Browse Topic: Jet engines
This document is offered to provide state-of-the-art information about design factors that must be considered in the design of new or significantly modified engine test cells used to test propeller equipped turboprop engines in either QEC or bare engine configurations. The report does not address design considerations for test cells designed to test turboprop engines with dynamometer type load absorption devices because they are essentially tested as turboshaft engines. Design considerations for those test cells are presented in AIR4989, Reference 2.1.
This document establishes general design criteria, tolerances, and limits of application for tooling, fixtures, and accessories for mounting and driving gas turbine engine rotors on horizontal and vertical balancing machines.
An Army-funded research project has led to the development of more efficient materials for developing thermoelectric generators that convert waste heat to clean energy for a variety of applications. The Pennsylvania State University, University Park, PA Thermoelectric generators that can convert waste heat to clean energy could soon be as efficient as other renewable energy sources, like solar, according to a team led by Penn State scientists. Using high-entropy materials, the researchers created more efficient thermoelectric materials than previously possible, an advancement that they said could even help make long-distance space exploration possible. In a study partially funded by the U.S. Army with results published in the journal Joule last year, the researchers demonstrated how thermoelectric devices - including the radioisotope thermoelectric generators that produce energy for NASA's space exploration vehicles - can convert differences in temperature to electricity. When they are
Thermoelectric generators that can convert waste heat to clean energy could soon be as efficient as other renewable energy sources, like solar, according to a team led by Penn State scientists. Using high-entropy materials, the researchers created more efficient thermoelectric materials than previously possible, an advancement that they said could even help make long-distance space exploration possible.
This paper presents experimental research aimed at developing novel low lubrication methods for rotorcraft and jet engines, focusing on sustaining minimal lubrication to prevent catastrophic bearing failure during loss of lubrication (LoL) events or to increase fuel consumption performance on once-through, fuel-oil bearing lubrication engines. Utilizing two high-speed bearing test rigs simulating low and high thrust class engine conditions, the study establishes lower bounds for oil flow rates necessary to maintain thermal stability and prevent thermal runaway in hybrid ball bearings. These findings inform the design of the Zulu Pod (ZPod), a passively driven, self-contained oil delivery system that uses engine compressor bleed air to precisely meter lubricant flow. Engine test stand results demonstrate that replacing traditional fuel-oil lubrication with the ZPod system reduces thrust specific fuel consumption (TSFC) by an average of 7%, with up to 11% savings, without compromising
This SAE Aerospace Standard (AS) establishes minimum requirements for eddy current inspection of circular holes in nonferrous, metallic, low conductivity (less than 5% IACS) aircraft engine hardware with fasteners removed. The inspection is intended to be performed at maintenance and overhaul facilities on engine run hardware.
What if the future of space travel were to look less like Space-X’s rocket-based Starship and more like NASA’s “Hyper-X,” the hypersonic jet plane that, 20 years ago this year, flew faster than any other aircraft before or since?
A new aviation supply chain integrity coalition has offered 13 recommended actions to prevent the circulation of non-serialized aircraft parts throughout the global aviation industry. Embry-Riddle Aeronautical University, Daytona Beach, FL In the summer of 2023, a receiving clerk in the procurement department of TAP Air Portugal, a Lisbon-based airline, made a curious discovery: A $65 engine part that should have appeared brand-new showed signs of significant wear. The clerk checked the documentation from the London-based parts supplier and noticed that the submitted documentation was also suspicious. Using his safety training, the employee immediately reported the anomaly to TAP Air Portugal management, which raised the issue with the jet engine's manufacturer. Little did the procurement clerk know at the time, but this escalation led to one of the biggest investigations in the history of the aviation supply chain, as reported by Reuters and the British Broadcasting Corporation in
Hypersonic propulsion would allow for air travel at speeds of Mach 6 to 17, or more than 4,600 to 13,000 miles per hour, and has applications in commercial and space travel.
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.
Hypersonic flight vehicles have potential applications in strategic defence, space missions, and future civilian high-speed transportation systems. However, structural integration has significant challenges due to extreme aero-thermo-mechanical coupled effects. Scramjet-powered air-breathing hypersonic vehicles experience extreme heat loads induced by combustion, shock waves and viscous heat dissipation. An active cooling thermal protection system for scramjet applications has the highest potential for thermal load management, especially for long-duration flights, considering the weight penalty associated with the heavier passive thermal insulation structures. We consider the case of active cooling of scramjet engine structural walls with endothermic hydrocarbon fuel. We have developed a semi-analytical quasi-2D heat transfer model considering a prismatic core single cooling channel segment as a representative volume element (RVE) to analyse larger-scale problems. The model includes
In the pursuit of High-Speed Vertical Takeoff and Landing (HSVTOL) platforms, VerdeGo Aero offers its VH-5 hybrid-electric turbofan as the answer to missions requiring high power, vertical lift, and jet-like speeds. To evaluate the possibility of designing a real HSVTOL aircraft around VerdeGo's VH-5 powerplant, this paper investigates the size and expected performance of a militarized spinoff of NASA's Class B, High-Efficiency Civil TiltRotor (HECTR) concept, which has been renamed the VerdeGo Hybrid-Electric Combative TiltRotor, or "VHECTR" for short. Through an in-depth conceptual weight buildup of four commonly proposed tiltrotor architectures, this paper suggests that an entirely new, turbofan-driven propulsion system is needed if modern day HSVTOL demands are to be met. Hence, a separate, yet more conventional "Modified HECTR" tiltrotor configuration is considered to contest the proposed, VH-5 powered VHECTR concept. However, the results of a full-scale aircraft comparison
The development of hypersonic missiles represents the most significant advancement of defense weaponry since the 1960s. However, they also pose unique challenges for both design and technology. The term “hypersonic” refers to any speed faster than five times the speed of sound, or above Mach 5. Modern hypersonic missile systems require extensive communications interconnects within a highly confined space. This space requirement creates a demand for solutions combining small form factor with reduced weight and rugged construction to withstand high vibration and impact conditions from deployment to target. Currently there are two types of hypersonic weapons. Hypersonic glide vehicles (HGVs), also known as boost-glide vehicles, typically launch from ballistic missiles and are released at a specific altitude, speed, and with the flight path tailored to a target without being powered. Hypersonic cruise missiles (HCMs) are powered all the way to their targets, flying at lower altitudes than
A team at NASA's Jet Propulsion Laboratory that's creating a snake-like robot for traversing extreme terrain is taking on the challenge with the mentality of a startup: Build quickly, test often, learn, adjust, repeat. Called EELS (short for Exobiology Extant Life Surveyor), the self-propelled, autonomous robot was inspired by a desire to look for signs of life in the ocean hiding below the icy crust of Saturn's moon Enceladus by descending narrow vents in the surface that spew geysers into space.
An investigation into emissions differences and their correlations with differing combustion characteristics between F24 and Jet-A was conducted. Raw emissions data was taken from a single stage jet engine by a FTIR gas analyzer. Measurements of H2O, CO2, CO, NOx, and total hydrocarbon emissions (THC) were taken at 60K, 65K, and 70K RPM. At 70K RPM Jet-A and F-24 the emissions were similar at approx.: 4% H2O, 3% CO2, 970 PPM CO, 28 PPM NOx. Jet-A THC emissions were approx.: 1200 PPM THC, F24 THC emissions were lower by over 60%. The significantly lower amount of THC emissions for F24 suggests more complete combustion compared to Jet-A.
Jet Propulsion Laboratory Pasadena, CA
Aerospace manufacturers know what it means to work with high stakes. Extremely tight tolerances, expensive materials and complicated processes define the industry. But few aerospace components are more critical - or more challenging - than the turbine discs that go into the hot side of jet engines. When machining these rotating components, everything must be correct, secure and reliable - not only to meet stringent surface integrity requirements, but also to avoid devastatingly expensive failures. A mistake that leads to a scrapped component can cost a manufacturer upward of $100,000, depending on when the mistake happened in the production process.
Hybrid electric aircraft propulsion is an emerging technology that presents a variety of potential benefits along with technical integration challenges. Developing these new propulsion architectures with their complex control systems, and ultimately proving their benefit, is a multistep process. This process includes concept development and analysis, dynamic simulation, hardware-in-the-loop testing, full-scale testing, and so on. This effort is being revolutionized and indeed enabled by new digital tools that support increasing the technology readiness level throughout the maturation process. As part of this Digital Transformation, NASA has developed a suite of publicly available digital tools that facilitate the path from concept to implementation. This paper describes the NASA-developed tools and puts them in the context of control system development for hybrid electric aircraft propulsion. The three MATLAB®-based software packages are the Toolbox for the Modeling and Analysis of
In an application first, the physics of why the sky is blue is used to measure gas flows without obstructive sensors. A longstanding industry partnership between Virginia Polytechnic Institute and State University (Virginia Tech) and Pratt & Whitney has resulted in a new laser-optical technology that aims to revolutionize in-flight thrust measurement.
There’s nothing more core to turbomachinery than moving fluid at increasingly high speeds and pressures. Whether we’re talking about industrial turbines, air breathing jet engines, or liquid-rocket space applications, the higher the pressure and the higher the flow rate, the better the performance.
This SAE Aerospace Recommended Practice (ARP) describes a recommended practice and procedure for the correlation of test cells that are used for the performance testing of turbofan and turbojet engines. Test cell correlation is performed to determine the effect of any given test cell enclosure and equipment on the performance of an engine relative to the baseline performance of that engine. When baseline testing is performed in an indoor test cell, the baseline performance data are adjusted to open air conditions. Although no original equipment manufacturer (OEM) documents are actually referenced, the experience and knowledge of several OEM’s contributed to the development of this document. Each engine Manufacturer has their own practices relating to correlation and they will be used by those OEMs for the purpose of establishing certified test facilities.
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
The discovery of a new category of shape-memory materials — ceramic as opposed to metal — could open a new range of applications, especially for high-temperature settings, such as actuators inside a jet engine.
An MIT-developed heat treatment aims to transform the microscopic structure of 3D-printed metals, making the materials stronger and more resilient in extreme thermal environments. The technique also aims to make it possible to 3D print high-performance blades and vanes for power-generating gas turbines and jet engines, which would enable improved fuel consumption and energy efficiency.
Researchers at NASA’s Jet Propulsion Laboratory (JPL) are developing a novel microthruster that could provide easy-to-control propulsion during spaceflight. Using solid silver as the fuel source, this innovative microthruster provides thrust via electrospray without heating the fuel reservoir or transporting liquid metals. Instead of transporting a molten metal, this design transports metal ions via a solid electrolyte film.
Turboprop aircraft have the capability of reversing thrust to provide extra stopping power during landing. Reverse thrust helps save the wear and tear on the brakes and reduces the landing distance under various conditions. The article explains a methodology to predict the disking drag (reverse thrust) from the Computational Fluid Dynamics (CFD) technique using Blade Element Momentum (BEM) theory and estimation of the same from high-speed taxiing trial (HSTT) and ground roll data for a turboprop aircraft using system identification techniques. One-dimensional kinematic equation was used for modeling the aircraft dynamics, and the error between measured and estimated responses was optimized using the Output Error Optimization Method (OEOM). The estimated propeller drag was matched with CFD predictions to arrive at a relation between the propeller blade pitch angle and throttle position. The present study also investigates the estimation of the braking friction coefficient from the
This SAE Aerospace Information Report presents the following factors that affect hydraulic pump life and performance: a The need to supply hydraulic fluid at the correct pressure and quality to the pump inlet port b Considerations for the pump output c Factors to be considered for the pump case drain lines d The mounting of the hydraulic pump e Hydraulic fluid properties, including cleanliness
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