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Hydraulic spool valves are found in most hydraulic circuits in which flow is to be modulated. Therefore their dynamic performance is critical to the overall performance of the circuit. Fundamental to this performance is the presence of flow reaction forces which act on the spool. These forces can result in the necessity of using two stage devices to drive the spool and in some cases have been directly linked to valve and circuit instabilities. As such, a great deal of research and design has concentrated on ways to reduce or compensate for flow forces. In one particular series of studies conducted on flow divider valves, it was established that a rim machined into the land of the spool reduced the flow dividing error by approximately 70-80%, and it was deduced that the main contribution to this error was flow forces. Direct verification of the claim regarding flow force reduction was not achieved and hence was the motivation for this particular study. <p> This thesis will consider the reaction (flow) force associated with a conventional spool land and one with a rim machined into it, and a modified form of the rimmed land referred to as a sharp edge tapered rim spool land. The rim and the sharp edge tapered rim were specially designed geometrical changes to the lands of the standard spool in order to reduce the large steady state flow forces (SSFF) inherent in the standard spool valve. In order to analyze the flow field inside the interior passages of the valve, three configurations of the spool were considered for orifice openings of 0.375, 0.5, 0.75 and 1.05 mm. Computational Fluid Dynamics (CFD) analysis was used to describe the fluid mechanics associated with the steady state flow forces as it provided a detailed structure of the flow through the valve, and to identify the flow mechanism whereby flow forces are reduced by the machining of a rim and tapered rim on the land of the spool. For all openings of the spool, the sharp tapered rim valve provides the largest reduction in SSFF. It was also observed that for all cases studied, the inflow SSFFs were smaller than for the outflow conditions. <p>The prediction of the steady state flow force on the rim spool was investigated in a flow divider valve configuration, and the results from the CFD analysis indicated a reduction by approximately 70%.

Hydraulic spool valves are found in most hydraulic circuits in which flow is to be modulated. Therefore their dynamic performance is critical to the overall performance of the circuit. Fundamental to this performance is the presence of flow reaction forces which act on the spool. These forces can result in the necessity of using two stage devices to drive the spool and in some cases have been directly linked to valve and circuit instabilities. As such, a great deal of research and design has concentrated on ways to reduce or compensate for flow forces. In one particular series of studies conducted on flow divider valves, it was established that a rim machined into the land of the spool reduced the flow dividing error by approximately 70-80%, and it was deduced that the main contribution to this error was flow forces. Direct verification of the claim regarding flow force reduction was not achieved and hence was the motivation for this particular study. <p> This thesis will consider the reaction (flow) force associated with a conventional spool land and one with a rim machined into it, and a modified form of the rimmed land referred to as a sharp edge tapered rim spool land. The rim and the sharp edge tapered rim were specially designed geometrical changes to the lands of the standard spool in order to reduce the large steady state flow forces (SSFF) inherent in the standard spool valve. In order to analyze the flow field inside the interior passages of the valve, three configurations of the spool were considered for orifice openings of 0.375, 0.5, 0.75 and 1.05 mm. Computational Fluid Dynamics (CFD) analysis was used to describe the fluid mechanics associated with the steady state flow forces as it provided a detailed structure of the flow through the valve, and to identify the flow mechanism whereby flow forces are reduced by the machining of a rim and tapered rim on the land of the spool. For all openings of the spool, the sharp tapered rim valve provides the largest reduction in SSFF. It was also observed that for all cases studied, the inflow SSFFs were smaller than for the outflow conditions. <p>The prediction of the steady state flow force on the rim spool was investigated in a flow divider valve configuration, and the results from the CFD analysis indicated a reduction by approximately 70%.

abstract: This thesis seeks to further explore off-design point operation of gas turbines and to examine the capabilities of GasTurb 12 as a tool for off-design analysis. It is a continuation of previous thesis work which initially explored the capabilities of GasTurb 12. The research is conducted in order to: 1) validate GasTurb 12 and, 2) predict off-design performance of the Garrett GTCP85-98D located at the Arizona State University Tempe campus. GasTurb 12 is validated as an off-design point tool by using the program to predict performance of an LM2500+ marine gas turbine. Haglind and Elmegaard (2009) published a paper detailing a second off-design point method and it includes the manufacturer's off-design point data for the LM2500+. GasTurb 12 is used to predict off-design point performance of the LM2500+ and compared to the manufacturer's data. The GasTurb 12 predictions show good correlation. Garrett has published specification data for the GTCP85-98D. This specification data is analyzed to determine the design point and to comment on off-design trends. Arizona State University GTCP85-98D off-design experimental data is evaluated. Trends presented in the data are commented on and explained. The trends match the expected behavior demonstrated in the specification data for the same gas turbine system. It was originally intended that a model of the GTCP85-98D be constructed in GasTurb 12 and used to predict off-design performance. The prediction would be compared to collected experimental data. This is not possible because the free version of GasTurb 12 used in this research does not have a module to model a single spool turboshaft. This module needs to be purchased for this analysis. / Dissertation/Thesis / GTCP85 Data / M.S. Mechanical Engineering 2014

abstract: In previous work, the effects of power extraction for onboard electrical equipment and flight control systems were studied to determine which turbine shaft (i.e. high power shaft vs low power shaft) is best suited for power extraction. This thesis will look into an alternative option, a three-spool design with a high-pressure turbine, low-pressure turbine, and a turbine dedicated to driving the fan. One of the three-spool turbines is designed to be a vaneless counter-rotating turbine. The off-design performance of this new design will be compared to the traditional two-spool design to determine if the additional spool is a practical alternative to current designs for high shaft horsepower extraction requirements. Upon analysis, this thesis has shown that a three-spool engine with a vaneless counter-rotating stage has worse performance characteristics than traditional two-spool designs for UAV systems. / Dissertation/Thesis / Masters Thesis Aerospace Engineering 2019

This thesis of a Master´s distant study program of M-STM Machinery technolofy and industrial design specialization proposes more efficient and quicker way of assembeling pipe technology systems using prefabrication of so called SPOOL "figure" in advance. The thesis proposes and from the technical-economical point of view assesses ways of manufacturing and proceeding the workshop weldings on pipe systems. While construction and design the programes of Areva and Autodesk companies were used.

This thesis presents a solution enabling lower losses in hydraulic actuator systems. A mobile fluid power system often contains several different actuators supplied with a single load sensing pump. One of the main advantages is the need of only one system pump. This makes the fluid power system compact and cost-effective. A hydraulic load often consists of two ports, e.g. motors and cylinders. Such loads have traditionally been controlled by a valve that controls these ports by one single control signal, namely the position of the spool in a control valve. In this kind of valve, the inlet (meter-in) and outlet (meter-out) orifices are mechanically connected. The mechanical connection makes the system robust and easy to control, at the same time as the system lacks flexibility. Some of the main drawbacks are The fixed relation between the inlet and outlet orifices in most applications produce too much throttling at the outlet orifice under most operating conditions. This makes the system inefficient. The flow directions are fixed for a given spool position; therefore, no energy recuperation and/or regeneration ability is available. In this thesis a novel system idea enabling, for example, recuperation and regeneration is presented. Recuperation is when flow is taken from a tank, pressurized by external loads, and then fed back into the pump line. Regeneration is when either cylinder chambers (or motor ports) are connected to the pump line. Only one system pump is needed. Pressure compensated (load independent), bidirectional, poppet valves are proposed and utilized. The novel system presented in this thesis needs only a position sensor on each compensator spool. This simple sensor is also suitable for identification of mode switches, e.g. between normal, differential and regenerative modes. Patent pending. The balance of where to put the functionality (hardware and/or software) makes it possible to manoeuvre the system with maintained speed control in the case of sensor failure. The main reason is that the novel system does not need pressure transducers for flow determination. Some features of the novel system: Mode switches The mode switches are accomplished without knowledge about the pressures in the system Throttle losses With the new system approach, choice of control and measure signals, the throttle losses at the control valves are reduced Smooth mode switches The system will switch to regenerative mode automatically in a smooth manner when possible Use energy stored in the loads The load, e.g. a cylinder, is able to be used as a motor when possible, enabling the system to recuperate overrun loads The system and its components are described together with the control algorithms that enable energy efficient operation. Measurements from a real application are also presented in the thesis.

Directional control valves are widely used in hydraulic systems to control the flow direction and the flow rate. In order to design an actuator for such a valve a preliminary analysis of forces acting on the spool is necessary. The dominant axial force is the so called steady flow force, which is analysed within this study. For this purpose a 2/2-way spool valve with a sharp control edge was manufactured and investigated. CFD simulations were carried out to visualize the fluid flow inside the valve. The measured and simulated axial forces and pressure drops across the test valve are compared and show good qualitative correlation. However, the simulated values of axial forces are in average by 32 % lower compared with the measured ones. Therefore, the components of the axial force were scrutinized revealing a dominancy of the pressure force acting on ring areas in the spool chamber. Although CFD simulations are preferably used to save resources, the results of this study emphasise the importance of the experiments.

<p>Avsikten med denna avhandling är att utvärdera den FE-modell som använts i modalanalyser av komponenten fan booster spool, framtagen och tillverkad av Volvo Aero Corporation, Trollhättan. Detaljen ingår i den civila flygplansmotorn GEnx som är utvecklad för flygplanet Boeing 787 Dreamliner.</p><p>Inledande tester av spolen påvisade en mycket god korrelation mellan analys och test men när spolen senare provkördes i en komplett monterad motor noterades en uppenbar skillnad i resultat. Den andra noddiameterns egenfrekvenser indikerade att spolen i test hade ett något styvare beteende än vad som beräknats i analys.</p><p>En teori utvecklades som byggde på att en initiell kontakt mellan rotor och ett slitskikt på statorn kunde framkalla en förstyvande effekt på spolen när rotorn på grund av rotationslaster expanderar radiellt. Detta examensarbete initierades då för att undersöka om denna kontakt kunde inkluderas i FE-modellen och för att utreda om kontakten har en möjlighet att förstyva spolen.</p><p>Avhandlingen utvärderar FE-modellen med avseende på randvillkor, laster och modelleringsteknik i FE-programmet Ansys 10.0. En grundlig kartläggning av spolens känslighet påvisar en robust komponent med hög motståndskraft mot yttre och inre störningar.</p><p>En förstyvande effekt relaterad till en initiell kontakt mellan slitskikt och spole bekräftas i denna avhandling. Kontakten har visat sig ha särskild inverkan på den andra noddiametern och dess egenfrekvenser. Ett förslag på modelleringsteknik där den förstyvande effekten inkluderas har däremot inte föreslagits i detta arbete då effekten enligt uppgift går förlorad efter en inkörningsperiod.</p><p>Det har i detta arbete visats att det kommando som i Ansys tidigare använts för att kompensera för så kallade spin softening-effekter, kspin, resulterar i konservativa värden för spolens egenfrekvenser. En rekommendation baserad på de resultat som framkommit är därför att utesluta funktionen kspin i modalanalyser för denna komponent. Valet av sektorstorlek och kopplingsmetod mellan masselement och spole har också visats ha en tydlig inverkan på de beräknade egenfrekvenserna.</p><p>Spolens radiella förskjutningar har analyserats som funktion av rotationshastigheten. Resultatet visar att den hastighet då kontakt mellan tätningständer och spole etableras är nästintill identisk med den hastighet då töjningar först börjar uppträda i spolen enligt testdata från töjningsgivarprov.</p>

<p>This thesis presents a solution enabling lower losses in hydraulic actuator systems. A mobile fluid power system often contains several different actuators supplied with a single load sensing pump. One of the main advantages is the need of only one system pump. This makes the fluid power system compact and cost-effective.</p><p>A hydraulic load often consists of two ports, e.g. motors and cylinders. Such loads have traditionally been controlled by a valve that controls these ports by one single control signal, namely the position of the spool in a control valve. In this kind of valve, the inlet (meter-in) and outlet (meter-out) orifices are mechanically connected. The mechanical connection makes the system robust and easy to control, at the same time as the system lacks flexibility. Some of the main drawbacks are</p><p><strong> </strong></p><p><strong>The fixed relation </strong>between the inlet and outlet orifices in most applications produce too much throttling at the outlet orifice under most operating conditions. This makes the system inefficient.</p><p><strong> </strong></p><p><strong>The flow directions </strong>are fixed for a given spool position; therefore, no energy recuperation and/or regeneration ability is available.</p><p>In this thesis a novel system idea enabling, for example, recuperation and regeneration is presented. Recuperation is when flow is taken from a tank, pressurized by external loads, and then fed back into the pump line. Regeneration is when either cylinder chambers (or motor ports) are connected to the pump line. Only one system pump is needed. Pressure compensated (load independent), bidirectional, poppet valves are proposed and utilized.</p><p>The novel system presented in this thesis needs only a position sensor on each compensator spool. This simple sensor is also suitable for identification of mode switches, e.g. between normal, differential and regenerative modes. Patent pending.</p><p>The balance of where to put the functionality (hardware and/or software) makes it possible to manoeuvre the system with maintained speed control in the case of sensor failure. The main reason is that the novel system does not need pressure transducers for flow determination. Some features of the novel system:</p><p><strong>Mode switches </strong>The mode switches are accomplished without knowledge about the pressures in the system</p><p><strong>Throttle losses </strong>With the new system approach, choice of control and measure signals, the throttle losses at the control valves are reduced</p><p><strong>Smooth mode switches </strong>The system will switch to regenerative mode automatically in a smooth manner when possible</p><p><strong>Use energy stored in the loads </strong>The load, e.g. a cylinder, is able to be used as a motor when possible, enabling the system to recuperate overrun loads</p><p>The system and its components are described together with the control algorithms that enable energy efficient operation. Measurements from a real application are also presented in the thesis.</p>