This study characterizes the performance of a commercial in-runner brushless direct-current motor in relation to the start-up of and power generation in a hobby class gas turbine engine. A modular motor test stand is designed and implemented to create representative scenarios for engine start-up and power generation. The start-up configuration consists of the test motor driving a flywheel sized to represent the rotational components of a hobby class gas turbine engine. The power generation configuration consists of the test motor braking while being driven by another motor. The test motor can produce 0.26 Nm of torque given a maximum current of 45 A and accelerate a rotational mechanical system at approximately 800 RPM/s during transient runs in start-up testing. The test motor is also able to generate an average power of approximately 1.09 kW at 80 kRPM for 5 sec with an average system efficiency of 77.9% in power generation testing.

There is widespread interest in using pressure gain combustion in gas turbine engines to increase gas turbine engine efficiency and reduce fuel consumption. However, the fluctuating turbine inlet conditions inherent with pressure gain combustion cause a decrease in turbine efficiency. Designing a turbine for pulsing flow would counteract these losses. An optimization of turbine geometry for pulsing flow was conducted with entropy generation as the objective function. A surrogate model was used for the optimizations based on data extracted from two-dimensional computational fluid dynamics simulations. Optimizations run for different pulsing amplitudes informed a revised turbine design. The new turbine geometry was validated with a periodic, time-accurate simulation, and a decrease in entropy generation of 35% was demonstrated. The design recommendations were to weight the design of the turbine toward the peak of the pressure pulse, to consider the range of inlet angles and decrease the camber near the leading edge, and to reduce the blade turning.

Quantifying the pressure pulse severity of pressure gain combustion devices is challenging due to the wide variation in pressure pulse waveforms. A deterministic and consistent metric would be useful when describing the unsteadiness of a pressure gain combustion device, especially when integrating the device with a turbine. This paper uses data from a rotating detonation engine coupled to a turbine to compare different methods of calculating pressure pulse severity. Based on the analysis in this paper, the square root of the sum of the squares of the Fourier coefficients shows promise as a method to quantify the pressure pulse severity of pressure gain combustion devices.

One of the challenges of integrating pressure gain combustion into a gas turbine engine is that a turbine driven by pulsing flow experiences a decrease in efficiency. Computational fluid dynamic simulations validated with experiments showed that pulse amplitude is the driving factor for decreased turbine efficiency and not the pulsing frequency. A quadratic correlation between turbine efficiency and corrected pulse amplitude is presented. Incidence variation is shown to cause the change in turbine efficiency and a correlation between corrected incidence and corrected amplitude is shown to predict turbine efficiency.

Propulsion system development for Remotely Piloted Aircraft (RPA) necessitates characterization of engine performance at expected altitude operating conditions. For these purposes, an air-cycle based cooling system was designed, built, and demonstrated to simulate engine intake air temperatures at standard conditions over 20,000 ft. This system uses a commercial-off-the-shelf (COTS) turbocharger to expand compressed air supplied by facility air compressors to reach the desired temperature. Pressure is controlled using a throttle to restrict flow and an electric motor driven supercharger to reduce the engine intake and exhaust pressures to the desired testing conditions. This system is scalable for different sized engines by changing the turbocharger and supercharger used to handle the desired flow rates. This altitude system is also mobile so it can be set up in different test cells without major modifications to the facility. This approximately $50,000 system is a relatively low-cost alternative to the use of an altitude chamber which can cost around $500,000 – $1,000,000. The design and operational capabilities of this altitude simulation system are presented. System performance data with an engine operating at altitude conditions over 20,000 ft. are presented. This study will inform other engine research laboratories interested in adding altitude testing capabilities with limited space and budget.

Using un-shrouded thermocouples to measure the temperature of a working fluid can result in velocity error of up to 9◦C. However, these type of thermocouples are often used to measure temperatures in turbomachinery applications due to space and monetary constraints. Applying a recovery factor to the thermocouple reading can correct the measurement to the total temperature and reduce the velocity error by up to 83%. While some information about thermocouple recovery factors is available, it is only for a small subset of thermocouples. The method for experimentally obtaining the recovery factor is discussed. The recovery factor for grounded and exposed, /16 inch diameter, Type T, sheathed thermocouples is determined to be 0.815. This recovery factor is compared with previous research and used to effectively correct thermocouple measurements.

Modern aircraft are almost entirely powered by gas turbine engines (GTEs). Improving the e ciency is a constant topic in the GTE eld and pulse detonation engines (PDEs) are being investigated as a possible way to increase the e ciency of the modern GTE. The rst advantage lies in decreased fuel consumption since the PDE cycle consumes fuel in short bursts instead of a constant stream. The second advantage comes from the pressure rise associated with the near constant volume combustion of PDEs. A pressure rise in the combustion chamber of a GTE would decrease the number of necessary compressor stages to achieve a desired turbine inlet pressure. This in turn decreases the amount of work required to drive the compressor. The engine could be downsized or the extra work could be used to produce more thrust. The use of PDEs as a viable component of GTEs has been established experimentally both in a ight test and in the lab. In 2008, the Air Force Research Laboratory at Wright-Patterson Air Force Base used a PDE to propel an aircraft. Although not conclusive, laboratory results obtained by Rasheed et al. show that the integration of PDEs into GTEs have potential e ciency increases. Despite the potential advantages, the e ects of the pressure pulses created by pulse detonations on the turbine are not well understood. The successful integration of PDEs into GTEs requires a better understanding of turbine performance under pulsed conditions. The objective of the current work is to design a test facility to compare turbine performance under steady conditions with turbine performance under pulsed conditions. This work builds on research by previous authors who have also performed experiments to compare the performance of a PDE driven turbine with the performance of a steady ow driven turbine. Rouser et al. experimentally examined radial turbine performance under pulsed ow. The e ects of pulsed ow on axial turbines, however, is the topic addressed by this paper. Previous work on pulsed ow through an axial turbine used a mixing region to combine PDE exhaust with bypass air to mitigate the negative e ects of high temperature on the turbine. This bypass region also dampened the pressure pulse seen by the turbine. The current work uses compressed air in place of combustion gases to drive an axial turbine. The use of compressed air to create the pressure pulses allows for direct coupling of the turbine and pressure pulse, thus providing a better picture of the e ect of pulsed ow on axial turbine performance than has been accomplished in previous work.

Pulse detonation engines show potential to increase the efficiency of conventional gas turbine engines if used in place of the steady combustor. However, since the interaction of pressure pulses with the turbine is not yet well understood, we built a rig to compare steady flow with pulsing flow. Compressed air is used in place of combustion gases and pressure pulses are created by rotating a ball valve with a motor. This work accomplishes two main objectives that are different from previous research in this area. First, we compare steady flow through an axial turbine closely coupled with full annular pulsed flow. Second, the error in turbine efficiency is approximately half the error of previous research comparing steady and pulsed flow through an axial turbine. Our data shows that a turbine driven by full annular pressure pulses has operation curves that are similar in shape to steady state operation curves, but with a decrease in turbine performance that is dependent on pulsing frequency. We demonstrate that the turbine pressure ratio increases with pulsed flow through the turbine and that this increase is less for higher pulsing frequencies. For 40 Hz operation the turbine pressure ratio increases by 0.06, for 20 Hz it increases by 0.12, and for 10 Hz it increases by 0.14. We demonstrate that the peak turbine efficiency is lower for pulsed flow when compared with steady flow. The difference between steady and pulsed flow peak efficiency is less severe at higher pulsing frequencies. For 40 Hz operation the turbine efficiency decreases by 5 efficiency points, for 20 Hz it decreases by 9 points, and for 10 Hz it decreases by 11 points. We demonstrate that the specific power at a given pressure ratio for pulsed flow is lower than that of steady flow and that the decrease in specific power is lower for higher pulsing frequencies. On average, the difference in specific power between steady and pulsed flow is 0.43 kJ/kg for 40 Hz, 1.40 kJ/kg for 20 Hz, and 1.91 kJ/kg for 10 Hz.

Nanoinjection is an innovative approach for the electromechanical injection of DNA into cells, in which DNA is electrically attracted to a lance, inserted into a cell, and repelled by reversing the electrical polarity. In previous work, the lance has been micromachined as part of an on-chip microelectromechanical system. This work investigates a Stand-Alone Lance concept, where the lance and other components are independent of a common substrate. The Stand-Alone Lance may make nanoinjection more accessible to researchers and be more compatible with lab equipment commonly available in transgenic facilities. Required parameters for the electrode are investigated using a mathematical computer model. Different materials and fabrication processes for the metal lance are also considered. Additional testing was performed using tungsten probes, including mock injections on mouse egg cells. Based upon the optimistic cell viability rate, it is recommended to further investigate the use of the Stand-Alone Lance to perform nanoinjections.

§** An experimental study is conducted to investigate matching USAF Group I/II RPA propeller performance to an engine map and RPA mission to maximize efficiency and range. Performance characterization of the Fuji Imvac BF-34EI engine is presented. Propeller performance is characterized for 28 commercial-off-the-shelf (COTS) propellers in a vertical wind tunnel using a pneumatic motor to drive the propeller. Propeller thrust, torque, and rotational speed are measured at different forward velocities to characterize propeller efficiency. An uncertainty analysis at a characteristic point is conducted for the measured values and is found to be 3.9%. RPA mission profile requirements are presented. A method to compare different propellers is presented. Propellers are first sorted and downselected by required rate of climb (ROC) for RPA take-off/climb-out conditions. The remaining propellers are then further downselected based on minimizing fuel consumption for RPA cruise conditions. It is discovered that performance differences can occur even between propellers of the same nominal size but from different manufacturers. Of the limited number of propellers characterized in this study, the APC C2 17x10, Top Flight PP 18x12, and APC C3 22x10 are determined to be the best matched COTS propellers in their respective diameter classes to the Fuji Imvac BF-34EI. The data used in the selection process and more detailed data for the three aforementioned propellers is presented. Propeller data for each of the three propellers is overlaid on a typical USAF Group I/II RPA engine map. Even among propellers of the same diameter, mission duration can be extended as much as 100 miles (20%) by selecting the optimal propeller for a given engine.

Effect of Full-Annular Pressure Pulses on Axial Turbine Performance Mark H. Fernelius Department of Mechanical Engineering, BYU Master of Science Pulse detonation engines show potential to increase the efficiency of conventional gas turbine engines if used in place of the steady combustor. However, since the interaction of pressure pulses with the turbine is not yet well understood, a rig was built to compare steady flow with pulsing flow. Compressed air is used in place of combustion gases and pressure pulses are created by rotating a ball valve with a motor. This work accomplishes two main objectives that are different from previous research in this area. First, steady flow through an axial turbine is compared with full annular pulsed flow closely coupled with the turbine. Second, the error in turbine efficiency is approximately half the error of previous research comparing steady and pulsed flow through an axial turbine. The data shows that a turbine driven by full annular pressure pulses has operation curves that are similar in shape to steady state operation curves, but with a decrease in turbine performance that is dependent on pulsing frequency. It is demonstrated that the turbine pressure ratio increases with pulsed flow through the turbine and that this increase is less for higher pulsing frequencies. For 10 Hz operation the turbine pressure ratio increases by 0.14, for 20 Hz it increases by 0.12, and for 40 Hz it increases by 0.06. It is demonstrated that the peak turbine efficiency is lower for pulsed flow when compared with steady flow. The difference between steady and pulsed flow peak efficiency is less severe at higher pulsing frequencies. For 40 Hz operation the turbine efficiency decreases by 5 efficiency points, for 20 Hz it decreases by 9 points, and for 10 Hz it decreases by 11 points. It is demonstrated that the specific power at a given pressure ratio for pulsed flow is lower than that of steady flow and that the decrease in specific power is lower for higher pulsing frequencies. On average, the difference in specific power between steady and pulsed flow is 0.43 kJ/kg for 40 Hz, 1.40 kJ/kg for 20 Hz, and 1.91 kJ/kg for 10 Hz.