Browse Topic: Jet engines
Historical rotor designs for Earth and Mars have typically landed at thrust-weighted solidities of ∼0.1-0.15 as a best compromise of performance and weight. Comprehensive analysis predicts that high solidity rotor designs of more than twice this range have the potential to significantly increase the lift capability of future Mars explorers severely limited by packaging and weight. However, there is limited existing experimental data of high solidity rotor designs at representative densities to quantify the efficiency impact and verify models of the aerodynamic environment. Therefore, the Mars Exploration Program (MEP) funded a joint test campaign between NASA's Jet Propulsion Laboratory, NASA Ames Research Center, and AeroVironment, Inc.to validate performance predictions for low- and high- solidity rotor variants at Mars pressures. Experimental setup, test matrix, data processing, data quality, and performance results for the High Solidity Test (HST) campaign are presented and discussed.
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 placed near a heat source - like a steam pipe in a power plant - charge carriers, like electrons, move from the hot side to the cold side, producing an electric current.
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 engine thrust or bearing health. The ZPod offers a simplified, efficient alternative to fuel-lubricated systems by eliminating fuel diversion for lubrication, enhancing fuel efficiency, and maintaining bearing performance in attritable or single-use engines. Additionally, the study highlights the potential of minimal lubrication supplied by the ZPod to extend operational life during LoL scenarios, enabling safer aircraft recovery. Future work will focus on extending testing to higher thrust classes and optimizing ZPod designs for broader applications.
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 2023.
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 various mechanisms of heat transfer as well as the coolant’s energy transport (non-cracking fuel). Using this model, we aim to study the effect of active cooling on the system's thermal behaviour and heat transfer characteristics. The model predicts the temperature distribution in the channel and the interfaces. Parametric analysis is undertaken to assess the active cooling system design parameters which affect the heat transfer characteristics of the system. Such semi-analytical models help investigate the effect of the cooling channel geometry and flow parameters, which can be a decisive prerequisite to the configuration design of a scramjet engine.
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, aerodynamic analysis, and mission analysis alongside the V-22 Osprey indicate the VHECTR concept is more HSVTOL mission capable with greater time and fuel savings than any advanced tiltrotor system to date.
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 HGVs and launched from rockets or jet aircraft. Power for HCMs comes from air-breathing scramjet engines, which have been in development since the 1950s and most successful since the 2000s.
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 Thermodynamic Systems (T-MATS), the Electrical Modeling and Thermal Analysis Toolbox (EMTAT), and the Thermal Systems Analysis Toolbox (TSAT). These tools are interactive, complementary, and compatible with each other. T-MATS is a modular thermodynamic modeling framework designed for creating custom component level models of jet engines. EMTAT is a modeling framework used to simulate a variety of power electronic devices, using both physics-based and power flow calculations. TSAT is a framework for modeling and analysis of dynamic heat transfer. These packages all consist of graphical, drag-and-drop, parameterizable building blocks representing various components of the system to be modeled, e.g., compressors, turbines, motors, energy storage devices, etc. They are designed to enable the user to model and simulate the end-to-end dynamic operation of a hybrid electric gas turbine engine powertrain at the timescale of the turbomachinery, capturing mechanical, electrical, and thermal interactions. This paper demonstrates through multiple examples how these tools have been used successfully in a variety of applications, including several of the early stages of hybrid electric gas turbine engine propulsion system development, from the initial system modeling to real-time interactive pilot-in-the-loop simulation to physical hardware-in-the-loop testing, each step bringing the technology closer to fruition.
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.
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.
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.
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