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 10

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.
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.
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.
A Comparative Assessment of Highspeed Rotorcraft Concepts (HSRC) : Reaction Driven Stopped Rotor/Wing and Variable Diameter Tiltrotor

(Georgia Institute of Technology, 1997-10) Tai, Jimmy C. M. ; Mavris, Dimitri N. ; Schrage, Daniel P.

The objective of this paper is to illustrate the methods and tools developed to size and synthesize a stopped rotor/wing vehicle using a reaction drive system, including how this design capability is incorporated into a sizing and synthesis tool, VASCOMP II. This new capability is used to design a vehicle capable of performing a V-22 escort mission, and a sized vehicle description with performance characteristics is presented. The resulting vehicle is then compared side-by-side to a variable diameter tiltrotor designed for the same mission. Results of this analysis indicate that the reaction-driven rotor concept holds promise relative to alternative concepts, but that the variable diameter tiltrotor has several inherent performance advantages. Additionally, the stopped rotor/wing needs considerably more development to reach maturity.
An Assessment of Reaction Driven Stopped Rotor/Wing Using Circulation Control in Forward Flight

(Georgia Institute of Technology, 1996-10) Tai, Jimmy C. M. ; Mavris, Dimitri N. ; Schrage, Daniel P.

The desire of achieving faster cruise speed for rotorcraft vehicles has been around since the inception of the helicopter. Many unconventional concepts have been considered and researched such as the advanced tilt rotor with canards, the tilt-wing, the folding tiltrotor, the coaxial propfan/folding tiltrotor, the variable diameter tiltrotor, and the stopped rotor/wing concept, in order to fulfill this goal. The most notable program which addressed the technology challenges of accomplishing a high speed civil transport mission is the High Speed Rotorcraft Concept (HSRC) program. Among the long list of potential configurations to fulfill the HSRC intended mission, the stopped rotor/wing is the least investigated due to the fact that the existing rotorcraft synthesis codes cannot handle this type of vehicle. In order to develop such a tool, a designer must understand the physics behind this unique concept. The uniqueness of stopped rotor/wing vehicles that use reaction drive can be found in the tight coupling that is present between the rotor and the engine which in turn requires these subsystems to be sized concurrently rather than in isolation. A methodology and simulation tool capable of handling this coupling is under development at the Aerospace Systems Design Laboratory (ASDL) at Georgia Institute of Technology. The development of a new design tool (TJCC) and the use of a statistical technique called Response Surface Methodology linked into the V/STOL Aircraft Sizing and Performance Computer Program (VASCOMP II) has provided the capability of sizing stopped rotor/wings. The potential success of a stopped rotor/wing configuration can only be determined through direct performance comparisons with other high speed rotorcraft concepts using analytical methods of comparable sophistication. The authors have previously presented limited results from this study detailing the rotor/wing performance during hover. In this paper the forward flight regime for both the helicopter and fixed wing modes are discussed. Representative results presented include performance characteristics such as the horsepower required curves versus forward flight for both the rotorcraft and fixed wing modes of operation. Furthermore, the mass flow requirements, and transition performance associated with this aircraft are also examined in this paper.
An Application of Response Surface Methodology to the Design of Tipjet Driven Stopped Rotor/Wing Concepts

(Georgia Institute of Technology, 1995-09) Tai, Jimmy C. M. ; Mavris, Dimitri N. ; Schrage, Daniel P.

The possibility of a new aircraft that is capable of solving the increasing demand of inter-city transportation has attracted the attention of the aerospace industry for quite some time. Under the High Speed Rotorcraft Concept (HSRC) program, both NASA and the U.S. helicopter industry have studied a series of candidate rotorcraft configurations capable of cruising at high speeds and capable of taking off and landing vertically at vertiports located at downtown. Among these candidates, the stopped rotor/wing configuration has been the least studied due to lack of appropriate analytical tools to assist in its design and due to a general lack of understanding of the physics behind this unconventional concept. Even though the HSRC program has since been canceled, Georgia Tech's Aerospace Systems Design Laboratory (ASDL) recognized the need for a design methodology capable of handling the synthesis and sizing of such vehicles and has continued its pursuit. Therefore, such a computer simulation code has been developed to size reaction driven stopped rotor/wing vehicles which may or may not enable Circulation Control. The difficulty in sizing such a concept is primarily due to the unique coupling of rotor and engine which need to be sized concurrently since they are directly linked to each other and cannot be studied in isolation. This coupling, in fact, is not seen in any other concept. The methodology and computer simulation tool presented in this paper show how this coupling is accomplished. Furthermore, the results from this rotor/engine coupling are presented in the form of Response Surface Equations that is derived through the application of Response Surface Methodology. These RSE's also provide the designer with a unique ability to predict what the response will be, based on the settings of the design variables that he/she chooses. The robustness advantages of using these RSE's are also presented in the vehicle sizing portion of the overall design methodology for the stopped rotor/wing configurations.
A Multidisciplinary Design Optimization Approach to Sizing Stopped Rotor Configurations Utilizing Reaction Drive and Circulation Control

(Georgia Institute of Technology, 1994-09) Mavris, Dimitri N. ; Tai, Jimmy C. M. ; Schrage, Daniel P.

Over the years, the U. S. rotorcraft industry and NASA have conducted numerous studies to determine possible candidates for a potential High Speed Rotorcraft Concept (HSRC) and to identify and provide suggestions and solutions to technology issues that might hinder the development of such concept. Many feasible concepts have been proposed and studied including the tilt rotor, the tilt wing, the folding tilt rotor, the variable diameter tilt rotor, the advanced canard tilt rotor, the coaxial propfan/folding tilt rotor, and the stopped rotor/wing configuration. Among these concepts, the rotor/wing still remains the least studied compared with the other candidates. This can be attributed primarily to lack of suitable analytical tools to assist the design process and to unfamiliarity with this unconventional concept. The potential success of a stopped rotor/wing configuration can only be determined through direct performance comparisons with the concepts mentioned above using analytical methods of comparable sophistication. The intention of this paper is to address the issues associated with sizing and optimizing a stopped rotor/wing configuration which incorporates a tip jet drive system and Circulation Control devices. In addition, a methodology has been formulated and is presented which forms a foundation upon which a new sizing code capable of handling this unique concept can be developed. Since the subject of this paper deals with a concept that enables relatively uncommon technologies, a review of the physics associated with these concepts is also presented.