DNS study of pulsed film cooling for enhanced cooling effectiveness

Muldoon, Frank; Acharya, Sumanta

doi:10.1016/j.ijheatmasstransfer.2009.01.030

Cited by 58 publications

(17 citation statements)

References 18 publications

(26 reference statements)

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“…The present study focusses on deriving this scaling by fitting empirical data of a synthetic jet in a turbulent boundary layer. Applications of unsteady jets in cross flow include control of the jet in cross flow (Narayanan et al 2003), separation control (Dandois et al 2007), thrust vector control (Miller et al 2001), film cooling (Muldoon and Acharya 2009) and skin-friction control. Recent results have shown that skin-friction drag can be reduced up to 3% by targeting the large-scale structures of a high-Reynolds number turbulent boundary layer using a pulsed jet (Abbassi et al 2017).…”

Section: Introductionmentioning

confidence: 99%

Trajectory of a synthetic jet issuing into high-Reynolds-number turbulent boundary layers

et al. 2018

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Synthetic jets are zero-net-mass-flux actuators that can be used in a range of flow control applications. For some applications the scaling of the trajectory of the jet with actuation and cross-flow parameters is important. This scaling is investigated for changes in the friction Reynolds number, changes in the velocity ratio (defined as a ratio between the mean jet blowing velocity and the free-stream velocity) and changes in the actuation frequency of the jet. A distinctive aspect of this study are the high-Reynolds number turbulent boundary layers (up to Re τ = 12 800) of the cross flow. To our knowledge, this is the first study to investigate the effect of the friction Reynolds number of the cross-flow on the trajectory of an (unsteady) jet, as well as the first study to systematically investigate the scaling of the trajectory with actuation frequency. A broad range of parameters is varied (rather than an in-depth investigation of a single parameter) and the results of this study are meant to indicate the relative importance of each parameter rather than the exact influence on the trajectory. Within the range of parameters explored, the critical ones are found to be the velocity ratio as well as a non-dimensional frequency based on the jet actuation frequency, the cross-flow velocity and the jet dimensions. The Reynolds number of the boundary layer is shown to only have a small effect on the trajectory. An expression for the trajectory of the jet is derived from the data, which (in the limit) is consistent with known expressions for the trajectory of a steady jet in a cross-flow.

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Section: Introductionmentioning

confidence: 99%

Trajectory of a synthetic jet issuing into high-Reynolds-number turbulent boundary layers

et al. 2018

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“…When excited by certain UV light (385 nm in present study), it will emit light with a longer wavelength, and the intensity of the released light is proportional to surrounding partial pressure of oxygen via a process called oxygen quenching (Bell, et al, 2001). The relationship between the emitted light and the partial pressure of oxygen can be described by the Stern-Volmer equation (Liu, et al, 2005):…”

Section: Psp Technique and Experimental Set Upmentioning

confidence: 87%

Experimental Study on Spatio-Temporal Variation of Double-Row Holes Film Cooling Effectiveness with Oscillating Mainstream

Chen¹,

Zhou²,

Qenawy³

et al. 2019

Proceedings of Global Power &Amp; Propulsion Society

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The effect of mainstream oscillations on double-row holes film cooling effectiveness was experimentally investigated. During the experiment, carbon dioxide (CO2) was used as the coolant and was discharged from 35°inclined double-row holes with in-line and staggered arrangement. As a baseline study, a single row injection was pre-considered and the double-row film cooling cases with periodic freestream were assessed in detail to explore the frequency effect (i.e. set to 5 Hz and 25 Hz with fixed amplitude) on adiabatic effectiveness. The adiabatic effectiveness was measured by fast-response pressuresensitive paint (fast-PSP) and was further analysed in term of the time-averaged (̅) and phase-averaged (̃) results. The time-averaged results showed that double-row could restrain the negative effects of mainstream oscillations and enhance the positive effects, compared with the baseline. The phaseaveraged results showed that the double-row could have more stable coolant coverage than single row. Moreover, the staggered arrangement had comprehensive better protection than the in-line at high blowing ratio, but at lower blowing ratio reversed.

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“…Their numerical results indicated that for high pulsation frequencies, the downwash motion of the jet pulse provokes the disintegration of the jet structure, which improves the thermal protection effect, and the overlapping of the jet pulses helps the spreading of coolant over the flat plate. Muldoon and Acharya [5] used Direct Numerical Simulations (DNS) to examine the pulsed film cooling, and found that the pulsing increases overall film cooling effectiveness in comparison with un-pulsed flow at BR ¼ 1.5. Later on, using the same geometry and method of [5], Babaee et al [6] optimized the forcing parameters of film cooling effectiveness, the best film cooling effectiveness is found at DC ¼ 0.14 and Strouhal number St ¼ 1.03, and the physical mechanisms are explored, including the ingestion of the crossflow into the delivery tube and separation of distinct vortex rings from the flat plate.…”

Section: Introductionmentioning

confidence: 99%

“…Muldoon and Acharya [5] used Direct Numerical Simulations (DNS) to examine the pulsed film cooling, and found that the pulsing increases overall film cooling effectiveness in comparison with un-pulsed flow at BR ¼ 1.5. Later on, using the same geometry and method of [5], Babaee et al [6] optimized the forcing parameters of film cooling effectiveness, the best film cooling effectiveness is found at DC ¼ 0.14 and Strouhal number St ¼ 1.03, and the physical mechanisms are explored, including the ingestion of the crossflow into the delivery tube and separation of distinct vortex rings from the flat plate. In addition, Muldoon and Acharya [7] conducted DNS using a sinusoidal pulsed jet injected vertically into a crossflow, and their results indicated that the pulsing drastically changes the jet spreading and penetration, and increases the mixing of the jet with the crossflow.…”

Section: Introductionmentioning

confidence: 99%

Numerical investigations of pulsed film cooling on an entire turbine vane

Wang

2015

Applied Thermal Engineering

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DNS study of pulsed film cooling for enhanced cooling effectiveness

Cited by 58 publications

References 18 publications

Trajectory of a synthetic jet issuing into high-Reynolds-number turbulent boundary layers

Trajectory of a synthetic jet issuing into high-Reynolds-number turbulent boundary layers

Experimental Study on Spatio-Temporal Variation of Double-Row Holes Film Cooling Effectiveness with Oscillating Mainstream

Numerical investigations of pulsed film cooling on an entire turbine vane

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