An integrated algorithm for hypersonic fluid–thermal–structural analysis of aerodynamically heated cylindrical leading edge

2019 ◽  
Vol 233 (14) ◽  
pp. 5177-5191 ◽  
Author(s):  
Jiawei Li ◽  
Jiangfeng Wang
Keyword(s):  
Structural Analysis ◽  
Finite Volume Method ◽  
Finite Volume ◽  
Maximum Temperature ◽  
Aerodynamic Heating ◽  
Hypersonic Vehicles ◽  
Time Step ◽  
Heated Cylinder ◽  
Leading Edges ◽  
Volume Method

The accurate and efficient prediction of the fluid–thermal–structural performance of thermal protection systems on hypersonic vehicles to protect against severe aerodynamic heating is attracting increasing worldwide attention. In this paper, a new integrated fluid-structural-thermal investigation based on the finite volume method is proposed to study the thermal behavior of aerodynamically heated cylinder leading edges in hypersonic flows. A unified integral equation system is developed based on the governing equations for the physical processes of aerodynamic heating and structural heat transfer, which is resolved by using an up-wind finite volume method and a new two-thermal-resistance model in one integrated, vectorized computer program. To demonstrate its capability and reliability, applications for steady/unsteady fluid–thermal–structural analysis are demonstrated on aerodynamically heated cylinder leading edges at Ma 6.47. The results show that the steady maximum temperature of the cylinder can reach approximately 648 K at the stagnation point, and the unsteady results are in good agreement with the experimental data and related references. Compared with the partitioned approach, the integrated method shows better computational stability with relatively small sensitivity to mesh scale and time step, reducing the computation time for the same unsteady case by approximately 50%. The present study indicates that the integrated approach has potential for significant improvements and efficiency in predicting long-endurance fluid-structural-thermal problems of hypersonic vehicles.

Evaluation of numerical diffusion of the finite volume method when modelling surface waves

2019 ◽  
pp. 106-119
Author(s):  
Елена Сергеевна Тятюшкина ◽  
Андрей Сергеевич Козелков ◽  
Андрей Александрович Куркин ◽  
Вадим Викторович Курулин ◽  
Валентин Робертович Ефремов ◽  
...  
Keyword(s):  
Finite Volume Method ◽  
Finite Volume ◽  
Calculation Method ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Time Step ◽  
Navier Stokes Equations ◽  
Numerical Diffusion ◽  
Volume Method

Обсуждается применение метода конечных объемов при решении уравнений Навье-Стокса для моделирования поверхностных волн. Сформулирована задача о распространении поверхностных волн, которая используется для оценки численной диффузии в решении уравнений Навье-Стокса. Предлагается методика оценки численной диффузии, выражаемой коэффициентом уменьшения амплитуды волны при прохождении ею одной своей длины (коэффициентом затухания). Дана оценка размеров сетки и шага по времени, выраженных в безразмерных величинах относительно параметров волны, необходимых для обеспечения приемлемого значения коэффициента затухания. Показана степень влияния каждого из сеточных параметров на увеличение коэффициента затухания. The application of numerical simulation methods based on the solution of the full three-dimensional Navier-Stokes equations for modelling of wave propagation on the water surface requires the construction of a grid model containing countable nodes throughout the entire volume of water medium. Insufficient grid resolution leads to insufficient detailing of the fields of velocity and pressure, as well as volume fraction of the liquid, which increases the numerical diffusion of the method and, ultimately, leads to an underestimation of oscillation amplitudes of the medium. A large time step also results in a “blurring” of the solution and significantly reduces its stability, especially when using the schemes which compress the front of the media interface. This paper presents the results of an assessment of acceptable grid sizes and time steps expressed in dimensionless parameters with respect to the wave parameters necessary to ensure accuracy of the solution sufficient for geophysical applications. The estimate is given for the method of calculating three-dimensional multiphase flows with a free surface based on solving the Navier-Stokes equations in a one-velocity approximation based on a completely implicit connection between velocity and pressure using the finite volume method. The finite volume method for the numerical solution of the Navier-Stokes equations is implemented for use on arbitrary unstructured grids. The methodology for estimation of numerical diffusion of the calculation method is proposed. This estimation is expressed as a percentage of the wave amplitude decrease at the distance equal to the one wavelength. In turn the methodology is based on the parameters entered to estimate the acceptable grid sizes and time step for the calculation method. Based on the described methodology, the results of the estimation of the grid resolution in the horizontal and vertical directions, the estimation of the time step, and the evaluation of the influence of the discretization scheme of the convective term are presented.

Simulation of sediment transportation on Natorsa Creek by RiverFlow2D and SRH-2D

2020 ◽  
Author(s):  
Po-Nien Su
Keyword(s):  
Finite Volume Method ◽  
Finite Volume ◽  
Operation Time ◽  
Absolute Error ◽  
Field Investigation ◽  
Time Interval ◽  
Time Step ◽  
Sediment Size ◽  
Sediment Transportation ◽  
Volume Method

<p>In recent years, two-dimensional sediment transportation on movable bed models have been widely used in hydraulic engineering. Because of different assumptions, each model has its own feasibility on specified issues and areas. The SRH-2D model is an implicit method of the finite-volume method without CFL stability conditions, and requires more calculations than the explicit one at each time step. On the other hand, RiverFlow2D is an explicit method of finite-volume method with CFL conditions and saves much more time. In order to compare the results from these two software, a case study of Natorsa Creek, Kaohsiung, Taiwan, is carried out on the sensitivity analysis and different structure setups associated with rainfall data, water level record and DTM. The principle results are as following: This study uses average absolute error (MAE) and mean square root error (RSML) to investigate the sensitivities of SRH-2D and RiverFlow2D models and finds out the operation time increased with shorter time interval. Although SRH-2D supports three formulas while RiverFlow2D supports ten, it takes more factors into account like secondary flow, sediment size distribution, and the bed armoring effect. The simulation of scour-and-fill condition by these two models has shown similar result. However, there still exists small discrepancy between software simulation and field investigation.</p>

scholarly journals Numerical Study on Transient Heat Transfer of a Quartz Lamp Heating System

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Yan Yu ◽  
Pingjian Ming ◽  
Song Zhou
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Finite Volume Method ◽  
Finite Volume ◽  
High Speed ◽  
Numerical Study ◽  
Heating System ◽  
Aerodynamic Heating ◽  
Thermal Testing ◽  
Volume Method

Thermal ground testing is an accepted and frequently used method for simulating the aerodynamic heating of high speed flight vehicles. A numerical method based on a finite volume method for a quartz lamp heating system, used in thermal testing, is proposed. In this study, the unstructured finite-volume method (UFVM) for radiation has been formulated and implemented in a fluid flow solver GTEA on unstructured grids. For comparison and validation of the proposed method, a 2D furnace with cooling pipes was chosen. The results obtained from the proposed FVM agreed well with the exact solutions. Numerical results show that the quartz lamp can be simplified as a slat with the same temperature radiation source, and a simplified 2D thermal testing case was then simulated with the coupling effects of radiation, convection, and conduction heat transfer. Different temperature loading curves and ratios of intervals between the lamps and lamp length (l/s) were studied using the proposed method. The radiation heat flux on the metal surface was a wave-shaped curve. Comparing the different interval ratios, we found that the smaller the interval ratio, the larger the maximum value and the smaller the difference between the maximum and minimum heat flux.

scholarly journals Simulasi Lemari Pengering Tenga Surya Dengan Prisma Kaca Menggunakan Computational Fluid Dynamics

2021 ◽  
Vol 5 (1) ◽  
pp. 1
Author(s):  
Lohdy Diana ◽  
Arrad Ghani Safitra ◽  
Fifi Hesty Sholihah ◽  
Ahmad Taufiqurrahman Azhar
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Finite Volume Method ◽  
Finite Volume ◽  
Time Step ◽  
Volume Method

<p>Lemari pengering merupakan bagian penting pada pemanas udara tenaga surya. Lemari pengering diharapkan mampu menyimpan panas dalam waktu yang lama. Hal tersebut menyebabkan analisa thermal pada lemari pengering perlu dilakukan. Tujuan dari penelitian ini adalah untuk mengetahui karakteristik termal dan aliran yang terjadi pada lemari pengering. Karakteristik tersebut antara lain distribusi temperatur, perubahan temperatur dan kecepatan, dan pola aliran udara. Metode yang digunakan pada penelitian ini adalah <em>Finite Volume Method</em> berupa simulasi menggunakan software komputasi fluida atau <em>Computational Fluid Dynamics</em>, simulasi menggunakan model tiga dimensi pada kondisi transient dengan time step 0.015. Data simulasi diambil saat 5 detik, 15 detik, 25 detik, dan 35 detik. Hasil simulasi diperoleh perubahan distribusi temperatur udara terhadap waktu yang terjadi pada bidang XY dan bidang XZ lemari pengering. Berdasarkan hasil simulasi diketahui terjadi penurunan temperatur udara. Temperatur udara tertinggi terjadi pada bagian bawah lemari pengering dengan temperatur udara sebesar 331 K. Prisma kaca pada bagian atas lemari pengering mampu memberikan panas pada udara. Terjadi aliran balik di dalam lemari pengering yang menyebabkan udara panas dari saluran masukkan tidak terdistribusi merata.</p>

A New Multicomponent Diffusion Formulation for the Finite-Volume Method

2004 ◽  
Author(s):  
Daniel N. Pope ◽  
George Gogos
Keyword(s):  
Drag Coefficient ◽  
Finite Volume Method ◽  
Thermal Diffusion ◽  
Finite Volume ◽  
Soret Effect ◽  
Maximum Temperature ◽  
Binary Diffusion ◽  
Numerical Predictions ◽  
Complete Formulation ◽  
Volume Method

A new multicomponent formulation, which is appropriate for use with the finite-volume method, has been developed to accurately describe the diffusion velocity. The new formulation is presented and applied to the numerical simulation of n-heptane fuel droplet combustion in a zero-gravity, forced convection environment at 1 atm. Combustion is modeled using finite-rate chemical kinetics and a one-step overall reaction. Results obtained using the complete formulation are compared to the results obtained while assuming (1) thermal diffusion (Soret effect) is negligible and (2) thermal diffusion is negligible and all binary diffusion coefficients are the same. The effect these assumptions have on the results at a fixed Reynolds number (Re∞=10) is investigated for a low (300 K) and a high (1200 K) ambient temperature. The use of a single binary diffusion coefficient produces results that are significantly different from the results obtained using the complete formulation. These differences include a much lower maximum temperature (700 K lower), a “longer” flame and lower (8–20%) values for the evaporation constant and drag coefficient. Thermal diffusion caused only minor changes (~1%) in the numerical predictions for the maximum temperature, evaporation constant and drag coefficient.

Numerical Simulation of the Interaction Between Fluid Flow and Elastic Flaps Oscillations

2013 ◽  
Author(s):  
Charbel Habchi ◽  
Serge Russeil ◽  
Daniel Bougeard ◽  
Jean-Luc Harion ◽  
Sebastien Menanteau ◽  
...  
Keyword(s):  
Fluid Flow ◽  
Finite Volume Method ◽  
Finite Volume ◽  
Constitutive Law ◽  
Complex Case ◽  
Arbitrary Lagrangian Eulerian ◽  
Complex Flow ◽  
Time Step ◽  
Fixed Point Algorithm ◽  
Volume Method

Several numerical methods have been developed recently to solve problems including the interaction between viscous fluid flow and elastic solid structures. In this work, an in-house partitioned numerical solver is developed by using the open source C++ library OpenFOAM. Finite volume method is used to discretize the fluid flow problem on a moving mesh in an Arbitrary Lagrangian-Eulerian formulation and by using an adaptive time step. The structural elastic deformation is analyzed in a Lagrangian formulation using the St. Venant-Kirchhoff constitutive law. The solid structure is discretized by the finite volume method in an iterative segregated approach. The automatic mesh motion solver is based on Laplace smoothing equation with variable mesh diffusion. The strong coupling between the segregated solvers and the equilibrium on the fluid-structure interface are achieved by using an iterative implicit fixed-point algorithm with dynamic Aitken’s relaxation method. The solver is first validated on a benchmark largely used in the open literature. Then, a more complex case is studied including two elastic flaps immersed in a pulsatile fluid flow. The present solver predicts accurately the interaction between the complex flow structures generated by the flaps and the effect of the flaps oscillations on each other.

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