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Carlson H.A.,Clear Science Corp. | Verberg R.,Clear Science Corp. | Harris C.A.,U.S. Air force
Physics of Fluids | Year: 2017

A physics-based, reduced-order, aeroservoelastic model of an F-18 aircraft has been developed using the method of proper orthogonal decomposition (POD), introduced to the field of fluid mechanics by Lumley. The model is constructed with data from high-dimensional, high-fidelity aeroservoelastic computational fluid dynamics (CFD-ASE) simulations that couple equations of motion of the flowto a modal model of the aircraft structure. Through POD modes, the reduced-order model (ROM) predicts both the structural dynamics and the coupled flow dynamics, offering much more information than typically employed, low-dimensional models based on system identification are capable of providing. ROMaccuracy is evaluated through direct comparisons between predictions of the flow and structural dynamics with predictions from the parent, the CFD-ASE model. The computational overhead of the ROM is six orders of magnitude lower than that of the CFD-ASE model-accurately predicting the coupled dynamics from simulations of an F-18 fighter aircraft undergoing flutter testing over a wide range of transonic and supersonic flight speeds on a single processor in 1.073 s.


Grant
Agency: Department of Defense | Branch: Air Force | Program: STTR | Phase: Phase I | Award Amount: 100.00K | Year: 2012

ABSTRACT: Clear Science Corp. and Princeton University propose to develop a computational framework for accurately and efficiently modeling the full set of physics associated with aircraft operations. The critical attributes of the proposed framework are accuracy, computational efficiency, and inclusiveness. More accurate computational models will support higher fidelity analysis during the aircraft design process with higher confidence in the results, enabling reductions in the required number of expensive and time-consuming ground and flight tests. Computationally efficient models will support flight simulations for the design of guidance, navigation, and control (GNC) systems, can be utilized as pilot training software, can support flight testing to reduce risks to test pilots and aircraft, and can be integrated into advanced control systems. The computational framework will accommodate the complexities of the full aircraft with separating stores and cargo, landing gear, propulsion systems, and a diverse set of physics (aerodynamics, structural dynamics, flight control system dynamics, aeroelasticity, aero-acoustics, etc.). Phase I will focus on comparative evaluations of candidate modeling methods, using a representative, canonical problem in the assessment. The evaluation will culminate with a down-selection of the most promising framework, along with identification of an appropriate test problem for model development and demonstration in Phase II. BENEFIT: The commercial product to be developed is a virtual flight simulation tool to enable GNC design, pilot-in-the-loop training exercises, and advanced flow control systems in next-generation aircraft. This translates into shorter time-to-market cycles and more affordable aircraft for the US military, along with safer test programs. Potential applications of the virtual flight testing tool include fixed-wing aircraft, rotorcraft, and even non-conventional aircraft like flapping-wing micro-air vehicles. The tool will be designed to accommodate systems operating in the low subsonic, subsonic, transonic, supersonic, and hypersonic flight regimes. Applications extend from military aircraft to commercial airliners, launch vehicles, and space planes---each requiring cross-disciplinary, computationally intensive simulations of the aerodynamics, aerothermodynamics, aeroservoelasticity, and flight control systems. Commercial applications extend to a host of products outside the aerospace industry: automobiles, manufacturing processes involving fluid flows, nuclear power plant equipment, new green energy-production platforms, etc. Primary customers include US DoD agencies, prime defense contractors like Boeing, Lockheed-Martin, Raytheon, and Northrop-Grumman, NASA, and smaller commercial aircraft manufacturers like Cessna and Gulf Stream.


Grant
Agency: Department of Defense | Branch: Air Force | Program: STTR | Phase: Phase II | Award Amount: 750.00K | Year: 2013

ABSTRACT: Clear Science Corp. and Princeton University propose to develop and demonstrate software that accurately and efficiently simulates the full set of physics associated with aircraft flight operations. The critical attributes of the proposed framework are accuracy, computational efficiency, and inclusiveness. More accurate computational models will support higher fidelity analysis during the aircraft design process with higher confidence in the results, enabling reductions in the required number of expensive and time-consuming ground and flight tests. Computationally efficient models will support flight simulations for the design of guidance, navigation, and control systems, can be utilized as pilot training software, can support flight testing to reduce risks to test pilots and aircraft, and can be integrated into advanced control systems. The computational framework will accommodate the complexities of the full aircraft with flight control, propulsion systems, separating stores and cargo, landing gear, and a diverse set of physics (aerodynamics, structural dynamics, aeroelasticity, aero-acoustics, aerothermodynamics). Phase I work demonstrated key components of the flight simulator: aerodynamic models of forces and moments as functions of operational variables, the coupled effects of aeroelasticity, coupled flight mechanics models, and integrated flight controllers. Phase II work will integrate more features of aircraft operation into the software including propulsion systems and coupled control system hardware and software. BENEFIT: The commercial product to be developed is a virtual flight simulation tool to enable GNC design, pilot-in-the-loop training exercises, and advanced flow control systems in next-generation aircraft. This translates into shorter time-to-market cycles and more affordable aircraft for the US military, along with safer test programs. Potential applications of the virtual flight testing tool include fixed-wing aircraft, weapon systems, rotorcraft, and even non-conventional aircraft like flapping-wing micro-air vehicles. The tool will be designed to accommodate systems operating in the low subsonic, subsonic, transonic, supersonic, and hypersonic flight regimes. Applications extend from military aircraft to commercial airliners, launch vehicles, and space planes, each requiring cross-disciplinary, computationally intensive simulations of the aerodynamics, aerothermodynamics, aeroservoelasticity, and flight control systems. Commercial applications extend to products outside the aerospace industry: automobiles, manufacturing equipment involving fluid flows, nuclear power plant equipment, new green energy-production platforms, etc. Primary customers include US DoD agencies and NASA, prime defense contractors like Boeing, Lockheed-Martin, Northrop-Grumman, Raytheon, Sikorsky, and smaller commercial aircraft manufacturers like Cessna and Gulf Stream.


Thirunavukkarasu V.,Clear Science Corp. | Carlson H.A.,Clear Science Corp. | Wallace R.D.,Syracuse University | Shea P.R.,Syracuse University | Glauser M.N.,Syracuse University
AIAA Journal | Year: 2012

Closed-loop systems have been developed for controlling the flow above a three-dimensional turret. The top of the turret is hemispherical, houses a flat optical aperture, and can rotate about two axes (pitch and yaw). The extent of separation and concomitant turbulence levels in the flow above the aperture change as the turret rotates. The control objective is to minimize the separation and turbulence in the dynamic environment created by the articulating turret. The closed-loop control systems include dynamical and measurement-based estimators, controllers, filters, and compensators. These components are developed using both computational data from computational fluid dynamics simulations and experimental data from wind-tunnel runs within the common framework of SMARTFLOW: engineering software for flow control system design. The control systems are evaluated through a series of controlin- the-loop computational fluid dynamics simulations, demonstrating the merits of feedback control through robustness in the presence of measurement noise, modeling errors, and highly unsteady conditions. The computational fluid dynamics simulations also demonstrate reductions in actuation energy below levels required by open-loop systems. Copyright © 2012 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.


Grant
Agency: Department of Defense | Branch: Air Force | Program: SBIR | Phase: Phase II | Award Amount: 750.00K | Year: 2015

ABSTRACT: Clear Science Corp. proposes to develop and demonstrate software that accurately and efficiently simulates the full set of physics associated with aircraft flight operations through the integration of its physics-based reduced-order modeling (PBROM) technology into CREATE-AV Kestrel, the fixed-wing-aircraft component of the Department of Defense's (DoDs) CREATE Program. The Kestrel computational fluid dynamics (CFD) code will provide high-fidelity data for the construction of PBROMs that retain the accuracy of the parent model but enable analysis over the entire range of flight operations at a fraction of the computational overhead. Integration of the PBROM technology into Kestrel will provide the greater DoD engineering community access to tools that assist in the development of aerodynamic models for stability and control analyses and more general design and analysis of military aircraft. The proposed project will develop user test cases for Kestrel involving an F-16 fighter aircraft with articulating control surfaces and an open-source-fighter (OSF) version of the aircraft. The parent CFD models are representative of production and early-development fighter aircraft models with 36 and 4.5 million cells in the grids, respectively. Corresponding PBROMs will be used demonstrate virtual flight tests of the aircraft and stability and control analyses. BENEFIT: The proposed software fits into the framework of the ``Digital Thread" initiative at the Arnold Engineering Development Center (AEDC) with the objective of a 25% reduction in the development cycle time for air vehicles, achieved by streamlining research, development, test, and evaluation (RDT&E). Achieving the goal will leverage innovative modeling and simulation (M&S) tools that improve all stages of the development cycle with fast and comprehensive early-concept evaluation, identification of optimal, targeted ground tests, and streamlined flight testing from first flight to initial operational capability. The primary customers will be government personnel and government contractors who use the Kestrel. Applications include support of new aircraft development from conceptual design trade studies to flight testing and aircraft certification, along with support of modifications to existing, enabling new mission roles in the existing military fleet. The proposed software is designed to make the engineering development process more reliable and efficient through accurate and faster analyses at each stage. The technology provides a framework that efficiently integrates M&S and T&E.


Grant
Agency: Department of Defense | Branch: Air Force | Program: SBIR | Phase: Phase II | Award Amount: 739.49K | Year: 2015

ABSTRACT:Clear Science Corp. proposes to develop and demonstrate software that enables safer, more efficient and accurate flight testing of military aircraft. The computational tool is designed to reduce costs by identifying critical and benign areas in the operational envelope and using the information to streamline testing. The proposed technology systematically merges modeling and simulation (M&S) and test and evaluation (T&E) to optimize the warfighters that are designed, produced, and tested by the U. S. military. The modeling technology will also reduce risk by providing reliable predictions to clear aircraft for successive test points prior to flight sorties. The proposed modeling technology is physics-based, leveraging the accuracy of high-fidelity models at a fraction of the computational expense. The software will be developed and tested with existing data from the X-53 Active Aeroelastic Wing (AAW) Flight Test Program. The program included a comprehensive set of flutter, loads, and handling qualities tests of a modified F-18A fighter aircraft, generating data that are representative of the types typically produced during military aircraft certification. Models will be calibrated in near real time in a series of tests that utilize flight data in the same chronological sequence that they became available during the flight tests.BENEFIT:The commercial product to be developed is flight test support software that enables near real-time predictions and model updating with flight data. The primary customers will be flight test facilities including the 412th Test Wing at Edwards Air Force Base. The tool will be configured for the full range of fixed-wing aircraft that undergo flight testing by the U. S. military. Applications include flutter, loads and handling qualities tests. Defense budget constraints require expanding mission roles in the existing military fleet with adaptable external store configurations and flight envelopes that require a continuing series of flight testing. The proposed software is designed to make this process safer, more reliable, and less expensive through more accurate and faster predictions during the course of each flight test, along with the ability to quickly adjust test plans based on systematic identification of the critical drivers of static and dynamic loading on the aircraft. Commercial opportunities for the software exist with military aircraft manufacturers including Lockheed Martin, Boeing, and Northrop Grumman. Non-military applications extend to commercial aircraft with a large potential commercial market. Other applications include loads testing on rotorcraft and launch vehicles.


Grant
Agency: National Aeronautics and Space Administration | Branch: | Program: SBIR | Phase: Phase I | Award Amount: 100.00K | Year: 2011

Clear Science Corp. proposes to develop an aerodynamic modeling tool that assimilates data from different sources and facilitates uncertainty quantification. The technical merit and feasibility of the technology will be demonstrated in Phase I through a series of verification and validation tests that utilize both computational and wind tunnel data in constructing aerodynamic models for the Orion launch abort system (LAS). Aerodynamic models provide inputs to the guidance, navigation, and control system. The proposed software will enable performance predictions over a wide range of operational conditions through the fusion of data from multiple sources including high-dimensional computational simulations, wind tunnel tests, and flight tests. The software will also facilitate uncertainty analyses to determine the propagation of variability in inputs into output variability and sensitivity analyses to identify critical design and modeling parameters and operational variables. Complex systems like the LAS are designed with a mixture of heterogeneous data, and uncertainties in the data can be a critical factor in evaluating designs. The objective is to develop assimilation methods that reduce the number of expensive wind tunnel tests and CFD simulations required during system design while maintaining and improving the quality of aerodynamic models and systematically assessing uncertainties.


Grant
Agency: National Aeronautics and Space Administration | Branch: | Program: SBIR | Phase: Phase I | Award Amount: 125.00K | Year: 2016

Clear Science Corp. proposes to develop and demonstrate computational fluid dynamics (CFD)-based, reduced-order aeroservoelasticity modeling and simulation technology for fast and accurate predictions of nonlinear flight dynamics, enabling real-time, piloted and unpiloted flight simulations and providing a tool to design flight controllers for highly flexible, lightweight aircraft. Physics-based, reduced-order models (ROMs) will be developed and demonstrated with data from CFD models of the X-56, an experimental aircraft that NASA and the U. S. Air Force are using to test systems for flutter suppression and gust-load alleviation. Extended range and low fuel consumption through lightweight materials and large wing spans (high lift-to-drag ratios) are the drivers in next-generation aircraft like the X-56, but these attributes create challenges in maintaining flight safety, ride quality, and long-term structural durability. The development of flight controllers that can actively manage aeroservoelastic effects (body-freedom flutter, control reversal, gust loading) without compromising safety and aerodynamic performance is a key objective of both the X-56 Program and the proposed project. Through the proposed technology, nonlinear, aeroservoelastic ROMs can be coupled to other components of a flight simulator (six-degrees-of-freedom flight mechanics models and control software) to improve the fidelity of simulations that support controller design for a wide range of operating conditions.


Grant
Agency: Department of Defense | Branch: Navy | Program: STTR | Phase: Phase I | Award Amount: 80.00K | Year: 2013

Clear Science Corp. and the University of Texas at Austin will develop and demonstrate technology that accurately quantifies aero-optical distortion associated with high-energy laser (HEL) weapons on rotorcraft and will utilize the information in designing adaptive optics (AO) systems to maximize HEL system performance over the full range of flight conditions. Aero-optical distortion arises from vortical structures in the downwash flow during hover and in the wake during forward flight. Our team will utilize state-of-the-art rotorcraft wind tunnel facilities and computational models to develop and evaluate AO software and hardware. Flow simulations and direct measurements of aero-optical effects in the wind tunnel will provide data for statistical analyses of the flow dynamics and system specifications that match feedback algorithms, sensor and actuator bandwidths, and on-board processor speeds with the relevant temporal and spatial time scales. Candidate AO systems will be designed to minimize sensing, processing, and actuation latencies and compensate for measurement errors due to platform vibrations, sensor misalignment, and other disturbances. The objective is a robust, closed-loop adaptive optics system, providing optimal, reliable performance over the full range of helicopter operating conditions.


Grant
Agency: Department of Defense | Branch: Air Force | Program: SBIR | Phase: Phase I | Award Amount: 150.00K | Year: 2013

ABSTRACT: Clear Science Corp. proposes to develop and demonstrate accurate and computationally efficient analysis software for computing aircraft store trajectories and quantifying the risk of trajectory deviations resulting from unsteady flow in the weapons bay. The software will include physics-based, reduced-order models that predict six-degrees-of-freedom aerodynamic forces and moments acting on the store with hook ups to the Flowfield Influence Prediction Trajectory Generation Program (FLIP 4) and statistical analysis algorithms. The goal is more accurate evaluations of new aircraft/store configurations with quick turnaround times that account for all of the relevant aerodynamics including sensitivities to initial conditions (store release times) resulting from unsteadiness in the surrounding flow. These unsteady effects become more likely with gravity-dropped, lighter stores, and the likelihood of negative consequences increases in weapons that are designed for agility (neutrally stable or even unstable missile airframes). Negative consequences include collisions between the store and aircrafteither inside the bay or outside as a result of store orientation prior to firing. Targeted applications extend from initial screenings early in the weapon design and aircraft integration planning processes to final stores certification. In Phase I, the technology will be developed and validated using high-fidelity data for relevant aircraft-store configurations. BENEFIT: The commercial product to be developed is engineering software for analyzing store separation. The technology bridges the gap between comprehensive but lower-fidelity design tools that rely on simplified and/or empirical aerodynamic models and high-fidelity CFD models that are restrictive because of high computational overhead. Benefits include more reliable weapon systems with increased range, standoff distance and kill probability. The technology will reduce the risk of accidents in military aircraft, protecting crews and assets. Commercial opportunities for the store-separation analysis tool exist with military aircraft and missile manufacturers including Raytheon, Boeing, Lockheed-Martin, and Northrop Grumman. Customers also include U.S. Air Force, Navy, and Army engineers responsible for aircraft stores certification. Non-military applications range from airborne weather sensor deployment to cargo extraction on aircraft involved in search and rescue operations. Applications of the modeling technology extend from aerodynamics and store separation to structural mechanics, aero-acoustics, and guidance, navigation, and control in fixed-wing aircraft, rotorcraft, and launch vehicles.

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