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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
221

Shock Wave Attenuating Structural Part of Grenade : Evaluating Structural Designs with FEM Simulations: Testing and Analysis of Innovative Concepts / Chockvågsdämpande Strukturell Del av Granat : Utvärdering av strukturella konstruktioner med FEM-simuleringar: Testning och analys av innovativa koncept

Brunzell, Albin January 2024 (has links)
In the 1970s, the tandem shaped charge was developed to overcome countermeasures like active armor and thicker armor. It uses a leading charge to clear a path for the main trailing charge, theoretically improving penetration. However, disturbances from shock waves can cause under-performance. To address this, the leading charge's shock waves must be minimized to protect the main charge. Designing a part with shock wave attenuating properties can help achieve this.There is limited information on grenade structures that reduce shock wave stresses from impact and detonation. Most studies on shock wave attenuation focus on protecting buildings and humans, with few addressing structures designed to withstand and then halt the transmission of shock waves. Here we report on simulations in IMPETUS Afea where an explicit FEM solver approach have been made to compare four different concepts to an original structure. Physical theories about attenuation of shock waves in solids has been applied. The first concept utilize a mass with different area increases in the propagation path of the shock wave. The second concept use the characteristics of interfaces between two different materials, with different shock wave impedance which will reflect and transmit the incoming wave. The third concept incorporate a brittle ceramic which should shatter when a shock wave propagates to it, if the brittle structure fracture, no more shock waves can be transmitted. The fourth concept utilize the properties of porous metals. All concepts shows shock wave attenuating effects, but only the third concept which totally disconnects the leading shaped charge to the main charge might be a full solution. The fourth concept compared to the third has other advantages, it attenuate the shock wave to more than 90%, not halt the transmission. Configuration of the porosity in the structural part can be made to have characteristics that can solve the problem. Concept three and four are the main recommendations for a feasibility study. / På 1970-talet utvecklades tandem-RSV laddningar för att övervinna motmedel som aktivt pansar och tjockare pansar. De använder en förladdning för att skapa en väg för den efterföljande huvudladdningen, vilket teoretiskt sett förbättrar prestandan. Störningar från tryckvågor från olika källor orsaka prestandaförluster. För att hantera detta måste islagets och förladdningens tryckvågor minimeras för att skydda huvudladdningen. Att designa en mellandel med egenskaper som dämpar tryckvågor kan hjälpa till att uppnå detta. Information om granatstrukturer som minskar tryckvågsbelastningar från islag och detonation är begränsad. De flesta studier om dämpning av tryckvågor fokuserar på att skydda byggnader och människor, med få som behandlar strukturer designade för att motstå och sedan stoppa överföringen av tryckvågor. Här rapporterar vi om simuleringar genomförda i IMPETUS Afea med en explicit FEM-lösare för att jämföra fyra olika koncept mot en originalstruktur. Fysiska teorier om dämpning av tryckvågor i fasta material har tillämpats. Det första konceptet utnyttjar en massa med olika areaökningar i tryckvågens propagationsväg. Det andra konceptet använder egenskaperna hos gränsytor mellan två olika material med olika tryckvågsimpedanser som kommer att reflektera och transmittera den inkommande tryckvågen. I det tredje konceptet appliceras en spröd keram som bör splittras när en tryckvåg fortplantas till den. Om den spröda strukturen spricker kan då inga fler tryckvågor överföras genom strukturen. Det fjärde konceptet utnyttjar egenskaperna hos porösa metaller. Alla koncept visar tryckvågsdämpande effekter. Men endast det tredje konceptet som helt kopplar bort förladdningen från huvudladdningen kan vara en fullständig lösning. Det fjärde konceptet jämfört med det tredje har andra fördelar; det dämpar tryckvågen till mer än 90%, men stoppar inte överföringen helt. Konfigurationen av porositeten i den strukturella delen kan utformas för att ha egenskaper som kan lösa problemet. Koncept tre och fyra är de huvudsakliga rekommendationerna för en genomförbarhetsstudie.
222

Viscous-inviscid interactions of dense gases

Park, Sang-Hyuk 11 May 2006 (has links)
The interaction of oblique shocks and oblique compression waves with a laminar boundary layer on an adiabatic flat plate is analyzed by solving the Navier-Stokes equations in conservation-law form numerically. The numerical scheme is based on the Beam and Warming’s implicit method with approximate factorization. We examine the flow of Bethe-Zel’dovich-Thompson (BZT) fluids at pressures and temperatures on the order of those of the thermodynamic critical point. A BZT fluid is a single-phase gas having specific heat so large that the fundamental derivative of gas dynamics, Γ, is negative over a finite range of pressures and temperatures. The equation of state is the well-known Martin-Hou equation. The main result is the demonstration that the natural dynamics of BZT fluids can suppress boundary layer separation. Physically, this suppression can be attributed to the decrease in adverse pressure gradients associated with the disintegration of compression discontinuities in BZT fluids. / Ph. D.
223

Computational Methods for Optimizing Rotating Detonation Combustor (RDC) to Integrate with Gas Turbine

Raj, Piyush 05 July 2024 (has links)
Pressure Gain Combustion (PGC) systems have gained significant focus in recent years due to its potential for increased thermodynamic efficiency over a constant pressure cycle (or Brayton cycle). A rotating detonation combustor (RDC) is a type of PGC system, which is thermodynamically more efficient than the conventional gas turbine combustor. One of the main aspects of the detonation process is the rapid burning of the fuel-oxidizer mixture, due to which there is not enough time for the pressure to equilibrate. Therefore, the process is thermodynamically closer to a constant volume process, which is thermodynamically more efficient than a constant pressure cycle. RDC, if integrated successfully with a turbine, can increase thermal efficiency and reduce carbon emissions, especially when hydrogen is introduced into the fuel stream. However, due to highly unsteady flow generated from RDC, a systematic approach to transition the flow exiting the RDC to supply steady, subsonic flow at the turbine inlet has not been developed so far. Numerical simulations serve as a valuable tool to provide insight into the flow physics and to optimize the RDE design. Numerical studies have explored RDC by utilizing high-fidelity 3D simulations. However, these CFD studies require significant computational resources, due to the large differences in length and time scales between the flow field and the chemical reactions involved. The motivation of this dissertation is to investigate these research gaps and to develop computationally efficient methods for RDC designs to be integrated with downstream turbine section. First, this research work develops a methodology to predict the unsteady flow field exiting an RDC using 2D reacting simulations and to validate the approach using experimental measurements. Next, computational techniques are applied to condition the flow within the annulus by strategically constricting the flow area. A design of experiment (DoE) study is used to optimize the area profiling of the combustor. Additionally, the performance of the profiled design is compared against the baseline and the conventional nozzle design used in the literature. However, these numerical works use a perfectly premixed condition, whereas, the actual setup consists of discrete fuel/oxidizer injectors providing a non-uniform mixture in the combustor. To eliminate the assumption of perfectly premixed conditions, a method is developed to model the dynamic injector response of fuel/oxidizer plenums. The goal of this approach is to provide an inhomogeneous mixture composition without having to resolve/mesh the individual injectors. This research work provides a robust and computationally efficient methods for minimizing unsteadiness, maximizing pressure gain, and modeling dynamic injector response of an RDC. / Doctor of Philosophy / Traditional gas turbine combustor utilizes deflagration combustion. In recent years, detonation-based combustion has been explored as an alternative to enhance the efficiency of a modern gas turbine combustor. Rotating Detonation Combustor (RDC) utilizes detonation-based combustion and is thermodynamically efficient compared to conventional gas turbine combustors. The RDC consists of a detonation wave front and an oblique shock wave, which travel towards the exit of the combustor. Thus, the flow exiting the RDC is highly unsteady. The turbine requires a relatively steady flow at the inlet guide vanes. Therefore, the flow exiting the RDC needs to be conditioned before integrating with a downstream turbine section to gain the thermodynamic benefits of RDC. Numerical simulation of an RDC provides additional flexibility over experiments in understanding the flow physics. In addition, simulations are vital in optimizing the RDC designs such that the flow exiting the combustor is relatively uniform without comprising the pressure gain benefits of RDC. However, one of the challenges is that the RDC simulations are computationally expensive. Therefore, computationally efficient methods are required to understand and optimize the RDC designs to minimize the unsteady flow behavior and maximize the pressure gain. The objective is to utilize 2D and 3D reacting simulations to understand the flow behavior and to develop an optimization workflow to condition the flow exiting the combustor. Additionally, the optimized design is evaluated against the baseline and the conventional design used previously in the literature. Moreover, in most RDCs, the fuel and oxidizer are injected using discrete injectors. Due to the discrete injection, the fuel/oxidizer mixture is never perfectly premixed and results in a localized variation in fuel-oxidizer composition in the combustor. A novel method is developed to model the dynamic injector response of discrete fuel/oxidizer injection. The goal is to provide an inhomogeneous mixture composition without having to resolve/mesh the individual injectors. The emphasis of this study is to provide insight into the importance of flow conditioning exiting the RDC and the development of efficient CFD methods to optimize RDC to seamlessly integrate with a downstream turbine section.
224

Couplage micro/hydro pour la simulation d’ondes de choc et de détonation / Micro/hydro coupling for the simulation of detonation and shock waves

Faure, Gérôme 29 November 2017 (has links)
Cette thèse étudie des modèles mésoscopiques adaptés à la simulation d'ondes de choc et de détonation dans des fluides. Ces phénomènes mettent en jeu des processus complexes et nécessitent des systèmes de taille suffisante pour les observer. L'enjeu est ainsi de gagner en échelle par rapport aux méthodes microscopiques, précises mais coûteuses, tout en conservant les propriétés essentielles. Dans cette optique, le développement de méthodes multi-échelles couplant différentes résolutions au sein d'une même simulation permet d'adopter une description plus fine dans certaines régions. Nous étudions plus particulièrement la SDPD (Smoothed Dissipative Particle Dynamics) qui couple une discrétisation particulaire des équations de Navier-Stokes et des fluctuations thermiques variant avec la résolution. La reformulation de la SDPD en termes d'énergie interne, en plus de la position et de la quantité de mouvement, permet de rapprocher structurellement la SDPD et la DPDE (Dissipative Particle Dynamics with Energy conservation). Des schémas numériques conçus pour la DPDE sont adaptés à la SDPD afin d'assurer la conservation de l'énergie et la stabilité de la dynamique. Nous étudions également les propriétés statistiques de la SDPD et établissons des estimateurs de la température et de la pression. La cohérence multi-échelle de laSDPD est démontrée par des simulations à l’équilibre et pour des ondes de choc et nous proposons un couplage entre la SDPD à différentes résolutions. Enfin, la pertinence physique de la méthode est illustrée par la simulation d’ondes de détonation et d’éjection de matière / This thesis studies mesoscopic models adapted to the simulation of shock and detonation waves in fluids. These phenomena require systems sufficiently large to observe the complex processes occurring in this context. The aim is thus to increase the accessible time and length scales of microscopic methods, accurate but expensive, while preserving their essential properties. To this end, the multiscale coupling of methods at different resolutions allows to finely describe a specific region, limiting the computational cost. In particular, we study Smoothed Dissipative Particle Dynamics (SDPD) which couples a particle discretization of the Navier-Stokes equations and thermal fluctuations that scale consistently with the resolution. The SDPD equations are reformulated in terms of internal energies, which increases the structural similarity with Dissipative Particle Dynamics with Energy conservation (DPDE). We adapt numerical schemes for DPDE to the context of SDPD in order to ensure energy conservation and stability. We study the statistical properties of SDPD and determine estimators for temperature and pressure. The size consistency in SDPD is established for equilibrium and shock waves, which leads us to propose a multiscale coupling of SDPD at different resolutions. Finally, its physical relevance is illustrated by simulating micro-jetting and detonation waves
225

Subjecting the CHIMERA supernova code to two hydrodynamic test problems, (i) Riemann problem and (ii) Point blast explosion

Unknown Date (has links)
A Shock wave as represented by the Riemann problem and a Point-blast explosion are two key phenomena involved in a supernova explosion. Any hydrocode used to simulate supernovae should be subjected to tests consisting of the Riemann problem and the Point-blast explosion. L. I. Sedov's solution of Point-blast explosion and Gary A. Sod's solution of a Riemann problem have been re-derived here from one dimensional fluid dynamics equations . Both these problems have been solved by using the idea of Self-similarity and Dimensional analysis. The main focus of my research was to subject the CHIMERA supernova code to these two hydrodynamic tests. Results of CHIMERA code for both the blast wave and Riemann problem have then been tested by comparing with the results of the analytic solution. / by Abu Salah M. Ahsan. / Thesis (M.S.)--Florida Atlantic University, 2008. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2008. Mode of access: World Wide Web.
226

Estudo experimental de jatos evaporativos. / Experimental study of evaporating jets.

Vieira, Marcelo Mendes 17 December 1999 (has links)
Foi construído um arranjo experimental para estudar o comportamento dos jatos evaporativos. Um injetor foi projetado para controlar e manter constantes a pressão e temperatura de reservatório durante a injeção. Um bocal cônico convergente de seção reta com diâmetro de saída de 0,30 mm e ângulo entre sua geratriz e seu eixo simetria igual à 10º forma o elemento principal do injetor. O jato é descarregado em uma câmara de baixa pressão de dimensões suficientemente grandes para manter a pressão constante durante o curto período de ensaio, igual à 1 s. Quando injetado, o líquido sofre uma repentina queda de pressão ocasionando sua evaporação. Os fluidos utilizados são os combustíveis querosene e óleo diesel, e a substância n-dodecano, os quais se caracterizam pela possibilidade de uma evaporação completa, de forma adiabática. Utilizou-se o método \"schlieren\" para a visualização do escoamento. A análise dos jatos é feita de forma qualitativa através dos registros fotográficos. Foram observados os seguintes tipos de jato: (1) contínuo, (2) pulverizante e (3) evaporação na superfície. O primeiro jato não implica em imediata mudança de fase tornando o jato de líquido emergente intacto. Com o aumento da temperatura de injeção, existe o espalhamento e a evaporação do jato, formando o segundo tipo de jato, onde é possível visualizar o campo do gradiente de densidade do escoamento e a formação de ondas de evaporação e de choque que pode ocorrer a uma distância proporcional a vários diâmetros à jusante. Em jatos com evaporação completa, foram constadas a formação de ondas de choque tanto de formas elipsóide como de esferóide para elevadas temperaturas. As fotografias digitais são submetidas à filtragem e processamento matemático para melhor destacar tais fenômenos do escoamento. / An experimental apparatus has been built to study the behaviour of flashing jets. An injector was designed to control and maintain the jet pressure and temperature at constant values during the injection process. A conical convergent nozzle whose main dimensions are 0,30 mm of exit diameter, 8 mm long, and a convergence half-angle of 10º is the central component of the injection system. The jet is discharged into a low-pressure chamber large enough to keep the reservoir pressure constant during the short test period of about 1 s. As the testing liquid expands in the nozzle it undergoes a sudden pressure drop causing its evaporation. The fluids are usual fuels, such as kerosene and diesel oil, and the substance ndodecane, which are distinguishable by the possibility of a complete evaporation in an isoentropic expansion process. The photographic method \"schlieren\" is used for flow visualisation. A qualitative analysis is made of the photographic documentation of the images obtained using a CCD camera. The images can be grouped into three categories of jets: (1) continuous, (2) shattering, and (3) with surface evaporation. The first regime has an undisturbed a liquid column, which remains more or less intact during the injection process. In the second type, the existing liquid jet is shattered by vapour nucleation and, in some cases, shock waves are clearly visible. It happens at higher temperature than the preceding evaporation mode. Finally, in special situations, the jet undergoes an evaporation at its surface and the two-phase mixture expands at a high speed followed by a shock wave before the mixture attains the pressure reservoir.
227

On numerical studies of explosion and implosion in air.

January 2006 (has links)
Fu Sau-chung. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references (leaves 68-71). / Abstracts in English and Chinese. / Abstract --- p.i / Acknowledgement --- p.iii / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Background of Explosion and Implosion Problems --- p.1 / Chapter 1.2 --- Background of the Development of Numerical Schemes --- p.2 / Chapter 1.3 --- Organization of the Thesis --- p.5 / Chapter 2 --- Governing Equations and Numerical Schemes --- p.6 / Chapter 2.1 --- Governing Equations --- p.6 / Chapter 2.2 --- Numerical Schemes --- p.8 / Chapter 2.2.1 --- Splitting Scheme for Partial Differential Equations with Source Terms --- p.8 / Chapter 2.2.2 --- Boundary Conditions --- p.9 / Chapter 2.2.3 --- "Numerical Solvers for the ODEs - The Second-Order, Two-Stage Runge-Kutta Method" --- p.10 / Chapter 2.2.4 --- Numerical Solvers for the Pure Advection Hyperbolic Problem - The Second-Order Relaxed Scheme --- p.11 / Chapter 3 --- Numerical Results --- p.29 / Chapter 3.1 --- Spherical Explosion Problem --- p.30 / Chapter 3.1.1 --- Physical Description --- p.32 / Chapter 3.1.2 --- Comparison with Previous Analytical and Experimental Results --- p.33 / Chapter 3.2 --- Cylindrical Explosion Problem --- p.46 / Chapter 3.2.1 --- Physical Description --- p.46 / Chapter 3.2.2 --- Two-Dimensional Model --- p.49 / Chapter 3.3 --- Spherical Implosion Problem --- p.52 / Chapter 3.3.1 --- Physical Description --- p.52 / Chapter 3.4 --- Cylindrical Implosion Problem --- p.53 / Chapter 3.4.1 --- Physical Description --- p.53 / Chapter 3.4.2 --- Two-Dimensional Model --- p.53 / Chapter 4 --- Conclusion --- p.65 / Bibliography --- p.68
228

Estudo experimental de jatos evaporativos. / Experimental study of evaporating jets.

Marcelo Mendes Vieira 17 December 1999 (has links)
Foi construído um arranjo experimental para estudar o comportamento dos jatos evaporativos. Um injetor foi projetado para controlar e manter constantes a pressão e temperatura de reservatório durante a injeção. Um bocal cônico convergente de seção reta com diâmetro de saída de 0,30 mm e ângulo entre sua geratriz e seu eixo simetria igual à 10º forma o elemento principal do injetor. O jato é descarregado em uma câmara de baixa pressão de dimensões suficientemente grandes para manter a pressão constante durante o curto período de ensaio, igual à 1 s. Quando injetado, o líquido sofre uma repentina queda de pressão ocasionando sua evaporação. Os fluidos utilizados são os combustíveis querosene e óleo diesel, e a substância n-dodecano, os quais se caracterizam pela possibilidade de uma evaporação completa, de forma adiabática. Utilizou-se o método \"schlieren\" para a visualização do escoamento. A análise dos jatos é feita de forma qualitativa através dos registros fotográficos. Foram observados os seguintes tipos de jato: (1) contínuo, (2) pulverizante e (3) evaporação na superfície. O primeiro jato não implica em imediata mudança de fase tornando o jato de líquido emergente intacto. Com o aumento da temperatura de injeção, existe o espalhamento e a evaporação do jato, formando o segundo tipo de jato, onde é possível visualizar o campo do gradiente de densidade do escoamento e a formação de ondas de evaporação e de choque que pode ocorrer a uma distância proporcional a vários diâmetros à jusante. Em jatos com evaporação completa, foram constadas a formação de ondas de choque tanto de formas elipsóide como de esferóide para elevadas temperaturas. As fotografias digitais são submetidas à filtragem e processamento matemático para melhor destacar tais fenômenos do escoamento. / An experimental apparatus has been built to study the behaviour of flashing jets. An injector was designed to control and maintain the jet pressure and temperature at constant values during the injection process. A conical convergent nozzle whose main dimensions are 0,30 mm of exit diameter, 8 mm long, and a convergence half-angle of 10º is the central component of the injection system. The jet is discharged into a low-pressure chamber large enough to keep the reservoir pressure constant during the short test period of about 1 s. As the testing liquid expands in the nozzle it undergoes a sudden pressure drop causing its evaporation. The fluids are usual fuels, such as kerosene and diesel oil, and the substance ndodecane, which are distinguishable by the possibility of a complete evaporation in an isoentropic expansion process. The photographic method \"schlieren\" is used for flow visualisation. A qualitative analysis is made of the photographic documentation of the images obtained using a CCD camera. The images can be grouped into three categories of jets: (1) continuous, (2) shattering, and (3) with surface evaporation. The first regime has an undisturbed a liquid column, which remains more or less intact during the injection process. In the second type, the existing liquid jet is shattered by vapour nucleation and, in some cases, shock waves are clearly visible. It happens at higher temperature than the preceding evaporation mode. Finally, in special situations, the jet undergoes an evaporation at its surface and the two-phase mixture expands at a high speed followed by a shock wave before the mixture attains the pressure reservoir.
229

Macroscopic modelling of chemically reacting and radiating rarefied flows

Mark Goldsworthy Unknown Date (has links)
The Direct Simulation Monte Carlo method is a computational tool for modelling rarefied flows. The Macroscopic Chemistry Method was developed to simplify the modelling of dissociation and recombination reactions in DSMC. The ability to understand and predict the behaviour of chemically reacting, rarefied flows is a critical aspect in the development of high altitude, high speed bodies such as re-entry craft, high altitude aircraft, space transport vehicles and missiles. Computational methods are an invaluable source of information when experimental techniques are difficult, costly or time-consuming. However, traditional methods of modelling chemical kinetics using DSMC suffer from a number of drawbacks. The Macroscopic Chemistry Method overcomes a number of these problems, but has previously only been applied to simulations of a single diatomic gas. The Macroscopic Chemistry Method (MCM) is extended to consider multiple species and multiple reaction sets, thermal non-equilibrium effects, trace species modelling, unsteady flows, vibrational state specific chemistry, electronic excitation, relaxation and ionization and coupled nonequilibrium radiation emission. The Macroscopic Method is described as a general DSMC modelling philosophy rather than as a single formulated method. That is, the flexibility and utility of the method are shown through examples of applying a macroscopic approach to a number of problems, and by highlighting instances where a macroscopic approach is useful or even necessary. The problems investigated include reservoir relaxation calculations, 1-D shock, expansion and shock-expansion calculations, two-dimensional flows over a vertical step and through a cavity, and axis-symmetric flow about a sphere. The studies demonstrate that although MCM may often present a simplified approach as compared to traditional 'non-macroscopic' methods, it does not necessarily lead to more approximate solutions. On the contrary, the ability of macroscopic methods to combine different models of physical processes with the most recent (verified) data means that they are particularly suited to simulate high altitude, rarefied flows. It is also shown that, like any model approach, the validity of the approximations employed must be justified for a particular problem. In general, macroscopic methods of varying complexity and accuracy may be implemented to model a specific physical process. Adoption of the Macroscopic Chemistry Method in DSMC has the potential to enhance the modelling of chemical kinetics, charged-particle effects and radiation in rarefied hypersonic flows. This capability may be attributed to the simplicity and flexibility which the macroscopic approach affords over methods which seek to avoid the use of collective information. Macroscopic methods have already been employed to model weakly ionized flows. Their further application to model chemical kinetics and other processes would be useful for modelling and understanding the behaviour of objects in rarefied hypersonic flow-fields.
230

Tratamiento del hombro doloroso en un servicio de rehabilitación y medicina física : estudio sobre los efectos de las ondas de choque y los ultrasonidos en el tratamiento del síndrome subacromial.

Fernández Fernández, Juan Reyes 10 May 2013 (has links)
Objetivos del estudio: establecer los efectos de ultrasonidos y ondas de choque radiales en el síndrome subacromial, determinar la posible influencia del sexo y analizar la rentabilidad de ambas técnicas. Realizamos un estudio en veinticuatro pacientes repartidos en dos grupos: un grupo recibió ondas de choque y el otro ultrasonidos. Los pacientes fueron evaluados mediante la escala DASH, Constant&Murley, UCLA, SF-36 y EVA, antes del tratamiento, al mes, a los tres meses y a los seis meses. El estudio no mostró diferencias entre ultrasonidos y ondas de choque, aunque ambos tratamientos mostraron eficacia. Dicha mejoría fue mayor en los varones. Obtuvimos un coste por paciente menor con las ondas de choque. Conclusiones: ambas técnicas son eficaces en el tratamiento del síndrome subacromial, aunque no encontramos diferencias estadísticamente significativas entre ellas. Los resultados fueron mejores en los varones. En dichas condiciones, el abordaje con ondas de choque radiales es más rentable. / Objectives: To set the utility of ultrasound and radial shock waves in subacromial syndrome; to determinate the possible influence of sex; to analyse the profitability of both techniques. We did a clinical trial in twenty-four patients, divided in two groups: one of them received shock waves treatment, the other group received ultrasounds. The patients were evaluated using DASH scale, Constant&Murley, UCLA, SF-36 and VAE scales before treatment, one month, three months and six months later. No significant differences were found between the two techniques, although both treatments improved symptoms and function. That improvement was better in males. We obtained a patients’ cost in shock waves group lower than in ultrasounds one. Conclusions: both techniques are effective in the treatment of subacromial syndrome, although we couldn’t find relevant differences. The results were better in males. Thus, radial shock waves treatment is more profitable than ultrasounds one.

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