0
Research Papers: Gas Turbines: Aircraft Engine

An Investigation Into the Effects of Highly Transient Flight Maneuvers With Heat and Mass Transfer on the T-38 Air Force Trainer Inlet

[+] Author and Article Information
Alan Hale, Jim Sirbaugh

Aerospace Testing Alliance Arnold Engineering Development Center, AEDC Arnold Air Force Base, TN 37389-9013

Andrew Hughes

 Tennessee Technology University, Cookeville, TN 38501-7310

David S. Kidman

Air Force Flight Test Center, Edwards Air Force Base, CA 93524

J. Eng. Gas Turbines Power 133(3), 031201 (Nov 12, 2010) (10 pages) doi:10.1115/1.4001995 History: Received April 12, 2010; Revised April 19, 2010; Published November 12, 2010; Online November 12, 2010

The T-38 talon currently serves as the primary United States Air Force trainer for fighter aircraft. This supersonic trainer was developed in the 1960s but continues to be used today as the result of various modernization programs throughout its service life. The latest propulsion modernization program focused on improved takeoff performance of the T-38’s inlets, improved reliability of the twin J85 afterburning turbojet engines, and reduced drag with an improved exhaust nozzle design. The T-38’s inlet includes bleed holes upstream of the engine face to provide cooling airflow from the inlet to the engine bay. However, at various flight conditions, the bay air is pressurized relative to the inlet, resulting in reverse flow of hot engine bay air into the inlet. This reverse flow causes total temperature distortion that may reduce the engine stability margin. Partial inlet instrumentation of the left engine was used to estimate the total temperature distortion associated with reverse flow, however, flight testing of highly transient maneuvers revealed levels of total temperature distortion greater than that predicted for reverse flow alone. This discovery led to the hypothesis that thermal energy storage of the aluminum inlet during transient flight maneuvers resulted in increased temperature distortion at the engine face. Flight data analysis demonstrated the need for a near-real-time thermal inlet distortion analysis capability. A two-dimensional (2D) transient axisymmetric heat and mass transfer model was developed through the use of a lumped-parameter boundary-layer model to simulate the inlet flow and determine the time-dependent inlet duct heat transfer. This model was validated with transient 2D computational fluid dynamics and two flight maneuvers. The analysis of flight maneuvers revealed that in the absence of engine bay air re-ingestion, the time lag associated with the heating and cooling of the inlet walls generates radial temperature distortion, which has the effect of reducing engine stability margin up to 5.44% for the maneuvers analyzed.

Copyright © 2011 by American Society of Mechanical Engineers
Your Session has timed out. Please sign back in to continue.

References

Figures

Grahic Jump Location
Figure 1

Typical engine inlet temperature distortions

Grahic Jump Location
Figure 2

Spatial total temperature distortion accountability

Grahic Jump Location
Figure 3

Engine-inlet temperature distortion from engine bay air re-ingestion

Grahic Jump Location
Figure 4

Dive and climb flight maneuver

Grahic Jump Location
Figure 5

Tip radial temperature distortion

Grahic Jump Location
Figure 6

Inlet geometry simplification for transient CFD operation

Grahic Jump Location
Figure 7

Inlet geometry simplification for transient CFD operation

Grahic Jump Location
Figure 8

Flight data (dive and climb maneuver)

Grahic Jump Location
Figure 9

Comparison of CFD results to flight data (dive and climb maneuver)

Grahic Jump Location
Figure 10

Update wall temperature due to heat transfer during the transient maneuver simulation

Grahic Jump Location
Figure 11

Interface of the nonviscous and boundary-layer solutions during the transient maneuver simulation

Grahic Jump Location
Figure 12

Comparison of TransBLayer results to CFD results (dive and climb maneuver)

Grahic Jump Location
Figure 13

Comparison of TransBLayer and CFD in boundary-layer height and profiles

Grahic Jump Location
Figure 14

Comparison of TransBLayer results to flight data (dive and climb maneuver)

Grahic Jump Location
Figure 15

Total temperature boundary-layer profiles (dive and climb maneuver)

Grahic Jump Location
Figure 16

High Mach climb and dive flight maneuver

Grahic Jump Location
Figure 17

Flight data (high Mach climb and dive maneuver)

Grahic Jump Location
Figure 18

Inlet air cooling (high Mach climb and dive maneuver)

Grahic Jump Location
Figure 19

Comparison of TransBLayer results to flight data (high Mach climb and dive maneuver)

Tables

Errata

Discussions

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In