Page 14Vortex engines

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aero-online.org January 2, 2013 ®

Contents2 WhatsOnline Top Products/Top News/Top Articles

SimulationFeature6 Ensuring on-time delivery Any delay in terms of schedule or not meeting

the specifications or budget can have a huge impact on the viability of a program as well as the companies involved. New software demonstrates companies can actually deliver on what they commit.

14 TechnologyUpdate Propulsion Vortex rocket engine reaps the whirlwind

Electronics Tracking the health of aircraft electrical

generators

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24 ResourceLinks

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Aerospace Engineering January 2, 20132

What'sOnline

High-intensity pressure transducersMeggitt Sensing Systems’ Endevco 8507C rugged, miniature piezoresistive pressure transducers, as well as its range of acoustic microphones, support the requirements of hypersonic, transonic, and “quiet flow” wind tunnel testing; turbulent airflow measurements; and other high-intensity aerodynamic testing. The devices feature low-pressure offerings of 1, 2, 5, and15 psig ranges with a 300-mV full-scale output and up to 20X minimum burst pressure (1 and 2 psig versions). More detail at www.sae.org/mags/aem/11656.

Voltage regulators for space applicationsInternational Rectifier’s high-current, ultra-low dropout (ULDO) RAD-hard hybrid linear voltage regulators come in Standard Microcircuit Drawings (SMD) for space applications including satellites and launch vehicles. The Defense Logistics Agency (DLA), Land, and Maritime certified voltage regulators are also included in IR’s Radiation Hardness Assurance (RHA) program that

Top Productsguarantees the devices’ radiation performance to the component level. More detail at www.sae.org/mags/aem/11658.

Materials improve surface protectionW. L. Gore & Associates’ Gore Skyflex Aerospace Materials provide improved protection against chafing and abrasion in both rotary and fixed wing aircraft surfaces. Gore Skyflex Aerospace Materials for anti-chafe applications help minimize vibration force and reduce the abrasive effects of foreign debris between surfaces in applications such as access panels, fuel bladders, tail booms, and transmission panels, where mechanical wear from vibration can cause small particles to become trapped between the interfaces. More detail at www.sae.org/mags/aem/11657.

3January 2, 2013 Aerospace Engineering

Top Newsaero-online.org

XMC CardThe BU-67112 MIL-STD-1553 XMC card from Data Device Corp. (DDC) meets the data demands of mission-critical military aerospace applications. The card’s advanced I/O incorporates DDC’s Total-AceXtreme fully integrated MIL-STD-1553 component with unique low-power application-specific integrated circuit (ASIC) design. More detail at www.sae.org/mags/aem/11659.

Vacuum cups for heavy liftingVacuum cups from Vi-Cas Manufacturing come in sizes up to 15-in diameter to lift and manipulate large, bulky, or cumbersome materials such as aircraft fuselage segments and fabricated assemblies. Round, rectangular, or oval cups are available. More detail at www.sae.org/mags/aem/11655.

Raytheon Co. was awarded a $1.5 million Defense Advanced Research Projects Agency (DARPA) contract for phase one of the agency’s Space Enabled Effects for Military Engagements (SeeMe) program. During the next nine months, the company will complete the design for small satellites to enhance warfighter situational awareness in the battlespace. The SeeMe program will provide useful on-demand imagery information directly to the warfighter in the field from a low-cost satellite constellation launched on a schedule that conforms to U.S. Department of Defense operational tempos. More detail at www.sae.org/mags/aem/11647.

Aerospace Engineering January 2, 20134

What'sOnline

Two heavyweights in the automotive and aerospace industries are joining minds on lighter materials. BMW and Boeing on Dec. 12 announced they would do joint research on carbon-fiber recycling and share knowledge about the material and its manufacture. As part of the collaboration agreement, the two companies will also share carbon-fiber manufacturing process simulations and ideas for manufacturing automation. More detail at www.sae.org/mags/aem/11642.

The U.S. Navy awarded ATK a $48-million production contract for the manufacture of the AAR-47 Missile Warning System. The award encompasses production of new assemblies, including optical sensor converters and computer processors, as well as options for retrofitting weapon replaceable assembly upgrades and delivery of ATK’s Countermeasures Signal Simulator (CSS) to test the systems operability. More detail at www.sae.org/mags/aem/11648.

Eaton Corp. will provide opportunities for University of Michigan students to work on relevant, hands-on projects as a sponsor of the university’s Multidisciplinary Design Program (MDP).

Top News, continued...The MDP challenges students to solve problems and create breakthroughs for sponsoring industries through multidiscipline team collaboration. For the first MDP project, a student team will focus on developing a robust, predictive, and validated fire-resistance model for Eaton’s high-performance quick-disconnect products. More detail at www.sae.org/mags/aem/11649.

AMETEK Inc. has acquired Aero Components International (ACI) and Avtech Avionics and Instruments (Avtech), both privately owned, U.S. FAA-certified aviation repair operations located in Miami, FL. ACI repairs and overhauls fuel, hydraulic, pneumatic, power generation, and heat exchanger components and is one of the few independent aviation repair shops with fuel repair capabilities. Avtech’s expertise is in the repair and maintenance of next generation and legacy avionics and instruments. More detail at www.sae.org/ mags/aem/11660.

5January 2, 2013 Aerospace Engineering

aero-online.orgcrunching. Read more at www.sae.org/mags/aem/11516.

For the ‘connected’ airplane, young engineers have right mind-set“I do a lot of recruiting. The kids I’m hiring now are phenomenal. They look at things differently. They’re energetic and they’re sharp,” said John Craig, Chief Engineer of Network Systems for Boeing Commercial Airplanes. Read more at www.sae.org/mags/aem/11572.

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Top articles of the monthBoeing gets 787 interior ‘right first time’

To achieve “right first time” successes, the Boeing Interiors group departed from the norm and used an automotive tool to reduce installation times from 3500 to 232 h on the 787. Read more at www.sae.org/mags/aem/11504.

More-electric aircraft are not without challengesEngineers study replacing hydraulic actuators in the primary flight-control systems with electromechanical systems. Read more at www.sae.org/mags/aem/11465.

Flow analysis of an air-to-air refueling system1-D and 3-D virtual prototyping provide an end to the over-engineering of subsystems in the days of cost and time

on-time delivery

The aerospace industry is facing numerous challenges moving forward, most notably

increasingly complex and competitive programs with competitors from different regions of the world, and the growing shortfall in terms of the number of skilled professionals working in the industry, with as much as 40% of the workforce becoming eligible for retirement within the next three years.

“We looked at these and said, how can we impact positively these challenges?” said Michel Tellier, Vice

Any delay in terms of schedule or not meeting the specifications or budget can have a huge impact on the viability of a program as well as the companies involved. New software demonstrates companies can actually deliver on what they commit.

Ensuring

by Matthew Monaghan

Aerospace Engineering January 2, 20136

Complex operations such as landing and taking off from an aircraft carrier can be simulated with the Winning Program 3DExperience solution.

on-time delivery

7January 2, 2013 Aerospace Engineering

Aerospace Engineering January 2, 20138

President, Industry Solutions, Aerospace and Defense, Dassault Systèmes (DS), at the company’s recent 3DExperience Forum in Orlando, FL. “The area where we have the greatest opportunity to impact these was actually in the early stages of the program—conceptual

design, advanced design, preliminary design—where you make the promise, decide on the technologies, decide on your partners, where fundamentally you stipulate what you’re going to do. This is an area that’s been historically underserved.”

According to a 2011 Roland Berger study, 70% of cost decisions made during a program’s concept and preliminary design phase impact 80% of the total life cycle cost. Many of these decisions have historically fallen on the shoulders of a select group of experts within an organization who relied on their knowledge and years of experience. While effective overall, this approach was not institutionalized and suffered in terms of collaboration among various departments.

“Fundamentally, the shift that’s happening demographically within the industry is important because now is the time to urgently capture that knowledge and experience and furthermore boost the ability of these teams to collaborate,” Tellier said in an interview with Aerospace Engineering.

“We have the technology in the V6 Experience platform to do systems-based design,” Tellier said. “We have the technology through our nonlinear solvers and our optimizers to generate and produce massive amounts of iterations automatically. We have the technology to be able to take a functionally architectured product and run it through use cases or flight scenarios or flight envelopes and understand what its behavior is going to be. We have the capability so that as you’re planning your program, you’re not just writing it down on a sheet of paper, you’re

Michel Tellier (left), Vice President, Industry Solutions, Aerospace and Defense, Dassault Systèmes, and Brian Christensen, Solution Experience Leader for Winning Program, at the 3DExperience Forum on Nov. 6 in Orlando, FL. (Matthew Monaghan)

on-time deliveryEnsuring

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Simulation Feature

implementing it into the same system so that every decision you make you can see what impact that decision is going to have on your schedule, cost, resources, and skills downstream.”

This capability has been dubbed “Winning Program,” the first DS “industry solution experience,” which enables aerospace and defense companies to configure the right concept for their customers and recognize from the earliest stages of the program that it can be delivered on budget and on time.

“We’re providing a platform that allows you to permit your architects to design the concept in an interrelated collaborative platform that brings those concepts together, so that the person working one system and the person working another system are all defining in the same space—an expert platform for these experts,” Tellier said. “That platform can then be exercised in terms of all the different flight scenarios, use cases, operational conditions, and circumstances

that you can do in the virtual world that you can’t do in the real world. So you know whether or not your design decisions are good. You can execute massive amounts of trade studies, massive amounts of iterations, and optimize your design.”

Know your roleIn today’s competitive aerospace market, companies must have efficient processes to develop proposed system configurations that can be delivered on time, responsive to the

The governance and collaboration proposal development feature of Winning Program ensures efficient and repeatable processes across dispersed teams and full visibility of the offer or proposal.

Aerospace Engineering January 2, 201310

The System Trade Studies solution provides the ability to view trade-offs of various designs to decide on an optimal systems architecture that includes proposed technologies.

platform manages the bidding process, organizes all requirements and constraints internally and externally, coordinates all of the work, and provides a communication platform with the customer.

“What we’re looking to do is create an environment where everyone knows what they

requirements of the business or request for proposal (RFP), technically feasible, and competitively priced.

“At the end of the day, this is where you make the promise; this is where you either win or lose,” Tellier said. “For any supplier, they get down selected or not. Their lifeblood is winning these programs. Winning today is about providing a promise or proposal that delivers the most value. You now have to provide proof that you can actually deliver on what you commit.”

With the Winning Program 3DExperience solution, users have access to full-program data, enhanced trade studies management, and the ability to define and manage proposed system configurations. Full analysis history can also be reused for future studies, and all program and proposal data can later be accessed.

Winning Program’s component management

on-time deliveryEnsuring

11January 2, 2013 Aerospace Engineering

Simulation Feature

need to do, when they need to do it, and what are their dependencies and what are the deliveries that they need to create,” said Brian Christensen, Solution Experience Leader for Winning Program. “We use a task-management system where we assign the tasks for everyone to do, therefore they know what they’re expected to do. This has a very valuable input into this process because many of these people are moving in and out of jobs, retiring, so it’s very important to have a controlled environment to know what needs to be done, when it needs to be done.”

As a result of this approach, problems can be pinpointed at any point in the development cycle and the root cause can be identified.

Carrier complexityFor any team, it is important for everyone to understand what is being done and the decisions being made. With that in mind, Winning Program provides the ability to model the entire systems infrastructure, including the requirements and functional, logical, and physical architectures.

“It’s no longer the state of the art to have a digital mockup of what you’re developing, but it’s really to have a functional digital mockup,” Tellier said. “We add behavior. It’s the ability to understand how all the different systems work together, how they behave together. With this capability, what we’re doing is throwing the entire flight envelope and operational envelope

in terms of test scenarios at this behavioral mockup, and that allows us to drive a massive amount of maturity into the design very early on.”

This ability to simulate multiple aspects provides the ability to simulate complex operations. For example, a virtual/physical model of an advanced design can be run against all of the flight conditions for landing and taking off from an aircraft carrier.

Within the Configuration Definition phase, Winning Program manages the generation of the best concept architecture to meet customer and business requirements.

Aerospace Engineering January 2, 201312

“What we were looking at was an integrated or competing set of requirements,” Christensen said. “We used a system model and simulated what it would be like to take off from an aircraft carrier. That generated our load models or the forces that we would have to experience. We then directly fed that into our analysis model, our FEA model, to see what stresses are to be experienced on the landing gear in those conditions. Typically, you would do some manual iterations to try to find the best one. Unfortunately, in today’s world you need thousands of iterations, so we use

our iSight capability to connect directly those two simulations and iterate through thousands of options resulting in an optimal design for the landing gear.”

This can be used to illustrate not just what a vehicle can do in the context of its own design state but also in the customer’s design state, incorporating personnel shifts as well as electronics, communication, control, and command forces.

“Fundamentally, this is the ability to not just demonstrate to your customer that you’ve understood their operating environment and you’ve validated your

on-time deliveryEnsuring

All of the program shifts for the personnel on an aircraft carrier can be implemented into the model.

13January 2, 2013 Aerospace Engineering

Simulation Feature

design in their environment; it’s also the opportunity to use this as a design link to drive the optimization of design for operations as well,” Tellier said.

This capability also provides significant benefits in the space and defense industries.

“In space, you don’t really design for mass-producibility, you design for the thing to survive in the environments it’s subjected to, and you can’t simulate those environments on Earth,” Tellier said. “All these systems have to be validated interconnectedly because that’s where the issues occur. [Winning Program] allows them to conceptually do all this integration and then validate it, which they need to do.

“The defense world is getting much more competitive, so being able to demonstrate that you have a viable program is the most important thing. It’s not so much about the product that you’re proposing to do on its own, it’s how well it integrates

into their infrastructure and that you can prove that you can get it done. Being able to efficiently conceptualize a design and then move it downstream is a huge value.”

Aerospace Engineering January 2, 201314

TechnologyUpdatePropulsion

Vortex rocket engine reaps the whirlwind The inner surfaces of rocket engines can be subjected to extremely high heat. Temperatures as high as 3227°C can result from the powerful, thrust-generating exothermal reaction between fuel and oxidizer, which runs hot enough to melt or damage the walls of the combustion chamber.

That’s why the cores of hot-running rocket engines are made of temperature-resistant materials that often incorporate networks of cooling passages. In these engine designs, vein-like ducts run with low-temperature (sometimes cryogenic) liquid propellants to carry off the heat and thus maintain structural integrity despite the violent conflagration just adjacent.

Rocket scientists and engineers at a small space-tech company in Madison, WI, think that they have developed a better way to burn rocket fuel. Orbital Technologies (Orbitec) has developed a system that keeps the hot burning gases away from the chamber walls. Orbitec’s vortex-cooled liquid engines inject liquid oxygen into the combustion chamber in such a way to generate a stable, tornado-like cyclonic flow that confines

the combustion to the central region of the chamber, which protects the surfaces. In October, Orbitec flight-tested its new rocket engine in the Mojave desert. The engine successfully powered a 25-ft long, 800-lb Prospector P-15 sounding rocket built by Garvey Spacecraft to 600 mph. California State University at Long Beach also took part as did subcontractors Moog, Barber Nichols, Concept NREC, and Boeing.

The motor was a version of the 30,000-lb thrust liquid engine that Orbitec is developing for the U.S. Air

A rocket powered by Orbitec’s vortex liquid-fuel engine climbs into the Mojave sky.

15January 2, 2013 Aerospace Engineering

propulsion, said a company spokesman. Orbitec, which has about 70 employees, also builds fire-suppression units as well as life-support and environmental control systems, such as kits that will enable astronauts on the International Space Station to grow fresh food next year.

“Our vortex generator eliminates the high temperatures at the inner surfaces of the engine,” said Martin Chiaverini, Principal Propulsion Engineer.

By carefully tweaking the oxidizer-injection parameters, he said, the vortex flow establishes radial gradients of

The Garvey Prospector P-15 sounding rocket sits on its launch rail prior to lift-off.

Force’s Advanced Upper Stage Engine Program and for several NASA in-space and planetary propulsion systems including the Space Launch System.

The patented vortex engine technology, funding for which has been provided by the USAF Research Laboratory and other U.S. Department of Defense agencies, is mature and ready for teaming partners and investment to help it enter applications in space and boost

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Aerospace Engineering January 2, 201316

TechnologyUpdate

pressure and density that cause the lower-density hot combustion products to be confined near the central axis of the combustion chamber while cold gases yet to be burned are spun out to the walls.

The new method, which enhances general burning efficiency, could be smaller and lighter-weight as well as significantly simpler and cheaper to build, by requiring less, and more regular materials.

“It’s very expensive to manufacture the internal regenerative-cooling channels and ducts that reject combustion heat”

by circulating unburned fuel through the chamber walls, Chiaverini continued. The passages are often leak-prone as well.

Because the vortex engines are not subject to severe thermal fatigue, they can be reused.

Orbitec’s engines might find use in the upper stages of launch vehicles that deliver satellites to orbit; upper-stage technologies tend to exert considerable leverage on overall mission costs.

Advanced upper stages could cut costs by allowing a given payload to be delivered using a smaller launch vehicle or by boosting the payload capacity of current launchers. The same fundamental technology could also be used on smaller systems for maneuvering spacecraft and to assist larger systems to make it off the launch pad, paving the way for significantly safer, low-cost space access.

The vortex, or swirl, generator technology, Chiaverini explained, relies on oxidizer injectors at the base of the combustion chamber that are aimed tangentially to the inner surface of the curving walls

“The angle sets up a circulating force that forms a vortex” that keeps the hot-burning reaction gases confined in the tame, central tornado, he added. The circumferential component of the injection flow forms a free vortex that

Swirl injectors just above the nozzle create a double vortex of cool outer and hot inner gases.

17January 2, 2013 Aerospace Engineering

spirals forward along the walls to the head end, where it turns inward to form a second vortex, concentrated along the axis, that flows in the reverse direction out of the chamber at the aft end.

Orbitec, established in 1988, has mounted a long RD&E effort aimed at perfecting the technology.

“In 1998, we were working on a small hybrid [part solid/part gas or liquid] rocket for NASA Marshall,” he recalled, and were “trying to get the burning rate to increase so we tried using a swirl injector.” The team found that under the right conditions the vortex flow could be used to prevent flame spreading along solid fuel surfaces, rather than enhancing the burning. “Next we tried the technology on a liquid-fuel rocket.”

Since then, with USAF, NASA, and some DARPA funding support, the company has tested its patented concept using several liquid and gaseous propellants including (gaseous and liquid) hydrogen, kerosene, propane, and gaseous methane in rocket motors that produce thrusts ranging from 10 to 7500 lb. Chiaverini does not see any fundamental barriers to additional scale-up.

The recent flight test also demonstrated a new igniter and nozzle. The novel igniter, which is the size of a

The Orbitec vortex engine may find use in rockets of various sizes and missions.

thumbnail, employs acoustic resonance heating to spark off the fuel, he said. When a valve opens, oxygen gas flows into a resonant cavity to cause shockwave compression-heating that ignites the fuel in milliseconds. The highly reliable device, also USAF-funded, “doesn’t take much energy to light off the fuel.”

The flight test also demonstrated the extreme heat-resistance of a new lightweight carbon-carbon composite nozzle extension from Alliant Techsystems. The uncooled nozzle extension, which glowed white hot in tests, was attached to the cooled metal housing using that company’s dissimilar materials-joining technology.

Steven Ashley

Aerospace Engineering January 2, 201318

TechnologyUpdateElectronics

Tracking the health of aircraft electrical generators The U.S. Navy’s P-3 aircraft uses a Bendix (later AlliedSignal and currently Honeywell) generator that was designed more than 30 years ago. The P-3 generator is a salient eight-pole (eight rotor bars), 6000-rpm, three-phase brushless ac generator. The running speed of the generator is 5700 to 6300 rpm (line frequency of 380 Hz to 420 Hz). The rated voltage and power is 115-V ac and 60 kVA (20 kVA/phase), respectively. It has a 12-pole ac exciter and a three-phase, half-wave diode rectifier rotating with the exciter armature and main generator field assembly. A single-phase permanent magnet generator (PMG) furnishes control voltage and power for the voltage regulator.

The electrical and mechanical issues (due to being continuously operated beyond design point and less than optimal drive end bearing support) combine to cause premature failures of the P-3 generators. Repairs are time consuming and costly.

Currently, diagnostic/prognostic technologies are not implemented for

P-3 generators and other electrical power systems. Although some time series data (such as phase voltage and current) is collected during ground testing, no time series data is collected in flight for the generators.

Researchers NAVAIR and Global Technology Connection have developed feature extraction and diagnostic algorithms to ultimately 1) differentiate between generator failure modes and normal aircraft operational modes; and 2) determine the degree of damage of a generator, providing maintenance personnel with information about the current health state and remaining life of generators so that timely action can be taken. Health-monitoring algorithms Researchers came up with basic modules of the proposed diagnostic and health-management system architecture based upon data-driven algorithms. Also, they showed how the architecture can provide inputs to the condition-based maintenance (CBM) module for maintenance execution.

The feature extraction unit takes raw sampled data from a generator and converts it to a form suitable for the diagnostic and prognostic modules. The diagnostician monitors continuously

19January 2, 2013 Aerospace Engineering

critical feature data and decides upon the existence of impending or incipient failure conditions. The detection and identification of an impending failure triggers the prognosticator. The prognosticator reports the remaining useful lifetime of the failing machine or component to the CBM module. The CBM module schedules the maintenance so that uptime is maximized while certain constraints are satisfied.

The prognostic architecture is based on three constructs: 1) a static “virtual sensor” that relates known measurements to material deterioration; 2) a predictor that attempts to project the current state of the damaged material into the future thus revealing the time evolution of the damage and allowing the estimation of the material’s

remaining useful lifetime; and 3) a Confidence Prediction Neural Network (CPNN), whose task is to account for uncertainty and manage/shrink the prediction bounds. Feature extraction Initial time-domain and frequency-domain feature extraction algorithms were developed to distinguish between healthy and common failure modes such as bearing failure. The time domain features and frequency domain features based upon Electrical Signature Analysis (ESA) were calculated from (demodulated) voltage and current. In this work, the time domain features were statistics of demodulated three-phase voltage vs. its phase angle, while the

Schematic of the disassembled parts of a brushless ac generator for the P-3.

1 . Stator assembly2 . Rotor and shaft3 . Rotating diode assembly4 . Exciter rotor5 . End bell

6 . PM generator stator7 . Permanent magnetic rotor core8 . Generator to air duct adapter9 . Fan assembly10 . Drive shaft assembly

Aerospace Engineering January 2, 201320

frequency domain features were magnitude deviation statistics of selected (inter) harmonics of demodulated three-phase voltage and exciter current.

Each extracted feature from a set of time- and frequency-domain-based features was evaluated separately by statistical comparison with the corresponding feature database. This feature database was determined from the feature construction, selection, and extraction analysis of healthy/low-hour generators operating at various loads and operating frequency.

Statistical margins were defined to denote the range of healthy/low-hour generators. Values outside of this range indicate the presence of a degraded/high-hour generator. Consequently, the healthy operation range was based on separate asymmetrical calculations of high and low margins that were calculated by generalized higher moments of features. Electrical signature analysis ESA is the term used for the evaluation of the voltage and current waveforms. This provides an increased advantage to diagnostics as power-, motor-, and load-related signals can be quickly compared. A key consideration when using ESA is

that voltage signatures relate to the upstream of the circuit being tested (toward power generation) and current signatures relate to the downstream of the circuit being tested (toward the motor and load).

ESA uses the machine being tested as a transducer, allowing the user to evaluate the electrical and mechanical condition from the control or switchgear. Typically, ESA is done in the frequency domain, relying upon FFT techniques for accurate analysis.

Frequency-domain-based ESA techniques have been developed to detect and track a seeded bearing failure in a P-3 generator, which was not detectable in the vibration signals using visual inspection alone (no large spikes in vibration data were observed).

Also, frequency-domain techniques have been used to identify the location/component of degradations in P-3 generators using available phase voltage and current waveforms. In this work, ESA was done both in the time-domain as well as the frequency-domain.

Time-domain based ESA was used to assess the general health of generators by analyzing the amplitude demodulated signal vs. phase angle of the complex signals, while frequency-domain based ESA was used to identify the location/component of degradations in P-3

TechnologyUpdate

21January 2, 2013 Aerospace Engineering

generators using available phase voltage and current waveforms. Fault classifier The diagnostician, implemented as a multiple-input, multiple-output fuzzy neural network (FNN), serves as a nonlinear discriminator to classify impending faults. The fault classifier is trained to recognize generator faults from a vector of (inter) harmonic signatures corresponding to air gap, rotor, stator, rotating diodes, and bearing failures.

Air gap and rotor winding failures are detected from demodulated line

frequency harmonics with the latter utilizing only even harmonics. Stator winding and rotating diode failures are detected from exciter current harmonics. The first 10 harmonics of bearing fundamental train frequency (FTF), ball pass outer race (BPOR), ball pass inner race (BPIR), and the two times the ball spin frequency (2×BSF) were used to identify bearing failures.

The bearing fault signatures appeared as harmonics of FTF × RS, BPOR × RS, BPIR × RS, and 2 × BSF × RS in the demodulated three-phase voltage where RS is the running speed of the generator. The bearing parameters

Basic modules and overall architecture for diagnostic and prognostic assessment of aircraft electric power systems.

Aerospace Engineering January 2, 201322

(rolling element diameter, pitch diameter, contact angle, and number of rolling elements) needed to calculate FTF, BPOR, BPIR, and 2×BSF were obtained from a manufacturer’s catalog given the particular manufacturer and size of the bearing.

A virtual sensor calculated a failure measure indirectly through a (neural network) mapping of features and operating condition. Consider, for example, the case of an electrical generator. No direct measurement of the degree of stator/rotor winding degradation, bearings damage, etc., occurring in a generator is possible when it is in an operational state. That is, there is no such device as a “fault meter” capable of providing direct

measurements of the fault evolution. The fault dimensions take the form of a vector of integer state-of-health (SOH) values where the values range from 100 (healthy) to 0 (fault). Results and conclusions Time domain features based upon ESA that were previously developed to detect the degree of damage in P-3 generators have been augmented by frequency-domain analysis algorithms that can accurately differentiate between normal operational modes and generator failure modes.

The results showed that the high accuracy frequency-domain analysis algorithms were able to accurately detect bearing and rotating diode

Applying ESA to motor and generator systems.

TechnologyUpdate

23January 2, 2013 Aerospace Engineering

failures for two P-3 generators at full- , half-, and no-load operating conditions. The deviations in the magnitudes of the (inter) harmonics above the -80 dB threshold for phase voltages and the -40 dB threshold for exciter current were used to determine what type of failure mode the generator was experiencing.

Also, the general harmonics to detect air gap, bearing, rotating diode, stator winding, and rotor winding were determined. Physical inspections have not been performed on the two P-3

generators to verify the diagnostic results.

Further work is needed to determine how the reference time-domain feature and the magnitudes of key frequency harmonics change with respect to nonlinear, leading power factor, and lagging power factor loads at various load levels.

This article is based on SAE technical paper 2012-01-2234 by Freeman Rufus and Ash Thakker, Global Technology

Connection Inc.; Sean Field, Naval Air Systems Command; and Nathan Kumbar, NAVAIR.

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Digital Aerospace Engineering,® January 2, 2013, Volume 3, Number 1. Digital Aerospace Engineering (ISSN 2156-7751) is published six times a year by SAE International.® SAE International is not responsible for the accuracy of information in the editorial, articles, and advertising sections of this publication. Readers should independently evaluate the accuracy of any statement in the editorial, articles, and advertising sections of this publication that are important to him/her and rely on his/her independent evaluation. For permission to use content in other media, contact copyright@sae.org. To purchase reprints, contact advertising@sae.org. Copyright © 2013 by SAE International. The Aerospace Engineering title and logo are registered in the U.S. Patent and Trademark Office, and feature articles are indexed and included in the SAE Global Mobility Database.

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• Pre-register by March 1 and save! SAE 2013 Safety Management Systems Symposium (for Aerospace Design and Manufacturing) • March 19-20, 2013 • Madrid, Spain

• Call for Papers – Abstracts due Feb. 19 for SAE 2013 AeroTech Congress & Exhibition • September 24-26, 2013 • Montreal, Canada

• Now Available! Metals & Alloys in the Unified Numbering System, 12th edition

• NEW! Implementation of SAE AS6081-Counterfeit Electronic Parts for Distributors Seminar • January 22-23, 2013, Merritt Island, Florida, USA

• SAE Standards Subscription: Integrated Vehicle Health Management

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SAE offers high-quality, technologically relevant, and timely education and training for design, manufacturing, and quality professionals in the Aerospace industry. PLUS multiple learning formats accommodate any learning style and need:• Seminars• Engineering Academies• e-Learning including Webinars and e-Seminars• and Customizable and cost-effective In-House learning

Course offerings for the Aerospace industry include:• New! IAQG Sanctioned Aerospace Auditor Transition Training (AATT)• New! Aerospace Program Management - It’s More than Scheduling and Delivery Seminar• Accelerated Test Methods for Ground and Aerospace Vehicle Development e-Seminar• Understanding the FAA Aircraft Certifi cation Process Seminar• Understanding the AS9100 Rev C Webinar and Understanding AS9100C Quality Management System Standard Seminar

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Implement a control plan; reduce risk of counterfeit parts entering inventory.Use SAE AS5553

Evaluate if distributors can detect counterfeit parts in their inventories.Use SAE ARP6178

Tell customers a system is in place to mitigate the risk of counterfeit parts.Certify to SAE AS6081

Accreditation ensures standardized testing of suspect electronic parts. Use SAE AS6171

Do you DISTRIBUTE, supply, or sell electronic parts and/or components?

Do you TEST electronic components or certify distributors to AS6081?

Do you PURCHASE electronic components?

Protection from counterfeit electronic parts in a suite of standards.

Ground-breaking standards in response to industry need since 1916. ■ www.sae.org

STOP illegitimate electronic parts from entering ANY market’s supply chain.

Visit SAE’s web portal on this topic at counterfeitparts.sae.org/

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