Heat transfer performance comparison of steam and air in gas turbine cooling channels with different rib angles

2013 ◽  
Vol 49 (11) ◽  
pp. 1577-1586 ◽  
Author(s):  
Xiaojun Shi ◽  
Jianmin Gao ◽  
Liang Xu ◽  
Fajin Li
Keyword(s):  
Heat Transfer ◽  
Gas Turbine ◽  
Heat Transfer Performance ◽  
Performance Comparison ◽  
Transfer Performance ◽  
Turbine Cooling ◽  
Cooling Channels ◽  
Gas Turbine Cooling

Research on the Effects of Dimples and Protrusions on Flow and Heat Transfer in Matrix Cooling Channels in Turbine Blades

2019 ◽  
Author(s):  
Yigang Luan ◽  
Lianfeng Yang ◽  
Yue Yin ◽  
Pietro Zunino
Keyword(s):  
Heat Transfer ◽  
Gas Turbine ◽  
Heat Transfer Performance ◽  
Turbine Blades ◽  
Inlet Temperature ◽  
Transfer Performance ◽  
Turbine Inlet Temperature ◽  
Turbine Engine ◽  
Cooling Channels ◽  
Flow And Heat Transfer

Abstract Nowadays, gas turbine engines play an indispensable role in modern industry, which have been widely used especially in the aviation, marine and energy fields. The turbine inlet temperature is one of the most important factors that influences the performance of the turbine engine. It’s acknowledged that the higher turbine inlet temperature contributes to the overall gas turbine engine efficiency. Therefore, the internal cooling technology of turbine blades is of vital importance. This paper mainly studies the effects of dimples and protrusions on flow and heat transfer in matrix cooling channels and optimize the performance of the matrix cooling structure by numerical simulation and experiment methods. Thirteen cases have been calculated under Re = 10,000∼80,000 by the commercial code ANSYS Fluent. Structures with different layouts of dimples and protrusions were considered, such as the number, distance and the depth ratio. The original model has been strengthened due to the dimple and protrusion structure, which improves heat transfer performance as well as the thermal performance factor (TPF) on condition that the pressure loss increases slightly. Meanwhile, the optimized structures have been made and tested by the transient liquid crystal technique (TLC). A comparison between the CFD results and the experimental data is made. Note that the heat transfer performance is much better when the ratio of the dimple depth and the dimple diameter is equal to 0.3, compared with the ratio of 0.1 and 0.2. In terms of the cases with two sides dimples, the heat transfer can be enhanced by increasing the number of the dimples. In addition, the heat transfer performance is the best when both of dimples and protrusions are applied. Nu/Nu0 and TPF increase by up to approximately 7% and 5% respectively.

Build Direction Effects on Additively Manufactured Channels

2015 ◽  
Author(s):  
Jacob C. Snyder ◽  
Curtis K. Stimpson ◽  
Karen A. Thole ◽  
Dominic Mongillo
Keyword(s):  
Heat Transfer ◽  
Gas Turbine ◽  
Pressure Loss ◽  
Small Scale ◽  
Turbine Cooling ◽  
Gas Turbine Cooling ◽  
Gas Turbine Heat Transfer ◽  
Manufacturing Techniques ◽  
Traditional Manufacturing

With the advances of Direct Metal Laser Sintering (DMLS), also generically referred to as additive manufacturing, novel geometric features of internal channels for gas turbine cooling can be achieved beyond those features using traditional manufacturing techniques. There are many variables, however, in the DMLS process that affect the final quality of the part. Of most interest to gas turbine heat transfer designers are the roughness levels and tolerance levels that can be held for the internal channels. This study investigates the effect of DMLS build direction and channel shape on the pressure loss and heat transfer measurements of small scale channels. Results indicate that differences in pressure loss occur between the test cases with differing channel shapes and build directions, while little change is measured in heat transfer performance.

Scaling Heat-Transfer Coefficients Measured Under Laboratory Conditions to Engine Conditions

2017 ◽  
Author(s):  
T. I.-P. Shih ◽  
C.-S. Lee ◽  
K. M. Bryden
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Gas Turbine ◽  
Scaling Factor ◽  
Rate Of Change ◽  
Transfer Enhancement ◽  
Scaling Factors ◽  
Turbine Cooling ◽  
Pin Fins ◽  
Gas Turbine Cooling

Almost all measurements of the heat-transfer coefficient (HTC) or Nusselt number (Nu) in gas-turbine cooling passages with heat-transfer enhancement features such as pin fins and ribs have been made under conditions, where the wall-to-bulk temperature, Tw/Tb, is near unity. Since Tw/Tb in gas-turbine cooling passages can be as high as 2.2 and vary appreciably along the passage, this study examines if it is necessary to match the rate of change in Tw/Tb when measuring Nu, whether Nu measured at Tw/Tb near unity needs to be scaled before used in design and analysis of turbine cooling, and could that scaling for ducts with heat-transfer enhancement features be obtained from scaling factors for smooth ducts because those scaling factors exist in the literature. In this study, a review of the data in the literature shows that it is unnecessary to match the rate of change in Tw/Tb for smooth ducts at least for the rates that occur in gas turbines. For ducts with heat-transfer enhancement features, it is still an open question. This study also shows Nu measured at Tw/Tb near unity needs to be scale to the correct Tw/Tb before it can be used for engine conditions. By using steady RANS analysis of the flow and heat transfer in a cooling channel with a staggered array of pin fins, the usefulness of the scaling factor, (Tw/Tb)r, from the literature for smooth ducts was examined. Nuengine, computed under engine conditions, was compared with those computed under laboratory conditions, Nulab, and scaled by (Tw/Tb)r; i.e., Nulab,scaled = Nulab (Tw/Tb)r. Results obtained show the error in Nulab,scaled relative to Nuengine can be as high as 36.6% if r = −0.7 and Tw/Tb = 1.573 in the “fully” developed region. Thus, (Tw/Tb)r based on smooth duct should not be used as a scaling factor for Nu in cooling passages with heat-transfer enhancement features. To address this inadequacy, a method is proposed for generating scaling factors, and a scaling factor was developed to scale the heat transfer from laboratory to engine conditions for a channel with pin fins.

An Evaluation of the Application of Nanofluids in Intercooled Cycle Marine Gas Turbine Intercooler

2015 ◽  
Vol 138 (1) ◽  
Author(s):  
Ningbo Zhao ◽  
Xueyou Wen ◽  
Shuying Li
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Gas Turbine ◽  
Heat Transfer Performance ◽  
Volume Concentration ◽  
Inlet Temperature ◽  
Transfer Performance ◽  
Pumping Power ◽  
Flow And Heat Transfer ◽  
Overall Performance

Coolant is one of the important factors affecting the overall performance of the intercooler for the intercooled (IC) cycle marine gas turbine. Conventional coolants, such as water and ethylene glycol, have lower thermal conductivity which can hinder the development of highly effective compact intercooler. Nanofluids that consist of nanoparticles and base fluids have superior properties like extensively higher thermal conductivity and heat transfer performance compared to those of base fluids. This paper focuses on the application of two different water-based nanofluids containing aluminum oxide (Al2O3) and copper (Cu) nanoparticles in IC cycle marine gas turbine intercooler. The effectiveness-number of transfer unit method is used to evaluate the flow and heat transfer performance of intercooler, and the thermophysical properties of nanofluids are obtained from literature. Then, the effects of some important parameters, such as nanoparticle volume concentration, coolant Reynolds number, coolant inlet temperature, and gas side operating parameters on the flow and heat transfer performance of intercooler, are discussed in detail. The results demonstrate that nanofluids have excellent heat transfer performance and need lower pumping power in comparison with base fluids under different gas turbine operating conditions. Under the same heat transfer, Cu–water nanofluids can reduce more pumping power than Al2O3–water nanofluids. It is also concluded that the overall performance of intercooler can be enhanced when increasing the nanoparticle volume concentration and coolant Reynolds number and decreasing the coolant inlet temperature.

Optimization of a U-Bend for Minimal Pressure Loss in Internal Cooling Channels—Part II: Experimental Validation

2013 ◽  
Vol 135 (5) ◽  
Author(s):  
Filippo Coletti ◽  
Tom Verstraete ◽  
Jérémy Bulle ◽  
Timothée Van der Wielen ◽  
Nicolas Van den Berge ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Pressure Loss ◽  
Heat Transfer Performance ◽  
Internal Cooling ◽  
Transfer Performance ◽  
Cooling Channel ◽  
Piv Measurements ◽  
Cooling Channels ◽  
Numerical Predictions ◽  
The Impact

This two-part paper addresses the design of a U-bend for serpentine internal cooling channels optimized for minimal pressure loss. The total pressure loss for the flow in a U-bend is a critical design parameter, as it augments the pressure required at the inlet of the cooling system, resulting in a lower global efficiency. In the first part of the paper, the design methodology of the cooling channel was presented. In this second part, the optimized design is validated. The results obtained with the numerical methodology described in Part I are checked against pressure measurements and particle image velocimetry (PIV) measurements. The experimental campaign is carried out on a magnified model of a two-legged cooling channel that reproduces the geometrical and aerodynamical features of its numerical counterpart. Both the original profile and the optimized profile are tested. The latter proves to outperform the original geometry by about 36%, in good agreement with the numerical predictions. Two-dimensional PIV measurements performed in planes parallel to the plane of the bend highlight merits and limits of the computational model. Despite the well-known limits of the employed eddy viscosity model, the overall trends are captured. To assess the impact of the aerodynamic optimization on the heat transfer performance, detailed heat transfer measurements are carried out by means of liquid crystals thermography. The optimized geometry presents overall Nusselt number levels only 6% lower with respect to the standard U-bend. The study demonstrates that the proposed optimization method based on an evolutionary algorithm, a Navier–Stokes solver, and a metamodel of it is a valid design tool to minimize the pressure loss across a U-bend in internal cooling channels without leading to a substantial loss in heat transfer performance.

The Effect of Initial Cross Flow on the Cooling Performance of a Narrow Impingement Channel

2005 ◽  
Vol 127 (4) ◽  
pp. 358-365 ◽  
Author(s):  
Andrew C. Chambers ◽  
David R. H. Gillespie ◽  
Peter T. Ireland ◽  
Geoffrey M. Dailey
Keyword(s):  
Heat Transfer ◽  
Large Scale ◽  
Heat Transfer Performance ◽  
Cooling System ◽  
Cross Flow ◽  
Scale Model ◽  
Transfer Performance ◽  
Test Technique ◽  
Turbine Blade Cooling ◽  
Turbine Cooling

Impingement channels are often used in turbine blade cooling configurations. This paper examines the heat transfer performance of a typical integrally cast impingement channel. Detailed heat transfer coefficient distributions on all heat transfer surfaces were obtained in a series of low temperature experiments carried out in a large-scale model of a turbine cooling system using liquid crystal techniques. All experiments were performed on a model of a 19-hole, low aspect ratio impingement channel. The effect of flow introduced at the inlet to the channel on the impingement heat transfer within the channel was investigated. A novel test technique has been applied to determine the effect of the initial cross flow on jet penetration. The experiments were performed at an engine representative Reynolds number of 20,000 and examined the effect of additional initial cross flow up to 10 percent of the total mass flow. It was shown that initial cross flow strongly influenced the heat transfer performance with just 10 percent initial cross flow able to reduce the mean target plate jet effectiveness by 57 percent.

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