pressures. The effect of flow field characteristics was gotten for flotation machine. Simulation results show that the best inflation pressure was 120000 Pa.


2014 ◽  
Vol 716-717 ◽  
pp. 780-784
Author(s):  
Shuo Li ◽  
Shu Cai Wang ◽  
Fang Cheng ◽  
Gao Bing Xia

The gas flow in the cold storage plays a very important role in the effect of cold storages of procambarus clarkii. Only the reasonable gas flow ensures the uniform temperature field.The paper uses the technique of computational fluid dynamics (CFD) to conduct the numerical simulation of the flow field and finds out the law of the distribution of the temperature field,on the basis of which the numerical simulation of non steady state of the freezing process of the frozen products is carried out.The experiments prove that the simulation results can better reflect the reality,and show that CFD tools can play an important role in the design and optimization of cold storages.


2016 ◽  
Vol 10 (1) ◽  
pp. 848-858
Author(s):  
Jun Wang ◽  
Yan Yu ◽  
Xinfeng Wei ◽  
Qinghua Gong ◽  
Haixian Xiong

Debris flows are a common natural disaster in mountainous areas and often cause severe casualties and property loss. Debris-flow run-out effects analysis can provide an idea of the spatial risks posed to the downstream area of a debris flow, which is extremely important for local populations’ lives, disaster mitigation and planning the layout of economic construction. The objective of this study is to develop a new method to quantify debris flow run-out effects by combining debris flow simulation results and data for different types of land use within the inundated area. After a three-dimensional numerical simulation platform was established, the numerical simulation method was applied as a modeling tool to simulate the inundated areas and final buried depths under rainfalls with different return periods. The simulated result for flow depth under a 100-year return period rainfall event was validated based on field measurements. Finally, the debris-flow run-out effects under different return periods were analyzed by combining the simulation results and land use data. The proposed method can enhance the accuracy of debris-flow spatial risk assessment and has great value for application.


2013 ◽  
Vol 634-638 ◽  
pp. 3774-3777
Author(s):  
Min Hua Zhang ◽  
Hong Mei Zheng ◽  
Cui Liu ◽  
Yin Hu Qu ◽  
Tao Liang ◽  
...  

the inner flow fields of twelve Hema-type ATY nozzles which have different structure and parameters are simulated by the Fluent software, which is based on the CFD (Computational Fluid Dynamics) theory.Then the simulation results are analyzed,through wich the best designed nozzle is determined.


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