Person:

Tai, Jimmy C. M.

Permanent Link

https://hdl.handle.net/1853/71759

Associated Organization(s)

Organizational Unit

Daniel Guggenheim School of Aerospace Engineering

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Publication Search Results

Now showing 1 - 10 of 14

Development of an Open Rotor Propulsion System Model and Power Management Strategy

(Georgia Institute of Technology, 2023-01) Clark, Robert A. ; Perron, Christian ; Tai, Jimmy C. M. ; Airdo, Benjamin ; Mavris, Dimitri N.

The development of an open rotor propulsion system architecture model and fuel burn-minimizing power management strategy is investigated. The open rotor architecture consists of a single-rotor open rotor (SROR) connected to the low speed shaft of a traditional turbojet engine in a puller configuration. The proposed architecture is modeled in the Numerical Propulsion System Simulation (NPSS) tool, and performance is evaluated across a complete flight envelope typical for a narrow body commercial airliner. Rotor performance maps are generated using a custom blade element momentum theory (BEMT) code, while compressor performance maps are created using CMPGEN. The performance of the overall propulsion system is detailed in the context of a notional 150 passenger aircraft mission, and a method for scheduling rotor power across the flight envelope is developed in order to minimize aircraft mission fuel burn. It is demonstrated that the power absorbed by the rotor can be optimized by scheduling rotor blade pitch angle versus fan speed. A power management technique using the optimal blade pitch angle at only six points in the flight envelope was shown to provide significant computational benefits without sacrificing any fuel burn when compared to a method using a schedule generated from data across the complete flight envelope.
Development of a Parametric Variable Cycle Engine Model Using the Multiple Design Point Approach

(AIAA, 2023-01) Clark, Robert ; Tai, Jimmy C. M. ; Mavris, Dimitri N.

The development of a parametric variable cycle engine (VCE) model is investigated. The model is developed using the multiple design point (MDP) approach, which allows for the sizing of an engine that meets design criteria across multiple flight conditions. The proposed architecture, a three-stream double-bypass architecture, is modeled in the Numerical Propulsion System Simulation (NPSS) tool. A double bypass architecture is selected due to the need to maintain continuous third-stream flow to be used as a heat sink for cooled-cooling and aircraft cooling heat exchangers. Results show that a VCE utilizing an aft variable area bypass injector (VABI), variable compressor inlet guide vanes (IGVs), and variable nozzle throats can be modulated to provide higher sea-level static (SLS) thrust and lower cruise specific fuel consumption (SFC) than a standard mixed-flow turbofan engine. Furthermore, engine pressure ratio (EPR) is shown to be a convenient thermodynamic parameter, such that variable geometry schedules can be developed as a function of EPR only, without respect to flight altitude or Mach number.
The Environmental Design Space: Modeling and Performance Updates

(Georgia Institute of Technology, 2021-01) Salas Nunez, Luis ; Tai, Jimmy C. M. ; Mavris, Dimitri N.

The Environmental Design Space (EDS) is a modeling and simulation environment devised for the design and evaluation of subsonic aircraft. One of the main features that sets it apart from other similar frameworks is its capability to perform aircraft performance and sizing, exhaust emissions, and noise prediction. These three elements are seamlessly executed due to the integration of multiple industry-standard tools. Since its conception in 2008, EDS has been used to support multiple research entities and projects for the evaluation of current and future aircraft concepts and technologies. Its results and assumptions have been calibrated and revised through the years in conjunction with panels of experts in the field. Therefore, it has undergone continuous development that has increased its capability, allowing it to model not only traditional tube-and-wing aircraft, but also unconventional configurations. At the writing of this paper, its capabilities extend beyond standard single and dual spool engines to include geared fans, ultra high bypass turbofans, open rotors, and partially turboelectric propulsion architectures. This paper presents an overview of how EDS has been used to support major research efforts. Then, an approach to develop and calibrate engine and aircraft models to match existing open-source data is presented. Finally, a summary of available advanced engine and aircraft architectures is shown. The results demonstrate EDS capability to create models that closely match existing systems performance, and its flexibility to keep supporting future aircraft design and technology development studies.
CFD Study of an Over-Wing Nacelle Configuration

(Georgia Institute of Technology, 2018-10-05) Berguin, Steven H. ; Renganathan, Sudharshan Ashwin ; Ahuja, Jai ; Chen, Mengzhen ; Perron, Christian ; Tai, Jimmy C. M. ; Mavris, Dimitri N.

Engine bypass ratio (BPR) has grown significantly over the years, due to a desire for increased efficiency, and the large fan diameters that have resulted are forcing the engines so close to the wing that there is no room left for them to grow any larger due to ground clearance constraints. As BPR increases even further in the future, conventional Under-Wing Nacelle (UWN) installations will therefore no longer be possible without drastic modification of the wing and landing gear. Over-Wing nacelle concepts solve this problem by offering a convenient installation for high BPR turbofans and, additionally, offer the potential to mitigate community noise through engine noise shielding using the wing as a shield. However, OWN has historically warranted concern about unacceptably high drag levels at transonic speeds and the purpose of this research was to determine whether or not drag can be improved enough to take advantage of the aforementioned cross-disciplinary benefits. To do so, three studies were conducted: study 1 conducted a simple nacelle sweep in order to identify and visualize the physical mechanisms driving the configuration, study 2 then conducted a sensitivity analysis in order to understand important design variables and, finally, study 3 performed single point optimization for a trailing edge OWN concept. Overall, results suggests that OWN drag can be improved to levels commensurate with its Under-Wing Nacelle (UWN) counterpart. However, limitations of the analysis tools employed for this research (in the area of shape optimization) were insufficient to outperform the UWN baseline. Such limitations were successfully overcome by modern OWN concepts, such as the Honda Business Jet and the military Lockheed HWB for air mobility missions. Overall, it is therefore the authors' opinion that either leading-edge or trailing-edge mounted OWN configurations are concepts worth investigating further for civil transport applications.
Modeling Airlift Operations for Humanitarian Aid and Disaster Relief to Support Acquisition Decision-Making

(Georgia Institute of Technology, 2018-06) Weit, Colby J. ; Chetcuti, Steven ; Chan, Cherlyn ; Muehlberg, Marc ; Wei, Lansing ; Gilani, Hassan ; Schwartz, Katherine G. ; Sudol, Alicia M. ; Tai, Jimmy C. M. ; Mavris, Dimitri N.

In a fiscally constrained environment, it is crucial that both equipment manufacturers and defence invest in technology that shows marked operational improvement. A priori identification of cost-benefit at the early acquisition stage is often limited and incomplete, leading to poor value propositions. This conundrum motivates the need to develop a method to evaluate technologies such as levels of autonomy, stealth capability, improved engines, etc. and make tradeoffs against operational measures of performance and effectiveness (MOP/Es) rather than solely against vehicle performance characteristics. The objective of this study is to create an environment in which those trades against MOEs could be performed rapidly to inform technology investment and acquisition decision-making. This environment is built on top of representative models of a discrete event simulation of disaster relief airlift operations to compare technology modifications or vehicle acquisition options rapidly against operational measures of effectiveness.
Sensitivity Analysis of Aero-Propulsive Coupling for Over-Wing-Nacelle Concepts

(Georgia Institute of Technology, 2018) Berguin, Steven H. ; Renganathan, Sudharshan Ashwin ; Ahuja, Jai ; Chen, Mengzhen ; Tai, Jimmy C. M. ; Mavris, Dimitri N.

A sensitivity analysis is performed to quantify the relative impact of perturbing a set of design variables representing an airplane configuration with Over-Wing Nacelles (OWN), operating at transonic cruise. The goal is to study the impact of perturbing the engine's XYZ position and power setting on installation drag, engine inlet pressure recovery, and lift curve characteristics. High- fidelity Reynolds Averaged Navier-Stokes (RANS) simulations of the Common Research Model (CRM) modified with powered, over-wing nacelles are performed and dominant main effects and interactions are identified. The most dominant effect was by far the engine's X position, but it was also found that podded OWN configurations exhibit statistically significant, aero-propulsive coupling. Specifically, certain engine locations cause changes in the flow-field that deteriorate inlet pressure recovery and, vice versa, a change in engine boundary conditions can affect installation drag. It is therefore recommended to simulate OWN concepts using a coupled MDA or MDAO approach to capture interdependencies between aerodynamics and propulsion.
Boeing propulsion sub-systems: NPSS/WATE parametric model, stage-stack & mean-line, and transient analyses

(Georgia Institute of Technology, 2012-12-31) Mavris, Dimitri N. ; Tai, Jimmy C. M. ; Schutte, Jeff ; Denney, Russell ; Kestner, Brian
Elements of an Emerging Virtual Stochastic life Cycle Design Environment

(Georgia Institute of Technology, 1999-10) Mavris, Dimitri N. ; DeLaurentis, Daniel A. ; Hale, Mark A. ; Tai, Jimmy C. M.

The challenge of designing next-generation systems that meet goals for system effectiveness, environmental compatibility, and cost has grown to the point that traditional design methodologies are becoming ineffective. Increases in the analysis complexity required, the number of objectives and constraints to be evaluated, and the multitude of uncertainties in today? design problems are primary drivers of this situation. A new environment for design has been formulated to treat this situation. It is viewed as a testbed, in which new techniques in such areas as design-oriented/physics-based analysis, uncertainty modeling, technology forecasting, system synthesis, and decision-making can be posed as hypotheses. Several recent advances in elements of this multidisciplinary environment, termed the Virtual Stochastic Life Cycle Design Environment, are summarized in this paper.
Additional development and systems analyses of pneumatic technology for high speed civil transport aircraft

(Georgia Institute of Technology, 1999) Willie, F. Scott ; Lee, Warren J. ; Niebur, Curt S. ; Gregory, Scott D. ; Mavris, Dimitri N. ; Tai, Jimmy C. M. ; Kirby, Michelle Rene ; Roth, Bryce Alexander ; Engler, R. J. (Robert J.)
A multidisciplinary design approach to size stopped rotor/wing configurations using reaction drive and circulation control

(Georgia Institute of Technology, 1998-08) Tai, Jimmy C. M.