Implementation of Vortex Cavities ina Turbojet Diffuser

Sponsor: Williams International

Progress Report 5

December 5, 2006

TEAM CRUISE CONTROL Michael Feldman

Marvin Kong

Nansi Xue

Table of Contents•Completed Experimental Set-up

•Testing and Data

Completion of Experimental Set-up

•All preparation work completed

•Made adapters that connect the pitot /static tubes to the manometers

•Made pitot and static tubes from the 1/8” copper tubes

•Glued the PVC pipe to the diffuser adapter

Actual Testing•SLA models are received on Friday, Dec 2nd

•Drilling and attachment of the pitot/static tubes done on the following Monday morning

•Testing were carried out on Monday and Tuesday

Testing Results - Monday •Two static pressure taps and one pitot tube at each inlet/ outlet

•Monday testing done with a flow choker – Inlet Mach number ≈ 0.3

Testing Results - Monday •Pressure measurements converted to pressure coefficients to evaluate diffuser efficiency

•4.7” baseline diffuser has the highest efficiency (Cp = 0.7)

•2.7” model with vortex cavity is more efficient than 2.7” baseline, but only slightly

0.000

0.100

0.200

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0.700

0.800

1

Inlet Mach No = 0.3

Pre

ss

ure

Co

eff

icie

nt

(Cp

)

4.7" Baseline

2.7" Baseline

2.7" with Vortex Cavity

Testing Results - Tuesday•Flow choker was removed for higher flow speed – Inlet Mach No. ≈ 0.4

•Increase in flow speed leads to decrease in diffuser efficiency

Testing Results - Monday •4.7” baseline Cp decreased from 0.7 to 0.53

•2.7” baseline Cp increased from 0.25 to 0.37

•Cp of 2.7” model with vortex cavity decreases only slightly

•4.7” baseline model still has the highest efficiency

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0.600

1

Inlet Mach No = 0.4

Pre

ss

ure

Co

eff

icie

nt

(Cp

)

4.7" Baseline

2.7" Baseline

2.7" with Vortex Cavity

Testing Results - Summary •Decreasing diffuser length from 4.7” to 2.7” leads to drastic decrease in efficiency

•Implementing vortex cavity at low Mach numbers seems to improve diffuser performance, but the effect is minimal. Vortex cavity ceases to be useful at Mach No = 0.34

•More analysis to be done and possible errors and improvements in testing to be concluded.

Pressure Coefficient against Inlet Mach No

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.25 0.27 0.29 0.31 0.33 0.35 0.37 0.39 0.41 0.43 0.45

Inlet Mach No

Pre

ss

ure

Co

eff

icie

nt

(Cp

)

4.7" baseline

2.7" baseline

2.7" w/ V.C

0.342

Final Cost •Increase in cost due to additional soldering equipment, PVC pipe, and pitot tubes

Any Questions?