This study investigates the stress wave force balance technique for the measurement of forces on a fuelled hypersonic flight vehicle in an impulse-type test facility. A three component force balance for the measurement of lift, thrust and pitching moment on a supersonic combustion ramjet engine was designed, built, calibrated and tested. The force balance was designed using finite element analysis and consisted of four stress bars instrumented for the measurement of strain. Relative errors of less than 2% were obtained for the recovered simulated calibration loads, while errors of less than 3% were obtained for lift and thrust components for simulated fuel-on and fuel-off force loading distributions. Tests in a calibration rig showed that the balance was capable of recovering the magnitude of point loads to within 3% and their lines of action to within 1% of the chord of the model. Additional errors result when testing in a wind tunnel. The uncertainties for the experiments with fuel injection are estimated at 9%, 7% and 9% for the coefficients of lift, thrust and pitching moment. The scramjet vehicle was 0.566m long and weighed approximately 6kg. It consisted of an inlet, combustion chamber and thrust surface. Fuel could be injected through a series of injectors located on the scramjet inlet. The scramjet model was set at zero angle of attack. Experiments were performed in the T4 Free Piston Shock Tunnel at a total enthalpy of 3.3MJ/kg, a nozzle supply pressure of 32MPa and a Mach number of 6.6, with equivalence ratios up to 1.4. Fuel-off force coefficients were measured to within 2% of theoretical values based on predictions using CFD and hypersonic theory. The fuel-off centre-of-pressure was measured to within 4% of the predicted value. The force coefficients varied linearly with equivalence ratio. Good comparison of the measured lift and thrust forces with theoretical values was obtained with increasing flow rates of fuel. The lift-to-drag ratio increased from 3.0 at the fuel-off condition to 17.2 at an equivalence ratio of 1.0. Poor agreement between the measured pitching moment and theoretical values was obtained due to difficulties in predicting the pressure distribution with heat addition on the latter parts of the thrust surface. A shift in the centre-of-pressure of approximately 10% of model chord was measured as the equivalence ratio varied from 0.0 to 1.0. For the design tested, the thrust produced was not enough to overcome drag on the vehicle, even at the highest equivalence ratio tested. Tests at higher stagnation enthalpies (up to 4.9MJ/kg) showed the lift and pitching moment coefficients remained constant with an equivalence ratio of 0.8 but the thrust coefficient decreased exponentially with increasing stagnation enthalpies. Good agreement of experimental values of lift and thrust force with predicted values was obtained for equivalence ratios of 0.0 and 0.8. Choking occurred at stagnation enthalpies of less than 3.0MJ/kg and a nozzle supply pressure of 32MPa with fuel injection at an equivalence ratio of approximately 0.8, resulting in a drag force of approximately 2.5 times the fuel-off drag force. Tests at a nozzle supply enthalpy of 3.3MJ/kg and nozzle supply pressures of 32, 26 and 16MPa were performed at equivalence ratios of 0.0 and 0.8. The fuel-off lift coefficient remained constant but the thrust coefficient increased. This is attributed to a reduction in skin friction associated with longer lengths of laminar boundary layers as the Reynolds number was decreased. The measured fuel-off lift and thrust coefficients agreed with the predicted values to within the known test flow and force prediction uncertainties. Combustion did not occur at a nozzle supply pressure of 16MPa. This work has demonstrated that overall scramjet vehicle performance measurements (such as lift-to-drag ratio and shifts in centre-of-pressure) can be made in a free piston shock tunnel.

This study investigates the stress wave force balance technique for the measurement of forces on a fuelled hypersonic flight vehicle in an impulse-type test facility. A three component force balance for the measurement of lift, thrust and pitching moment on a supersonic combustion ramjet engine was designed, built, calibrated and tested. The force balance was designed using finite element analysis and consisted of four stress bars instrumented for the measurement of strain. Relative errors of less than 2% were obtained for the recovered simulated calibration loads, while errors of less than 3% were obtained for lift and thrust components for simulated fuel-on and fuel-off force loading distributions. Tests in a calibration rig showed that the balance was capable of recovering the magnitude of point loads to within 3% and their lines of action to within 1% of the chord of the model. Additional errors result when testing in a wind tunnel. The uncertainties for the experiments with fuel injection are estimated at 9%, 7% and 9% for the coefficients of lift, thrust and pitching moment. The scramjet vehicle was 0.566m long and weighed approximately 6kg. It consisted of an inlet, combustion chamber and thrust surface. Fuel could be injected through a series of injectors located on the scramjet inlet. The scramjet model was set at zero angle of attack. Experiments were performed in the T4 Free Piston Shock Tunnel at a total enthalpy of 3.3MJ/kg, a nozzle supply pressure of 32MPa and a Mach number of 6.6, with equivalence ratios up to 1.4. Fuel-off force coefficients were measured to within 2% of theoretical values based on predictions using CFD and hypersonic theory. The fuel-off centre-of-pressure was measured to within 4% of the predicted value. The force coefficients varied linearly with equivalence ratio. Good comparison of the measured lift and thrust forces with theoretical values was obtained with increasing flow rates of fuel. The lift-to-drag ratio increased from 3.0 at the fuel-off condition to 17.2 at an equivalence ratio of 1.0. Poor agreement between the measured pitching moment and theoretical values was obtained due to difficulties in predicting the pressure distribution with heat addition on the latter parts of the thrust surface. A shift in the centre-of-pressure of approximately 10% of model chord was measured as the equivalence ratio varied from 0.0 to 1.0. For the design tested, the thrust produced was not enough to overcome drag on the vehicle, even at the highest equivalence ratio tested. Tests at higher stagnation enthalpies (up to 4.9MJ/kg) showed the lift and pitching moment coefficients remained constant with an equivalence ratio of 0.8 but the thrust coefficient decreased exponentially with increasing stagnation enthalpies. Good agreement of experimental values of lift and thrust force with predicted values was obtained for equivalence ratios of 0.0 and 0.8. Choking occurred at stagnation enthalpies of less than 3.0MJ/kg and a nozzle supply pressure of 32MPa with fuel injection at an equivalence ratio of approximately 0.8, resulting in a drag force of approximately 2.5 times the fuel-off drag force. Tests at a nozzle supply enthalpy of 3.3MJ/kg and nozzle supply pressures of 32, 26 and 16MPa were performed at equivalence ratios of 0.0 and 0.8. The fuel-off lift coefficient remained constant but the thrust coefficient increased. This is attributed to a reduction in skin friction associated with longer lengths of laminar boundary layers as the Reynolds number was decreased. The measured fuel-off lift and thrust coefficients agreed with the predicted values to within the known test flow and force prediction uncertainties. Combustion did not occur at a nozzle supply pressure of 16MPa. This work has demonstrated that overall scramjet vehicle performance measurements (such as lift-to-drag ratio and shifts in centre-of-pressure) can be made in a free piston shock tunnel.

This study investigates the stress wave force balance technique for the measurement of forces on a fuelled hypersonic flight vehicle in an impulse-type test facility. A three component force balance for the measurement of lift, thrust and pitching moment on a supersonic combustion ramjet engine was designed, built, calibrated and tested. The force balance was designed using finite element analysis and consisted of four stress bars instrumented for the measurement of strain. Relative errors of less than 2% were obtained for the recovered simulated calibration loads, while errors of less than 3% were obtained for lift and thrust components for simulated fuel-on and fuel-off force loading distributions. Tests in a calibration rig showed that the balance was capable of recovering the magnitude of point loads to within 3% and their lines of action to within 1% of the chord of the model. Additional errors result when testing in a wind tunnel. The uncertainties for the experiments with fuel injection are estimated at 9%, 7% and 9% for the coefficients of lift, thrust and pitching moment. The scramjet vehicle was 0.566m long and weighed approximately 6kg. It consisted of an inlet, combustion chamber and thrust surface. Fuel could be injected through a series of injectors located on the scramjet inlet. The scramjet model was set at zero angle of attack. Experiments were performed in the T4 Free Piston Shock Tunnel at a total enthalpy of 3.3MJ/kg, a nozzle supply pressure of 32MPa and a Mach number of 6.6, with equivalence ratios up to 1.4. Fuel-off force coefficients were measured to within 2% of theoretical values based on predictions using CFD and hypersonic theory. The fuel-off centre-of-pressure was measured to within 4% of the predicted value. The force coefficients varied linearly with equivalence ratio. Good comparison of the measured lift and thrust forces with theoretical values was obtained with increasing flow rates of fuel. The lift-to-drag ratio increased from 3.0 at the fuel-off condition to 17.2 at an equivalence ratio of 1.0. Poor agreement between the measured pitching moment and theoretical values was obtained due to difficulties in predicting the pressure distribution with heat addition on the latter parts of the thrust surface. A shift in the centre-of-pressure of approximately 10% of model chord was measured as the equivalence ratio varied from 0.0 to 1.0. For the design tested, the thrust produced was not enough to overcome drag on the vehicle, even at the highest equivalence ratio tested. Tests at higher stagnation enthalpies (up to 4.9MJ/kg) showed the lift and pitching moment coefficients remained constant with an equivalence ratio of 0.8 but the thrust coefficient decreased exponentially with increasing stagnation enthalpies. Good agreement of experimental values of lift and thrust force with predicted values was obtained for equivalence ratios of 0.0 and 0.8. Choking occurred at stagnation enthalpies of less than 3.0MJ/kg and a nozzle supply pressure of 32MPa with fuel injection at an equivalence ratio of approximately 0.8, resulting in a drag force of approximately 2.5 times the fuel-off drag force. Tests at a nozzle supply enthalpy of 3.3MJ/kg and nozzle supply pressures of 32, 26 and 16MPa were performed at equivalence ratios of 0.0 and 0.8. The fuel-off lift coefficient remained constant but the thrust coefficient increased. This is attributed to a reduction in skin friction associated with longer lengths of laminar boundary layers as the Reynolds number was decreased. The measured fuel-off lift and thrust coefficients agreed with the predicted values to within the known test flow and force prediction uncertainties. Combustion did not occur at a nozzle supply pressure of 16MPa. This work has demonstrated that overall scramjet vehicle performance measurements (such as lift-to-drag ratio and shifts in centre-of-pressure) can be made in a free piston shock tunnel.

This study investigates the stress wave force balance technique for the measurement of forces on a fuelled hypersonic flight vehicle in an impulse-type test facility. A three component force balance for the measurement of lift, thrust and pitching moment on a supersonic combustion ramjet engine was designed, built, calibrated and tested. The force balance was designed using finite element analysis and consisted of four stress bars instrumented for the measurement of strain. Relative errors of less than 2% were obtained for the recovered simulated calibration loads, while errors of less than 3% were obtained for lift and thrust components for simulated fuel-on and fuel-off force loading distributions. Tests in a calibration rig showed that the balance was capable of recovering the magnitude of point loads to within 3% and their lines of action to within 1% of the chord of the model. Additional errors result when testing in a wind tunnel. The uncertainties for the experiments with fuel injection are estimated at 9%, 7% and 9% for the coefficients of lift, thrust and pitching moment. The scramjet vehicle was 0.566m long and weighed approximately 6kg. It consisted of an inlet, combustion chamber and thrust surface. Fuel could be injected through a series of injectors located on the scramjet inlet. The scramjet model was set at zero angle of attack. Experiments were performed in the T4 Free Piston Shock Tunnel at a total enthalpy of 3.3MJ/kg, a nozzle supply pressure of 32MPa and a Mach number of 6.6, with equivalence ratios up to 1.4. Fuel-off force coefficients were measured to within 2% of theoretical values based on predictions using CFD and hypersonic theory. The fuel-off centre-of-pressure was measured to within 4% of the predicted value. The force coefficients varied linearly with equivalence ratio. Good comparison of the measured lift and thrust forces with theoretical values was obtained with increasing flow rates of fuel. The lift-to-drag ratio increased from 3.0 at the fuel-off condition to 17.2 at an equivalence ratio of 1.0. Poor agreement between the measured pitching moment and theoretical values was obtained due to difficulties in predicting the pressure distribution with heat addition on the latter parts of the thrust surface. A shift in the centre-of-pressure of approximately 10% of model chord was measured as the equivalence ratio varied from 0.0 to 1.0. For the design tested, the thrust produced was not enough to overcome drag on the vehicle, even at the highest equivalence ratio tested. Tests at higher stagnation enthalpies (up to 4.9MJ/kg) showed the lift and pitching moment coefficients remained constant with an equivalence ratio of 0.8 but the thrust coefficient decreased exponentially with increasing stagnation enthalpies. Good agreement of experimental values of lift and thrust force with predicted values was obtained for equivalence ratios of 0.0 and 0.8. Choking occurred at stagnation enthalpies of less than 3.0MJ/kg and a nozzle supply pressure of 32MPa with fuel injection at an equivalence ratio of approximately 0.8, resulting in a drag force of approximately 2.5 times the fuel-off drag force. Tests at a nozzle supply enthalpy of 3.3MJ/kg and nozzle supply pressures of 32, 26 and 16MPa were performed at equivalence ratios of 0.0 and 0.8. The fuel-off lift coefficient remained constant but the thrust coefficient increased. This is attributed to a reduction in skin friction associated with longer lengths of laminar boundary layers as the Reynolds number was decreased. The measured fuel-off lift and thrust coefficients agreed with the predicted values to within the known test flow and force prediction uncertainties. Combustion did not occur at a nozzle supply pressure of 16MPa. This work has demonstrated that overall scramjet vehicle performance measurements (such as lift-to-drag ratio and shifts in centre-of-pressure) can be made in a free piston shock tunnel.

Made available in DSpace on 2014-06-11T19:28:34Z (GMT). No. of bitstreams: 0 Previous issue date: 2006-01Bitstream added on 2014-06-13T18:57:57Z : No. of bitstreams: 1 muta_hs_me_guara.pdf: 492160 bytes, checksum: c31427e991b74ee256fe65b5d34cc2ce (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Na fisioterapia existem procedimentos que dependem da percepção manual do fisioterapeuta por estarem relacionados à aplicação de forças graduadas. Alguns estudos demonstraram que há uma grande dificuldade na percepção da força, ocorrendo grande variabilidade em sua aplicação. O objetivo deste estudo foi desenvolver um equipamento portátil para a medida de forças aplicadas por fisioterapeutas durante a realização da técnica de pressão póstero anterior central na coluna lombar e analisar alguns parâmetros envolvidos no método de mobilização articular. Houve variabilidade na forma de aplicação das cargas em diferentes aspectos. Dessa forma, podemos demonstrar com esses resultados, que a percepção manual do fisioterapeuta durante a realização da técnica de pressão póstero anterior central não foi tão precisa comparando os valores estimados com os valores das cargas aplicadas durante o intervalo de coleta. / In Physical Therapy there are some procedures that depend on manual sensibility of physical therapist because that involves graded forces. Some studies have shown that there is a great difficulty in the perception of the force, occuring great variability on the application. The purpose of this study is to develop a portable device to measure the forces applied by physical therapists during the procedure of posteroanterior central pressure in the lumbar spine and to analyze some parameter involved in the method of articular mobilization. There was variability in application of the technique in many ways. Therefore, we can show with these results that the manual sensibility of the physical therapists during the application of the posteroanterior central pressure technique wasnþt accurate comparing the estimated values to the actual results obtained during the experiment interval of time.

No description available.

The longitudinal forces generated from the Friction Stir Welding process are substantial. An understanding of these forces is critical to proper tool design. This study describes a technique to measure the longitudinal force distribution on a friction stir weld pin tool. Total longitudinal forces were recorded on a dynamometer while welding 6061 aluminum with non-threaded pins that varied in length and diameter. A model was developed that characterizes pin force as a function of pin length and diameter. Results suggest that force generally increases with pin length, while forces remain relatively constant with pin diameter. Unexpected force variation was found at large pin lengths, which yielded several possible models of the force distribution. All of the modeled force distributions proved to be non-uniform and increase linearly with pin length, which produces a pin force that increases with the square of the pin length.

No description available.

Control of radiated acoustic noise is vital to the survivability and the detectability of submersible watercraft. Two primary sources of radiated fluid noise in submersible vessels are the boundary layer turbulence along the forebody and propulsor fluid-structure interaction. The propulsor contains several locations of such interaction, one of which was investigated in this research. Specifically, this research focused on experimentally investigating active flow control techniques to reduce rotor-stator interaction noise sources. Two of the three flow control configurations applied to the flow involved the application of active flow control to the leading edge of a single exit guide vane (EGV) mounted downstream of a seven-bladed rotor. The leading edge blowing configuration (LEB) consisted of a single jet expelled from the leading edge of the EGV against the oncoming flow. This interaction between the wake and jet should offset or disrupt the coherency of any incoming flow structures. The second active flow control method applied to the EGV involved a tangential blowing configuration (TB) where two symmetric tangential jets were used to create an insulating fluid layer that reduced the effect of passing flow structures on the EGV. The final flow control design was the implementation of trailing edge wake filling on a three bladed rotor. A rotor was designed to ingest lower velocity flow from the hub and pump the fluid out of a blowing slot at the blade trailing edge. The blowing slot was concentrated on the outer third of the blade span in order to maximize pumping effect. In order to quantify the effects of the active flow control techniques on rotor-stator interaction, the fluctuating lift force on the EGV was measured. Since this fluctuating force serves as a primary acoustic source, the effects of the active flow control on the radiated interaction sound can be estimated. These active flow control techniques were intended for reduction of blade passing frequency tonal sound radiation. The LEB configuration showed minor changes in overall spectral response; however, there was no significant reduction in forcing at the BPF measured. Similarly the TB configuration also yielded no measurable change in BPF tonal forcing. The first generation design of the self-pumping rotor also proved to have problems. Experiments showed that the application of the flow control on the self-pumping rotor did not generate the expected increase in torque demand or changes in the tonal forcing on the EGV. Field alterations to the rotor were unable to improve the performance; therefore, the conclusion became that the initial design was unable to pump fluid due to excessive pressure losses. Further design iterations are required to perfect the functionality of the self-pumping rotor. / Master of Science

Polymer nanofibers are gaining importance due to their wide applicability in diverse fields, such as tissue engineering, fuel cells, photonics and sensors. For these applications, manufacturing aligned polymer nanofibers with precisely controlled morphology and well characterized mechanical properties in a bottom up configuration is essential. In this work, we developed an isodiametric design space for fabrication of aligned polystyrene nanofibers (diameter 60-800nm) using non-electrospinning Spinneret based Tunable Engineered Parameter (STEP) technique. By adjusting the processing parameters such as relative humidity, solvent volatility and polarity, porous polymer tubes are demonstrated having large specific surface areas. Combining STEP with sol-gel process, aligned inorganic nanofibers, such as Titanium Oxide (TiO2) with varied morphologies can be conveniently obtained. Mechanical properties of aligned polymer nanofibers (diameter from 50nm to several hundred nanometers) with fixed-fixed boundary conditions were estimated using a lateral force microscope (LFM). We find that the tension in the fiber caused during fabrication process scales with fiber diameter and it dominates fiber stiffness. Our studies demonstrate isotropic arrangement of polymer chains in the fibers and anisotropic arrangement in the necking region for fibers undergone deformation. Finally, this study demonstrates development of force sensors capable of measuring single cell forces, which scale with the fiber structural stiffness. The ability to measure cell forces during cell division, migration and apoptosis provides new insights in cell mechanobiology. / Ph. D.