Browse Topic: Turbojet engines
This SAE Aerospace Information Report (AIR) describes procedures for calculating fuel consumption for civil jet airplanes through all modes of operation for all segments of a flight. Turboprop and piston airplanes, as well as helicopters or unconventional aircraft, are not included in this AIR. The principle purpose of these procedures is to assist model developers in calculating airplane fuel consumption in a consistent and accurate manner that can be used to address various environmental assessments including those related to policy decisions and regulatory requirements. This AIR is intended to directly support the emission calculations documented in AIR5715. The models described in this AIR are intended to be used from the start of the takeoff roll to the end of the ground roll; taxi fuel consumption models are not included. If modelers have access to higher fidelity methods, they should use those methods in lieu of the ones in this AIR.
Turbojet rotors operate at high angular speeds and undergo intense dynamic loads in operation. Therefore, it is important to evaluate the dynamic behavior of this type of system still in the design phase. In this work, the transverse vibrations of a rotor-bearing assembly of a low-powered aeronautical turbine are analyzed using a finite element model that considers the shaft as flexible and the various compressor and turbine discs as point masses. The influence of the speed of rotation on the variation in the stiffness of the rolling bearings as well as on the damping of the squeeze film dampers is taken into account. Classic results of rotor dynamics (unbalance response, Campbell diagram, bearing efforts) are obtained. The work was carried out in routines developed using numerical computing software.
This SAE Aerospace Information Report (AIR) has been written for individuals associated with the ground-level testing of large and small gas turbine engines and particularly for those who might be interested in upgrading their existing or acquiring new test cell facilities.
This SAE Aerospace Information Report (AIR) has been written for individuals associated with the ground-level testing of large and small gas turbine engines and particularly for those who might be interested in upgrading their existing or acquiring new test cell facilities.
This SAE Aerospace Information Report (AIR) has been written for individuals associated with ground level testing of turbofan and turbojet engines and particularly for those who might be interested in investigating the performance characteristics of a new test cell design or of proposed modifications to an existing test cell by means of a scale model test.
ABSTRACT 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.
This SAE Aerospace Information Report (AIR) reviews the precautions that must be taken and the corrections which must be evaluated and applied if the experimental error in measuring the temperature of a hot gas stream with a thermocouple is to be kept to a practicable minimum. Discussions will focus on Type K thermocouples. These are defined in NBS Monograph 125 as nickel-chromium alloy versus nickel-aluminum alloy thermocouples.
This SAE Aerospace Information Report (AIR) has been written for individuals associated with the ground-level testing of gas turbine engines and particularly for those who might be interested in upgrading their existing engine test facility to meet the airflow requirements for higher thrust engine models. The intellectual property rights on the material contained in this document are protected by US Patent Number 5,293,775 dated March 15, 1994 assigned to United Technologies Corporation, Hartford, Connecticut, USA. Any individual, or organization, attempting to use the system described in this document should get a clearance from United Technologies Corporation, to avoid any potential liability arising from patent infringement.
This Icing Technology Bibliography is a compendium of references from the open literature that were published prior to the original 1987 issuance of the AIR, including both national and foreign sources. Due to the generality of the subject, and the difficulty of fully investigating every available source, the Bibliography in this document is not intended to be complete.
Document provides information on how military/commercial/gas turbine engine test cell/system users may benefit from this unique Coanda/Refraction concept.
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.
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.
WHEN IT COMES TO REVIVING HIGH-SPEED AIR TRAVEL, IT ALL COMES DOWN TO PROPULSION, PROPULSION, PROPULSION. OVER THE DECADES, much research in the U.S., Europe, Russia, and Japan has been undertaken on aspects of ultra-high-speed flight, including radical airframe shapes, the use of unconventional materials, and ramjet and hybrid engines. Although Russia developed, and for a brief period in the late 1970s operated, its own Tu-144 supersonic air transport (and used it mostly as a high-speed freight carrier), only the Anglo-French Concorde resulted in scheduled-service supersonic passenger air traval. Work on follow-on supersonic air transports continued in the 1980s but none of it came to anything, as rising fuel prices and environmental concerns killed off enthusiasm for speed. The industry concentrated instead on making conventional aircraft that were quieter and less fuel-thirsty.
When it comes to reviving high-speed air travel, it all comes down to propulsion, propulsion, propulsion. Over the decades, much research in the U.S., Europe, Russia, and Japan has been undertaken on aspects of ultra-high-speed flight, including radical airframe shapes, the use of unconventional materials, and ramjet and hybrid engines. Although Russia developed, and for a brief period in the late 1970s operated, its own Tu-144 supersonic air transport (and used it mostly as a high-speed freight carrier), only the Anglo-French Concorde resulted in scheduled-service supersonic passenger air traval. Work on follow-on supersonic air transports continued in the 1980s but none of it came to anything, as rising fuel prices and environmental concerns killed off enthusiasm for speed. The industry concentrated instead on making conventional aircraft that were quieter and less fuel-thirsty.
A single lightweight engine capable of operating over a wide range of Mach numbers from startup to the hypersonic regime is proposed for automobiles and airplanes. Traditional piston engines, turbojet engines, and scram jet engines operate only under a narrower range of conditions. A compression system of colliding super multijets is proposed instead of a traditional turbofan. This ultimate engine system can be extended with a special piston system to achieve an improved fuel consumption rate, while maintaining a low noise level.
The purpose of this section is to provide methods and a set of convenient working charts to estimate penalty values in terms of take-off fuel weight for any given airplane mission. The curves are for a range of specific fuel consumption (SFC) and lift/drag ratio (L/D) compatible with the jet engines and supersonic aircraft currently being developed. A typical example showing use of the charts for an air conditioning system is given. Evaluation of the penalty imposed on aircraft performance characteristics by the installation of an air conditioning system is important for two reasons: 1 It provides a common denominator for comparing systems in the preliminary design stage, thus aiding in the choice of system to be used. 2 It aids in pinpointing portions of existing systems where design improvements can be most readily achieved. All factors that influence the flight performance of an aircraft can be expressed in terms of weight, external and momentum drags, and changes in powerplant performance due to bleed air or shaft power extraction, or both. These factors lend themselves to numerical analysis, and the purpose of this chapter is to present and discuss methods that permit their evaluation. The methods of evaluating performance penalties to an aircraft in flight employ such parameters as flight range, aircraft gross weight, fuel load, payload, speed-altitude characteristics (Refs. 1-3), and the effects of power, landing, and take-off field length limiting cases. Two major criteria need to be considered in arriving at system take-off weight penalties: 1 Air vehicle weight is assumed fixed, and degradation in range occurs as a result of weight displacing fuel. 2 Range is assumed fixed, and the resultant take-off weight penalty is added to the total airplane weight. The latter method will be discussed in this section, and is based, in part, on Ref. 4. The former method (degradation in range) can be found, in detail, in Ref. 5. The optimization process consists of calculating specific penalty numbers for system fixed weight, variable weight, power consumption, ram air, and bleed air consumption, in terms of take-off weight and selecting the system that results in greater payload or range.
This SAE Aerospace Information Report (AIR) has been written for individuals associated with ground level testing of turbofan and turbojet engines and particularly for those who might be interested in investigating the performance characteristics of a new test cell design or of proposed modifications to an existing test cell by means of a scale model test.
This SAE Aerospace Information Report (AIR) has been written for individuals associated with the ground-level testing of gas turbine engines and particularly for those who might be interested in upgrading their existing engine test facility to meet the airflow requirements for higher thrust engine models. The intellectual property rights on the material contained in this document are protected by US Patent Number 5,293,775 dated March 15, 1994 assigned to United Technologies Corporation, Hartford, Connecticut, USA. Any individual, or organization, attempting to use the system described in this document should get a clearance from United Technologies Corporation, to avoid any potential liability arising from patent infringement.
Document provides information on how military/commercial/gas turbine engine test cell/system users may benefit from this unique Coanda/Refraction concept.
The global aerospace industry gears up for big changes in fuel burn, emissions, and noise. It used to be that environment was on the agenda when aerospace professionals gathered for a symposium. Now environment is the agenda. The new mindset was never more evident than it was this past summer at the Paris Air Show, where exhibitor after exhibitor touted their “green” credentials. One company, CFM International, went so far as to carpet its stand with live green grass.
Items per page:
50
1 – 50 of 138