Matching Items (29)

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Effect of Winglet Morphology on Variable Range Commercial Aircraft

Description

Winglets and wingtip structures have been prominent in commercial aircraft design in the past few decades. These designs are known to reduce the induced drag on an aircraft wing, thus

Winglets and wingtip structures have been prominent in commercial aircraft design in the past few decades. These designs are known to reduce the induced drag on an aircraft wing, thus increasing its overall fuel efficiency. Several different winglet designs exist, and little reason is offered as to why different winglet designs are used in practice on different aircraft, especially those of variable range. This research tests existing winglets (no winglet, raked winglet, flat plate winglet, blended winglet, and wingtip fence) on a span-constrained wing planform design both computationally and in the wind tunnel. While computational tests using a vortex lattice code indicate that the wingtip fence minimizes induced drag and maximizes lift to drag ratio in most cases, wind tunnel tests show that at different lift coefficients and angles of attack, the raked winglet and blended winglet optimize the aerodynamic efficiency at incompressible flow velocities. Applying the wing aerodynamic data to existing variable range commercial aircraft, mission performance analysis is run on a Bombardier CRJ200, Airbus A320, and Airbus A340-300. By comparing flight lift coefficients in cruise for these aircraft to the lift coefficients at which winglets minimize drag in compressible flows, optimal winglet designs are chosen. It is found that the short range CRJ200 is best equipped with a flat plate or blended winglet, the medium range A320 can reduce drag with either a wingtip fence, raked winglet, or blended winglet, and the long range A340 performs best with a flat plate, blended, or raked winglet. Overall, despite the discrepancy in winglet selection depending on which experimental results are used, it is clear that addition of a winglet to a span-constrained wing is beneficial in that it reduces induced drag and therefore increases overall fuel efficiency.

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Date Created
  • 2017-05

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Monatomic Gas Effects on Brayton Cycle Propulsion and Power Systems

Description

Monatomic gases are ideal working mediums for Brayton cycle systems due to their favorable thermodynamic properties. Closed Brayton cycle systems make use of these monatomic gases to increase system performance

Monatomic gases are ideal working mediums for Brayton cycle systems due to their favorable thermodynamic properties. Closed Brayton cycle systems make use of these monatomic gases to increase system performance and thermal efficiency. Open Brayton cycles, on the other hand, operate with primarily diatomic and polyatomic gases from air and combustion products, which have less favorable properties. The focus of this study is to determine if monatomic gases can be utilized in an open Brayton cycle system, in a way that increases the overall performance, but is still cost effective.
Two variations on open cycle Brayton systems were analyzed, consisting of an “airborne” thrust producing propulsion system, and a “ground-based” power generation system. Both of these systems have some mole fraction of He, Ne, or Ar injected into the flow path at the inlet, and some fraction of monatomic gas recuperated and at the nozzle exit to be re-circulated through the system. This creates a working medium of an air-monatomic gas mixture before the combustor, and a combustion products-monatomic gas mixture after combustor. The system’s specific compressor work, specific turbine work, specific net power output, and thermal efficiency were analyzed for each case. The most dominant metric for performance is the thermal efficiency (η_sys), which showed a significant increase as the mole fraction of monatomic gas increased for all three gas types. With a mole fraction of 0.15, there was a 2-2.5% increase in the airborne system, and a 1.75% increase of the ground-based system. This confirms that “spiking” any open Brayton system with monatomic gas will lead to an increase in performance. Additionally, both systems showed an increase in compressor and turbine work for a set temperature difference with He and Ne, which can additionally lead to longer component lifecycles with less frequent maintenance checks.
The cost analysis essentially compares the operating cost of a standard system with the operating cost of the monatomic gas “spiked” system, while keeping the internal mass flow rate and total power output the same. This savings is denoted as a percent of the standard system with %NCS. This metric lumps the cost ratio of the monatomic gas and fuel (MGC/FC) with the fraction of recuperated monatomic gas (RF) into an effective cost ratio that represents the cost per second of monatomic gas injected into the system. Without recuperation, the results showed there is no mole fraction of any monatomic gas type that yields a positive %NCS for a reasonable range of current MGC/FC values. Integrating recuperation machinery in an airborne system is hugely impractical, effectively meaning that the use of monatomic gas in this case is not feasible. For a ground-based system on the other hand, recuperation is much more practical. The ground-based system showed that a RF value of at least 50% for He, 89% for Ne, and 94% for Ar is needed for positive savings. This shows that monatomic gas could theoretically be used cost effectively in a ground-based, power-generating open Brayton system. With an injected monatomic gas mole fraction of 0.15, and full 100% recuperation, there is a net cost savings of about 3.75% in this ground-based system.

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Date Created
  • 2017-05

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Studying the Effect of Model Input on Output Accuracy Using an Automated CFD Tool

Description

This project aims to study the relationship between model input parameters and model output accuracy of the Tool for Automation of Computational Aerodynamics of Airfoils (TACAA). The input parameters of

This project aims to study the relationship between model input parameters and model output accuracy of the Tool for Automation of Computational Aerodynamics of Airfoils (TACAA). The input parameters of study are Mach number and Reynolds number, and inputs are tested through three flight speed regimes and from laminar to turbulent flow. Each of these input parameters are tested for the NACA 0012 and SC-1095 airfoils to ensure that the accuracy is similar regardless of geometric complexity. The TACAA program was used to run all simulation testing, and its overall functionality is discussed. The results gathered from the preliminary testing showed that the spread of variable input data points caused data gaps in the transonic regime results, which provided motivation to conduct further testing within the transonic region for both airfoils. After collecting all TACAA results, data from wind tunnel testing was compiled to compare. The comparison showed that (1) additional testing would be necessary to fully assess the accuracy of the results for the SC-1095 airfoil and (2) TACAA is generally accurate for compressible, turbulent flows.

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Date Created
  • 2020-05

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Design of Indraft Supersonic Wind Tunnel

Description

The objective of this project is to design an indraft supersonic wind tunnel that is safe and comparatively simple to construct. The processes and methodology of design are discussed. As

The objective of this project is to design an indraft supersonic wind tunnel that is safe and comparatively simple to construct. The processes and methodology of design are discussed. As with every supersonic wind tunnel, the critical components are the nozzle, diffuser, and the means of achieving the pressure differential which drives the flow. The nozzle was designed using method of characteristics (MOC) and a boundary layer analysis experimental proven on supersonic wind tunnels [5]. The diffuser was designed using the unique design features of this wind tunnel in combination with equations from Pope [7]. The pressure differential is achieved via a vacuum chamber behind the diffuser creating a pressure differential between the ambient air and the low pressure in the tank. The run time of the wind tunnel depends on the initial pressure of the vacuum tank and the volume. However, the volume of the tank has a greater influence on the run time. The volume of the tank is not specified as the largest tank feasible should be used to allow the longest run time. The run time for different volumes is given. Another method of extending the run duration is added vacuum pumps to the vacuum chamber. If these pumps can move a sufficient mass out of the vacuum chamber, the run time can be significantly extended. The mounting design addresses the loading requirements which is closely related to the accuracy of the data. The mounting mechanism is attached to the rear of the model to minimize shockwave interference and maximize the structural integrity along the direction with the highest loading. This mechanism is then mounted to the bottom of the wind tunnel for structural rigidity and ease of access.

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Date Created
  • 2020-05

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Design of a Gravity-Fed Hydrodynamic Testing Tunnel

Description

The purpose of this project is to determine the feasibility of a water tunnel designed to meet certain constraints. The project goals are to tailor a design for a given

The purpose of this project is to determine the feasibility of a water tunnel designed to meet certain constraints. The project goals are to tailor a design for a given location, and to produce a repeatable design sizing and shape process for specified constraints. The primary design goals include a 1 m/s flow velocity in a 30cm x 30cm test section for 300 seconds. Secondary parameters, such as system height, tank height, area contraction ratio, and roof loading limits, may change depending on preference, location, or environment. The final chosen configuration is a gravity fed design with six major components: the reservoir tank, the initial duct, the contraction nozzle, the test section, the exit duct, and the variable control exit nozzle. Important sizing results include a minimum water weight of 60,000 pounds, a system height of 7.65 meters, a system length of 6 meters (not including the reservoir tank), a large shallow reservoir tank width of 12.2 meters, and height of 0.22 meters, and a control nozzle exit radius range of 5.25 cm to 5.3 cm. Computational fluid dynamic simulation further supports adherence to the design constraints but points out some potential areas for improvement in dealing with flow irregularities. These areas include the bends in the ducts, and the contraction nozzle. Despite those areas recommended for improvement, it is reasonable to conclude that the design and process fulfill the project goals.

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Date Created
  • 2014-05

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Validation and Refinement of a Drag Build Up Method for Unmanned Aerial Vehicles

Description

The emerging market for unmanned aerial vehicles, or UAV's, demands the development of effective design tools for small-scale aircraft. This research seeks to validate a previously developed drag build-up method

The emerging market for unmanned aerial vehicles, or UAV's, demands the development of effective design tools for small-scale aircraft. This research seeks to validate a previously developed drag build-up method for small air vehicles. Using the method, a drag prediction was made for an off-the-shelf, remotely controlled aircraft. The Oswald efficiency was predicted to be 0.852. Flight tests were then conducted using the RC plane, and the aircraft performance data was compared with the predicted performance data. Although there were variations in the data due to flight conditions and equipment, the drag build up method was capable of predicting the aircraft's drag. The experimental Oswald efficiency was found to be 0.863 with an error of 1.27%. As for the CDp the prediction of 0.0477 was comparable to the experimental value of 0.0424. Moving forward this method can be used to create conceptual designs of UAV's to explore the most efficient designs, without the need to build a model.

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Date Created
  • 2014-05

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Exploration of Lunar Contingency Devices

Description

The Micro-g NExT 2019 challenge set out to find a new device to replace the Apollo mission lunar contingency sampler in preparation for the 2024 Artemis mission. The 2019 challenge

The Micro-g NExT 2019 challenge set out to find a new device to replace the Apollo mission lunar contingency sampler in preparation for the 2024 Artemis mission. The 2019 challenge set a series of requirements that would enable compatibility with the new xEMU suit and enable astronauts to effectively collect and secure an initial sample upon landing. The final prototype developed by the team features a sliding plate design with each plate slightly shorter than the previous. The device utilizes the majority of the xEMU suit’s front pocket volume while still allowing space for the astronaut’s hand and the bag for the sample. Considering safety concerns, the device satisfies NASA’s requirements for manual handheld devices and poses no threat to the astronaut under standard operation. In operation, the final design experiences an acceptable level stress in the primary use direction, and an even less in the lateral direction. Using assumptions such as the depth and density of lunar soil to be sampled, the working factor of safety is about 2 for elastic deformation, but the tool can still be operated and even collapsed at roughly double that stress. Unfortunately, the scope of this thesis only covers the effectiveness of resin prototypes and simulations of aluminum models, but properly manufactured aluminum prototypes are the next step for validating this design as a successor to the design used on the Apollo missions.

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Created

Date Created
  • 2021-05

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Exploration of Lunar Contingency Devices

Description

The Micro-g NExT 2019 challenge set out to find a new device to replace the Apollo mission lunar contingency sampler in preparation for the 2024 Artemis mission. The 2019 challenge

The Micro-g NExT 2019 challenge set out to find a new device to replace the Apollo mission lunar contingency sampler in preparation for the 2024 Artemis mission. The 2019 challenge set a series of requirements that would enable compatibility with the new xEMU suit and enable astronauts to effectively collect and secure an initial sample upon landing. The final prototype developed by the team features a sliding plate design with each plate slightly shorter than the previous. The device utilizes the majority of the xEMU suit’s front pocket volume while still allowing space for the astronaut’s hand and the bag for the sample. Considering safety concerns, the device satisfies NASA’s requirements for manual handheld devices and poses no threat to the astronaut under standard operation. In operation, the final design experiences an acceptable level stress in the primary use direction, and an even less in the lateral direction. Using assumptions such as the depth and density of lunar soil to be sampled, the working factor of safety is about 2 for elastic deformation, but the tool can still be operated and even collapsed at roughly double that stress. Unfortunately, the scope of this thesis only covers the effectiveness of resin prototypes and simulations of aluminum models, but properly manufactured aluminum prototypes are the next step for validating this design as a successor to the design used on the Apollo missions.

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Agent

Created

Date Created
  • 2021-05

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Exploration of Lunar Contingency Devices

Description

The Micro-g NExT 2019 challenge set out to find a new device to replace the Apollo mission lunar contingency sampler in preparation for the 2024 Artemis mission. The 2019 challenge

The Micro-g NExT 2019 challenge set out to find a new device to replace the Apollo mission lunar contingency sampler in preparation for the 2024 Artemis mission. The 2019 challenge set a series of requirements that would enable compatibility with the new xEMU suit and enable astronauts to effectively collect and secure an initial sample upon landing. The final prototype developed by the team features a sliding plate design with each plate slightly shorter than the previous. The device utilizes the majority of the xEMU suit’s front pocket volume while still allowing space for the astronaut’s hand and the bag for the sample. Considering safety concerns, the device satisfies NASA’s requirements for manual handheld devices and poses no threat to the astronaut under standard operation. In operation, the final design experiences an acceptable level stress in the primary use direction, and an even less in the lateral direction. Using assumptions such as the depth and density of lunar soil to be sampled, the working factor of safety is about 2 for elastic deformation, but the tool can still be operated and even collapsed at roughly double that stress. Unfortunately, the scope of this thesis only covers the effectiveness of resin prototypes and simulations of aluminum models, but properly manufactured aluminum prototypes are the next step for validating this design as a successor to the design used on the Apollo missions.

Contributors

Agent

Created

Date Created
  • 2021-05

147606-Thumbnail Image.png

Exploration of Lunar Contingency Devices

Description

The Micro-g NExT 2019 challenge set out to find a new device to replace the Apollo mission lunar contingency sampler in preparation for the 2024 Artemis mission. The 2019 challenge

The Micro-g NExT 2019 challenge set out to find a new device to replace the Apollo mission lunar contingency sampler in preparation for the 2024 Artemis mission. The 2019 challenge set a series of requirements that would enable compatibility with the new xEMU suit and enable astronauts to effectively collect and secure an initial sample upon landing. The final prototype developed by the team features a sliding plate design with each plate slightly shorter than the previous. The device utilizes the majority of the xEMU suit’s front pocket volume while still allowing space for the astronaut’s hand and the bag for the sample. Considering safety concerns, the device satisfies NASA’s requirements for manual handheld devices and poses no threat to the astronaut under standard operation. In operation, the final design experiences an acceptable level stress in the primary use direction, and an even less in the lateral direction. Using assumptions such as the depth and density of lunar soil to be sampled, the working factor of safety is about 2 for elastic deformation, but the tool can still be operated and even collapsed at roughly double that stress. Unfortunately, the scope of this thesis only covers the effectiveness of resin prototypes and simulations of aluminum models, but properly manufactured aluminum prototypes are the next step for validating this design as a successor to the design used on the Apollo missions.

Contributors

Agent

Created

Date Created
  • 2021-05