scholarly journals Numerical Simulations of the Internal Ballistics of Paraffin–Oxygen Hybrid Rockets at Different Scales

Aerospace ◽  
2021 ◽  
Vol 8 (8) ◽  
pp. 213
Author(s):  
Mario Tindaro Migliorino ◽  
Daniele Bianchi ◽  
Francesco Nasuti
Keyword(s):  
Numerical Simulations ◽  
Radiation Effects ◽  
Scale Effects ◽  
Numerical Approach ◽  
Surface Radiation ◽  
Rocket Engines ◽  
Regression Rate ◽  
Internal Ballistics ◽  
Hybrid Rockets ◽  
Time Space

Hybrid rockets are considered a promising future propulsion alternative for specific applications to solid or liquid rockets. In order to raise their technology readiness level, it is important to perform predictive numerical simulations of their internal ballistics. The objective of this work is to describe and validate a numerical approach based on Reynolds-averaged Navier–Stokes simulations with sub-models for fluid–surface interaction, radiation, chemistry, and turbulence. Particular attention is given to scale effects by considering two different paraffin–oxygen hybrid rocket engines and a simplified grain evolution approach from the initial to the final port diameter. Moreover, a mild sensitivity of the computed regression rate to paraffin’s melting temperature, surface radiation emissivity, and Schmidt numbers is observed. Results highlight the increasing importance of radiation effects at larger scales and pressures. A numerical rebuilding of regression rate and pressure is obtained with simulations at the time-space-averaged port diameter, producing a reasonable agreement with the available experimental data, but a noticeable improvement is obtained by considering the grain evolution in time.

Liver Radioembolization: An Analysis of Parameters that Influence the Catheter-Based Particle-Delivery via CFD

2020 ◽  
Vol 27 (10) ◽  
pp. 1600-1615 ◽  
Author(s):  
Jorge Aramburu ◽  
Raúl Antón ◽  
Alejandro Rivas ◽  
Juan C. Ramos ◽  
Bruno Sangro ◽  
...  
Keyword(s):  
Numerical Simulations ◽  
Particle Distribution ◽  
Numerical Approach ◽  
Radioactive Microspheres ◽  
Tumor Bearing ◽  
Hemodynamic Pattern ◽  
Valuable Treatment ◽  
Catheter Tip ◽  
Radiation Induced ◽  
Computational Fluid Dynamics Cfd

Radioembolization (RE) is a valuable treatment for liver cancer. It consists of administering radioactive microspheres by an intra-arterially placed catheter with the aim of lodging these microspheres, which are driven by the bloodstream, in the tumoral bed. Even though it is a safe treatment, some radiation-induced complications may arise. In trying to detect or solve the possible incidences that cause nontarget irradiation, simulating the particle- hemodynamics in hepatic arteries during RE by computational fluid dynamics (CFD) tools has become a valuable approach. This paper reviews the parameters that influence the outcome of RE and that have been studied via numerical simulations. In this numerical approach, the outcome of RE is regarded as successful if particles reach the artery branches that feed tumor-bearing liver segments. Up to 10 parameters have been reviewed. The variation of each parameter actually alters the hemodynamic pattern in the vicinities of the catheter tip and locally alters the incorporation of the particles into the bloodstream. Therefore, in general, the local influences of these parameters should result in global differences in terms of particle distribution in the hepatic artery branches. However, it has been observed that under some (qualitatively described) appropriate conditions where particles align with blood streamlines, the local influence resulting from a variation of a given parameter vanishes and no global differences are observed. Furthermore, the increasing number of CFD studies on RE suggests that numerical simulations have become an invaluable research tool in the study of RE.

scholarly journals Challenges of Ablatively Cooled Hybrid Rockets for Satellites or Upper Stages

Aerospace ◽  
2021 ◽  
Vol 8 (7) ◽  
pp. 190
Author(s):  
Francesco Barato
Keyword(s):  
Combustion Chamber ◽  
Solid Fuel ◽  
Diameter Ratio ◽  
Propulsion System ◽  
Burning Time ◽  
Regression Rate ◽  
Hybrid Propulsion ◽  
Deep Impact ◽  
Time Ratio ◽  
Hybrid Rockets

Ablative-cooled hybrid rockets could potentially combine a similar versatility of a liquid propulsion system with a much simplified architecture. These characteristics make this kind of propulsion attractive, among others, for applications such as satellites and upper stages. In this paper, the use of hybrid rockets for those situations is reviewed. It is shown that, for a competitive implementation, several challenges need to be addressed, which are not the general ones often discussed in the hybrid literature. In particular, the optimal thrust to burning time ratio, which is often relatively low in liquid engines, has a deep impact on the grain geometry, that, in turn, must comply some constrains. The regression rate sometime needs to be tailored in order to avoid unreasonable grain shapes, with the consequence that the dimensional trends start to follow some sort of counter-intuitive behavior. The length to diameter ratio of the hybrid combustion chamber imposes some packaging issues in order to compact the whole propulsion system. Finally, the heat soak-back during long off phases between multiple burns could compromise the integrity of the case and of the solid fuel. Therefore, if the advantages of hybrid propulsion are to be exploited, the aspects mentioned in this paper shall be carefully considered and properly faced.

scholarly journals Biphasic Dispersion Fuels for High-Regression-Rate Hybrid Rockets

2019 ◽  
Vol 35 (5) ◽  
pp. 964-972 ◽  
Author(s):  
Joshua D. Mathews ◽  
Jason R. Gabl ◽  
Timothée L. Pourpoint
Keyword(s):  
Regression Rate ◽  
Hybrid Rockets

scholarly journals Numerical simulation of dispersion of ammonia in industry space using the ANSYS

2018 ◽  
Vol 247 ◽  
pp. 00044
Author(s):  
Zdzisław Salamonowicz
Keyword(s):  
Numerical Simulations ◽  
Roughness Parameter ◽  
Numerical Approach ◽  
Chemical Equipment ◽  
Empirical Models ◽  
Average Roughness ◽  
Danger Zone ◽  
Industrial Installation ◽  
Heavy Gas ◽  
Selection Of

The article presents issues related to numerical simulations of the spread of dangerous substances in the air after emergency release from industrial installation. The work contains the results of numerical simulations of dispersion of ammonia and chlorine after emergency release made by using the ANSYS program, validated based on commonly used models: Gauss and heavy gas. Validation of experimental results based on research and empirical models allowed the selection of boundary parameters and the implementation of dispersion modelling in 3-d space taking into account technical infrastructure. Existing empirical models include terrain obstacles in the form of average roughness parameter, which is shown in general by the range of the danger zone without local topographic conditions. The numerical approach to modelling, in contrast to empirical models, allows to more accurately show the physicochemical phenomena occurring after release in 3-d space, both in the area around the chemical equipment and the buildings along the dangerous substance cloud.

scholarly journals Seismic stimulation for enhanced oil recovery

Geophysics ◽  
2008 ◽  
Vol 73 (5) ◽  
pp. O23-O35 ◽  
Author(s):  
Steven R. Pride ◽  
Eirik G. Flekkøy ◽  
Olav Aursjø
Keyword(s):  
Pressure Gradient ◽  
Numerical Simulations ◽  
Oil Recovery ◽  
Scale Effects ◽  
Fluid Pressure ◽  
Oil Production ◽  
Two Dimensions ◽  
Lattice Boltzmann Model ◽  
Pore Scale ◽  
Capillary Barriers

The pore-scale effects of seismic stimulation on two-phase flow are modeled numerically in random 2D grain-pack geometries. Seismic stimulation aims to enhance oil production by sending seismic waves across a reservoir to liberate immobile patches of oil. For seismic amplitudes above a well-defined (analytically expressed) dimensionless criterion, the force perturbation associated with the waves indeed can liberate oil trapped on capillary barriers and get it flowing again under the background pressure gradient. Subsequent coalescence of the freed oil droplets acts to enhance oil movement further because longer bubbles overcome capillary barriers more efficiently than shorter bubbles do. Poroelasticity theory defines the effective force that a seismic wave adds to the background fluid-pressure gradient. The lattice-Boltzmann model in two dimensions is used to perform pore-scale numerical simulations. Dimensionless numbers (groups of material and force parameters) involved in seismic stimulation were defined carefully so that numerical simulations could be applied to field-scale conditions. Using defined analytical criteria, there is a significant range of reservoir conditions over which seismic stimulation can be expected to enhance oil production.

scholarly journals Estimates Related to the Extended Spectral Control of the Wave Equation

2018 ◽  
Vol 10 (4) ◽  
pp. 156
Author(s):  
Cheikh Seck ◽  
Abdoulaye Sène ◽  
Mary Niane
Keyword(s):  
Wave Equation ◽  
Numerical Simulations ◽  
Numerical Approach ◽  
Regular Domain ◽  
Spectral Control

In this work, we show through a numerical approach the extended spectral controllability of the wave equation over a portion of a regular domain, and that the spectrum obtained is quasi-symmetrical. Numerical simulations also verify the analytical estimates demonstrated in Niane and al. $[4]$ and the graphic illustrations relating to this spectral controllability were done.

Role of Injection in Hybrid Rockets Regression Rate Behaviour

2005 ◽  
Vol 21 (4) ◽  
pp. 606-612 ◽  
Author(s):  
Carmine Carmicino ◽  
Annamaria Russo Sorge
Keyword(s):  
Regression Rate ◽  
Hybrid Rockets ◽  
Rate Behaviour

Regression Rate Estimation for Swirling-Flow Hybrid Rocket Engines

2016 ◽  
Vol 32 (1) ◽  
pp. 18-22 ◽  
Author(s):  
Potchara Wongyai ◽  
David R. Greatrix
Keyword(s):  
Swirling Flow ◽  
Rocket Engines ◽  
Hybrid Rocket ◽  
Regression Rate ◽  
Rate Estimation

scholarly journals Dynamic Behaviour of the Loads of Podded Propellers in Waves: Experimental and Numerical Simulations

2014 ◽  
Author(s):  
Patrick Queutey ◽  
Jeroen Wackers ◽  
Alban Leroyer ◽  
GanBo Deng ◽  
Emmanuel Guilmineau ◽  
...  
Keyword(s):  
Numerical Simulations ◽  
Stokes Equations ◽  
Scale Effects ◽  
Computational Study ◽  
Essential Feature ◽  
Flow Distribution ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Flow Solver ◽  
Wave Basin

The paper focuses on the hydrodynamic flow around a ship with pods in waves and compares the results of an experimental campaign with numerical simulations conducted during the EU-funded STREAMLINE project. It was the first project for which the effect of waves on cavitation and ventilation was explored in both experimental and numerical ways for a ship with pods. The measurements were carried out in MARIN’s Depressurized Wave Basin (DWB) with a fully instrumented podded ship model, in sailing condition, in waves and depressurised conditions. In this way, the correct representation of cavitation and possible ventilation bubbles and vortices is ensured, resulting in a correct physical behaviour. The discretisation of the Reynolds-Averaged Navier-Stokes Equations (RANSE) is based on the unstructured finite-volume flow solver ISIS-CFD developed by ECN-CNRS. An essential feature for full RANSE simulations with this code is the use of a sliding grid technique to simulate the real propeller rotating behind a ship hull. The computational study in operational service conditions considered here has been conducted to evaluate the instantaneous flow distribution around the podded propellers and to analyse and to compare the unsteady behaviour of the forces induced by the rotating propeller in waves with the measurements from omnidirectional propeller loads as well as the blade forces and moments. The computational study has been done in model and full scale to evaluate the scale effects.

Sign in / Sign up

Export Citation Format

Share Document