Matching Items (15)
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- All Subjects: Aerospace Engineering
- Creators: Dahm, Werner
Description
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.
ContributorsMartinjako, Jeremy (Author) / Trimble, Steve (Thesis advisor) / Dahm, Werner (Committee member) / Middleton, James (Committee member) / Arizona State University (Publisher)
Created2014
Description
This thesis uses an aircraft aerodynamic model and propulsion data, which
represents a configuration similar to the Airbus A320, to perform trade studies to understand the weight and configuration effects of “out-of-trim” flight during takeoff, cruise, initial approach, and balked landing. It is found that flying an aircraft slightly above the angle of attack or pitch angle required for a trimmed, stabilized flight will cause the aircraft to lose speed rapidly. This effect is most noticeable for lighter aircraft and when one engine is rendered inoperative. In the event of an engine failure, if the pilot does not pitch the nose of the aircraft down quickly, speed losses are significant and potentially lead to stalling the aircraft. Even when the risk of stalling the aircraft is small, the implications on aircraft climb performance, obstacle clearance, and acceleration distances can still become problematic if the aircraft is not flown properly. When the aircraft is slightly above the trimmed angle of attack, the response is shown to closely follow the classical phugoid response where the aircraft will trade speed and altitude in an oscillatory manner. However, when the pitch angle is slightly above the trimmed condition, the aircraft does not show this phugoid pattern but instead just loses speed until it reaches a new stabilized trajectory, never having speed and altitude oscillate. In this event, the way a pilot should respond to both events is different and may cause confusion in the cockpit.
represents a configuration similar to the Airbus A320, to perform trade studies to understand the weight and configuration effects of “out-of-trim” flight during takeoff, cruise, initial approach, and balked landing. It is found that flying an aircraft slightly above the angle of attack or pitch angle required for a trimmed, stabilized flight will cause the aircraft to lose speed rapidly. This effect is most noticeable for lighter aircraft and when one engine is rendered inoperative. In the event of an engine failure, if the pilot does not pitch the nose of the aircraft down quickly, speed losses are significant and potentially lead to stalling the aircraft. Even when the risk of stalling the aircraft is small, the implications on aircraft climb performance, obstacle clearance, and acceleration distances can still become problematic if the aircraft is not flown properly. When the aircraft is slightly above the trimmed angle of attack, the response is shown to closely follow the classical phugoid response where the aircraft will trade speed and altitude in an oscillatory manner. However, when the pitch angle is slightly above the trimmed condition, the aircraft does not show this phugoid pattern but instead just loses speed until it reaches a new stabilized trajectory, never having speed and altitude oscillate. In this event, the way a pilot should respond to both events is different and may cause confusion in the cockpit.
ContributorsDelisle, Mathew Robert (Author) / Takahashi, Timothy (Thesis advisor) / White, Daniel (Committee member) / Niemczyk, Mary (Committee member) / Arizona State University (Publisher)
Created2018
Description
Two methods of improving the life and efficiency of the Pulsed Inductive Thruster
(PIT) have been investigated. The first is a trade study of available switches to
determine the best device to implement in the PIT design. The second is the design
of a coil to improve coupling between the accelerator coil and the plasma. Experiments
were done with both permanent and electromagnets to investigate the feasibility of
implementing a modified Halbach array within the PIT to promote better plasma
coupling and decrease the unused space within the thruster. This array proved to
promote more complete coupling on the edges of the coil where it had been weak in
previous studies. Numerical analysis was done to predict the performance of a PIT
that utilized each suggested switch type. This model utilized the Alfven velocity to
determine the critical mass and energy of these theoretical thrusters.
(PIT) have been investigated. The first is a trade study of available switches to
determine the best device to implement in the PIT design. The second is the design
of a coil to improve coupling between the accelerator coil and the plasma. Experiments
were done with both permanent and electromagnets to investigate the feasibility of
implementing a modified Halbach array within the PIT to promote better plasma
coupling and decrease the unused space within the thruster. This array proved to
promote more complete coupling on the edges of the coil where it had been weak in
previous studies. Numerical analysis was done to predict the performance of a PIT
that utilized each suggested switch type. This model utilized the Alfven velocity to
determine the critical mass and energy of these theoretical thrusters.
ContributorsRaines, Taylor (Author) / Takahashi, Timothy T (Thesis advisor) / White, Daniel B (Committee member) / Dahm, Werner (Committee member) / Arizona State University (Publisher)
Created2018
Description
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.
ContributorsBurgett, Luke Michael (Author) / Takahashi, Timothy (Thesis advisor) / Dahm, Werner (Committee member) / Trimble, Steve (Committee member) / Arizona State University (Publisher)
Created2019
Description
In this analysis, materials capable of being 3D printed such as acrylonitrile-butadiene styrene (ABS), polyethylene terephthalate-glycol (PETG), and polylactic acid (PLA) were analyzed mathematically to determine their potential application as a fuel source for a hybrid rocket engine currently being developed by Daedalus Astronautics. By developing a 3D printed fuel option, new fuel grain geometries can be manufactured and tested that have the potential to greatly improve regression and flow characteristics of hybrid rockets. In addition, 3D printed grains have been shown to greatly reduce manufacturing time while improving grain-to-grain consistency. In the end, it was found that ABS, although the most difficult material to work with, would likely provide the best results as compared to an HTPB baseline. This is because after conducting a heat conservation analysis similar to that employed by NASA's chemical equilibrium with applications code (CEA), ABS was shown to operate at similarly high levels of specific impulse at approximately the same oxidizer-to-fuel ratio, meaning the current Daedalus test setup for HTPB would be applicable to ABS. In addition, PLA was found to require a far lower oxidizer-to-fuel ratio to achieve peak specific impulse than any of the other fuels analyzed leading to the conclusion that in a flight-ready engine it would likely require less oxidizer and pressurization mass, and therefore, less overall system mass, to achieve thrust levels similar to ABS and HTPB. By improving the thrust-to-weight ratio in this way a more efficient engine could be developed. Following these results, future works will include the hot-fire testing of the four fuel options to verify the analysis method used. Additionally, the ground work has been set for future analysis and development of complex fuel port geometries which have been shown to further improve flight characteristics.
ContributorsWinsryg, Benjamin Rolf (Author) / White, Daniel (Thesis director) / Brunacini, Lauren (Committee member) / Mechanical and Aerospace Engineering Program (Contributor, Contributor) / Barrett, The Honors College (Contributor)
Created2017-05
Description
There are many computer aided engineering tools and software used by aerospace engineers to design and predict specific parameters of an airplane. These tools help a design engineer predict and calculate such parameters such as lift, drag, pitching moment, takeoff range, maximum takeoff weight, maximum flight range and much more. However, there are very limited ways to predict and calculate the minimum control speeds of an airplane in engine inoperative flight. There are simple solutions, as well as complicated solutions, yet there is neither standard technique nor consistency throughout the aerospace industry. To further complicate this subject, airplane designers have the option of using an Automatic Thrust Control System (ATCS), which directly alters the minimum control speeds of an airplane.
This work addresses this issue with a tool used to predict and calculate the Minimum Control Speed on the Ground (VMCG) as well as the Minimum Control Airspeed (VMCA) of any existing or design-stage airplane. With simple line art of an airplane, a program called VORLAX is used to generate an aerodynamic database used to calculate the stability derivatives of an airplane. Using another program called Numerical Propulsion System Simulation (NPSS), a propulsion database is generated to use with the aerodynamic database to calculate both VMCG and VMCA.
This tool was tested using two airplanes, the Airbus A320 and the Lockheed Martin C130J-30 Super Hercules. The A320 does not use an Automatic Thrust Control System (ATCS), whereas the C130J-30 does use an ATCS. The tool was able to properly calculate and match known values of VMCG and VMCA for both of the airplanes. The fact that this tool was able to calculate the known values of VMCG and VMCA for both airplanes means that this tool would be able to predict the VMCG and VMCA of an airplane in the preliminary stages of design. This would allow design engineers the ability to use an Automatic Thrust Control System (ATCS) as part of the design of an airplane and still have the ability to predict the VMCG and VMCA of the airplane.
This work addresses this issue with a tool used to predict and calculate the Minimum Control Speed on the Ground (VMCG) as well as the Minimum Control Airspeed (VMCA) of any existing or design-stage airplane. With simple line art of an airplane, a program called VORLAX is used to generate an aerodynamic database used to calculate the stability derivatives of an airplane. Using another program called Numerical Propulsion System Simulation (NPSS), a propulsion database is generated to use with the aerodynamic database to calculate both VMCG and VMCA.
This tool was tested using two airplanes, the Airbus A320 and the Lockheed Martin C130J-30 Super Hercules. The A320 does not use an Automatic Thrust Control System (ATCS), whereas the C130J-30 does use an ATCS. The tool was able to properly calculate and match known values of VMCG and VMCA for both of the airplanes. The fact that this tool was able to calculate the known values of VMCG and VMCA for both airplanes means that this tool would be able to predict the VMCG and VMCA of an airplane in the preliminary stages of design. This would allow design engineers the ability to use an Automatic Thrust Control System (ATCS) as part of the design of an airplane and still have the ability to predict the VMCG and VMCA of the airplane.
ContributorsHadder, Eric Michael (Author) / Takahashi, Timothy (Thesis advisor) / Mignolet, Marc (Committee member) / White, Daniel (Committee member) / Arizona State University (Publisher)
Created2016
Description
The aerospike nozzle belongs to the class of altitude compensating nozzles making it a strong candidate for Space Shuttle Main Engines. Owing to their higher efficiency compared to conventional bell nozzles, the aerospike nozzles are being studied extensively and are being used for many Single State to Orbit (SSTO) designs. A rocket engine nozzle with altitude compensation, such as the aerospike, consumes less fuel than a rocket engine with a bell nozzle. Aerospike nozzles are huge and are often difficult to construct and have to be truncated in order to make them feasible for application in a rocket propulsion system. Consequently, truncation of the aerospike leads to pressure loss under the base, which in-turn decreases the overall thrust produced by the rocket nozzle. To overcome this loss, a technique called base bleed is implemented in which a secondary jet is made to flow through the base of the truncated portion. This thesis uses dynamic pressure contour plots to find out the ideal base bleed mass flow rate to avoid base recirculation in 10 %, 20 % and 30 % truncated aerospike nozzles.
ContributorsNagarajan, Venkatraman (Author) / White, Daniel B (Thesis advisor) / Dahm, Werner (Thesis advisor) / Huang, Huei-Ping (Committee member) / Arizona State University (Publisher)
Created2017
Description
To ensure safety is not precluded in the event of an engine failure, the FAA has
established climb gradient minimums enforced through Federal Regulations.
Furthermore, to ensure aircraft do not accidentally impact an obstacle on takeoff due to
insufficient climb performance, standard instrument departure procedures have their own
set of climb gradient minimums which are typically more than those set by Federal
Regulation. This inconsistency between climb gradient expectations creates an obstacle
clearance problem: while the aircraft has enough climb gradient in the engine inoperative
condition so that basic flight safety is not precluded, this climb gradient is often not
strong enough to overfly real obstacles; this implies that the pilot must abort the takeoff
flight path and reverse course back to the departure airport to perform an emergency
landing. One solution to this is to reduce the dispatch weight to ensure that the aircraft
retains enough climb performance in the engine inoperative condition, but this comes at
the cost of reduced per-flight profits.
An alternative solution to this problem is the extended second segment (E2S)
climb. Proposed by Bays & Halpin, they found that a C-130H gained additional obstacle
clearance performance through this simple operational change. A thorough investigation
into this technique was performed to see if this technique can be applied to commercial
aviation by using a model A320 and simulating multiple takeoff flight paths in either a
calm or constant wind condition. A comparison of takeoff flight profiles against real
world departure procedures shows that the E2S climb technique offers a clear obstacle
clearance advantage which a scheduled four-segment flight profile cannot provide.
established climb gradient minimums enforced through Federal Regulations.
Furthermore, to ensure aircraft do not accidentally impact an obstacle on takeoff due to
insufficient climb performance, standard instrument departure procedures have their own
set of climb gradient minimums which are typically more than those set by Federal
Regulation. This inconsistency between climb gradient expectations creates an obstacle
clearance problem: while the aircraft has enough climb gradient in the engine inoperative
condition so that basic flight safety is not precluded, this climb gradient is often not
strong enough to overfly real obstacles; this implies that the pilot must abort the takeoff
flight path and reverse course back to the departure airport to perform an emergency
landing. One solution to this is to reduce the dispatch weight to ensure that the aircraft
retains enough climb performance in the engine inoperative condition, but this comes at
the cost of reduced per-flight profits.
An alternative solution to this problem is the extended second segment (E2S)
climb. Proposed by Bays & Halpin, they found that a C-130H gained additional obstacle
clearance performance through this simple operational change. A thorough investigation
into this technique was performed to see if this technique can be applied to commercial
aviation by using a model A320 and simulating multiple takeoff flight paths in either a
calm or constant wind condition. A comparison of takeoff flight profiles against real
world departure procedures shows that the E2S climb technique offers a clear obstacle
clearance advantage which a scheduled four-segment flight profile cannot provide.
ContributorsBeard, John Eng Hui (Author) / Takahashi, Timothy T (Thesis advisor) / White, Daniel (Committee member) / Niemczyk, Mary (Committee member) / Arizona State University (Publisher)
Created2017
Description
This thesis describes the extension of an aircraft-style time-step integrating mission performance simulation to address aero-spaceplane design challenges. The result is a computationally lean program compatible with current Multi-Disciplinary Optimization schemes to assist in the conceptual design of hypersonic vehicles. To do this the starting aircraft style “Mission Code” required enhancements to the typical point-mass simulation for high altitude and high Mach flight. Stability parameters and the rigid-body modes of Short-Period and Dutch-Roll are tracked to understand time-domain limits to aerodynamic control, along with monitoring the Lateral Control Departure Parameter to ensure that the aircraft is not prone to spin. Additionally, experience has shown that for high Mach Number flight designers must consider aerothermodynamic effects early in the vehicle design process, and thus, an engineering level aerothermodynamic model is included. Comparisons to North American X-15 flight test datasets demonstrate the validity of this method in that application, and trade studies conducted show the utility of this application.
ContributorsGriffin, Jack Aidan (Author) / Takahashi, Timothy (Thesis advisor) / Dahm, Werner (Committee member) / Rodi, Patrick (Committee member) / Arizona State University (Publisher)
Created2022
Description
The Doghouse Plot visually represents an aircraft’s performance during combined turn-climb maneuvers. The Doghouse Plot completely describes the turn-climb capability of an aircraft; a single plot demonstrates the relationship between climb performance, turn rate, turn radius, stall margin, and bank angle. Using NASA legacy codes, Empirical Drag Estimation Technique (EDET) and Numerical Propulsion System Simulation (NPSS), it is possible to reverse engineer sufficient basis data for commercial and military aircraft to construct Doghouse Plots. Engineers and operators can then use these to assess their aircraft’s full performance envelope. The insight gained from these plots can broaden the understanding of an aircraft’s performance and, in turn, broaden the operational scope of some aircraft that would otherwise be limited by the simplifications found in their Airplane Flight Manuals (AFM). More importantly, these plots can build on the current standards of obstacle avoidance and expose risks in operation.
ContributorsWilson, John Robert (Author) / Takahashi, Timothy T (Thesis advisor) / Middleton, James (Committee member) / White, Daniel (Committee member) / Arizona State University (Publisher)
Created2017