Aerodynamic and Aerothermal Investigation of the Flow Around an HPT Rotor Shroud: Heat Transfer and Cooling Effectiveness

An experimental study has been conducted to investigate the aerothermal performance of a shrouded high pressure turbine blade in a large scale rotating rig. The rotor blade and the associated shroud and casing geometry have been modelled in a large scale low speed turbine rig that was designed to investigate a novel passive shroud cooling methodology. The objective of the present paper is to describe the aerothermal performance of a passive shroud cooling strategy using measured heat transfer and adiabatic cooling effectiveness data. Improved physical understanding of the shroud aerodynamics as reported in the companion paper Lehmann et al. [1] will be used here to support the analysis. Highly resolved experimental heat transfer data was acquired on the shroud, the fins and on the shroud underside with the thin heater film method. The distribution of the adiabatic cooling effectiveness on the rotor shroud was measured with a combination of the Ammonia-Diazo and a foreign gas sampling technique. The measurements are complemented by steady numerical computations of the turbine stage. Due to the impact of vortical flow structures in the over shroud cavities, the Nusselt numbers on the shroud top surfaces were found to be of the same order as on the shroud underside. The passive shroud cooling concept was found to provide quite efficient and uniform cooling to the over-shroud surfaces while the distribution of coolant on the shroud underside was significantly affected by the rotor secondary flow.

Combustor-Turbine Aerothermal Interaction in an Axial Turbine: Influence of Varied Inflow Conditions on Endwall Heat Transfer and Film Cooling Effectiveness

Volume 5C: Heat Transfer ◽

10.1115/gt2016-57171 ◽

2016 ◽

Cited By ~ 3

Author(s):

Holger Werschnik ◽

Jonathan Hilgert ◽

Martin Bruschewski ◽

Heinz-Peter Schiffer

Keyword(s):

Heat Transfer ◽

Mass Flux ◽

Film Cooling ◽

Large Scale ◽

Double Row ◽

Cooling Effectiveness ◽

Nusselt Numbers ◽

Baseline Case ◽

The Large Scale Turbine Rig (LSTR) at Technische Universit ät Darmstadt, Germany is used to examine the aerothermal interaction of combustor exit flow conditions on the subsequent turbine stage. The rig resembles a high pressure turbine and is scaled to low Mach number conditions. A baseline configuration with axial, low-turbulent inflow and an aerodynamic inflow condition of a state-of-the-art lean combustor is modeled by the means of swirl generators, whose clocking position towards the nozzle guide vane’s leading edge can be varied. A hub side coolant injection consisting of a double-row of cylindrical holes is implemented to examine the impact on endwall cooling. This paper is directed to study the effect of swirling inflow on heat transfer and film cooling effectiveness on the hub side endwall. Nusselt numbers are calculated using infrared thermography and the auxiliary wall method. This method allows for a high spatial resolution and in addition also yields adiabatic wall temperature data within the same measurement using a superposition approach. Aerodynamic measurements and numerical simulations complement the examination. The results for the baseline case show Nusselt numbers to increase significantly with higher coolant mass flux rates for the whole endwall area. With swirling inflow, in general, a decrease of film cooling effectiveness and an increase of Nusselt numbers is observed for identical mass flux rates in comparison to the baseline case. The difference varies depending on clocking position.

Influence of Combustor Swirl on Endwall Heat Transfer and Film Cooling Effectiveness at the Large Scale Turbine Rig

Journal of Turbomachinery ◽

10.1115/1.4035832 ◽

2017 ◽

Vol 139 (8) ◽

Cited By ~ 8

Author(s):

Holger Werschnik ◽

Jonathan Hilgert ◽

Manuel Wilhelm ◽

Martin Bruschewski ◽

Heinz-Peter Schiffer

Keyword(s):

Heat Transfer ◽

Mass Flux ◽

Film Cooling ◽

Large Scale ◽

Guide Vane ◽

Leading Edge ◽

Double Row ◽

Cooling Effectiveness ◽

Nusselt Numbers

At the large scale turbine rig (LSTR) at Technische Universität Darmstadt, Darmstadt, Germany, the aerothermal interaction of combustor exit flow conditions on the subsequent turbine stage is examined. The rig resembles a high pressure turbine and is scaled to low Mach numbers. A baseline configuration with an axial inflow and a swirling inflow representative for a lean combustor is modeled by swirl generators, whose clocking position toward the nozzle guide vane (NGV) leading edge can be varied. A staggered double-row of cylindrical film cooling holes on the endwall is examined. The effect of swirling inflow on heat transfer and film cooling effectiveness is studied, while the coolant mass flux rate is varied. Nusselt numbers are calculated using infrared thermography and the auxiliary wall method. Boundary layer, turbulence, and five-hole probe measurements as well as numerical simulations complement the examination. The results for swirling inflow show a decrease of film cooling effectiveness of up to 35% and an increase of Nusselt numbers of 10–20% in comparison to the baseline case for low coolant mass flux rates. For higher coolant injection, the heat transfer is on a similar level as the baseline. The differences vary depending on the clocking position. The turbulence intensity is increased to 30% for swirling inflow.

Laminar Natural Convection in a Discretely Heated Cavity: II—Comparisons of Experimental and Theoretical Results

Journal of Heat Transfer ◽

10.1115/1.2836310 ◽

1995 ◽

Vol 117 (4) ◽

pp. 910-917 ◽

Cited By ~ 29

Author(s):

T. J. Heindel ◽

F. P. Incropera ◽

S. Ramadhyani

Keyword(s):

Heat Transfer ◽

Natural Convection ◽

Rayleigh Number ◽

Vertical Wall ◽

Three Dimensional ◽

Companion Paper ◽

Nusselt Numbers ◽

Numerical Predictions ◽

Number Flow ◽

Experimental Geometry

Three-dimensional numerical predictions and experimental data have been obtained for natural convection from a 3 × 3 array of discrete heat sources flush-mounted on one vertical wall of a rectangular cavity and cooled by the opposing wall. Predictions performed in a companion paper (Heindel et al., 1995a) revealed that three-dimensional edge effects are significant and that, with increasing Rayleigh number, flow and heat transfer become more uniform across each heater face. The three-dimensional predictions are in excellent agreement with the data of this study, whereas a two-dimensional model of the experimental geometry underpredicts average heat transfer by as much as 20 percent. Experimental row-averaged Nusselt numbers are well correlated with a Rayleigh number exponent of 0.25 for RaLz ≲ 1.2 × 108.

Selling Time Strategy dan Dampaknya terhadap Kesejahteraan Petani Garam

JEMMA | Journal of Economic, Management and Accounting ◽

10.35914/jemma.v3i2.435 ◽

2020 ◽

Vol 3 (2) ◽

pp. 154

Author(s):

M. Munir Syam AR ◽

Djoko Nestri Kwartatmono

Keyword(s):

Large Scale ◽

Sampling Technique ◽

Qualitative Approach ◽

High Salt ◽

Small Farmers ◽

Snowball Sampling ◽

Direct Selling ◽

Welfare Level ◽

The Impact ◽

Depth Interviews

AbstrakPenelitian ini bertujuan untuk mengeksplorasi faktor yang mendorong petani garam untuk menjual garam pasca panen/pungut secara langsung atau tidak langsung dan menganalisis dampak penerapan strategi tersebut terhadap tingkat kesejahteraan petani garam. Penelitian ini menggunakan pendekatan kualitatif deskriptif. Penelitian ini dilakukan di Desa Karanganyar, Kec. Kalianget, Kab. Sumenep. Objek dalam penelitian ini difokuskan pada produk garam. Teknik sampling yang digunakan adalah snowball sampling dengan informan yang berasal dari petani garam dari desa Karanganyar. Data diperoleh melalui observasi, dokumentasi dan indepth interview secara langsung kepada informan. Hasil penelitian ini menunjukkan bahwa terdapat empat faktor yang mempengaruhi petani garam dalam menerapkan strategi penjualan langsung atau tidak langsung yaitu harga garam, kebutuhan, kuantitas hasil produksi, dan gudang penyimpanan. Ketika harga garam mahal maka petani garam akan menggunakan strategi penjualan langsung. sebaliknya, ketika harga turun petani kecil tidak memiliki pilihan strategi selain menjual langsung tetapi petani dengan skala besar lebih fleksibel.Kata Kunci: Garam, Kesejahteraan, Strategi AbstractThis study aims to explore the drivinf factors of salt farmers to sell salt directly or indirectly and analyze the impact of implementing this strategy on the welfare level of salt farmers. This study uses a descriptive qualitative approach. This research was conducted in Karanganyar Village, Kalianget, Sumenep district.. The object of this study is focused on salt products. The sampling technique used snowball sampling with informants who came from salt farmers from Karanganyar village. Data obtained through observation, documentation and in-depth interviews with informants. The results of this study indicate that there are four factors that influence salt farmers in implementing direct or indirect sales strategies, namely the price of salt, needs, quantity of production, and warehouse. When the price of salt is high, salt farmers will use a direct selling strategy. otherwise when prices fall small farmers have no choice of strategy other than selling directly but large scale farmers are more flexible.Keywords: Salt, Welfare, Strategy

SURFACE HEATER FABRICATION USING MICRO-LITHOGRAPHY FOR TRANSPIRATION COOLING HEAT TRANSFER COEFFICIENT MEASUREMENTS

Journal of Turbomachinery ◽

10.1115/1.4053233 ◽

2021 ◽

pp. 1-23

Author(s):

Zheng Min ◽

Sarwesh Narayan Parbat ◽

Qing-Ming Wang ◽

Minking K. Chyu

Keyword(s):

Heat Transfer ◽

Heat Transfer Coefficient ◽

Steady State ◽

Transfer Coefficient ◽

Film Cooling ◽

Target Surface ◽

Transpiration Cooling ◽

Cooling Effectiveness ◽

Blowing Ratio ◽

Adiabatic Cooling

Abstract Transpiration cooling is able to provide more uniform coolant coverage than film cooling to effectively protect the component surface from contacting the hot gas. Due to numerous coolant ejection outlets within a small area at the target surface, the experimental thermo-fluid investigation on transpiration cooing becomes a significant challenge. Two classic methods to investigate film cooling, the steady-state foil heater method and the transient thermography technique, both fail for transpiration cooling because the foil heater would block numerous coolant outlets, and the semi-infinite solid conduction model no longer holds for porous plates. In this study, a micro-lithography method to fabricate a silver coil pattern on top of the additively manufactured polymer porous media as the surface heater was proposed. The circuit was deliberately designed to cover the solid surface in a combination of series connection and parallel connection to ensure the power in each unit cell area at the target surface was identical. With uniform heat flux generation, the steady-state tests were conducted to obtain distributions of a pair of parameters, adiabatic cooling effectiveness, and heat transfer coefficient (HTC). The results showed that the adiabatic cooling effectiveness could reach 0.65 with a blowing ratio lower than 0.5. Meanwhile, the heat transfer coefficient ratio (hf/h0) of transpiration cooling was close to 1 with a small blowing ratio at 0.125. A higher HTC ratio was observed for smaller pitch-to-diameter cases due to more turbulence intensity generated at the target surface.

Liquid-Solid Contact During Flow Film Boiling of Subcooled Freon-11

Journal of Heat Transfer ◽

10.1115/1.2910401 ◽

1990 ◽

Vol 112 (2) ◽

pp. 465-471 ◽

Cited By ~ 7

Author(s):

K. H. Chang ◽

L. C. Witte

Keyword(s):

Heat Transfer ◽

Large Scale ◽

Heat Fluxes ◽

Film Boiling ◽

Small Scale ◽

Solid Contact ◽

Heated Cylinder ◽

Experimental Heat ◽

Wall Superheat ◽

Flow Film Boiling

Liquid-solid contacts were measured for flow film boiling of subcooled Freon-11 over an electrically heated cylinder equipped with a surface microthermocouple probe. No systematic variation of the extent of liquid-solid contact with wall superheat, liquid subcooling, or velocity was detected. Only random small-scale contacts that contribute negligibly to overall heat transfer were detected when the surface was above the homogeneous nucleation temperature of the Freon-11. When large-scale contacts were detected, they led to an unexpected intermediate transition from local film boiling to local transition boiling. An explanation is proposed for these unexpected transitions. A comparison of analytical results that used experimentally determined liquid-solid contact parameters to experimental heat fluxes did not show good agreement. It was concluded that the available model for heat transfer accounting for liquid-solid contact is not adequate for flow film boiling.

Heat Transfer and Film Cooling on a Contoured Blade Endwall With Platform Gap Leakage

Journal of Turbomachinery ◽

10.1115/1.4035202 ◽

2017 ◽

Vol 139 (5) ◽

Cited By ~ 4

Author(s):

Stephen P. Lynch ◽

Karen A. Thole

Keyword(s):

Heat Transfer ◽

Turbine Blade ◽

Film Cooling ◽

Vortical Flow ◽

Leakage Flow ◽

Transfer Coefficients ◽

Cooling Effectiveness ◽

Heat Transfer Coefficients ◽

Manufacturing Assembly

Turbine blade components in an engine are typically designed with gaps between parts due to manufacturing, assembly, and operational considerations. Coolant is provided to these gaps to limit the ingestion of hot combustion gases. The interaction of the gaps, their leakage flows, and the complex vortical flow at the endwall of a turbine blade can significantly impact endwall heat transfer coefficients and the effectiveness of the leakage flow in providing localized cooling. In particular, a platform gap through the passage, representing the mating interface between adjacent blades in a wheel, has been shown to have a significant effect. Other important turbine blade features present in the engine environment are nonaxisymmetric contouring of the endwall, and an upstream rim seal with a gaspath cavity, which can reduce and increase endwall vortical flow, respectively. To understand the platform gap leakage effect in this environment, measurements of endwall heat transfer, and film cooling effectiveness were performed in a scaled blade cascade with a nonaxisymmetric contour in the passage. A rim seal with a cavity, representing the overlap interface between a stator and rotor, was included upstream of the blades and a nominal purge flowrate of 0.75% of the mainstream was supplied to the rim seal. The results indicated that the endwall heat transfer coefficients increased as the platform gap net leakage increased from 0% to 0.6% of the mainstream flowrate, but net heat flux to the endwall was reduced due to high cooling effectiveness of the leakage flow.

Liquid Crystal Visualization of Surface Heat Transfer on a Concavely Curved Turbulent Boundary Layer

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.3239615 ◽

1984 ◽

Vol 106 (3) ◽

pp. 619-627 ◽

Cited By ~ 16

Author(s):

J. C. Simonich ◽

R. J. Moffat

Keyword(s):

Heat Transfer ◽

Boundary Layer ◽

Turbulent Boundary Layer ◽

Large Scale ◽

Surface Heat ◽

Transfer Rates ◽

Surface Heat Transfer ◽

Experimental Heat ◽

Surface Heat Transfer Coefficient ◽

Transfer Measurement

An experimental heat transfer study on a concavely curved turbulent boundary layer has been performed. A new, instantaneous heat transfer measurement technique utilizing liquid crystals was used to provide a vivid picture of the local distribution of surface heat transfer coefficient. Large scale wall traces, composed of streak patterns on the surface, were observed to appear and disappear at random, but there was no evidence of a spanwise stationary heat transfer distribution, nor any evidence of large scale structures resembling Taylor-Gortler vortices. The use of a two-dimensional computation scheme to predict heat transfer rates in concave curvature regions seems justifiable.

Film Cooling Effectiveness and Heat Transfer Near Deposit-Laden Film Holes

Volume 3: Heat Transfer, Parts A and B ◽

10.1115/gt2009-59567 ◽

2009 ◽

Cited By ~ 2

Author(s):

Scott Lewis ◽

Brett Barker ◽

Jeffrey P. Bons ◽

Weiguo Ai ◽

Thomas H. Fletcher

Keyword(s):

Heat Transfer ◽

Heat Flux ◽

Film Cooling ◽

Density Ratio ◽

Flux Ratio ◽

Deposition Pattern ◽

Primary Flow ◽

Cooling Effectiveness ◽

Experiments were conducted to determine the impact of synfuel deposits on film cooling effectiveness and heat transfer. Scaled up models were made of synfuel deposits formed on film-cooled turbine blade coupons exposed to accelerated deposition. Three distinct deposition patterns were modeled: a large deposition pattern (max deposit peak ≅ 2 hole diameters) located exclusively upstream of the holes, a large deposition pattern (max deposit peak ≅ 1.25 hole diameters) extending downstream between the cooling holes, and a small deposition pattern (max deposit peak ≅ 0.75 hole diameter) also extending downstream between the cooling holes. The models featured cylindrical holes inclined at 30 degrees to the surface and aligned with the primary flow direction. The spacing of the holes were 3, 3.35, and 4.5 hole diameters respectively. Flat models with the same film cooling hole geometry and spacing were used for comparison. The models were tested using blowing ratios of 0.5–2 with a turbulent approach boundary layer and 0.5% freestream turbulence. The density ratio was approximately 1.1 and the primary flow Reynolds number at the film cooling row location was 300,000. An infrared camera was used to obtain the film cooling effectiveness from steady state tests and surface convective heat transfer coefficients using transient tests. The model with upstream deposition caused the primary flow to lift off the surface over the roughness peaks and allowed the coolant to stay attached to the model. Increasing the blowing ratio from 0.5 to 2 only expanded the region that the coolant could reach and improved the cooling effectiveness. Though the heat transfer coefficient also increased at high blowing ratios, the net heat flux ratio was still less than unity, indicating film cooling benefit. For the two models with deposition between the cooling holes, the free stream air was forced into the valleys in line with the coolant holes and degraded area-averaged coolant performance at lower blowing ratios. It is concluded that the film cooling effectiveness is highest when deposition is limited to upstream of the cooling holes. When accounting for the insulating effect of the deposits between the film holes, even the panels with deposits downstream of the film holes can yield a net decrease in heat flux for some cases.

The Influence of Coolant Unsteadiness on Impingement Heat Transfer

Volume 5A: Heat Transfer ◽

10.1115/gt2014-25897 ◽

2014 ◽

Cited By ~ 1

Author(s):

Victor J. Zimmer ◽

James L. Rutledge ◽

Chris Knieriem ◽

Shichuan Ou

Keyword(s):

Heat Transfer ◽

Nusselt Number ◽

Coolant Flow ◽

Time Resolved ◽

Average Mass ◽

Flow Unsteadiness ◽

Nusselt Numbers ◽

Jet Cooling ◽

The Mean ◽

Interest in impingement jet cooling and the associated convection phenomena has grown in the past few decades due in part to the desire for higher operating temperatures and reduced coolant flow in turbines. This study utilizes an array of 55 impingement jets to explore both steady and unsteady impingement flow conditions to evaluate the impact of the inherent unsteadiness present in engines compared to traditional steady experiments. Although unsteadiness occurs naturally in engines, intentional pulsation of coolant flow has also been proposed for flow control purposes, further underscoring the need for examination of the impact of pulsation on the heat transfer. Flow unsteadiness of varying amplitudes was induced at Strouhal numbers of magnitude 10−3 to 10−4. Infrared thermography was used to determine high spatial and temporal resolution Nusselt numbers. Time-resolved Nusselt number and mass flow characteristic waveforms were found to differ substantially as a function of the fluctuation amplitude relative to the mean. In some cases, transient coolant flow increases were associated with non-monotonic behavior in the time resolved Nusselt number. Although with certain configurations unsteady flow demonstrated time-averaged Nusselt numbers equivalent to steady flow with equivalent average mass flux, those with the greatest fluctuation in the amplitude of flow unsteadiness relative to the mean resulted in lower average Nusselt numbers.