Aerothermodynamic analysis of an experimental rocket aimed to test micro-launcher technologies

The current decrease in satellite size, associated with the rise in their launch rates, has created a market demand for a new class of launchers. This new class, known as micro launchers, can only put a fraction of the current launcher’s payload into orbit but can deliver micro and small satellites to their desired orbit for a fraction of the price. Due to this new demand, the European Space Agency has supported this market trend with programs that enable the development of the necessary technologies for these future micro-launchers. In this context, Omnidea leads a project to develop an experimental vehicle that aims at developing and testing these technologies in a relevant flight environment. The development of this dissertation is in the framework of this project and focus on performing an aerothermodynamic analysis of the experimental rocket through numerical simulations in subsonic, transonic and supersonic flight. These numerical simulations are performed for two different geometries, and one additional study case is dedicated to the engine on condition. The results are then used for an aerodynamic and thermodynamic study of the vehicle and, when possible, are compared to similar studies with a satisfactory agreement. Furthermore, is discussed the impact that the alterations between the rocket geometry have on the flow around the vehicle, and their cause, as well as their consequences, are pointed out. Regarding the engine on condition, it is possible to see the creation of several new flow disturbances and their impact on the thermodynamic and aerodynamic models. Additionally, some concerns about these new flow disturbances are raised, and suggestions are made for their correction. At last, this study also shows the CFD’s key role in providing data for the construction of aerothermodynamic databases of spacecraft.A atual diminuição na dimensão dos satélites, associada a um aumento do seu número de lançamentos, criou uma procura no mercado por uma nova classe de lançadores espaciais. Esta nova classe, é denominada por micro-lançadores, e apesar de só poder colocar em órbita uma fração da carga útil dos lançadores atuais, consegue transportar micro e pequenos satélites até à órbita desejada por uma fração do preço. Devido a esta nova procura, a Agência Espacial Europeia tem suportado esta tendência do mercado com programas que permitam desenvolver as tecnologias necessárias para estes futuros micro-lançadores. Neste contexto, a Omnidea lidera um projecto de desenvolvimento de um veículo experimental que tem como objectivo desenvolver e testar estas tecnologias num ambiente relevante de voo. O desenvolvimento desta dissertação insere-se no âmbito deste projeto e tem como principal objetivo a realização de análises aerotermodinâmicas do foguete experimental através de simulações numéricas em voo subsónico, transónico e supersónico. Estas simulações numéricas são ainda realizadas para duas geometrias diferentes, e um caso de estudo adicional é dedicado à condição do foguete com o motor em funcionamento. A partir dos resultados obtidos é então realizado um estudo aerodinâmico e termodinâmico do veículo e, quando possível, os resultados são comparados com estudos semelhantes onde é verificada uma correlação satisfatória. Além disso, é discutido o impacto que as alterações entre as geometrias do foguete têm no escoamento ao redor do veículo, e a sua causa, bem como as suas consequências, são destacadas. Em relação à condição com o motor em funcionamento, é possível observar a criação de vários novos distúrbios no escoamento bem como as suas repercussões nos modelos termodinâmicos e aerodinâmicos. Como tal, algumas preocupações sobre as novas perturbações no escoamento são levantadas e algumas sugestões para a sua correção são feitas. Por fim, este estudo demonstra ainda o papel fundamental que o CFD desempenha no fornecimento de dados para a construção de bases de dados aerotermodinâmicas de naves espaciais

A Non-Reacting Passive Scalar Comparison of StarCCM and OpenFOAM in a Supersonic Cavity Flame Holder

The scramjet engine equipped with a modern-day airliner would allow for very quick travel across the United States. The major problem is that designing such an engine and testing it to make sure it is safe would cost millions if not billions of dollars. Computational fluid dynamics allows for complex designs to be tested but can still take many days, weeks, or even months to complete. With the use of computational fluid dynamics (CFD), the scramjet engine can be analyzed to determine a quicker way to test and develop a reliable configuration in addition to analyzing the effects of different fuels on performance and efficiency. The current problem, when using CFD to analyze the scramjet engine, is that it cannot solve the simulation in a timely manner, which is very important in industry. While there are solvers for CFD that have chemistry for combustion, they are extraordinarily complex and again take a large amount of time to converge on a solution. Even solvers that only include a small number of species, such as five to ten, require numerous days or even weeks to converge on a solution when using HPC. Using the passive scalar function within CFD programs, various fuels can be analyzed for mixing, combustion, and performance. The passive scalar mimics injecting dyed air into the geometry; the converged solution displays how the air (fuel) would distribute throughout the geometry as time passes on. In recent years, much research has been done on the scramjet engine, but much more research and testing are needed before the scramjet engine can become widely accepted for use. Currently, scramjet engines are only utilized for military applications including aircrafts and missiles. This thesis was conducted to research the effects of using passive scalar mixing to simplify the simulation process of combustion within a scramjet engine cavity. The simulations were performed using Reynolds Average Navier Stokes, Detached Eddy Simulations, and Large Eddy Simulation solvers in StarCCM. In addition, OpenFOAM utilized the sonicFOAM solver to perform simulations. The simulations were based on the Air Force Research Lab, AFRL, scramjet testing model. To assess the accuracy of the simulation results, it is crucial to validate the simulations against experimental data. Therefore, the simulation results were compared with David Peterson’s simulation results ([5],[6],[7]) and agreed

Study of entry, descent and landing of a low mass system at Mars

Since the Mariner 4 Martian mission, which was the rst one in succeeding in the red planet, the spatial race to study Mars has experimented a huge growth. One of its challenges is to deal with the thin atmosphere of the red planet, which demands very accurate design of the entry, descent and landing (EDL) system. This thesis develops a preliminary design of the EDL system of a small payload (see (Pasolini et al., 2017)), which consists of an aeroshell system for the reentry and the hypersonic and supersonic phases. Once the capsule has reached a subsonic velocity, a parachute is used for descent in the last ight phase. This project also includes the development of a parametric ight simulator to calculate the trajectory of the capsule. A CFD model is used to calculate the aerodynamic parameters of the hypersonic and supersonic phases. For the subsonic ight, as there is a wide variety of results in the literature, a suitable parachute model is selected from existing experimental data

Particle-based method for investigation of the physical processes in the complex industrial tasks

The main task of this paper is improved of modeling accuracy and understanding of the physical process which arises in complex industrial tasks using Euler-Lagrange approach. There were two cases under the study. The first one was aimed to study the dynamics of selforganized turbulent structures. A first qualitative insight into the entrainment process in wind farm is obtained through particle tracking. The second case is focusing on developing the EulerLagrange approach for the understanding of the physical processes occurring the water droplets injection into a jet. The water droplets, coming out of the special sockets, are simulated by packages (parcels) of particles of a certain mass and size according to the specified flow rate. Parcels moving in the flow, breakup at high speeds, heating and evaporation are investigated

An open-source hybrid CFD-DSMC solver for high-speed flows

A new open-source hybrid CFD-DSMC solver, called hyperFoam, has been implemented within the OpenFOAM framework. The capabilities of the OpenFOAM computational fluid dynamics (CFD) solver rhoCentralFoam for supersonic simulations were analysed, showing good agreement with state-of-the-art solvers such as DLR-Tau, and then enhanced, by incorporating the local time stepping (LTS) and adaptive mesh refinement (AMR) techniques. These aspects would later be used for the development of the hypersonic CFD code hy2Foam.;hyperFoam relies on hy2Foam and the direct direct simulation Monte Carlo (DSMC) code dsmcFoam to be able to resolve the flow physics while under the slip-transition regime. Using a mixture of Boyd's Gradient-Length-Local Knudsen number and a generalised modified Chapman-Enskog parameter, hyperFoam is capable of identifying the continuum and rarefied zones within the computational domain and solve each with its respective CFD or DSMC solver.;hyperFoam has been used to simulate several Couette flow with heat transfer test cases, each of different complexity. Good agreement was shown between the DSMC and hybrid results for these simulations. The hybrid code was then used to analyse a hypersonic cylinder. Reasonably similar accuracy was found between the DSMC and hybrid results for vibrationless N2 and N2-O2. However, forO2 important discrepancies were found due to an inconsistency between continuum and rarefied vibrational modelling.A new open-source hybrid CFD-DSMC solver, called hyperFoam, has been implemented within the OpenFOAM framework. The capabilities of the OpenFOAM computational fluid dynamics (CFD) solver rhoCentralFoam for supersonic simulations were analysed, showing good agreement with state-of-the-art solvers such as DLR-Tau, and then enhanced, by incorporating the local time stepping (LTS) and adaptive mesh refinement (AMR) techniques. These aspects would later be used for the development of the hypersonic CFD code hy2Foam.;hyperFoam relies on hy2Foam and the direct direct simulation Monte Carlo (DSMC) code dsmcFoam to be able to resolve the flow physics while under the slip-transition regime. Using a mixture of Boyd's Gradient-Length-Local Knudsen number and a generalised modified Chapman-Enskog parameter, hyperFoam is capable of identifying the continuum and rarefied zones within the computational domain and solve each with its respective CFD or DSMC solver.;hyperFoam has been used to simulate several Couette flow with heat transfer test cases, each of different complexity. Good agreement was shown between the DSMC and hybrid results for these simulations. The hybrid code was then used to analyse a hypersonic cylinder. Reasonably similar accuracy was found between the DSMC and hybrid results for vibrationless N2 and N2-O2. However, forO2 important discrepancies were found due to an inconsistency between continuum and rarefied vibrational modelling

Analysis of the oscillations induced by a supersonic jet applied to produce nanofibers

Financiado para publicación en acceso aberto: Universidade de Vigo/CISUGHigh-performance fibers are key components for enhancing the mechanical properties of composite materials. The development of high strength nanofibers augurs the production of new nano-composites with outstanding features. However, the robust production of continuous glass nanofibers that can be feasible processed for efficiently manufacturing nanocomposites is still challenging. Recently, Cofiblas (Continuous Fiberizing by Laser melting and Supersonic dragging) was demonstrated as a technique capable of producing continuous glass nanofibers with unlimited length. Cofiblas process has some similarities with the widely known melt blowing technique for the production of polymeric fibers. In both techniques, the design of the gas nozzle is key to ensure the feasibility of the process since the turbulences of the gas jet may induce strong whipping of the filament. This paper gives novel experimental evidences on the correlation of the supersonic gas jet instabilities with the oscillation of the filament in the melt-blowing and Cofiblas processes, relating these oscillations with the presence of shock waves and unsteadiness in the flow, and gives valuable insight into the use of supersonic jets in the melt blowing process as an effective approach for the formation of nanofibers. A thin 3D-axisymmetric model in OpenFOAM® was put to test by comparing the performance of different solvers which were validated by flow visualization of the exit jet using digital holography (DH). In order to perform a realistic and thorough validation, we simulated the optical measurements of the flow from the CFD simulations of the mass density by Abel transform and numerical differentiation. The application of digital holography as the flow visualization technique makes possible both a precise validation of the density maps obtained from the Abel transformation of the 2D-alike results, and the analysis of the shockwave pattern in the air jet. Conversely, the numerical reconstruction of time-averaged holograms is employed to detect unsteadiness in the flow and to analyze the fiber oscillation, which is essential to assess the stability of the process. Lastly, the analysis and comparison of the vibration of the filament using the basic design and the optimized nozzle demonstrates a clear influence of the shock waves and flow unsteadiness in the stability of the filament.Agencia Estatal de Investigación | Ref. PGC2018-094900-B-I00Xunta de Galicia | Ref. ED431C 2019/23Ministerio de Universidades | Ref. FPU20/0311

Review of Vortex Lattice Method for Supersonic Aircraft Design

© The Author(s), 2023. Published by Cambridge University Press on behalf of Royal Aeronautical Society. This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (https://creativecommons.org/licenses/by/4.0/There has been a renewed interest in developing environmentally friendly, economically vi-able, and technologically feasible supersonic transport aircraft and reduced order modeling methods can play an important contribution in accelerating the design process of these future aircraft. This paper reviews the use of the vortex lattice method (VLM) in modeling the gen-eral aerodynamics of subsonic and supersonic aircraft. The historical overview of the vortex lattice method is reviewed which indicates the use of this method for over a century for devel-opment and advancements in the aerodynamic analysis of subsonic and supersonic aircraft. The preference of VLM over other potential flow-solvers is because of its low order highly efficient computational analysis which is quick and efficient. Developments in VLM covering steady, unsteady state, linear and non-linear aerodynamic characteristics for different wing planform for the purpose of several different types of design optimization is reviewed. For over a decade classical vortex lattice method has been used for multi-objective optimization studies for commercial aircraft and unmanned aerial vehicle’s aerodynamic performance op-timization. VLM was one of the major potential flow solvers for studying the aerodynamic and aeroelastic characteristics of many wings and aircraft for NASA’s supersonic transport mission (SST). VLM is a preferred means for solving large numbers of computational design parameters in less time, more efficiently, and cheaper when compared to conventional CFD analysis which lends itself more to detailed study and solving the more challenging configu-ration and aerodynamic features of civil supersonic transport.Peer reviewe

Modelling Aerothermal Heating with Conjugate Heat Transfer

Supersonic and hypersonic vehicles experience flows under complex thermodynamic conditions due to the presence of shock waves and large thermophysical gradients. A large thermal load is imparted to the vehicle from the high-speed flow, leading to the aerodynamic heating of the surface. Additionally, the vehicle must sustain heat loads from within its structure, such as the propulsion system. The accurate modelling of heat transfer at these highly non-adiabatic wall conditions is critical in designing optimal thermal protection systems for hypersonic vehicles. This thesis aims to assess the predictive capabilities of computational fluid dynamic solvers in modelling aerothermal heating in supersonic and hypersonic flows using Conjugate Heat Transfer (CHT) methodologies, and investigate the impact of internal heating sources on the thermal and aerodynamic loads on aerospace vehicles. The predictive capabilities of near-wall turbulence modelling at high-speed, non-adiabatic flow conditions are first assessed for two commercial and two open-source CFD solvers: OpenFOAM (open-source), SU2 (open-source), Star-CCM+ (commercial), and ANSYS CFX (commercial). The overall error and uncertainty that can be attributed to solver selection at these complex conditions is quantified. SU2 and Star-CCM+ are assessed on their ability to model aerodynamic heating using CHT, with comparisons to hypersonic experimental studies and prior numerical investigations. The results from the code validations are used as a basis to conduct a CHT analysis on a simplified model of a supersonic vehicle to investigate the impact of internal heating on the thermal boundary layer of the external flow. The results show notable variations between the solvers in the kinematic and thermodynamic profiles of the high-speed non-adiabatic boundary layers, which are quantified. Furthermore, the treatment of the boundary condition at the wall plays a significant role in the variation of wall properties, particularly with the wall temperature prediction. Moreover, CHT validation studies show that aerothermal heating predictions of current commercial and open-source CHT solvers agree well with experimental and numerical data, but significant prediction errors occur in regions of Shockwave Boundary Layer Interaction (SWBLI) and stagnation points. The addition of internal heating on the CHT simulations of the generic high-speed vehicle results in a reversal of the wall heat flux vector as the freestream Mach Number is increased, where the heated wall case at low supersonic speeds transforms to a cooled wall case at hypersonic speeds. This thesis work provides a solid groundwork for conducting CHT simulations of high-speed wall-bounded flows with internal heating, using RANS solvers

Computational Study of Hypersonic Flow Past Spiked Blunt Body Using RANS and DSMC Method

AbstractHypersonic vehicles when moving at very high speeds experience the problem of drag and heating. One of the ways to reduce this drag and heating is by the use of an aerospike. In the present study, the flow around a blunted body fitted with an aerospike is analyzed using a commercial software ANSYS Fluent and an open source Direct Simulation Monte Carlo (DSMC) code, called as dsmcFoam in OpenFOAM, at a high Mach number (M=6) at different length to diameter ratios (L/D = 1.5, 2) at an angle of attack 0o. The aerospike placed in front of the body replaces the strong detached shock wave ahead of the body with a system of weaker oblique shock waves. A recirculation region is developed between the shock and the blunt body, which acts like a streamlined profile, thus reducing the drag and wall heat flux

Aero -thermodyanamic Analysis of Re-entry Capsule in Slip Flow Regime

We carry out numerical simulations to predict the aero-thermodynamic characteristics of a bi-conical re-entry capsule in the slip flow regime. The open source software OpenFOAM(Open Field Operation and Manipulation) is used with the compressible computational fluid dynamics (CFD) solver rhoCentralFoam. CFD solver is implemented with both the conventional no-slip boundary conditions, and also the first-order Maxwell’s velocity slip and the Smoluchowski temperature jump boundary conditions. CFD solver has been vali-dated with the experimental data for the pressure coefficient and density variations on the capsule surface and also validated with surface pressure and temperature and velocity for a flow over flat plate and wedge surface for altitude above 60km and Mach number above 10