National Aeronautics and Space Administration

Glenn Research Center

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Return to Turbojets (1967 – 1974)
TF-30 Turbofan in PSL
TF-30 Turbofan in PSL

After nearly a decade of concentrating on rockets, NASA Lewis began returning to aircraft propulsion in 1966. The Boeing 707 and Douglas DC-8, powered by Pratt & Whitney J57 and J75 turbojets respectively, were the dominant jet airliners of the late-1950s and 1960s. During the interim, however, the aircraft industry was developing the next generation of the jet engine: the turbofan. These new turbofan engines would need to increase their performance and reduce noise levels before they would be viable. NASA Lewis instituted an Airbreathing Engine Division in 1966 that used the Propulsion Systems Laboratory, the F106 aircraft, a new Quiet Engine Test Stand, and the 10- by 10-Foot Supersonic Wind Tunnel to study the turbofans.

Documents:
     Research Division article (1970) (PDF, 452KB)
     F14 and F15 Managers Visit (1970) (PDF, 512KB)

Engine Calibration Study
GE J85 in PSL No.2
GE J85 in PSL No.2

In order to test different noise reducing components, nozzles, and compressor designs, NASA Lewis engineers first had to be able to determine baseline performance characteristics of an engine. General Electric’s J85-13 was selected for this calibration study. The J85 was a relatively slow and lightweight but efficient engine developed in the late 1950s. It was used extensively by the Center’s Airbreathing Engine Division in the late 1960s and early 1970s.

PSL was used to determine the correct nozzle inlet temperature and pressure and gas flow rate at transonic speeds. Using this data, NASA Lewis researchers were able to determine the engine’s gross thrust within a 0.06 percent error margin. These measurements could be the basis for future engine and nozzle tests in the PSL, on test aircraft, and in other facilities.

Reports:
     Inlet Temperature Distortion on the Stall Limits of J85-GE-13 (PDF, 24.7MB)

J85 on F-106 Aircraft
J85 on F-106 Aircraft
J85 in PSL Shop
J85 in PSL Shop
Instrumentation
Instrumentation
Effects of Air Flow Distortions and Altitude
TF-30 on stand
TF-30 readied for test

Pratt & Whitney’s TF-30 was the first 25,000-pound thrust turbofan. It was developed in the early 1960s for the Navy’s F4A Tomcat and the Air Force’s F-111. Unlike turbojets, turbofans send much of their intake air around its core. This results in increased thrust and fuel efficiency. It was found that the decreased pressure found at high altitudes and distortions in the air flow reduce the stability of the engine’s compressor.

NASA Lewis conducted a number of tests with TF30-P-1 and TF-30-P-2 engines in PSL No. 1 to examine this phenomenon. Initially screens and other devices were used to create the distortions, but it was found that using nozzles to inject air into the stream was most effective and cost-efficient to simulate the distortions. Using this method, engineers in PSL were able map the engine’s likeliness to stall from various pulses or distortions. It was found that the duration of a stall-inducing pulse was the inverse of its amplitude.

Reports:
     Afterburner Equipped Turbofan with and Without Inlet Flow Distortion (PDF, 12.5MB)
     Inducing Controlled Steady-state and Dynamic Inlet Pressure Disturbances (PDF, 8.86MB)
     Air Jets as a Steady-State Inlet Flow Distortion Device (PDF, 18.9MB)

Engine Assembly
Engine Assembly
TF-30 Compressor
TF-30 Compressor
TF-30 in PSL No. 1
TF-30 in PSL No. 1
Equipment Building Explosion
Interior of Equipment Building after explosion
Interior Damage

In the early morning hours of April 7, 1971, a massive explosion ripped through the floor of the Equipment Building seriously injuring two employees and causing major damage to the facility. During the confusion of the midnight shift change, a butterfly valve between the exhausters and the exhaust stack was left sealed. Although the crew quickly scrambled to depressurize the system, a 96-inch-diameter head ruptured below the floor. The 6-inch-thick concrete floor, I-beams, windows, and heavy equipment were damaged. A 30-foot-diameter hole was blown in the roof that was 35 feet above the floor. An Accident Review Board found that when the valve was sealed it caused the exhausters to operate like compressors. This action quickly over-pressurized the system. Several check valves were incorporated into the system afterwards and a Recertification Program was established.

Documents:
     Equipment Building Explosion article (1971) (PDF, 512KB)
     1971 Bldg 64 Explosion (PDF, 704KB)
     Recertification Program article (1987) (PDF, 528KB)


Exterior Damage
Exterior Damage
Failed Head
Failed Head
More Exterior Damage
Exterior Damage