Accession Number:

ADA151854

Title:

Gasdynamic Evaluation of Choking Cascade Turns

Descriptive Note:

Master's thesis

Corporate Author:

AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING

Personal Author(s):

• Perez, D. R.

Report Date:

1984-12-01

Pagination or Media Count:

78.0

Abstract:

This is a thesis. Uses for ram air in airborne vehicles are increasing along with the need for sophisticated ducting of the compressed air. Inlets operating supercritically, a normal shock in the subsonic diffuser, use an aerodynamic grid to control the normal shock position to a region of low total pressure losses. Turning of the flow requires long radius curves to maintain the total pressure. This study combines the internal shock positioning and flow turning into a flow choking cascade turn with a short radius. Several sets of 90 degree, turning sections, for turning compressed air, were selected, designed, and tested gas dynamically. Two of the turn sections were totally, subsonic and only turned the air flow. Two other sections turned and choked the flow during supercritical inlet operation. These flow controllers perform the same function has an aerodynamic grid and flow turning vanes used in current internal compressible airflow designs. These tests correlated the suitability of using a water table versus a gasdynamic apparatus for determining the flow control capabilities and pressure recovery of the cascades. The subsonic only turning section gave the best pressure recovery and total pressure distribution along the turning axis, but allowed the supercritical internal shock to move towards large shockboundary layer interaction. The two shock positioning cascades provided good internal shock control with only slightly lower pressure recovery. Further investigation is needed for the effects of back pressure fluctuations on the flow dynamics.

Descriptors:

• *DUCT BENDS
• *CASCADES(FLUID DYNAMICS)
• *CASCADE STRUCTURES
• *AIR INTAKES
• AIR FLOW
• THESES
• BOUNDARY LAYER
• GAS DYNAMICS
• RAMJET ENGINES
• COMPRESSIBLE FLOW
• INTERNAL
• SHOCK
• PRESSURE
• SUPERCRITICAL FLOW
• INLETS
• PRESSURE DISTRIBUTION
• RADIUS(MEASURE)
• BACK PRESSURE
• COMPRESSED AIR
• WATER TABLE
• SUBSONIC DIFFUSERS
• RAMJET INLETS
• VARIABLE PRESSURE
• AERODYNAMIC CONTROL SURFACES
• CURVED PROFILES
• DIFFUSERS
• GRIDS
• INTERACTIONS
• INLET GUIDE VANES
• POSITION(LOCATION)
• RECOVERY

Subject Categories:

• Fluid Mechanics
• Air Breathing Engines (Unconventional)

Distribution Statement:

APPROVED FOR PUBLIC RELEASE