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Relevant bibliographies by topics / Unsteady flow on film cooling

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Academic literature on the topic 'Unsteady flow on film cooling'

Author: Grafiati

Published: 4 June 2021

Last updated: 8 February 2022

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Journal articles on the topic "Unsteady flow on film cooling"

1

Martini, P., A. Schulz, H. J. Bauer, and C. F. Whitney. "Detached Eddy Simulation of Film Cooling Performance on the Trailing Edge Cutback of Gas Turbine Airfoils." Journal of Turbomachinery 128, no. 2 (February 1, 2005): 292–99. http://dx.doi.org/10.1115/1.2137739.

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The present study deals with the unsteady flow simulation of trailing edge film cooling on the pressure side cut back of gas turbine airfoils. Before being ejected tangentially on the inclined cut-back surface, the coolant air passes a partly converging passage that is equipped with turbulators such as pin fins and ribs. The film mixing process on the cut back is complicated. In the near slot region, due to the turbulators and the blunt pressure side lip, turbulence is expected to be anisotropic. Furthermore, unsteady flow phenomena like vortex shedding from the pressure side lip might influence the mixing process (i.e., the film cooling effectiveness on the cut-back surface). In the current study, three different internal cooling designs are numerically investigated starting from the steady RaNS solution, and ending with unsteady detached eddy simulations (DES). Blowing ratios M=0.5; 0.8; 1.1 are considered. To obtain both, film cooling effectiveness as well as heat transfer coefficients on the cut-back surface, the simulations are performed using adiabatic and diabatic wall boundary conditions. The DES simulations give a detailed insight into the unsteady film mixing process on the trailing edge cut back, which is indeed influenced by vortex shedding from the pressure side lip. Furthermore, the time averaged DES results show very good agreement with the experimental data in terms of film cooling effectiveness and heat transfer coefficients.

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2

Abhari, R. S. "Impact of Rotor–Stator Interaction on Turbine Blade Film Cooling." Journal of Turbomachinery 118, no. 1 (January 1, 1996): 123–33. http://dx.doi.org/10.1115/1.2836593.

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The goal of this study is to quantify the impact of rotor–stator interaction on surface heat transfer of film cooled turbine blades. In Section I, a steady-state injection model of the film cooling is incorporated into a two-dimensional, thin shear layer, multiblade row CFD code. This injection model accounts for the penetration and spreading of the coolant jet, as well as the entrainment of the boundary layer fluid by the coolant. The code is validated, in the steady state, by comparing its predictions to data from a blade tested in linear cascade. In Section II, time-resolved film cooled turbine rotor heat transfer measurements are compared with numerical predictions. Data were taken on a fully film cooled blade in a transonic, high pressure ratio, single-stage turbine in a short duration turbine test facility, which simulates full-engine nondimensional conditions. Film cooled heat flux on the pressure surface is predicted to be as much as a factor of two higher in the time average of the unsteady calculations compared to the steady-state case. Time-resolved film cooled heat transfer comparison of data to prediction at two spanwise positions is used to validate the numerical code. The unsteady stator–rotor interaction results in the pulsation of the coolant injection flow out of the film holes with large-scale fluctuations. The combination of pulsating coolant flow and the interaction of the coolant with this unsteady external flow is shown to lower the local pressure side adiabatic film effectiveness by as much as 64 percent when compared to the steady-state case.

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Lenzi, Tommaso, Alessio Picchi, Tommaso Bacci, Antonio Andreini, and Bruno Facchini. "Unsteady Flow Field Characterization of Effusion Cooling Systems with Swirling Main Flow: Comparison Between Cylindrical and Shaped Holes." Energies 13, no. 19 (September 23, 2020): 4993. http://dx.doi.org/10.3390/en13194993.

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The presence of injectors with strongly swirled flows, used to promote flame stability in the combustion chambers of gas turbines, influences the behaviour of the effusion cooling jets and consequently of the liner’s cooling capabilities. For this reason, unsteady behaviour of the jets in the presence of swirling flow requires a characterization by means of experimental flow field analyses. The experimental setup of this work consists of a non-reactive single-sector linear combustor test rig, scaled up with respect to the real engine geometry to increase spatial resolution and to reduce the frequencies of the unsteadiness. It is equipped with a radial swirler and multi-perforated effusion plates to simulate the liner cooling system. Two effusion plates were tested and compared: with cylindrical and with laid-back fan-shaped 7-7-7 holes in staggered arrangement. Time resolved Particle Image Velocimetry has been carried out: the unsteady characteristics of the jets, promoted by the intermittent interactions with the turbulent mainstream, have been investigated as their vortex structures and turbulent decay. The results demonstrate how an unsteady analysis is necessary to provide a complete characterization of the coolant behaviour and of its turbulent mixing with mainflow, which affect, in turn, the film cooling capability and liner’s lifetime.

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Baek, Seung, and Savas Yavuzkurt. "Effects of Flow Oscillations in the Mainstream on Film Cooling." Inventions 3, no. 4 (October 24, 2018): 73. http://dx.doi.org/10.3390/inventions3040073.

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The objective of this study is to investigate the effects of oscillations in the main flow and the coolant jets on film cooling at various frequencies (0 to 2144 Hz) at low and high average blowing ratios. Numerical simulations are performed using LES Smagorinsky–Lilly turbulence model for calculation of the adiabatic film cooling effectiveness and using the DES Realizable k-epsilon turbulence model for obtaining the Stanton number ratios (St/Sto). Additionally, multi-frequency inlet velocities are applied to the main and coolant flows to explore the effects of multi-frequency unsteady flows and the results are compared to those at single frequencies. The results show that at a low average blowing ratio (M = 0.5) if the oscillation frequency is increased from 0 to 180 Hz, the effectiveness decreases and the Stanton number ratio increases. However, when the frequency goes from 180 to 268 Hz, the effectiveness sharply increases and the Stanton number ratio increases slightly. If the frequency changes from 268 to 1072 Hz, the film cooling effectiveness decreases and the Stanton number ratio increases slightly. If the frequency goes from 1072 to 2144 Hz, the film cooling effectiveness climbs up and the Stanton number ratio decreases. The results show that at high average blowing ratio (M = 1.0) the trends of the film cooling effectiveness are similar to those at low blowing ratio (M = 0.5) except from 0 to 90 Hz. If the frequency goes from 0 to 90 Hz at M = 1.0, the film cooling effectiveness increases and the Stanton number ratio decreases. It can be said that it is important to include the effects of oscillating flows when designing film cooling systems for a gas turbine.

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Han, Je-Chin. "Recent Studies in Turbine Blade Cooling." International Journal of Rotating Machinery 10, no. 6 (2004): 443–57. http://dx.doi.org/10.1155/s1023621x04000442.

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Gas turbines are used extensively for aircraft propulsion, land-based power generation, and industrial applications. Developments in turbine cooling technology play a critical role in increasing the thermal efficiency and power output of advanced gas turbines. Gas turbine blades are cooled internally by passing the coolant through several rib-enhanced serpentine passages to remove heat conducted from the outside surface. External cooling of turbine blades by film cooling is achieved by injecting relatively cooler air from the internal coolant passages out of the blade surface in order to form a protective layer between the blade surface and hot gas-path flow. For internal cooling, this presentation focuses on the effect of rotation on rotor blade coolant passage heat transfer with rib turbulators and impinging jets. The computational flow and heat transfer results are also presented and compared to experimental data using the RANS method with various turbulence models such as k-ε, and second-moment closure models. This presentation includes unsteady high free-stream turbulence effects on film cooling performance with a discussion of detailed heat transfer coef- ficient and film-cooling effectiveness distributions for standard and shaped film-hole geometry using the newly developed transient liquid crystal image method.

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Izmodenova, T. Yu, N. N. Kortikov, and N. B. Kuznetsov. "Unsteady film cooling with imposed nonuniform pulsations of the main flow." Thermophysics and Aeromechanics 15, no. 4 (December 2008): 583–88. http://dx.doi.org/10.1007/s11510-008-0007-1.

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Kim, Sung In, and Ibrahim Hassan. "Unsteady Simulations of a Film Cooling Flow from an Inclined Cylindrical Jet." Journal of Thermophysics and Heat Transfer 24, no. 1 (January 2010): 145–56. http://dx.doi.org/10.2514/1.33167.

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Muldoon, Frank. "Control of a Simplified Unsteady Film-Cooling Flow Using Gradient-Based Optimization." AIAA Journal 46, no. 10 (October 2008): 2443–58. http://dx.doi.org/10.2514/1.34120.

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Abhari, R. S., and A. H. Epstein. "An Experimental Study of Film Cooling in a Rotating Transonic Turbine." Journal of Turbomachinery 116, no. 1 (January 1, 1994): 63–70. http://dx.doi.org/10.1115/1.2928279.

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Time-resolved measurements of heat transfer on a fully cooled transonic turbine stage have been taken in a short duration turbine test facility, which simulates full engine nondimensional conditions. The time average of this data is compared to uncooled rotor data and cooled linear cascade measurements made on the same profile. The film cooling reduces the time-averaged heat transfer compared to the uncooled rotor on the blade suction surface by as much as 60 percent, but has relatively little effect on the pressure surface. The suction surface rotor heat transfer is lower than that measured in the cascade. The results are similar over the central 3/4 of the span, implying that the flow here is mainly two dimensional. The film cooling is shown to be much less effective at high blowing ratios than at low ones. Time-resolved measurements reveal that the cooling, when effective, both reduced the dc level of heat transfer and changed the shape of the unsteady waveform. Unsteady blowing is shown to be a principal driver of film cooling fluctuations, and a linear model is shown to do a good job in predicting the unsteady heat transfer. The unsteadiness results in a 12 percent decrease in heat transfer on the suction surface and a 5 percent increase on the pressure surface.

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Yin, Hong. "Numerical simulation of swirling flow effect on the first stage vane film cooling distribution." International Journal of Modeling, Simulation, and Scientific Computing 07, no. 03 (August 23, 2016): 1650031. http://dx.doi.org/10.1142/s1793962316500318.

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In advanced gas turbine technology, lean premixed combustion is an effective strategy to reduce peak temperature and thus, NO[Formula: see text] emissions. The swirler is adopted to establish recirculation flow zone, enhancing mixing and stabilizing the flame. Therefore, the swirling flow is dominant in the combustor flow field and has impact on the vane. This paper mainly investigates the swirling flow effect on the turbine first stage vane cooling system by conducting a group of numerical simulations. Firstly, the numerical methods of turbulence modeling using RANS and LES are compared. The computational model of one single swirl flow field is considered. Both the RANS and LES results give reasonable recirculation zone shape. When comparing the velocity distribution, the RANS results generally match the experimental data but fail to at some local area. The LES modeling gives better results and more detailed unsteady flow field. In the second step, the RANS modeling is incorporated to investigate the vane film cooling performance under the swirling inflow boundary condition. According to the numerical results, the leading edge film cooling is largely altered by the swirling flow, especially for the swirl core-leading edge aligned case. Compared to the pressure side, the suction side film cooling is more sensitive to the swirling flow. Locally, the film cooling jet is lifted and turned by the strong swirling flow.

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Dissertations / Theses on the topic "Unsteady flow on film cooling"

1

Blake, Sarah Anne. "Turbine blade platform film cooling with simulated stator-rotor purge flow with varied seal width and upstream wake with vortex." [College Station, Tex. : Texas A&M University, 2007. http://hdl.handle.net/1969.1/ETD-TAMU-1340.

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Friedrichs, Stefan. "Endwall film-cooling in axial flow turbines." Thesis, University of Cambridge, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.627225.

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Golsen, Matthew J. "Investigation on interactions of unsteady wakes and film cooling on an annular endwall." Honors in the Major Thesis, University of Central Florida, 2011. http://digital.library.ucf.edu/cdm/ref/collection/ETH/id/386.

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In recent decades, greater interest in the effect of rotational wakes on gas turbine film cooling applications has produced increasing numbers of studies on these unsteady phenomena. Wakes are primarily shed from upstream components such as transition duct walls, stator vanes, and rotors. Studies have shown that in areas of unsteady flow, the best performing parameters in conventional steady investigations may not be the best for unsteady applications. One common method of modeling the unsteady wake interaction in subsonic flows is the use of spoke wheel type wake generators using cylindrical rods to produce the velocity detriment and local increase in turbulence intensity. Though the impact of wakes have been studied for decades on airfoil losses and boundary layer transition, only recently has the film cooling and wake interaction been investigated. The existing work is primarily on leading edge models and airfoil cascades. The primary parameter characterizing the unsteady wakes is the dimensionless or reduced frequency known as the Strouhal number. The film cooling jet itself has dominant frequencies resulting from the shear and the jet trailing wake shedding, depending on the injectant flow rate. There exist great deficiencies in the fundamental understanding of the interaction of these two frequencies. Heat transfer considerations are also relatively recent being studied only since the early 1990's. Heat transfer coefficients and film cooling effectiveness have been reported for leading edge and linear airfoil cascades. In the case of the linear cascade, no data can be taken near the endwall region due to the varying tangential velocity of wake generating rod. The current work expands on this initiative incorporating a sector annular duct as the test setting for the rotating wakes focusing on this endwall region.; Studies in to the effect of the rods in this alternate orientation include film cooling effectiveness using temperature sensitive paint, impact of wake rod to film cooling hole diameter ratio, and time accurate numerical predictions and comparisons with experimental work. Data are shown for a range of momentum flux ratios and Strouhal numbers. The result of this work sets the stage for the complete understanding of the unsteady wake and inclined jet interaction.
B.S.M.E.
Bachelors
Engineering and Computer Science
Mechanical Engineering

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4

Popp, Oliver. "Steady and Unsteady Heat Transfer in a Film Cooled Transonic Turbine Cascade." Diss., Virginia Tech, 1999. http://hdl.handle.net/10919/28513.

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The unsteady interaction of shock waves emerging from the trailing edge of modern turbine nozzle guide vanes and impinging on downstream rotor blades is modeled in a linear cascade. The Reynolds number based on blade chord and exit conditions (5*10^6) and the exit Mach number (1.2) are representative of modern engine operating conditions. The relative motion of shocks and blades is simulated by sending a shock wave along the leading edges of the linear cascade instead of moving the blades through an array of stationary shock waves. The blade geometry is a generic version of a modern high turning rotor blade with transonic exit conditions. The blade is equipped with a showerhead film cooling scheme. Heat flux, surface pressure and surface temperature are measured at six locations on the suction side of the central blade. Pressure measurements are taken with Kulite XCQ-062-50a high frequency pressure transducers. Heat flux data is obtained with Vatell HFM-7/L high speed heat flux sensors. High speed heat flux and pressure data are recorded during the time of the shock impact with and without film cooling. The data is analyzed in detail to find the relative magnitudes of the shock effect on the heat transfer coefficient and the recovery temperature or adiabatic wall temperature (in the presence of film cooling). It is shown that the variations of the heat transfer coefficient and the film effectiveness are less significant than the variations of recovery temperature. The effect of the shock is found to be similar in the cases with and without film cooling. In both cases the variation of recovery temperature induced by the shock is shown to be the main contribution to the overall unsteady heat flux. The unsteady heat flux is compared to results from different prediction models published in the literature. The best agreement of data and prediction is found for a model that assumes a constant heat transfer coefficient and a temperature difference calculated from the unsteady surface pressure assuming an isentropic compression.
Ph. D.

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5

Yang, Huitao. "Investigations of flow and film cooling on turbine blade edge regions." Texas A&M University, 2006. http://hdl.handle.net/1969.1/4338.

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The inlet temperature of modern gas turbine engines has been increased to achieve higher thermal efficiency and increased output. The blade edge regions, including the blade tip, the leading edge, and the platform, are exposed to the most extreme heat loads, and therefore, must be adequately cooled to maintain safety. For the blade tip, there is tip leakage flow due to the pressure gradient across the tip. This leakage flow not only reduces the blade aerodynamic performance, but also yields a high heat load due to the thin boundary layer and high speed. Various tip configurations, such as plane tip, double side squealer tip, and single suction side squealer tip, have been studied to find which one is the best configuration to reduce the tip leakage flow and the heat load. In addition to the flow and heat transfer on the blade tip, film cooling with various arrangements, including camber line, upstream, and two row configurations, have been studied. Besides these cases of low inlet/outlet pressure ratio, low temperature, non-rotating, the high inlet/outlet pressure ratio, high temperature, and rotating cases have been investigated, since they are closer to real turbine working conditions. The leading edge of the rotor blade experiences high heat transfer because of the stagnation flow. Film cooling on the rotor leading edge in a 1-1/2 turbine stage has been numerically studied for the design and off-design conditions. Simulations find that the increasing rotating speed shifts the stagnation line from the pressure side, to the leading edge and the suction side, while film cooling protection moves in the reverse direction with decreasing cooling effectiveness. Film cooling brings a high unsteady intensity of the heat transfer coefficient, especially on the suction side. The unsteady intensity of film cooling effectiveness is higher than that of the heat transfer coefficient. The film cooling on the rotor platform has gained significant attention due to the usage of low-aspect ratio and low-solidity turbine designs. Film cooling and its heat transfer are strongly influenced by the secondary flow of the end-wall and the stator-rotor interaction. Numerical predictions have been performed for the film cooling on the rotating platform of a whole turbine stage. The design conditions yield a high cooling effectiveness and decrease the cooling effectiveness unsteady intensity, while the high rpm condition dramatically reduces the film cooling effectiveness. High purge flow rates provide a better cooling protection. In addition, the impact of the turbine work process on film cooling effectiveness and heat transfer coefficient has been investigated. The overall cooling effectiveness shows a higher value than the adiabatic effectiveness does.

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6

Hosder, Serhat. "Unsteady Skin-Friction Measurements on a Maneuvering Darpa2 Suboff Model." Thesis, Virginia Tech, 2001. http://hdl.handle.net/10919/33582.

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Steady and unsteady flow over a generic Suboff submarine model is studied. The skin-friction magnitudes are measured by using hot-film sensors each connected to a constant temperature anemometer. The local minima in the skin-friction magnitudes are used to obtain the separation locations. Steady static pressure measurements on the model surface are performed at 10Â° and 20Â° angles of attack. Steady and unsteady results are presented for two model configurations: barebody and sail-on-side case. The dynamic plunge-pitch-roll model mount (DyPPiR) is used to simulate the pitchup maneuvers. The pitchup maneuver is a linear ramp from 1Â° to 27Â° in 0.33 seconds. All the tests are conducted at ReL=5,500,000 with a nominal wind tunnel speed of 42.7Â±1 m/s. Steady results show that the flow structure on the leeward side of the barebody can be characterized by the crossflow separation. In the sail-on-side case, the separation pattern of the non-sail region follow the barebody separation trend closely. The flow on the sail side is strongly affected by the presence of the sail and the separation pattern is different from the crossflow separation. The flow in the vicinity of the sail-body junction is dominated by the horseshoe type separation. Unsteady results of the barebody and the non-sail region of the sail-on-side case show significant time lags between unsteady and steady crossflow separation locations. These effects produce the difference in separation topology between the unsteady and steady flowfields. A first-order time lag model approximates the unsteady separation locations reasonably well and time lags are obtained by fitting the model equation with the experimental data. The unsteady separation pattern of the sail side does not follow the quasi-steady data with a time lag and the unsteady separation structure is different from the unsteady crossflow separation topology observed for the barebody and the non-sail region of the sail-on-side case.
Master of Science

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7

Al, Shadidi Kamilla. "Oil Cooling of Electric Motor using CFD." Thesis, KTH, Tillämpad termodynamik och kylteknik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-149673.

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This thesis investigated the heat transfer of internally oil cooled rotors in permanent magnet electric machines which are, among other things, used in hybrid vehicles or zero emission vehicles. The magnets become sensitive and can be demagnetized at high working temperatures, hence the need of cooling. The scope of this work included CFD simulations in STAR-CCM+. Three different 3D multiphase models simulating the oil propagation in the rotor were performed. A Lagrangian multiphase model combined with a fluid film model was the most suitable model for simulating the spray of the oil and the film thickness along the inner rotor wall. It was noticed that periodic boundaries caused problems for the fluid film model, therefore a complete geometry was preferred over a truncated model. The 3D solutions provided thicker film thicknesses than the analytical solutions from the fluid film thickness theory. The maximum analytical thickness was of the same order of magnitude as the surface average film thickness provided by the multiphase models. This thickness was assumed to be constant when used as the base for the fluid region in the 2D one-phase models.The study showed that aluminum was the most suitable rotor material due to its high conductive capacity, which provided a more even distribution of the temperature in the solid and hence resulted in lower overall temperatures. The cooling power increased linearly with the volumetric flow rate, however the heat transfer coefficient decreased for the higher flow rates. A volumetric flow rate of 10dl/min was recommended. A 2D model was compared to a preliminary experiment and showed that these were not correlated. The conclusion was that more experiments and simulations are needed in order to confirm the validity of the 2D model.

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Veley, Emma Michelle. "Measurement of Unsteady Characteristics of Endwall Vortices Using Surface-Mounted Hot-Film Sensors." Wright State University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=wright1534450563500249.

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Scrittore, Joseph. "Experimental Study of the Effect of Dilution Jets on Film Cooling Flow in a Gas Turbine Combustor." Diss., Virginia Tech, 2008. http://hdl.handle.net/10919/28171.

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Cooling combustor chambers for gas turbine engines is challenging because of the complex flow fields inherent to this engine component. This complexity, in part, arises from the interaction of high momentum dilution jets required to mix the fuel with effusion film cooling jets that are intended to cool the combustor walls. The dilution and film cooling flow have different performance criteria, often resulting in conflicting flow mechanisms. The purpose of this study is to evaluate the influence that the dilution jets have on the film cooling effectiveness and how the flow and thermal patterns in the cooling layer are affected by both the dilution flow and the closely spaced film cooling holes. This study also intends to characterize the development of the flow field created by effusion cooling injection without dilution injection. This work is unique because it allows insight into how the full-coverage discrete film cooling layer is interrupted by high momentum dilution jets and how the surface cooling is affected. The film cooling flow was disrupted along the combustor walls in the vicinity of the high momentum dilution jets and the surface cooling effectiveness was reduced with increased dilution jet momentum. This was due to the secondary flows that were intensified by the increased jet momentum. High turbulence levels were generated at the dilution jet shear layer resulting in efficient mixing. The film cooling flow field was affected by the freestream turbulence and complex flow fields created by the combined dilution and effusion cooling flows both in the near dilution jet region as well as downstream of the jets. Effusion cooling holes inclined at 20Ë created lower coolant layer turbulence levels and higher surface cooling effectiveness than 30Ë cooling holes. Results showed an insensitivity of the coolant penetration height to the diameter and angle of the cooling hole in the region downstream of the dilution mixing jets. When high momentum dilution jets were injected into crossflow, a localized region in the flow of high vorticity and high streamwise velocity was created. When film cooling air was injected the inlet flow field and the dilution jet wake were fundamentally changed and the vortex diminished significantly. The temperature field downstream of the dilution jet showed evidence of a hot region which was moderated appreciably by film cooling flow. Differences in the temperature fields were nominal compared to the large mass flow increase of the coolant. A study of streamwise oriented effusion film cooling flow without dilution injection revealed unique and scaleable velocity profiles created by the closely spaced effusion holes. The effusion cooling considered in these tests resulted in streamwise velocity and turbulence level profiles that scaled well with blowing ratio which is a finding that allows the profile shape and magnitude to be readily determined at these test conditions. Results from a study of compound angle effusion cooling injection showed significant differences between the flow field created with and without crossflow. It was found from the angle of the flow field velocity vectors that the cooling film layer grew nearly linearly in the streamwise direction. The absence of crossflow resulted in higher turbulence levels because there was a larger shear stress due to a larger velocity difference between the coolant and crossflow. The penetration height of the coolant was relatively independent of the film cooling momentum flux ratio for both streamwise oriented and compound angle cooling jets.
Ph. D.

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10

Araújo, Gomes Reinaldo [Verfasser]. "On Aerothermal Effects of Film Cooling on Turbine Blades with Flow Separation / Reinaldo Araújo Gomes." München : Verlag Dr. Hut, 2010. http://d-nb.info/100833121X/34.

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Books on the topic "Unsteady flow on film cooling"

1

Simon, Frederick F. Jet model for slot film cooling with effect of free-stream and coolant turbulence. Cleveland, Ohio: Lewis Research Center, 1986.

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2

Garg, Vijay Kumar. Effect of coolant temperature and mass flow on film cooling of turbine blades. [Washington, D.C: National Aeronautics and Space Administration, 1997.

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Heidmann, James D. Coarse grid modeling of turbine film cooling flows using volumetric source terms. [Cleveland, Ohio]: National Aeronautics and Space Administration, Glenn Research Center, 2001.

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Lepicovsky, J. Application of thin-film thermocouples to localized heat transfer measurements. [Washington, DC]: National Aeronautics and Space Administration, 1995.

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Lepicovsky, J. Application of thin-film thermocouples to localized heat transfer measurements. [Washington, DC]: National Aeronautics and Space Administration, 1995.

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The effect of wake passing on turbine blade film cooling. [Washington, DC]: National Aeronautics and Space Administration, 1996.

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United States. National Aeronautics and Space Administration., ed. A numerical study of the effect of wake passing on turbine blade film cooling. [Washington, D.C.]: National Aeronautics and Space Administration, 1995.

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Nan-Suey, Liu, and NASA Glenn Research Center, eds. Film cooling flow effects on post-combustor trace chemistry. Cleveland, Ohio: National Aeronautics and Space Administration, Glenn Research Center, 2003.

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Prediction of film cooling on gas turbine airfoils. [Washington, DC]: National Aeronautics and Space Administration, 1994.

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1934-, Hoffman Joe D., and United States. National Aeronautics and Space Administration., eds. The prediction of nozzle performance and heat transfer in hydrogen/oxygen rocket engines with transpiration cooling, film cooling, and high area ratios. [Washington, DC]: National Aeronautics and Space Administration, 1994.

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Book chapters on the topic "Unsteady flow on film cooling"

1

Reijasse, P., and L. Boccaletto. "Film Cooling Mass Flow Rate Influence on a Separation Shock in an Axisymmetric Nozzle." In IUTAM Symposium on Unsteady Separated Flows and their Control, 349–56. Dordrecht: Springer Netherlands, 2009. http://dx.doi.org/10.1007/978-1-4020-9898-7_30.

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Levenspiel, Octave. "Unsteady-State Heating and Cooling of Solid Objects." In Engineering Flow and Heat Exchange, 223–51. Boston, MA: Springer US, 2014. http://dx.doi.org/10.1007/978-1-4899-7454-9_11.

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Medic, Gorazd, and Paul Durbin. "RANS Simulations for Film-Cooling Analysis and Design." In Modelling Fluid Flow, 213–28. Berlin, Heidelberg: Springer Berlin Heidelberg, 2004. http://dx.doi.org/10.1007/978-3-662-08797-8_15.

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Dam, C. P., M. Hafez, D. Brucker, and S. Elli. "Unsteady Viscous Flow Calculations Including Surface Heating and Cooling Effects." In Proceedings of the Eighth GAMM-Conference on Numerical Methods in Fluid Mechanics, 79–88. Wiesbaden: Vieweg+Teubner Verlag, 1990. http://dx.doi.org/10.1007/978-3-663-13975-1_9.

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Peter, Johannes M. F., and Markus J. Kloker. "Numerical Simulation of Film Cooling in Supersonic Flow." In Notes on Numerical Fluid Mechanics and Multidisciplinary Design, 79–95. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-53847-7_5.

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Abstract High-order direct numerical simulations of film cooling by tangentially blowing cool helium at supersonic speeds into a hot turbulent boundary-layer flow of steam (gaseous H2O) at a free stream Mach number of 3.3 are presented. The stagnation temperature of the hot gas is much larger than that of the coolant flow, which is injected from a vertical slot of height s in a backward-facing step. The influence of the coolant mass flow rate is investigated by varying the blowing ratio F or the injection height s at kept cooling-gas temperature and Mach number. A variation of the coolant Mach number shows no significant influence. In the canonical baseline cases all walls are treated as adiabatic, and the investigation of a strongly cooled wall up to the blowing position, resembling regenerative wall cooling present in a rocket engine, shows a strong influence on the flow field. No significant influence of the lip thickness on the cooling performance is found. Cooling correlations are examined, and a cooling-effectiveness comparison between tangential and wall-normal blowing is performed.

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Sharma, Hitesh, Dushyant Singh, and Ashutosh Kumar Singh. "Numerical Solution of Foreign-Gas Film Cooling in Supersonic Flow." In Lecture Notes in Mechanical Engineering, 807–14. Singapore: Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-15-7711-6_79.

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Ademane, Vashista G., Vijaykumar Hindasageri, and Ravikiran Kadoli. "A Numerical Study on Heat Transfer Characteristics of Two-Dimensional Film Cooling." In Numerical Heat Transfer and Fluid Flow, 613–19. Singapore: Springer Singapore, 2018. http://dx.doi.org/10.1007/978-981-13-1903-7_70.

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Sindhu, J. L. K., S. Mohammed Ibrahim, and K. P. J. Reddy. "Experimental Investigation of Film Cooling Technique over a Blunt Body in Hypersonic Flow." In 31st International Symposium on Shock Waves 2, 1127–33. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-319-91017-8_140.

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Liu, Shi, and Hong Yin. "Research on the swirling flow effect of the combustor–turbine interaction on vane film cooling." In Advances in Materials Science, Energy Technology and Environmental Engineering, 145–56. P.O. Box 11320, 2301 EH Leiden, The Netherlands, e-mail: Pub.NL@taylorandfrancis.com , www.crcpress.com – www.taylorandfrancis.com: CRC Press/Balkema, 2016. http://dx.doi.org/10.1201/9781315227047-29.

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Keller, Michael, and Markus J. Kloker. "Direct Numerical Simulations of Film Cooling in a Supersonic Boundary-Layer Flow on Massively-Parallel Supercomputers." In Sustained Simulation Performance 2013, 107–28. Cham: Springer International Publishing, 2013. http://dx.doi.org/10.1007/978-3-319-01439-5_8.

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Conference papers on the topic "Unsteady flow on film cooling"

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Deinert, M., and J. Hourmouziadis. "Film Cooling in Unsteady Flow With Separation Bubble." In ASME Turbo Expo 2004: Power for Land, Sea, and Air. ASMEDC, 2004. http://dx.doi.org/10.1115/gt2004-53075.

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This study gives a detailed experimental evaluation of film cooling characteristics in unsteady flow with a separation bubble. The research project is divided into two phases. In the first phase, which is presented here, only the variation of the velocity caused by upstream blades is simulated in the experiments while the free-stream turbulence intensity is retained at a constant low level. The experiments are carried out on a flat plate with superimposed pressure distribution typical of turbine blading. A contoured wall opposite the flat plate generates this pressure distribution with a strong adverse pressure gradient, which induces a separation bubble in the middle of the plate. The measurements are conducted in an open-circuit, low-speed, suction-type wind tunnel, which can generate periodically pulsating flow. The flat plate is 1000 mm in length and has a width of 400 mm. The cooling air enters the test section through a row of 7 cylindrical film-cooling holes with sharp edges and an inclination angle of 35 degrees. The film cooling holes, which are 8 mm in diameter and have a pitch to diameter ratio of 3:1, are located in the middle of the flat plate. The main objective is to investigate the influence of the separation bubble on the cooling air flow and different film cooling parameters under periodically unsteady flow conditions. Therefore, measurements of the flow velocity and temperature using hot and cold wire anemometry for different boundary conditions were carried out. The results show that the periodic changes of size and shape of the separation bubble in a film cooled flow field under unsteady flow conditions are still dominated by the superimposed periodically changing pressure distribution. The incoming cooling air influences the separation bubble in two ways. On the one hand, the separation bubble is displaced by the film cooling jet, which means that it is only present upstream of the air injection point and on the other hand the separation bubble is thicker directly in front of the incoming film cooling jet because of the superimposed pressure field upstream of the jet. The results of flow temperature measurements show a small low-temperature area upstream of the film cooling jet at the position of the separation bubble.

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Kim, Sung In, and Ibrahim Hassan. "Unsteady Heat Transfer Analysis of a Film Cooling Flow." In 46th AIAA Aerospace Sciences Meeting and Exhibit. Reston, Virigina: American Institute of Aeronautics and Astronautics, 2008. http://dx.doi.org/10.2514/6.2008-1287.

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Kim, Sung In, Ibrahim G. Hassan, and Xuezhi Zhang. "Unsteady Simulation of Film Cooling Flow From an Inclined Cylindrical Jet." In ASME/JSME 2007 Thermal Engineering Heat Transfer Summer Conference collocated with the ASME 2007 InterPACK Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/ht2007-32401.

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Film cooling is extensively used to provide protection against the severe thermal environment in gas turbine engines. Most of the computational studies on film cooling flow have been done using steady Reynolds-Averaged Navier-Stokes (RANS) calculation procedures. However, the turbulent stress field is highly anisotropic in the wake region of the coolant jet, and the inherent unsteadiness of the coolant jet-crossflow interactions may have important implications in the cooling performance. In this paper, a computational investigation about the unsteady behavior of jet-in-crossflow applications is performed using DES. Detailed computation of a single row of 35 degree round holes on a flat plate has been obtained for a blowing ratio of 1.0 and a density ratio of 2.0. Firstly, time step size, grid resolution tests have been conducted. Comparison of the time-averaged DES prediction with the measured film cooling effectiveness shows that DES prediction is reasonable. From present simulations, the typical coherent vortical structures of the jet-in-crossflows can be seen. The unsteady physics of jet-in-crossflow interactions and a jet liftoff in film cooling flows have been explored.

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Fawcett, Richard J., Andrew P. S. Wheeler, Li He, and Rupert Taylor. "Experimental Investigation Into Unsteady Effects on Film Cooling." In ASME Turbo Expo 2010: Power for Land, Sea, and Air. ASMEDC, 2010. http://dx.doi.org/10.1115/gt2010-22603.

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The benefits of different film cooling geometries are typically assessed in terms of their time averaged performance. It is known that the mixing between the coolant film and the main turbine passage flow is an unsteady process. The current study investigates the forms of unsteadiness which occur in engine-representative film cooling flows, and how this unsteadiness affects the mixing with the mainstream flow. Cylindrical and fan-shaped cooling holes across a range of hole blowing ratios have been studied experimentally using Particle Image Velocimetry and High Speed Photography. Coherent unsteadiness is found in the shear layer between the jet and the mainstream, for both cylindrical and fan-shaped cooling holes. Its occurrence and sense of rotation is found to be controlled by the velocity difference between the mainstream flow and the jet which is largely determined by the blowing ratio.

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Bernsdorf, Stefan, Martin G. Rose, and Reza S. Abhari. "Experimental Validation of Quasi-Steady Assumption in Modelling of Unsteady Film-Cooling." In ASME Turbo Expo 2006: Power for Land, Sea, and Air. ASMEDC, 2006. http://dx.doi.org/10.1115/gt2006-90166.

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This paper reports on the validation of the assumption of quasi steady behaviour of pulsating cooling injection in the near hole flow region. The respective experimental data are taken in a flat plate wind tunnel at ETH Zu¨rich. The facility simulates the film cooling row flow field on the pressure side of a turbine blade. Engine representative non-dimensionals are achieved, providing a faithful model at larger scale. Heating the free stream air and strongly cooling the coolant gives the required density ratio between coolant and free-stream. The coolant is injected with different frequency and amplitude. The three dimensional velocities are recorded using non-intrusive PIV, seeding is provided for both air streams. Two different cylindrical hole geometries are studied, with different angles. Blowing ratio is varied over a range to simulate pressure side film cooling. The general flow field, the jet trajectory and the streamwise circulation are utilized in the validation of the quasi steady assumption.

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Gomes, Reinaldo A., and Reinhard Niehuis. "Film Cooling Effectiveness Measurements With Periodic Unsteady Inflow on Highly Loaded Blades With Main Flow Separation." In ASME Turbo Expo 2009: Power for Land, Sea, and Air. ASMEDC, 2009. http://dx.doi.org/10.1115/gt2009-59791.

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Film cooling experiments were performed using a highly loaded HPT blade linear cascade. A large region with main flow separation is found on the pressure side and film cooling is provided into this area with three rows of either cylindrical or fan-shaped holes. The measurements comprise adiabatic film cooling effectiveness and profile static pressure measurements. The surface temperature was acquired with thermochromatic liquid crystals and using a hue to temperature correlation. The results shown are for variations of main flow Mach and Reynolds numbers at engine relevant levels and of coolant mass flows. The results for steady and periodic unsteady inflow with highly turbulent wakes created by cylindrical bars moving upstream in a plane parallel to the cascade are compared as two-dimensional surface plots, laterally averaged film cooling effectiveness and overall effectiveness over the entire surface.

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Rallabandi, Akhilesh P., Shiou-Jiuan Li, and Je-Chin Han. "Unsteady Wake and Coolant Density Effects on Turbine Blade Film Cooling Using PSP Technique." In 2010 14th International Heat Transfer Conference. ASMEDC, 2010. http://dx.doi.org/10.1115/ihtc14-22911.

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The effect of an unsteady stator wake (simulated by wake rods mounted on a spoke wheel wake generator) on the modeled rotor blade is studied using the Pressure Sensitive Paint (PSP) mass transfer analogy method. Emphasis of the current study is on the mid-span region of the blade. The flow is in the low Mach number (incompressible) regime. The suction (convex) side has simple angled cylindrical film-cooling holes; the pressure (concave) side has compound angled cylindrical film cooling holes. The blade also has radial shower-head leading edge film cooling holes. Strouhal numbers studied range from 0 to 0.36; the exit Reynolds Number based on the axial chord is 530,000. Blowing ratios range from 0.5 to 2.0 on the suction side; 0.5 to 4.0 on the pressure side. Density ratios studied range from 1.0 to 2.5, to simulate actual engine conditions. The convex suction surface experiences film-cooling jet lift-off at higher blowing ratios, resulting in low effectiveness values. The film coolant is found to reattach downstream on the concave pressure surface, increasing effectiveness at higher blowing ratios. Results show deterioration in film cooling effectiveness due to increased local turbulence caused by the unsteady wake, especially on the suction side. Results also show a monotonic increase in film-cooling effectiveness on increasing the coolant to mainstream density ratio.

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Ravelli, S., and G. Barigozzi. "Application of Unsteady CFD Methods to Trailing Edge Cutback Film Cooling." In ASME Turbo Expo 2014: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/gt2014-25435.

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The main purpose of this numerical investigation is to overcome the limitations of the steady modeling in predicting the cooling efficiency over the cutback surface in a high pressure turbine nozzle guide vane. Since discrepancy between Reynolds-averaged Navier–Stokes (RANS) predictions and measured thermal coverage at the trailing edge was attributable to unsteadiness, Unsteady RANS (URANS) modeling was implemented to evaluate improvements in simulating the mixing between the mainstream and the coolant exiting the cutback slot. With the aim of reducing the computation effort, only a portion of the airfoil along the span was simulated at an exit Mach number of Ma2is = 0.2. Three values of the coolant-to-mainstream mass flow ratio were considered: MFR = 0.66%, 1.05%, and 1.44%. Nevertheless the inherent vortex shedding from the cutback lip was somehow captured by the URANS method, the computed mixing was not enough to reproduce the measured drop in adiabatic effectiveness η along the streamwise direction, over the cutback surface. So modeling was taken a step further by using the Scale Adaptive Simulation (SAS) method at MFR = 1.05%. Results from the SAS approach were found to have potential to mimic the experimental measurements. Vortices shedding from the cutback lip were well predicted in shape and magnitude, but with a lower frequency, as compared to PIV data and flow visualizations. Moreover, the simulated reduction in film cooling effectiveness toward the trailing edge was similar to that observed experimentally.

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Adami, P., F. Montomoli, E. Belardini, and F. Martelli. "Interaction Between Wake and Film Cooling Jets: Numerical Analysis." In ASME Turbo Expo 2004: Power for Land, Sea, and Air. ASMEDC, 2004. http://dx.doi.org/10.1115/gt2004-53178.

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The present work presents the results obtained from the numerical investigation of the 3D unsteady flow field in a film-cooled turbine vane. The blade under research is the AGTB-B1 investigated in the cascade of the High Speed Cascade Wind Tunnel of the University of Armed Forces Munich. The unsteady flow consists of a wake which periodically interacts with the shower-head film cooling system of the blade nose. The paper discusses the aerodynamical interaction between the film-cooled blade and the periodic wake produced by a moving row of bars placed in a plane upstream the cascade. The predictive approach is based on a U-RANS CFD solver using a conventional two-equation closure. The unsteady CFD results are discussed against the experimental data available. Special emphasis is devoted to the unsteady interaction of the wake with the shower-head film-cooling system of the blade.

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Collins, Matthew, and Thomas Povey. "Exploitation of Acoustic Effects in Film Cooling." In ASME Turbo Expo 2014: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/gt2014-26318.

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There have been numerous studies of the behavior of shaped film cooling holes for turbine applications. It is known that the introduction of coolant is an unsteady process, and a handful of studies have described and characterized the unsteadiness. To the authors’ knowledge there are no studies in which unsteady acoustic effects have been actively exploited such that they have led to novel designs with improved cooling performance. This paper discusses the fundamental mechanism of pressure wave propagation through cooling holes, and describes systems in which holes which have been acoustically shaped have led to a direct improvement in film cooling hole performance. The mechanism relies on sequential pressure wave reflection within an acoustically shaped hole, and is therefore applicable in regions where the external surface is subject to large pressure wave fluctuations at high frequency. The principle is developed analytically, and then demonstrated with a number of CFD simulations. We demonstrate that a desired temporal mass flow rate profile can be achieved by appropriate acoustic shaping of the cooling hole. The purpose of this paper is to describe the fundamental design considerations relevant to acoustic shaping. The discussion is developed with reference to a film cooling system for the over-tip region of an un-shrouded rotor. The performance benefit of the system in terms of modulation of unsteady mass flux and ingestion characteristics is quantified. It is believe that this is the first time this significant effect has been exploited in film cooling design.

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Reports on the topic "Unsteady flow on film cooling"

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Wang, L., H. Tsang, T. Simon, and E. Eckert. Measurements of mean flow and eddy transport over a film cooling surface. Office of Scientific and Technical Information (OSTI), May 1996. http://dx.doi.org/10.2172/251410.

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