scholarly journals NUMERICAL STUDY OF DYNAMICS INTRACHAMBER PROCESSES IN SOLID PROPELLANT SUSTAINER TAKING INTO ACCOUNT FLIGHT OVERLOADS. PART 1. CALCULATION METHOD

2021 ◽  
pp. 91-103
Author(s):  
Mikhail Egorov ◽  
◽  
Dmitry Egorov ◽  
Sergey Egorov ◽  
◽  
...  
Keyword(s):  
Combustion Chamber ◽  
Condensed Phase ◽  
Solid Propellant ◽  
Solution Method ◽  
Numerical Study ◽  
Three Dimensional ◽  
Combustion Model ◽  
Cruise Missile ◽  
Time Step ◽  
Nozzle Block

The dynamics of transient in-chamber processes (internal ballistics) of the cruise missile's second-stage cruise missile propulsion system is studied, taking into account, in the general case, distributed spatially-three-dimensional and time-varying flight overloads. The research method is the formulation of a computational experiment. Be considered coupled formulation of the problem, including: – transient triggering of igniter device (the rate of combustion of the igniting composition is described on the basis of experimental and theoretical approach afterburn combustion products in case igniting device); preheating, ignition and subsequent unsteady and turbulent combustion of solid propellant charge (used quasi-homogeneous combustion model based on the equations of heat conduction and chemical kinetics recorded for a condensed phase (solid fuel), taking into account the influence of the gas phase (torch) on the process of combustion in the condensed phase; the method of solving the problem – finite difference method); – non-stationary three-dimensional homogeneous-heterogeneous four phase flow of air and products of combustion in the combustion chamber, the nozzle block and the block launchers rocket engine (used approaches of continuum mechanics of multiphase media; the basic system of equations system of vortex differential equations of gas dynamics solution method – a multi-parameter class of difference schemes of splitting into physical processes of the method Davydova); – depressurization of the combustion chamber of the SRB (equation of motion of the plug nozzle block – Newton's second law; the proposed solution method – Euler's method). Each of the subtasks is considered in a relationship and resolved simultaneously – at one time step. To solve the formulated problem, a set of application programs has been developed using (for the main calculation module) the OpenCL multithreaded information processing standard. The performance of the software product was checked.

scholarly journals NUMERICAL STUDY OF THE DYNAMICS OF INTRA-CHAMBER PROCESSES IN A ROCKET ENGINE FOR MOBILE COMPLEXES WITH A MULTI-TURRET POWDER CHARGE

2020 ◽  
pp. 55-63
Author(s):  
Mikhail Egorov ◽  
◽  
Vitaliy Gorodnev ◽  
Dmitry Egorov ◽  
Sergey Egorov ◽  
...  
Keyword(s):  
Combustion Chamber ◽  
Numerical Study ◽  
Rocket Engine ◽  
Time Step ◽  
Powder Charge ◽  
Complex Technical System ◽  
Nozzle Block ◽  
Set Up ◽  
Physical And Chemical ◽  
Ignition Device

A solid-fuel rocket engine is a complex technical system in which a number of interrelated non – stationary and substantially nonlinear physical and chemical processes simultaneously occur. The type of SFRE under consideration has its own problems and design features. To optimize the parameters of a rocket engine, we study the dynamics of its internal processes. The research method is to set up a computational experiment. We consider the conjugate statement of the problem, which includes: triggering of the ignition device; – heating, ignition and subsequent unsteady and turbulent combustion of the powder charge; – unsteady threedimensional shock wave and a vortex of homogeneous-heterogeneous flow of air and products of combustion in the combustion chamber, nozzle block and launchers unit; – depressurization of the combustion chamber and the subsequent departure of the stub nozzle block. Each of the subtasks is considered in a relationship and resolved simultaneously - at a single time step. As a result of researches it is established that when triggered, the solid-propellant in the combustion chamber is implemented by an abnormal process associated with the segregation of the combustion mode of multi-turret powder charge. The results of numerical calculations are presented, on the basis of which constructive measures are developed to eliminate this undesirable effect.

A Navier–Stokes Analysis of Airfoils in Oscillating Transonic Cascades for the Prediction of Aerodynamic Damping

1997 ◽  
Vol 119 (1) ◽  
pp. 77-84 ◽  
Author(s):  
R. S. Abhari ◽  
M. Giles
Keyword(s):  
Numerical Study ◽  
Three Dimensional ◽  
Outer Region ◽  
Navier Stokes ◽  
Compressor Cascade ◽  
Time Step ◽  
Aerodynamic Damping ◽  
Transonic Compressor ◽  
Standard Configuration ◽  
The Impact

An unsteady, compressible, two-dimensional, thin shear layer Navier–Stokes solver is modified to predict the motion-dependent unsteady flow around oscillating airfoils in a cascade. A quasi-three-dimensional formulations is used to account for the stream-wise variation of streamtube height. The code uses Ni’s Lax–Wendroff algorithm in the outer region, an implicit ADI method in the inner region, conservative coupling at the interface, and the Baldwin–Lomax turbulence model. The computational mesh consists of an O-grid around each blade plus an unstructured outer grid of quadrilateral or triangular cells. The unstructured computational grid was adapted to the flow to better resolve shocks and wakes. Motion of each airfoil was simulated at each time step by stretching and compressing the mesh within the O-grid. This imposed motion consists of harmonic solid body translation in two directions and rotation, combined with the correct interblade phase angles. The validity of the code is illustrated by comparing its predictions to a number of test cases, including an axially oscillating flat plate in laminar flow, the Aeroelasticity of Turbomachines Symposium Fourth Standard Configuration (a transonic turbine cascade), and the Seventh Standard Configuration (a transonic compressor cascade). The overall comparison between the predictions and the test data is reasonably good. A numerical study on a generic transonic compressor rotor was performed in which the impact of varying the amplitude of the airfoil oscillation on the normalized predicted magnitude and phase of the unsteady pressure around the airfoil was studied. It was observed that for this transonic compressor, the nondimensional aerodynamic damping was influenced by the amplitude of the oscillation.

scholarly journals Numerical Simulation of the Dispersion and Deposition of a Spray Carried by a Pulsating Airflow in a Patient-Specific Human Nasal Cavity

2017 ◽  
Author(s):  
Ali Farnoud ◽  
Xinguang Cui ◽  
Ingo Baumann ◽  
Eva Gutheil
Keyword(s):  
Nasal Cavity ◽  
High Performance ◽  
Numerical Study ◽  
Three Dimensional ◽  
Flow Simulation ◽  
Patient Specific ◽  
Process Time ◽  
Nasal Valve ◽  
Time Step ◽  
Real Process

The present numerical study concerns the dispersion and deposition of a nasal spray in a patient-specific human nose. The realistic three-dimensional geometry of the nasal cavity is reconstructed from computer tomography (CT) scans. Identification of the region of interest, removal of artifacts, segmentation, generation of the .STL file and the triangulated surface grid are performed using the software packages ImageJ, meshLab, and NeuRA2. An unstructured computational volume grid with approximately 15 million tetrahedral grid cells is generated using the software Ansys ICEM-CFD 11.0. An unsteady Eulerian-Lagrangian formulation is used to describe the airflow and the spray dispersion and deposition in the realistic human nasal airway using two-way coupling. A new solver called pimpleParcelFoam is developed, which combines the lagrangianParcel libraries with the pimpleFoam solver within the software package OpenFOAM 3.0.0. A large eddy simulation (LES) with the dynamic sub-grid scale (SGS) model is performed to study the spray in both a steady and a pulsating airflow with an inflow rate of 7.5 L/min (or maximum value in case of the pulsating spray) and a frequency of 45 Hz for pulsation as used in commercial inhalation devices. 10,000 mono-disperse particles with the diameters of 2.4 µm and 10 µm are uniformly injected at the nostrils. In order to fulfil the stability conditions for the numerical solution, a constant time-step of 10−5 s is implemented. The simulations are performed for a real process time of 1 s, since after the first second of the process, all particles have escaped through the pharynx or they are deposited at the surface of the nasal cavity. The numerical computations are performed on the high-performance computer bwForCluster MLS&WISO Production using 256 processors, which take around 32 and 75 hours for steady and pulsating flow simulation, respectively. The study shows that the airflow velocity reaches its maximum values in the nasal valve, in parts of the septum and in the nasopharynx. A complex airflow is observed in the vestibule and in the nasopharynx region, which may directly affect the dispersion and deposition pattern of the spray. The results reveal that the spray tends to deposit in the nasal valve, the septum and in the nasopharynx due to the change in the direction of the airflow in these regions. Moreover, it is found that due to the pulsating airflow, the aerosols are more dispersed and penetrate deeper into the posterior regions and the meatuses where the connections to the sinuses reside.DOI: http://dx.doi.org/10.4995/ILASS2017.2017.4628

Numerical Computation of Specific Impulse and Internal Flow Parameters in Solid Fuel Rocket Motors with Two-Phase Сombustion Products

2021 ◽  
pp. 98-107
Author(s):  
T.S. Sultanov ◽  
G.A. Glebov
Keyword(s):  
Combustion Chamber ◽  
Condensed Phase ◽  
Solid Fuel ◽  
Solid Propellant ◽  
Rocket Engine ◽  
Specific Impulse ◽  
Two Phase ◽  
Solid Propellant Rocket ◽  
Solid Propellant Rocket Engine ◽  
Propellant Rocket

Eulerian --- Lagrangian method was used in the Fluent computational fluid dynamics system to calculate motion of the two-phase combustion products in the solid fuel rocket motor combustion chamber and nozzle. Condensed phase is assumed to consist of spherical particles with the same diameter, which dimensions are not changing along the motion trajectory. Flows with particle diameters of 3, 5, 7, 9, and 11 μm were investigated. Four versions of the engine combustion chamber configuration were examined: with slotted and smooth cylindrical charge channels, each with external and submerged nozzles. Gas flow and particle trajectories were calculated starting from the solid fuel surface and to the nozzle exit. Volumetric fields of particle concentrations, condensed phase velocities and temperatures, as well as turbulence degree in the solid propellant rocket engine flow duct were obtained. Values of particles velocity and temperature lag from the gas phase along the nozzle length were received. Influence of the charge channel shape, degree of the nozzle submersion and of the condensate particles size on the solid propellant rocket engine specific impulse were determined, and losses were estimated in comparison with the case of ideal flow

Numerical Study of Heat Feedback Influence on Combustion of ADN

2011 ◽  
Vol 396-398 ◽  
pp. 920-923 ◽  
Author(s):  
Yu Zhao ◽  
Fu Ting Bao ◽  
Sheng Chao Hu
Keyword(s):  
Experimental Data ◽  
Chemical Kinetics ◽  
Condensed Phase ◽  
Numerical Study ◽  
Combustion Model ◽  
Detailed Chemical Kinetics ◽  
Dark Zone ◽  
Model Match ◽  
Detailed Chemical

Based on detailed chemical kinetics, a combustion model for ADN was established first. The mechanism used consists of 33 species and 173 reactions. Results obtained from the model match the experimental data reasonably well. Then the model was carried out many times at various heat feedbacks from gas to condensed phase. And the calculations show that heat feedback is crucial to create a dark zone and determine the length of it.

Performance of the Various Sn Approximations of DOM in a 3D Combustion Chamber

2008 ◽  
Vol 130 (7) ◽  
Author(s):  
Manosh C. Paul
Keyword(s):  
Heat Transfer ◽  
Combustion Chamber ◽  
Radiative Heat Transfer ◽  
Radiative Heat ◽  
Numerical Study ◽  
Three Dimensional ◽  
Incident Radiation ◽  
Heat Fluxes ◽  
Radiative Energy ◽  
Carbon Dioxide Co2

We have carried out a three-dimensional numerical study to investigate the radiative heat transfer in a model gas turbine combustor. The combustion chamber is a representative of the Rolls-Royce Tay engine combustor. The discrete ordinate method (Sn) in general body-fitted coordinate system is developed and then applied to solve the filtered radiative transfer equation for the radiation modeling, and this has been combined with a large eddy simulation of the flow, temperature, and composition fields within the combustion chamber. Various approximations of Sn have been considered and their performances in the investigation of the radiative heat transfer are presented in the paper. The radiation considered in this work is due only to the hot combustion gases, notably carbon dioxide (CO2) and water vapor (H2O) also known as nonluminous radiation. The instantaneous results of the radiation properties such as the incident radiation and the radiative energy source or sink as the divergence of the radiative heat fluxes are computed inside the combustion chamber and presented graphically. Effects of the wall emissivity on the incident radiation inside the combustion chamber have been examined, and it has been found that the radiative energy is enhanced with the increment of the wall emissivity.

Viscous Flow Computations on a Smooth Cylinders: A Detailed Numerical Study With Validation

2007 ◽  
Author(s):  
Guilherme Vaz ◽  
Christophe Mabilat ◽  
Remmelt van der Wal ◽  
Paul Gallagher
Keyword(s):  
Experimental Data ◽  
Viscous Flow ◽  
Numerical Study ◽  
Three Dimensional ◽  
Turbulence Models ◽  
Reynolds Numbers ◽  
Navier Stokes ◽  
Detached Eddy Simulation ◽  
Time Step ◽  
Drag Forces

The objective of this paper is to investigate several numerical and modelling features that the CFD community is currently using to compute the flow around a fixed smooth circular cylinder. Two high Reynolds numbers, 9 × 104 and 5 × 105, are chosen which are in the so called drag-crisis region. Using a viscous flow solver, these features are assessed in terms of quality by comparing the numerical results with experimental data. The study involves grid sensitivity, time step sensitivity, the use of different turbulence models, three-dimensional effects, and a RANS/DES (Reynolds Averaged Navier Stokes, Detached Eddy Simulation) comparison. The resulting drag forces and Strouhal numbers are compared with experimental data of different sources. Major flow features such as velocity and vorticity fields are presented. One of the main conclusions of the present study is that all models predict forces which are far from the experimental values, particularly for the higher Reynolds numbers in the drag-crisis region. Three-dimensional and unsteadiness effects are present, but are only fully captured by sophisticated turbulence models or by DES. DES seems to be the key to better solve the flow problem and obtain better agreement with experimental data. However, its considerable computational demands still do not allow to use it for engineering design purposes.

Numerical Modeling of Co-Firing Chunk Coal and Oat Hulls in a Stoker Boiler

2011 ◽  
Author(s):  
Xinhui Zhang ◽  
Mohsen Ghamari ◽  
Albert Ratner
Keyword(s):  
Coal Combustion ◽  
Good Accuracy ◽  
Numerical Study ◽  
Three Dimensional ◽  
Combustion Model ◽  
Transfer Model ◽  
Light Weight ◽  
Economic Potential ◽  
Oat Hulls ◽  
Real Size

The current study presents a numerical study of co-firing chunk coal and one kind of light weight biomass, oat hulls, in a stoker boiler. First, a standard combustion model was applied to simulate coal combustion in a real size three dimensional boiler; the results were compared with the temperatures measured at different locations of the stoker boiler to assess the accuracy of heat sink and heat transfer model. Once a good accuracy was achieved, a devolatilization model for oat hulls was derived from experimental data and was matched with this combustion model to simulate combustion in a co-firing stoker boiler. The results showed that light biomass burns in suspension, similar to pulverized coal by following the air flow. Also, the peak temperature inside the furnace inversely varies with the increase of co-firing percentage of oat hulls. This numerical study reveals thermal and economic potential of using unprocessed light weight biomass on the existing combustion facility.

A Numerical Study on Sloshing Flows Coupled with Ship Motion—The Anti-Rolling Tank Problem

2002 ◽  
Vol 46 (01) ◽  
pp. 52-62
Author(s):  
Yonghwan Kim
Keyword(s):  
Experimental Data ◽  
Numerical Method ◽  
Numerical Study ◽  
Computational Study ◽  
Three Dimensional ◽  
Ship Motion ◽  
Coupling Effects ◽  
Time Step ◽  
Numerical Result ◽  
Hull Forms

A computational study on the sloshing problem coupled with ship motion in waves is introduced. The ship motion excites the sloshing flow in the ship's liquid cargo, and the slosh-induced forces and moments affect the ship motion in return. This study applies a numerical method to solve the coupling problem of the ship motion and sloshing flow. In particular, it concentrates on the anti-rolling tank, which has the most significant coupling effects of two problems. The three-dimensional sloshing flow has been simulated using the finite-difference method, while the ship motion has been obtained using a time-domain panel method. At each time step, the instantaneous displacement, velocity and acceleration of ship motion have been applied to the excitation of liquid motion, and the corresponding slosh-induced forces and moments have been added to the wave-induced excitation. The computational model is a modified S175 hull, and the computational results have been compared with the experimental data of a supply vessel. Although the two hull forms are not identical, the numerical result for the modified S175 hull shows the same trend of the roll RAOs with experimental data when the anti-rolling tanks are considered. Therefore, the numerical method introduced in this study is expected to be very useful in observing the coupling effects of sloshing and ship motion problems.

Mixing and Combustion Characteristics of a Side Dump Combustor With Noncircular Fuel Injectors

1994 ◽  
Author(s):  
T. M. Liou ◽  
L. Chen
Keyword(s):  
Numerical Study ◽  
Three Dimensional ◽  
Reacting Flows ◽  
Combustion Characteristics ◽  
Combustion Model ◽  
Mean Velocity ◽  
Dump Combustor ◽  
Aspect Ratios ◽  
Switching Phenomenon ◽  
Axis Switching

A numerical study of the mixing and combustion characteristics of an axial jet issued from rectangular injectors of different aspect ratios (3 and 1/3) in a three-dimensional side-dump combustor is presented. The Reynolds number based on the bulk mean velocity and combustor duct height was 5.9×104 and the momentum ratio of the axial-fuel jet to the side-air jets was 0.2. A two equation k-ε turbulence model incorporating with a two-step finite-rate combustion model was adopted to simulate the nonreacting and reacting flows in a side-dump combustor. The computed nonreacting flow pattern was verified by the available experimental data. A comparison between the reacting and nonreacting flow patterns was made. The axis switching phenomenon previously observed for the unconfined or confined noncircular jets was examined in detail for the present side-dump combustor. It was found that the axis switching phenomenon was incomplete and that the aspect ratio had weak effects on the turbulent mixing and combustion in the ducted rocket combustor under the investigated conditions.

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