Person:

Mavris, Dimitri N.

Permanent Link

https://hdl.handle.net/1853/71501

Associated Organization(s)

Organizational Unit

Daniel Guggenheim School of Aerospace Engineering

Organizational Unit

Aerospace Systems Design Laboratory (ASDL)

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Publication Search Results

Now showing 1 - 10 of 81

Helicopter Operations Weather Information Survey Dataset

(Georgia Institute of Technology, 2020-11-23) Payan, Alexia P. ; Ramee, Coline ; Speirs, Andrew ; Mavris, Dimitri N. ; Feigh, Karen M.

To better understand the kind of weather information used by rotorcraft operators and get their opinion on the weather products that are available to them, the research team created an online survey. The survey consisted of three main sections: 1) Demographics, 2) Flight environment, and 3) Safety Operations. The information collected was used to analyze the number and types of weather information sources used by pilots in different phases of flight, identify differences between industries and study pilots training for adverse weather conditions. The data contained here is an anonymized version of answers to the survey.
Design and Analysis of the Thermal Management System of a Hybrid Turboelectric Regional Jet for the NASA ULI

(Georgia Institute of Technology, 2020-08) Shi, Mingxuan ; Sanders, Mitchell ; Alahmad, Alan ; Perullo, Christopher ; Cinar, Gokcin ; Mavris, Dimitri N.

A team of researchers from multiple universities are collaborating on the demonstration of a hybrid turboelectric regional jet for 2030 under the NASA ULI Program. The thermal management is one of the major challenges for the development of such an electric propulsion concept. Existing studies hardly modeled the thermal management systems with the propulsion systems nor integrated it to the aircraft for system- and mission-level analyses. Therefore, it is very difficult to verify whether a design of the thermal management system is feasible and optimal based on current literature. To fill this gap, this paper presents a design of the thermal management system for the hybrid turboelectric regional jet under the ULI program and integrates it to the aircraft. The TMS is tested against the cooling requirements, where the thermal loads from the electric propulsion system are quantified through the whole mission. Potential solutions for peak thermal loads during takeoff and climb are also proposed and analyzed, where additional coolant or phase change materials are used. Moreover, the impacts of the TMS on the system- and mission-level performance are investigated by the presented integration approach as well. It is discovered that a basic oil-air thermal management system cannot fully remove the heat during the early mission segments. Using additional coolant or phase change materials as heat absorption can handle such heating problem, but penalty due to additional weight is added. It is found that greater penalties in fuel burn and takeoff weight are added by additional coolant solution than the phase change material solution.
A Coupled Approach to the Design Space Exploration of Nuclear Thermal Propulsion Systems

(Georgia Institute of Technology, 2020-08) Petitgenet, Victor L. ; Roper, Christopher D. ; Shalat, David ; Yatsko, Andrew J. ; Krecicki, Matt ; Kotlyar, Dan ; Mavris, Dimitri N.

Nuclear Thermal Propulsion (NTP) is identified as one of the preferred propulsion technologies for future manned missions to Mars and other interplanetary destinations. NTP systems can improve the returns and mitigate the risks of such missions by reducing travel time and improving payload capacity as compared to traditional chemical propulsion systems. Due to the complexity and tightly coupled nature of the nuclear reactor and surrounding NTP subsystems, the traditional decoupled approach to NTP system analysis is inadequate. A new approach is needed to enable a high-fidelity design space exploration exercise for NTP systems. The approach outlined in this paper will address an integrated model of the reactor and supporting subsystems. This model, along with the incorporation of Design of Experiments and Surrogate Modeling, will allow for the exploration of the performance of a large number of NTP system designs with respect to metrics such as specific impulse and thrust to weight ratio. The subsystems analysis is handled by Numerical Propulsion Systems Simulation (NPSS) while reactor modeling is conducted using various numerical codes. This paper proposes and demonstrates a coupled design space exploration approach for NTP systems and uses these findings to consider vehicle-level implications.
An Update on Sizing and Performance Analysis of a Hybrid Turboelectric Regional Jet for the NASA ULI Program

(Georgia Institute of Technology, 2020-08) Perullo, Christopher ; Shi, Mingxuan ; Cinar, Gokcin ; Alahmad, Alan ; Sanders, Mitchell ; Mavris, Dimitri N. ; Benzakein, Mike J.

Under the NASA University Leadership Initiative (ULI) program, a team of universities are collaborating on the advancement of technologies a hybrid turboelectric regional jet, with an intent to enter service in the 2030 timeframe. In the previous studies of the ULI program, the in-service benefits of the technologies under development were analyzed by integrating the technologies of interest to a 2030 regional jet with a hybrid turbo-electric distributed propulsion system. As the program has progressed, the projected performances for each technology and subsystem have been updated. This paper presents an update in the sizing and performance analysis of the regional jet with the hybrid turbo-electric distributed propulsion system, by integrating the updated values of the technologies and subsystems to the vehicle. The updates in this paper include the DC/AC conversion links, efficiency of generator and cabling losses, weight of the wires, the battery cooling through the environmental control system, motor and inverter cooling by the thermal management system, and the redundancy strategy of the propulsion system. The updates of the results from the integrated model include the overall efficiency of the propulsion system, mission fuel savings, mission energy flow distribution, and the optimal hybridization rate in climb and cruise. The overall fuel saving benefit for the target 600-nmi mission is 19.9% compared to the baseline aircraft.
Verification and Measurement of Thrust Vectoring Using Thermal Mapping Techniques

(Georgia Institute of Technology, 2020-08) Shapochka, Mark Y. ; Roush, Karl W. ; Yatsko, Andrew J. ; Mavris, Dimitri N.

The feasibility of thrust vectoring measurement using thermal mapping techniques was investigated. In this study, thermal maps are represented by generated figures which display temperatures spatially using a grid of evenly spaced thermocouples. For the purpose of measurement of thrust vectoring, thermal maps as well as the distance from the engine nozzle exit to the thermocouple grid were used to triangulate the vectored angle. This investigation was intended to be conducted using a small gas turbine engine in instrumented experiments. The assessment of feasibility was based on cost analysis, as well as the accuracy of experimental results.
Feasibility Assessments of a Hybrid Turboelectric Medium Altitude Long Endurance Unmanned Aerial Vehicle

(Georgia Institute of Technology, 2020-08) Cinar, Gokcin ; Markov, Alexander A. ; Gladin, Jonathan C. ; Garcia, Elena ; Mavris, Dimitri N. ; Patnaik, Soumya S.

Electrified propulsion systems can provide potential environmental and performance benefits for future aircraft. The choice of the right propulsion architecture and the power management strategy depends on a number of factors, the airframe, electrification objectives and metrics of interest being the most critical ones. Therefore, the generic advantages and disadvantages of various electrified propulsion architectures must be quantified to assess feasibility and any possible benefits. Moreover, the objectives and the metrics of interest can be different for military applications than commercial ones. This research investigates the feasibility of turboelectric and hybrid turboelectric propulsion architectures integrated within a medium altitude long endurance surveillance unmanned aerial vehicle. The electrified propulsion system is desired to provide the same endurance and takeoff and landing field length characteristics of the baseline aircraft. This paper presents the results of the first phase of this research where only the electrified propulsion system is sized while the airframe is kept fixed. Physics-based models and a generic mission analysis methodology are used to evaluate the performance of the major subsystems of the propulsion system and to provide a full flight mission history. A state of the art rechargeable battery is employed for the hybrid case. Various power management strategies where the battery is discharged and charged in different flight segments are explored for varying sizes of battery packs. Results indicate that, while none of the architectures can offset the added weight and the efficiency factors of the electrical components as expected, the hybrid turboelectric propulsion architecture can provide fuel burn and performance benefits when sized for, and operated under, a specific set of power management strategies.
A Data-Driven Approach using Machine Learning to Enable Real-Time Flight Path Planning

(Georgia Institute of Technology, 2020-06) Kim, Junghyun ; Briceno, Simon ; Justin, Cedric Y. ; Mavris, Dimitri N.

As aviation traffic continues to grow, most airlines are concerned about flight delays, which increase operating costs for the airlines. Since most delays are caused by weather, pilots and flight dispatchers typically gather all available weather information prior to departure to create an efficient and safe flight plan. However, they may have to perform in-flight re-planning because weather information can significantly change after the original flight plan is created. One potential issue is that weather forecasts being currently used in the aviation industry may provide relatively unreliable information and are not accessible fast enough so that it challenges pilots to perform in-flight re-planning more accurately and frequently. In this paper, we propose a data-driven approach that uses an unsupervised machine learning technique to provide a more reliable and up-to-date area of convective weather. To evaluate the proposed methodology, we collect the American Airlines flight (AA1300) information and actual weather-related data on October 6th, 2019. Preliminary results show that the proposed methodology provides a better picture of the nearby convective weather activity compared to the most well-known convective weather product.
Optimal Siting of Sub-Urban Air Mobility (sUAM) Ground Architectures using Network Flow Formulation

(Georgia Institute of Technology, 2020-06) Venkatesh, Nikhil ; Payan, Alexia P. ; Justin, Cedric Y. ; Kee, Ethan C. ; Mavris, Dimitri N.

Air Mobility (AM) operating models have steadily made their way into public conscience over the past decade due to increased research activity pioneered by large technology corporations such as Uber and Amazon. Estimates concur that there are around 250 startup businesses with 22 major players working on such technologies with over $25 billion dollars in venture capital funding in 2017[1]. Given the meteoric rise of Air Mobility as one of the leading 21st century disruptive technologies, research effort across the spectrum of functions that can make AM concepts a reality are burgeoning - ranging from vehicle design to operations planning. More specifically, research efforts within the operations planning space deal with service route identification, ground infrastructure (such as charging stations and ports) placement and others. To this effect, the present study seeks to evaluate the feasibility and tractability of a formalized optimization method towards the siting of "vertiports" - ground infrastructure that aids the embarkation and disembarkation of AM commuters - as applied to a Sub-Urban Air Mobility (sUAM) operating model. Mixed-Integer Programming (MIP) formulations offer qualified benefits over other heuristic methods and the authors are confident of their relative performance given the proven track record of such methods in solving generalized facility location problems (GFLP). In this study, two optimization problems were considered: capacitated vertiport siting, where any vertiport considered would need to adhere to capacity constraints; and uncapacitated vertiport siting, where any vertiport considered does not have any capacity limit and can service unlimited demand. Results indicate that a network flow formulation using an MIP methodology is able to adequately place vertiports for sUAM business operations to satisfy demand flows associated with home-work commute.
Development of a Multi-Fidelity Reduced-Order Model Based on Manifold Alignment

(Georgia Institute of Technology, 2020-06) Perron, Christian ; Rajaram, Dushhyanth ; Mavris, Dimitri N.

This work presents the development of a novel multi-fidelity, parametric, and non-intrusive Reduced Order Modeling~(ROM) method to tackle the problem of achieving an acceptable predictive accuracy under a limited computational budget, i.e., with expensive simulations and sparse training data. Traditional multi-fidelity surrogate models that predict scalar quantities address this issue by leveraging auxiliary data generated by a computationally cheaper lower fidelity code. However, for the prediction of field quantities, simulations of different fidelities may produce high-dimensional responses with inconsistent dimensionality and topology, rendering the direct application of common multi-fidelity techniques challenging. The proposed approach uses manifold alignment to fuse inconsistent fields from high- and low-fidelity simulations by individually projecting their solution onto a common shared latent space. Hence, simulations using incompatible grids or geometries can be combined into a single multi-fidelity ROM without additional manipulation of the data. This method is applied to a variety of multi-fidelity scenarios using a transonic airfoil problem. In most cases, the new multi-fidelity ROM achieves comparable predictive accuracy at a substantially lower computational cost. Furthermore, it is demonstrated that the proposed method can readily combine disparate fields without any adverse effect on model performance.
A Certification-Driven Platform for Multidisciplinary Design Space Exploration in Airframe Early Preliminary Design

(Georgia Institute of Technology, 2020-06) Sarojini, Darshan ; Xie, Jiacheng ; Cai, Yu ; Corman, Jason A. ; Mavris, Dimitri N.

Following the conceptual phase of aircraft design, sizing and performance estimations shift from historical-based empirical equations to physics-based simulations. The initial aircraft configuration is refined with a larger number of objectives and requirements, and certification regulations play a critical role in defining these. Analysis tools in the early phases of preliminary design have an important trade-off between accuracy, complexity, and computational efficiency. A number of analysis frameworks currently exist with varying levels of fidelity, multidisciplinary coupling, and limitations in the number of disciplines, degrees of freedom, and requirements they are able to implement. To enable efficient design space exploration (DSE), this paper proposes an integrated preliminary design framework that couples aerodynamics, structures, subsystems, aircraft performance, flight dynamics, and certification testing at varying levels of fidelity. This framework serves as a numerical testbed that can be used to explore the aircraft configuration and disciplinary design spaces, strength of disciplinary couplings, and propagate disciplinary uncertainties across the entire aircraft system. The framework is demonstrated using the horizontal tail of a large twin-aisle aircraft as a test case.