As the Sun set on a pleasant late September evening in 1952, the exterior lights of the new Propulsion Systems Laboratory (PSL) were illuminated. A photographer and his assistant set up their tripod and camera at several locations around the facility, attempting to capture the sprawling tangle of steel, pipes, and valves. By the time that they had made it across the street to snap the two wide-angle shots, darkness had fallen and the most modern engine testing facility in the country shone brightly against the night sky over the National Advisory Committee for Aeronautics (NACA) Lewis Flight Propulsion Laboratory in Cleveland, Ohio. There were others gazing into the Midwestern darkness that evening. The Cold War had firmly taken root, and world tensions were elevated. Local teams of " skywatchers " from the Ground Observation Corps were scanning the night sky for enemy aircraft. The range and destructiveness of weaponry had increased dramatically in the 11 years since Pearl Harbor. " For the first time in our history, " one NACA Lewis sky-watcher declared, " a potential enemy has the power to make sudden, devastating attacks on any part of our country. " 1 In just weeks, United Nations forces would launch the ill-fated Battle of Triangle Hill—the last major offensive of the Korean War; General Dwight Eisenhower would be elected President, and the first hydrogen bomb would be detonated in the Marshall Islands. Aerospace development also was advancing dramatically. Jet engines were demonstrating tremendous increases in power, U.S. and Soviet engineers were racing to develop intercontinental ballistic missiles, and Harvey van Allen was beginning to circulate his blunt-body theory for atmospheric reentry. In addition, the International Geophysical Year had been set for 1957, and Colliers had captivated the public' s imagination with a cover story titled " Man on the Moon. " 2 In Cleveland, construction of the PSL, the nation' s largest facility for testing full-scale engines in simulated flight conditions, was completed. As the photographers documented the shining exterior on that September evening, a ramjet for the Navaho Missile program and a General Electric J73 turbojet for the F86H Sabre fighter were being installed inside its two test chambers. There were several ways to test engines, but test stands provided the most efficient and useful method. A single stand could be used to study many types of engines in an environment that was safer and more efficient …

Pursuit of Power: NASA's Propulsion Systems Laboratory No. 1 and 2

The New York Times announced America's entry into the 'long awaited' Jet Age when a Pan American (Pan Am) World Airways Boeing 707 airliner left New York for Paris on October 26, 1958. Powered by four turbojet engines, the 707 offered speed, more nonstop flights, and a smoother and quieter travel experience compared to newly antiquated propeller airliners. With the Champs-Elysees only 6 hours away, humankind had entered into a new and exciting age in which the shrinking of the world for good was no longer a daydream. Fifty years later, the New York Times declared the second coming of a 'cleaner, leaner' Jet Age. Decades-old concerns over fuel efficiency, noise, and emissions shaped this new age as the aviation industry had the world poised for 'a revolution in jet engines'. Refined turbofans incorporating the latest innovations would ensure that aviation would continue to enable a worldwide transportation network. At the root of many of the advances over the preceding 50 years was the National Aeronautics and Space Administration (NASA). On October 1, 1958, just a few weeks before the flight of that Pan Am 707, NASA came into existence. Tasked with establishing a national space program as part of a Cold War competition between the United States and the Soviet Union, NASA is often remembered in popular memory first for putting the first human beings on the Moon in July 1969, followed by running the successful 30-year Space Shuttle Program and by landing the Rover Curiosity on Mars in August 2012. What many people do not recognize is the crucial role the first 'A' in NASA played in the development of aircraft since the Agency's inception. Innovations shaping the aerodynamic design, efficient operation, and overall safety of aircraft made NASA a vital element of the American aviation industry even though they remained unknown to the public. This is the story of one facet of NASA's many contributions to commercial, military, and general aviation: the development of aircraft propulsion technology, which provides the power for flight.

https://ntrs.nasa.gov/api/citations/20180003207/downloads/20180003207.pdf

The Power for Flight: NASA’s Contributions to Aircraft Propulsion

This paper provides an examination of expected flow conditions from advanced compact inlet systems and their impact on aeromechanical stability of turbomachinery. Configuration characteristics are discussed along with results for total pressure distortion, swirl, and turbulence. Affects of high angle-of-attack subsonic maneuvering and supersonic operation are included. Aerodynamic flow characteristics which are related to aeromechanical high cycle fatigue are identified. These include amplitude and frequency of circumferential distortion components. Further consideration is given to the current methodology of aeromechanical testing using screen distortion devices. An unfavorable assessment is made on the ability of these type of tests to represent the expected flow conditions of compact inlets. Recommendations are made for development of new test techniques to provide a high fidelity simulation of inlet flow characteristics.

Inlet distortion considerations for high cycle fatigue in gas turbine engine

A review is presented of recent experimental results, analytical procedures and test techniques employed to evaluate the effects of inlet flow distortion on the stability characteristics of representative afterburning turbofan and turbojet compression systems. Circumferential distortions of pressure and temperature, separately and in combination are considered. Resulting engine sensitivity measurements are compared with predictions based on simplified parallel compressor models and with several distortion descriptor parameters.

/pdf/summary-of-recent-investigations-of-inlet-flow-distortion-ept1wx0zat.pdf

Summary of recent investigations of inlet flow distortion effect on engine stability

The peak static pressures measured at the inlet to the engine during stall are presented for a turbojet and two turbofan engines. It is shown for one turbofan and the turbojet that the static pressure ratio across the hammershock does not exceed significantly the normal shock pressure ratio necessary to stop the flow. The second turbofan engine did not follow this rule. Possible reasons for the departure are discussed. For the two turbofan engines the influence of the stall method on the hammershock intensity has been investigated. Data related to the spatial distribution of pressure in the hammershock are also presented. Nomenclature a = speed of sound Cp = specific heat at constant pressure M = Mach number P - total pressure P = static pressure T = static temperature t = time

J. E. Moss

Papers

Evaluation with a turbofan engine of air jets as a steady-state inlet flow distortion device Technical memorandum