Local instantaneous convective heat transfer characteristics of radial reattaching nozzles

Conference · Thu Jul 01 04:00:00 EDT 1999

OSTI ID:20002524

Furlow, J S; James, D L

An experimental investigation of pulsating radial reattaching (PRJR) nozzles was made to determine local instantaneous heat flux and surface temperature characteristics for different geometric, flow, and pulsation conditions. Local instantaneous heat flux and surface temperature measurements were made using a heat flux microsensor with a time constant of 6 microseconds. The experimental apparatus consisted of air flowing through an annular feeding tube, which exited via a mechanically pulsed nozzle diverter and impinged upon a heated plate at a specified distance below. cases were run which varied the gap based Reynolds number 1,936 to 3,983, pulsation rate 5 to 21 Hz, Strouhal number 0.02 to 0.09, non dimensional nozzle-to-plate ratio 1.161 to 1.3, gap height variation to nozzle radius ratio of 0.31, and exit angle 0 and 20{degree}. The heated plate onto which the flow impinged was supplied with a constant heat flux of 4.0 kW/m{sup 2}. Local instantaneous convective heat transfer coefficients varied by as much as 40% when compared to local time average coefficients. Fast Fourier transform analysis identified that the dominant frequency observed in power spectrum plots of heat flux corresponded to the pulsation frequency with other subharmonics also present. Also the data showed a phase lag in local heat transfer and surface temperature minima and maxima as a function of radial distance from the nozzle centerline.

• Research Organization: Texas Tech Univ., Lubbock, TX (US)
• OSTI ID: 20002524
• Report Number(s): CONF-990805--
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
GEOMETRY
HEAT FLUX
HEAT TRANSFER
JETS
NOZZLES
PULSATIONS
TEMPERATURE DISTRIBUTION
TEMPERATURE MEASUREMENT