Local and instantaneous heat transfer characteristics of arrays of pulsating jets

Book · Tue Dec 31 04:00:00 EST 1996

OSTI ID:445525

Sheriff, H S; Zumbrunnen, D A ^[1]

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1. Clemson Univ., SC (United States)

Recent investigations of impinging jets have revealed that pulsations in the incident flow can be an effective technique for modifying convective heat transfer characteristics. While these studies focused on single impinging jets, industrial applications of impinging jets usually involve arrays of jets. When so configured, inter-jet interaction becomes a major consideration in achieving uniform and high heat transfer. To explore the effects of flow pulsations on the heat transfer performance of jet arrays, an experimental investigation have been performed of instantaneous and time-averaged convective heat transfer to a square, in-line array of circular air jets. The flow pulsation frequency was varied from 10 Hz to 65 Hz which corresponded to Strouhal numbers based on the nozzle diameter and velocity from 0.004 to 0.028. The pulse magnitude, which was defined as the ratio of the root mean square of the pulsating component of flow velocity to the mean flow velocity, was varied from 10% to 60%. Dual sensor hot film anemometry was used to document the jet flow-field. Instantaneous and time-averaged convective heat transfer was documented using a heat flux microsensor. An ensemble averaging technique was used to separate the pulsating component of flow velocity from the turbulent component and thereby assess the effect of flow pulsation on turbulence intensity. Instantaneous and time-averaged convective heat transfer conditions are documented as a function of pulse magnitude and pulse frequency within an unit cell of the array.

• Sponsoring Organization: National Science Foundation, Washington, DC (United States)
• OSTI ID: 445525
• Report Number(s): CONF-961105--; ISBN 0-7918-1520-X
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
CONFIGURATION
EXPERIMENTAL DATA
FLUID FLOW
HEAT TRANSFER
JETS
NUSSELT NUMBER
PERFORMANCE