Browse Topic: Turbojet engines

Items (78)

The ice bath recommended herein is similar to that described in SAE AIR 46.* Some material not presented in AIR 46, including preferred dimensions, has been added.

E-32 Aerospace Propulsion Systems Health Management

Uncertainty of In-Flight Thrust Determination

AIR1678B (Current)10/22/2016

This document defines and illustrates the process for determination of uncertainty of turbofan and turbojet engine in-flight thrust and other measured in-flight performance parameters. The reasons for requiring this information, as specified in the E-33 Charter, are: determination of high confidence aircraft drag; problem rectification if performance is low; interpolation of measured thrust and aircraft drag over a range of flight conditions by validation and development of high confidence analytical methods; establishment of a baseline for future engine modifications. This document describes systematic and random measurement uncertainties and methods for propagating the uncertainties to the more complicated parameter, in-flight thrust. Methods for combining the uncertainties to obtain given confidence levels are also addressed. Although the primary focus of the document is in-flight thrust, the statistical methods described are applicable to any measurement process. The E-33 Committee has endeavoured to gather industry-wide expertise in in-flight measurement and uncertainty analysis to collect and promulgate recommended practices in the subject disciplines. The Committee is organized into subcommittees to address both the analytical and test methodology for determination of in-flight thrust and also the uncertainty of the determination. This document; Uncertainty of In-flight Thrust Determination, AIR1678, addresses the process for determining the uncertainty of in-flight thrust. A companion document, In-Flight Thrust Determination, AIR1703, addresses the basic methodology for determining in-flight thrust. The Committee, after reviewing recommended changes and clarification in definitions and application of statistical uncertainty items, made small revisions to the original document published in 1985. These changes were incorporated into AIR1678 Rev A. This Revision B has the same Scope as preceding versions. The nomenclature and methodology used herein are now consistent with evolving world and national standards promulgated primarily by ISO and ASME.

E-33 In Flight Propulsion Measurement Committee

Assessment and Calibration of Semi-Empirical Models for Predicting Pollutant Emissions of the Erica Tiltrotor Turboshaft Engine

F-0070-2014-9622

5/20/2014

In this paper, the most meaningful EINOx and EICO zero-dimensional emission prediction methods from the literature are described and reviewed, while a selection of them are tuned and validated against publicly available experimental data. The equations of these models are implemented in TSHAFT, a proprietary engine simulator developed at the University of Padova which predicts the performance of turbojet engines in both design and off-design operation modes under variable ambient conditions. Then, TSHAFT is set up to predict the emissions of a generic turboshaft engine ranging in power from 1,800 shp to over 5,000 shp, and the results are compared to proprietary experimental data obtained during an aircraft landing and take-off cycle (LTO) at standard sea level conditions. Finally, the emissions of a turboshaft engine of 3000 SHP engine are calculated for two flight conditions (i.e. hover and forward flight cruise) of the ERICA tiltrotor. Finally, the paper presents the results of the comparison in terms of pollutant emissions between the engine emissions related to the baseline installation geometry, and the optimized intake/exhaust configuration.

Mas, Lorenzo, Benini, Ernesto, Ponza, Rita

DRIVE - TYPE XV ENGINE ACCESSORY - DESIGN STANDARD FOR

AS20005 (Historical)

11/1/2012

E-25 General Standards for Aerospace and Propulsion Systems

Thermal Mechanical Fatigue Crack Growth Testing

TBMG-142988/1/2012

Turbines in aircraft turbojet engines are being subject to increasingly higher temperatures to improve fuel efficiency. High turbine efficiency requires the ability of turbine blades to withstand gas temperature of the order of 1350 to 1550 °C. In polycrystalline materials, these increased temperatures would cause creep strains along grain boundaries that would be unacceptable. Even single-crystal materials must be pushed to their limits to insure that engine performance is maximized. Airfoils in modern gas turbine aircraft use a systems approach for cooling to achieve required component life. There are three basic components to these systems: a cast nickel single-crystal superalloy in combination with thermal barrier coatings, and a sophisticated cooling scheme consisting of intricately designed channels and holes through the core and surface of the airfoil.

Gaseous and Particle Emissions from a Turbo-Jet Engine Operating on Alternative Fuels at Simulated Altitudes

2011-01-259710/18/2011

Gaseous and particle emission assessments on a 1.15 kN-thrust turbojet engine were conducted at five altitudes in an altitude chamber with Jet A-1 fuel, pure Fischer Tropsch (FT), and two mixed fuels of JP-8 with FT or Camelina-based hydro-processed jet fuels. In general, lower emissions in CO₂, NOx, and particle number as well as higher emissions in CO and THC were observed at higher altitudes compared to lower altitudes. These observations, which were similar for all test fuels, were attributed to the reduced combustion efficiency and temperature at higher altitudes. The use of alternative fuels resulted in lower CO₂ emissions, ranging from 0.7% to 1.7% for 50% to 100% synthetic fuel in the fuel mixture at various altitudes. In terms of CO, the use of 100% FT fuel resulted in CO reduction up to 9.7% at 1525 m altitude and up to 5.9% at 9145 m altitude. Significant reduction in particle diameter, number and mass emission rates were observed with the use of alternative fuels due to the low aromatic and sulfur content in the fuels. Higher reductions were observed for increasing percentage of the alternative synthetic fuel in the fuel mixture. With the use of pure FT fuel, up to 80% and 96% reductions in particle number emissions were observed at 1525 m and 9145 m altitudes, respectively. In comparison, a larger particle reduction benefit was observed for the Camelina-based hydro-processed jet fuel than for the FT fuel.

Chan, Tak W., Cuddihy, Kevin, Chishty, Wajid, Davison, Craig, McCurdy, Mark, Barton, Peter

Multivariable Aircraft Engine Controller Design Using an Optimal Loop Shaping Approach

2011-01-251110/18/2011

The current pressure for fuel burn savings and increasing performance in the commercial aerospace market demands highly complex engine control systems to optimize fuel consumption throughout the engine operating envelope, as well as meet the regulatory requirements in terms of safety and performance. These conflicting objectives normally lead to trade-off solutions that are difficult to precisely estimate. Therefore some decisions to characterize the engine controller still reside on experience from previous designs and, as a result, add subjectivity and increase the potential for wrong parameter selection. This paper proposes an algorithmic approach to design a turbojet engine controller in a multivariable, two-degree-of-freedom configuration, obtaining H-infinity robust stabilization. It introduces an optimized loop shaping design procedure, with the use of a Genetic Algorithm (GA), to further improve the control system performance, as well as bring the experience applied by controller designers and engineers to an automated process, when setting the parameters to shape the frequency response of the engine control loops. The resulting controller is evaluated by computer simulations under typical operating conditions and it is compared to other strategies like a discrete-time Linear Quadratic Regulator with Integral Action (LQI) as well as a Linear Quadratic Gaussian (LQG) controller with Loop Transfer Recovery (LTR). H-infinity controller presented a satisfactory behavior with smoother responses than the other controllers, however with higher rise times; control devices for the subject controller presented the best transient response among all others and indicated a positive impact in the fuel consumption. Finally, a noise immunity check revealed that this H-infinity controller was capable to properly attenuate high frequency noise normally present in the measurement systems.

Silva, Douglas F R, Barbosa, Joao, Adade Filho, Alberto

Universal Maintenance & Overhaul Stand for Turbo-Jet (10,000 Lbs. Thrust Class) and Turbo-Prop Engines

ARP458 (Current)12/16/2002

AGE-4 Packaging, Handling and Transportability Committee

An AJAX Technology Advanced SSTO Design Concept

985527

9/28/1998

ABSTRACT <div class="htmlview paragraph">This paper presents an advanced single stage-to-orbit (SSTO) design concept based on our understanding of Russian AJAX technologies. The concept brings together a unique set of subsystem components to enhance the performance of an advanced combined cycle engine powered SSTO design concept. A magnetohydrodynamic (MHD) generator-accelerator energy bypass system is used to maintain subsonic flow in the engine combustion chamber. And, an electromagnetic drag reduction system is used to reduce wave and base drag during ascent and reentry. The performance of the advanced highly reusable SSTO is compared to a reference advanced air-breathing rocket-based combined cycle ejector ram-scramjet powered SSTO design concept. The results indicate an approximate 15% performance increase compared to the reference design.</div>

Chase, R. L., Boyd, R., Czysz, P., Froning, H. D., Lewis, Mark, McKinney, L. E.

GUIDE FOR DETERMINING ENGINE STARTER DRIVE TORQUE REQUIREMENTS

AIR781 (Current)

9/1/1994

A general discussion is presented herein, to outline the starter functions which are necessary for a successful engine start. In addition, sample calculations are included to illustrate an accepted method of determining the engine starting time from known data. Further consideration is then given to the relationship between starter torque output and engine pad strength and a generalized formula is presented for calculating the theoretical transient torque peaks for a simplified starter-engine system. Sample calculations for actual tests are included, and the results of these calculations are compared with measured values.

AE-6 Starting Systems and Auxiliary Power Committee

The Pond Racer - An Exercise in the Control of Heat Transfer in a Tight Composite Compartment

9301543/1/1993

The POND RACER is an all-Composite, twin boom airplane Figure 1,(1), (2), (3), fitted with two, dual turbocharged automotive engines. The exhaust system, Figure 2, for this six cylinder power plant occupies the rear portion of a compact engine compartment. Initially, no provision was made for moving cooling air through this densely-packed engine compartment. Portions of the exhaust system passed within less than 2.5 cm (1 in.) of the composite cowl enclosing the engine compartment. The temperatures developed could result in failure of the computer,which controls the engine, other components, and the composite cowl in a matter of minutes. Currently-used insulation designs did not appear to provide enough capability to work for this application. A Thermal Protection System was developed, installed, and proven out during test flights. Analysis of the flight data, measured by thermocouples linked into the flight recorder, verified the adequacy of the Thermal Protection System. These results showed that an insulation design can provide acceptable performance by carefully integrating the thermal requirements into the interface created by the structure and its power-plant.

Trelease, Robert B.

Integrated Air Separation and Propulsion System for Aerospace Plane with Atmospheric Oxygen Collection

9209744/1/1992

Aerospace plane with atmospheric oxygen collection for oxidizer supplying on rocket part of trajectory is very attractive concept. The key unit of power plant of such plane is an air liquefaction and separation system. It is proposed to accomplish the oxygen extraction on the bank of vortex tubes of special kind. The compressor of low speed turbojet engine would served in oxygen collection phase of flight as pressure generator for air separation system. Poor air after oxygen extraction is supposed to use actively in one of power plant combustion chambers. The configuration of integrated air separation and propulsion system and results of estimation of system using on two stage aerospace plane are discussed.

Balepin, V.V., Tjurikov, E.V.

Prediction of Engine Casing Temperature of Fighter Aircraft for Infrared Signature Studies

9209614/1/1992

Prediction of Engine Casing Temperature of Combat Aircraft for various operating conditions needs modeling of convective and radiative heat flow from the jet pipe to the casing. Radiation modeling which implies modeling of multiple reflections and scattering is done here by the radiance-irradiance approach. The engine layout is approximated by three co-axial cylinders and axially discretized. The shape factors (which account for the directional dependence of radiation heat flow) for various configurations needed in radiation modeling are analytically obtained by a sequence of shape factor algebra from standard configurations. The resulting non-linear algebraic equations of combined convection and radiation heat flow are solved by an iterative technique to give the engine casing temperatures which may be used for infrared signature studies.

Mahulikar, Shripad Prabhakar

Propulsion Systems with Air Precooling for Aerospaceplane

9111824/1/1991

Using LH2 heat sink capacity for air precooling in turbojets allows to increase specific impulse and in many cases to reduce specific mass (mass-to-sea level thrust ratio). A number of precooled turbojet schemes are considered. Classification of turbojet according to the cooled air amount and depth of cooling is proposed. ATR with extended precooling (Tout=100K) is examined in more detail. For propulsion systems including different types of engines, running simultaneously the concept of LH2 heat sink capacity concentration for turbojet air precooling is proposed.

Rudakov, A.S., Balepin, V.V.

GUIDE TO TEMPERATURE MONITORING IN AIRCRAFT GAS TURBINE ENGINES

AIR1900 (Historical)2/7/1991

This Aerospace Information Report (AIR) provides an overview of temperature measurement for engine monitoring systems in various areas of aircraft gas turbine engines while focusing on current usage and methods, systems, selection criteria, and types of hardware. This document emphasizes temperature monitoring for diagnostics and condition monitoring purposes.

E-32 Aerospace Propulsion Systems Health Management

A Canadian Government Look at Airworthiness

880935

3/1/1988

The paper traces the development of the approach to airworthiness taken by Canadian government authorities from its origin through to current practices. It describes the Aerospace industry, the carriers and general aviation in statistical terms, indicates the impact of economic regulatory reform and suggests the way ahead for Canadian and other authorities lies in the attitude and methodologies practiced by the European authorities in their development of JARs. I SHOULD PERHAPS start this presentation with a short word about authorities. At the conclusion of a speech on safety regulation by Mr. Ronald Ashford of the UK Civil Aviation Authority, reported in Flight International of April 19, 1986, the following quotation from St. Paul to the Romans appeared: “You wish to have no fear of the authorities? Then continue to do right and you will have their approval, for they are God's agents working for your good”. Aprocryphal or not, this would appear to give some divine authority for our regulatory activities.

Mew, John F., Torck, James A.