Title page for ETD etd-12222011-143750

Type of Document Master's Thesis
Author Ferrar, Anthony Maurice
Author's Email Address aferrar@vt.edu
URN etd-12222011-143750
Title Measurements of Flow in Boundary Layer Ingesting Serpentine Inlets
Degree Master of Science
Department Mechanical Engineering
Advisory Committee
Advisor Name Title
O'Brien, Walter F. Jr. Committee Chair
Sharma, Om Committee Member
Tafti, Danesh K. Committee Member
  • boundary layer ingestion
  • wake ingestion
  • distortion
  • flow control
  • diffuser
  • inlet
Date of Defense 2011-12-15
Availability unrestricted
Highly integrated airframe-propulsion systems featuring ingestion of the airframe boundary

layer o er reduced noise, emissions, and fuel consumption. Embedded engine systems are

envisioned which require boundary layer ingesting (BLI) serpentine inlets to provide the

needed air

ow to the engine. These inlets produce distorted

ow pro les that can cause

aeromechanical, stability, and performance changes in embedded engines. Proper design

of embedded engine systems requires understanding of the underlying

uid dynamics that

occur within serpentine inlets.

A serpentine inlet was tested in a specially designed wind tunnel that simulated boundary

layer ingestion in a full-scale realistic environment. The measured total pressure pro les at

the inlet and exit planes of the duct, and the static pressure distributions along the walls

provided useful data related to the

ow in BLI serpentine inlet systems. A bleed

ow control

system was tested that utilized no more than 2% of the total inlet

ow. Two bleed slots

were employed, one near the rst bend of the S-duct and one near second. The bleed system

successfully reduced inlet distortions by as much as 30%, implying improvements in stall

margin and engine performance.

Analysis of the wake shape entering the S-duct showed that the airframe and inlet duct are

both important components of a wake-ingesting inlet/di usion system. Shape e ects and

static pressure distributions determined

ow transport within the serpentine inlet. Flow

separation within the S-duct increased distortion at the engine inlet plane. Discussion

of airframe/inlet/engine compatibility demonstrates that embedded engine systems require

multi-disciplinary collaborative design e orts. An included fundamental analysis provides

performance estimates and design guidelines. The ideal airframe performance improvement

associated with wake-ingestion is estimated.

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