Paduano James

Aurora Flight Science · Engineering

The word automatic is a compound of the Greek words auto.

A physics-based dynamic model of a twin-spool turboshaft engine that drives a variable pitch propeller is developed. The primary purpose for the development of this model is for researchers to use it to develop new engine control algorithms and study/predict off-design transient responses of gas turbine propulsion systems. In this model, the dynami...

The growing interest of rotary wing UAVs, for military and civilian applications, has encouraged designers to consider miniaturized configurations, more efficient in terms of endurance, payload capability and maneuverability. The purpose of this paper is to study a new configuration of coaxial rotor as applied to a micro aerial vehicle (MAV) with t...

This paper describes the Tactical Autonomous Aerial LOgistics System (TALOS), developed and flight tested during the first phase of the Office of Naval Research (ONR) Autonomous Aerial Cargo/Utility System (AACUS) Innovative Naval Prototype (INP) program. The ONR vision for AACUS is to create a retrofit perception/planning/human interface system th...

This chapter presents algorithms that use data from eddy-current sensors mounted in the engine casing for the purpose of gas turbine engine stability monitoring. To date, most signal-processing techniques using blade tip sensors have been limited to simple parametric measurements associated with the sensor waveform, for example measurement of zero-...

In this paper, we develop a nonlinear performance based model for a twin spool turboshaft engine which drives a variable pitch propeller. We also develop a piecewise linear representation of the model, which can be used for control of the turboshaft engine for large throttle commands (i.e. for the entire flight envelope). Finally we develop a decen...

In this paper, first a decentralized piecewise linear representation of the turboshaft system dynamics is developed. Then control theoretic concepts for decentralized adaptive control of a turboshaft engine piecewise linear model is developed. This controller can be used to control the engine for the entire flight envelope with decentralized adapti...

In this paper, a nonlinear performance based model for a twin spool turboshaft engine which drives a variable pitch propeller, is developed. Then a piecewise linear representa- tion of the model, which can be used for control of the turboshaft engine for large throttle commands (i.e. for the entire ight envelope), is developed. Open loop simulation...

In this paper we overview the distributed engine control problem and some potential solutions. The challenges that control designers will encounter for a distributed engine control design process is threefold. The first one is the modeling and formulation of uncertainties and deficiencies that electronics have in high temperature conditions. The se...

In this paper we overview the distributed engine control problem and some potential solutions. The challenges that control designers will encounter for a distributed engine control design process is threefold. The first one is the modeling and formulation of uncertainties and deficiencies that electronics have in high temperature conditions. The se...

In this paper we develop control theoretic concepts for decentralized adaptive control with partial communication for a twin spool gas turbine engine system. Distributed / decentralized adaptive control architecture creates tangible benets from the distribution of closed-loop feedback around the engine. The idea is to control the two subsystems of...

This paper aims to develop and describe control theoretic concepts for distributed control of gas turbine engines, and also to develop a dynamic engine model incorporating distributed components in compressor dynamics, engine cycles, and engine control. Concepts and architectures for distributed control are developed that create tangible benets fro...

The purpose of this paper is to develop control theoretic concepts for distributed control of gas turbine engines, and develop a dynamic engine model incorporating distributed components in compressor dynamics, engine cycles, and engine control. The latest results in distributed control combined with adaptive control theory are extended for turbofa...

A low-cost, robust, versatile digital shadowgraph visualization system is presented that provides a fast nonintrusive diagnostic for unsteady high-speed flows. The technique is particularly designed for real-time automated tracking of shock positions, enabling high-speed active shock control. The visualization system is based on a high-intensity wh...

Flow instabilities in transonic compressors include rotating stall and surge. Air Injection control has been demonstrated to be an effective strategy for actively suppressing rotating stall and surge. In industrial applications such as aero-engines, the implementation of air injection control schemes is constrained by factors such as the "cost" in...

This paper provides recent results on the use of multiple cameras in a coupled vision/inertial navigation framework for aerospace vehicle state estimation. The framework allows data from any number of cameras to be systematically combined. Multi-camera configurations including binocular and orthogonal cameras are considered. Kalman filtering concep...

S-duct Inlets are commonly used on subsonic cruise missiles, as they offer a good compromise between compactness, low observability and aerodynamic performance. Though currently used S-ducts exhibit good performance in terms of distortion and pressure recovery at the AIP, the situation can degrade drastically when the inlet is put in off-design con...

Abstract This paper presents a mathematical programming approach to online connectivityconstrained trajectory planning for autonomous,helicopters through cluttered environments. A lead vehicle must execute a certain mission whereby wireless line of sight communication to its ground station is lost. Relay helicopters are therefore introduced that mu...

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1992. Includes bibliographical references (p. 231-232). by James Donald Paduano. Ph.D.

Traditional aerodynamic inlet design tends to optimize the shape of the duct for the cruise condition. However, during manoeuvres both the external conditions and interaction with the forebody can create drastic losses. In particular, separation can occur inside the inlet duct and generate compressor face distortion leading to instabilities, especi...

This chapter presents algorithms that use data from eddy-current sensors mounted in the engine casing for the purpose of gas turbine engine stability monitoring. To date, most signal-processing techniques using blade tip sensors have been limited to simple parametric measurements associated with the sensor waveform, for example measurement of zero-...

A two-dimensional Mach 2.2 internal compression inlet with 97% total pressure recovery has been designed using viscid-inviscid computational tools. Losses are minimized by careful boundary-layer management combined with shape design for weak shocks. The resulting inlet has reduced stability to unstart in the face of atmospheric and engine-borne dis...

In this paper, we describe a new sensor technology aimed at better identifying the relative motion of two vehicles (eg the motion of a car from another car, or that of a ship from an helicopter etc.) or in general two objects of large or small sizes. The system described in this paper consists of an optical setup aimed at generating interference fr...

A complex representation of eddy-current sensor data is proposed and used for the detection of blade fault conditions in turbine engines. The representation is applied to the problem of detecting synchronous vibrations using a single sensor

This paper describes the design of and experiments with a nonlinear feedback controller implemented on an industrial type axial compressor. Two-dimensional (2-D) actuation with a ring of bleed valves was used to prevent surge and stall instabilities. For the interstage location of the bleed valves the nonlinear controller design was based on a modi...

This paper discusses the structure of the flow within the engine inlet of an uninhabited combat air vehicle (UCAV). The UCAV features a top-mounted, serpentine inlet leading to an engine buried within the fuselage. The performance of the inlet is found to depend strongly on a flow separation that occurs within the inlet. Both the time-averaged and...

Landing operations for small agricultural helicopters and, in general, docking operations between two vehicles, constitute an ongoing engineering challenge. This is due, in part, to the lack of small-sized and reliable local navigation system. This paper proposes a new, vision-based local navigation system that enables 6 degrees-of-freedom navigati...

Coordinated navigation to a single perfectly known target by multiple cooperating sensor-equipped agents in a partially known static environment is investigated. Original results on the spatial distribution of the agents under an optimal policy are derived using dynamic programming and neurodynamic programming techniques. Extension of the framework...

A low-cost and low-maintenance digital focused shadowgraph flow visualization system has been developed to provide fast diagnostics of rapidly changing phenomena in supersonic flows. The system is particularly designed for tracking shock positions in a supersonic inlet, enabling high-speed active shock control. It is based on a low-cost, high-inten...

This report describes the work done during the period between July 1, 2000 and June 30, 2003 on two topics: active control of separation and distortion in high subsonic supersonic inlets, and active control of inlet unstart in supersonic inlets. The report is divided into a summary, which highlights the major accomplishments of the program, and a s...

Aerodynamic-rotordynamic..... A first principles-based model of the fluid-induced forces acting on the rotor of an axial compressor is presented. These forces are primarily associated with the presence of a nonuniform flow field around the rotor, such as that produced by a rotor tip clearance asymmetry. Simple, analytical expressions for the forces...

This paper presents an integrated treatment of the dynamic coupling between the flow field (aerodynamics) and rotor structural vibration (rotordynamics) in axial compression systems. This work is motivated by documented observations of tip clearance effects on axial compressor flow field stability, the destabilizing effect of fluid-induced aerodyna...

A 2D Mach 2.2 internal compression inlet with 97% total pressure recovery has been designed using viscid-inviscid computational tools. Losses are minimized by careful boundary layer management combined with shape design for weak shocks. The resulting inlet has reduced stability to unstart in the face of atmospheric and engine-born disturbances, nec...

Substantial reductions in aircraft size are possible if shorter, more aggressive, serpentine inlet ducts are used for low- observability constrained propulsion installations. To ob- tain this benet, both inlet separation and compressor stall dynamics must be controlled. In this paper the integrated control of this coupled inlet/compression system i...

A model order reduction technique that yields low-order models of blade row unsteady aerodyamics is introduced. The technique is applied to linearized unsteady Euler CFD solutions in such a way that the resulting blade row models can be linked to their surroundings through their boundary conditions. The technique is applied to a transonic compresso...

This paper discusses developments in axial compressor stability modeling over the last several years and related work in active control of rotating stall and surge. Several major themes have emerged during this work. One theme is the interplay between hydrodynamic perturbations in axial compressors and instability inception. The former obey lineari...

An innovative concept for retrofitting a reconfiguration module to an existing control law is described. The concept is motivated by the need for low cost, add-on modules that improve air safety in the existing fleet of civil air transport vehicles. A direct adaptive, model reference control approach that accommodates control surface nonlinearities...

Active stabilization of surge was implemented on an Allied Signal LTS-101 axicentrifugal gas producer, reducing the surging mass flow by 1 percent, Sor an operating range increase of 11 percent. Control was achieved using high-response sensors in the inlet and diffuser throat, coupled to actuators that injected air near the diffuser throat. System...

This paper presents an experimental and analytical investigation of compressor stability assessment during engine transient operation. A 2-dimensional, linear, compressible, state-space analysis of stall-inception (Feulner et al. (1996)) was modified to account for engine transients and deterioration, with the latter modeled as increased tip-cleara...

This five year project has brought together researchers in nonlinear control theory (University of California and Caltech) and aeroengine dynamics and control (MIT) to develop new techniques for robust nonlinear Control of aeroengines. Technology transfer to the commercial sector has been achieved through strong and synergistic coupling with Pratt...

Magnetic bearings are widely used as active suspension devices in rotating machinery, mainly for active vibration control purposes. The concept of active tip clearance control suggests a new application of magnetic bearings as servo-actuators to stabilize rotating stall in axial compressors. This paper presents a first-of-a-kind feasibility study o...

Magnetic bearings are widely used as active suspension devices in rotating machinery, mainly for active vibration control purposes. The concept of active tip clearance control suggests a new application of magnetic bearings as servo-actuators to stabilize rotating stall in axial compressors. This paper presents a first-of-a-kind feasibility study o...

This report describes work carried out at the Gas Turbine Laboratory at MIT during the period 1/1/96 - 9/30/99, in the area of active control of turbomachinery. Within the overall project, three main research areas were pursued. These are, in brief: (1) Active control of rotating stall with inlet distortion; (2) Injectors as actuators for rotating...

To incorporate blade-row unsteady aerodynamics into system-level flutter and forced response models, a frequency domain Proper Orthogonal Decomposition was applied to an Euler CFD code which incorporates motion of an unstructured grid. With Arnoldi vectors as input-output generalizations of the basis functions, an efficient moc order reduction proc...

This paper presents the first attempt to stabilize rotating stall in a single-stage transonic axial flow compressor with inlet distortion using active feedback control. The experiments were conducted at the NASA Lewis Research Center on a single-stage transonic core compressor inlet stage. An array of 12 jet injectors located upstream of the compre...

This paper presents the first attempt to stabilize rotating stall in a single-stage transonic axial flow compressor with inlet distortion using active feedback control. The experiments were conducted at the NASA Lewis Research Center on a single-stage transonic core compressor inlet stage. An annular array of 12 jet-injectors located upstream of th...

A reduced order aerodynamic model is developed for aeroelastic analysis of turbomachines. The proper orthogonal decomposition technique is used to obtain the modal basis vectors of this model. Two-dimensional frequency domain solutions are used to obtain the basis vectors efficiently, however the model itself is developed in the time domain and is...

A reduced order aerodynamic model is developed for aeroelastic analysis of turbomachines. The proper orthogonal decompostion technique is used to obtain the modal basis vectors of this model. Two-dimensional frequency domain solutions are used to obtain the basis vectors efficiently, however the model itself is developed in the time domain and is c...

We compare linear and nonlinear controllers for an axial flow compressor. The control laws are designed for asymmetric interstage bleed valve actuation. We show that a nonlinear L_gV controller achieves a larger region of attraction than that achieved by an LQR controller

Rotating stall is one type of aerodynamic instability limiting the performance of aeroengines. A set of magnetic bearings supporting the compressor rotor is a potential actuator for active control of rotating stall. Based on a first-principles model we show that using this type of actuation, the first harmonic mode of rotating stall is linearly con...

Compressor stall and surge are complex nonlinear instabilities that reduce the performance and can cause failure of aircraft engines. We design a feedback controller that globally stabilizes a broad range of possible equilibria in a nonlinear compressor model. With a novel backstepping design we retain the system's useful nonlinearities which would...

Rotating stall and surge have been stabilized in a transonic single-stage axial compressor using active feedback control. The control strategy is to sense upstream wall static pressure patterns and feed back the signal to an annular array of twelve separately modulated air injectors. At tip relative Mach numbers of 1.0 and 1.5 the control achieved...

This paper describes the first experimental validation of transfer function modeling and active stabilization for axial compressors with circumferential inlet distortion. The inlet distortion experiments were carried out in a three stage low-speed compressor. Theory-experiment comparisons of steady performance, unsteady stall precursor, and forced...

The effectiveness of jet actuation for active modal control of rotating stall is investigated experimentally. The dominant physical effects of injection, such as momentum and mass addition, are elucidated. The results indicate that several of the theoretical assumptions used in past studies of jet injection for rotating stall control must be revise...

Atransferfunction estimationprocedurethatrelies on thetime-frequencyanalysis of input and output signalsis described. This method was developed in an attempt to better identify the aeroelastic behavior of NASA Dryden's F-18 systems research aircraft and to predict its è utter boundaries using in-èight experimental data. Numerical experimentson é el...

Describes alternative formulations of the rotating stall control problem in axial compressors. Jet injection instead of bleed valve actuation is introduced, and asymmetric instead of 1D (plenum bleed) control of rotating stall waves is cast into the Galerkin framework, resulting in a four-state nonlinear model. Shortcomings of very low-order modeli...

This paper discusses a new method to increase the stable operating range of a compressor operating in the presence of large total pressure inlet distortion by using low-bandwidth actuators. A stabilization criterion is defined and an algorithm for finding the optimal control law is presented. Practical issues related to the implementation of the id...

Robust linear control is used to stabilize the flow field perturbations which lead to rotating stall and surge in a transonic single-stage axial compressor. As in previous low-speed compressor control experiments with uniform inlet flow, a separate control is implemented for each of the decoupled spatial harmonics of the pre-stall perturbations. Ho...

This paper presents a new technique for precursor identification in high-speed compressors. The technique is a pseudo-correlation integral method referred to as the correlation method. To provide a basis for comparison, the traveling wave energy technique, which has been used extensively to study prestall data, is also briefly presented and applied...

Rotating stall and surge have been stabilized in a transonic single-stage axial compressor using active feedback control. The control strategy is to sense upstream wall static pressure patterns and feed back the signal to an annular array of twelve separately modulated air injectors. At tip relative Mach numbers of 1.0 and 1.5 the control achieved...

This paper describes flight control law validation issues raised at NASA Dryden, and recasts these problems into the real-μ analysis framework. To solve these problems, we extend the algorithm presented by Dailey to include repeated real perturbations, and describe how it can be used to find both a lower bound for real-μ and detailed direction info...

A new systematic method for nonlinear control design---backstepping---is applied to low-order compression system models. Backstepping achieves global asymptotic stability of both stall and surge in the presence of large uncertainties in the compressor model. Throughout our presentation, we explore the control design implications of the nonlinear eq...

Most existing subspace identification algorithms assume that a single input to output data set is available. Motivated by a real life problem on the F18-SRA experimental aircraft, we show how these algorithms are readily adapted to handle multiple data sets. We show by means of an example the relevance of such an improvement.

Using a two-dimensional compressible flow representation of axial compressor dynamics, a control-theoretic input-output model is derived, which is of general utility in rotating stall/surge active control studies. The derivation presented here begins with a review of the fluid dynamic model, which is a two-dimensional stage stacking technique that...

This paper summarizes basic research issues which can enable improved methodologies for High Cycle Fatigue mitigation in gas turbine engines. The paper is drawn from the results of a recent AFOSR Workshop on High Cycle Fatigue, which brought together a national community of industry, government, and academic researchers specifically to define these...

The goal of this program was to combine modern control concepts with new identification techniques to develop a comprehensive package for estimation of 'robust flutter boundaries' based on experimental data. The goal was to use flight data, combined with a fundamental physical understanding of flutter dynamics, to generate a prediction of flutter s...

This report describes the experiemental design and validation of sensing and actuation hardware to be incorporated into a NASA Lewis Research Center high-speed compressor test rig. The purpose of the control-augmented rig will be to investigate the dynamics of rotating stall in high-speed compressors, and to demonstrate stabilization of the perturb...

High-speed compressor data immediately prior to rotating stall inception are analyzed and compared to stability theory. New techniques for the detection of small-amplitude rotating waves in the presence of noise are detailed, and experimental and signal processing pitfalls discussed. In all nine compressors examined, rotating stall precedes surge....

An analytical model for control of rotating stall has been obtained from the basic fluid equations describing the process at inception. The model describes rotating stall as a traveling wave packet, sensed—in spatial components—via the Fourier decomposition of measurements obtained from a circumferential array of evenly distributed sensors (hot wir...

This paper presents a nonlinear formulation of the Moore-Greitzer rotating stall model that is suitable for control analysis and design. The model is validated by comparing stall inception experiments to simulated stall inception transients. The shape of the nonlinear compressor characteristic is shown to be a primary determinant of stall inception...

This paper describes an active multi-axis vibration cancellation system designed for the expander of a Hughes split Stirling cryocooler. The axial force and the two lateral torques generated by the expander are cancelled by an active counterbalance driven by electrodynamic forcing elements. The counterbalance drive signals are generated by an narro...

The vibration produced by Stirling cryocoolers is incompatible with precision-pointing imaging instruments. This paper examines a vibration cancellation system that was designed for the expander of a Hughes tactical cooler. This system uses a custom-designed multi-axis counterbalance and an analogue implementation of an adaptive feedforward compens...

The vibration produced by Stirling cryocoolers is incompatible with precision-pointing imaging instruments. This paper reviews vibration reduction techniques and then examines a vibration cancellation system that was designed for the displacer of a Hughes tactical cooler. This system uses a custom-designed multi-axis counterbalance and an analog im...

This article briefly describes the concept of “smart” engine components and discusses various applications of this concept that are currently in the research phase. The interdisciplinary nature of smart engine research is then illustrated through a review of dynamic control of aerodynamic instabilities in gas turbine compression systems (rotating s...

The onset of rotating stall has been delayed in a low-speed, single-stage, axial research compressor using active feedback control. Control was implemented using a circumferential array of hot wires to sense propagating waves of axial velocity upstream of the compressor. Using this information, additional circumferentially traveling waves were then...

This lecture discusses the use of closed loop control at the component level to enhance the performance of gas turbine engines. The general theme is the suppression of flow instabilities (rotating stall and surge) through use of feedback, either actively or by means of the aeromechanical coupling provided by tailored structures. The basic concepts...

Having demonstrated in previous years the ability to model, identify, and control rotating stall, our research has concentrated in the past year on refinements and extensions to the compressor modeling developed for active control research. The areas in which progress has been made are: (1) refinement of the basic fluid mechanics based on identific...

A low-speed axial research compressor has been fitted with movable inlet guide vanes to allow for feedback stabilization of rotating stall. A model exists whose structure captures the input-output behavior, and stabilization of rotating stall is possible using this model. Quantitative identification of the parameters in the rotating stall model req...

A recently developed sensitivity analysis technique for linear control systems, which is based on the gradients of the return-difference-matrix singular values, is improved by introducing system scaling, and extended to include digital systems. System scaling is used to improve the reliability of the singular values as measures of relative stabilit...

A sensitivity analysis technique for multiloop flight control systems is studied. This technique uses the scaled singular values of the return difference matrix as a measure of the relative stability of a control system. It then uses the gradients of these singular values with respect to system and controller parameters to judge sensitivity. The se...

This report presents the development and application of a sensitivity analysis technique for multiloop flight control systems. This analysis yields very useful information on the sensitivity of the relative-stability criteria of the control system, with variations or uncertainties in the system and controller elements. The sensitivity analysis tech...

A sensitivity analysis is presented that can be used to judge the impact of vehicle dynamic model variations on the relative stability of multivariable continuous closed-loop control systems. The sensitivity analysis uses and extends the singular-value concept by developing expressions for the gradients of the singular value with respect to variati...

Commuter aircraft with low wing loading that operate at low altitudes are particularly susceptible to unwanted accelerations caused by atmospheric gusts. This paper describes the design and analysis of a longitudinal digital Ride Quality Augmentation System (RQAS). The RQAS designs were conducted for a Cessna 402B aircraft using the flaps and the e...

A digital focused shadowgraph visualization system has been developed to provide an optical diagnostic for unsteady high-speed flows. The technique is particularly designed for tracking shock positions in a supersonic inlet. It provides a direct electronic output that represents shock position, enabling high-speed active shock control. The system f...

A series of high subsonic flow experiments (Mach number ~0.65) were conducted in a serpentine diffuser in which flow separation occurs. Periodic injection was introduced near the separation point, using various Coanda-type injector geometries and various injection mass flows, to improve pressure recovery and mitigate distortion and unsteadiness at...

A recent model of compression system instabilities that incorporates blade flexibility is reviewed and extended t o include actuators and sensors for control studies. This model allows stabilization of flutter, rotating stall, and surge to be considered in a single integrated analysis. Using this model, we demonstrate that rotating stall and flutte...

Experimental control of unsteadiness due to inlet flow separation is described. The control scheme is presented as part of an overall archi- tecture for integrated inlet/compressor control that attempts to mitigate both the source of separation in serpentine inlets and the effects on compressor operability. Experimental results on unsteadiness redu...