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.

Build Direction Effects on Additively Manufactured Channels

2016 ◽  
Vol 138 (5) ◽  
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 advance of direct metal laser sintering (DMLS), also generically referred to as additive manufacturing (AM), 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 Investigation in the Numerical Approach to Solve the Heat Transfer Phenomenon in Gas Turbine

2021 ◽  
pp. 1-23
Author(s):  
Sourabh Kumar ◽  
Ryoichi S. Amano
Keyword(s):  
Heat Transfer ◽  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Gas Turbine ◽  
Turbine Blades ◽  
Leading Edge ◽  
Internal Cooling ◽  
Dynamics Modeling ◽  
Turbine Cooling ◽  
Gas Turbine Cooling

Abstract The gas turbine engine's extreme conditions need a robust design to produce efficient energy and reliable operation. Flow and thermal analysis are essential for complex aerodynamic and thermodynamic interaction during turbine performance. There is a need to understand and predict the temperature to make the gas turbine engine efficient. This paper will outline the numerical methods applied for primary cooling methods in gas turbine blades. These include impinging leading-edge cooling, internal cooling in the midsection, and pin fin in the trailing edge. The main objective of this paper is to understand the numerical research done on improving gas turbine cooling. The emphasis will be on understanding the present CFD (Computational fluid dynamics) techniques applied for gas turbine cooling and further development. This paper briefly outlines the new conjugate heat transfer based CFD (computational fluid dynamics) modeling techniques that have evolved over the years due to recent computing power development.

Experimental and Analytical Analysis of Aero-Derivative Micro Gas Turbine Heat Transfer and Performance

2019 ◽  
Author(s):  
Aki Grönman ◽  
Petri Sallinen ◽  
Juha Honkatukia ◽  
Jari Backman ◽  
Antti Uusitalo ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Internal Heat ◽  
Small Scale ◽  
Micro Gas Turbine ◽  
Overall Performance ◽  
Flow Configurations ◽  
Gas Turbine Heat Transfer ◽  
And Performance

Abstract Small-scale gas turbines offer a light weight alternative to engine generators. Despite the many benefits of a micro gas turbine, its efficiency cannot match that of its competitors. This discrepancy is mostly due to Reynolds number losses in turbomachinery but also partly due to internal heat transfer problems, which degrade the performance below what is adiabatically expected. In general, a good understanding about the heat transfer inside the machine is of paramount importance, and innovative engineering solutions are required to improve overall performance. Overall, one of the less exploited areas in the public literature is the effect of the generator cooling approach. Small jet engines can be used as a simple and affordable foundation to produce portable aero derivative micro gas turbines for demonstrating the specific challenges they face but also to study different flow configurations. This study presents combined analytical and experimental analysis of a portable aero derivative micro gas turbine with three main objectives. The first objective is to evaluate the contributions of different heat leakage losses on the overall performance. The second objective is to compare the influence of different generator cooling approaches. And the third objective is to evaluate the effect of different technical modifications. As a result, suggestions are given about the most suitable machine layouts and the importance of several design choices.

Heat Transfer Measurements to a Gas Turbine Cooling Passage With Inclined Ribs

1998 ◽  
Vol 120 (1) ◽  
pp. 63-69 ◽  
Author(s):  
Z. Wang ◽  
P. T. Ireland ◽  
S. T. Kohler ◽  
J. W. Chew
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Gas Turbine ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Scale Model ◽  
Turbine Cooling ◽  
Gas Turbine Cooling ◽  
Cooling Passage

The local heat transfer coefficient distribution over all four walls of a large-scale model of a gas turbine cooling passage have been measured in great detail. A new method of determine the heat transfer coefficient to the rib surface has been developed and the contribution of the rib, at 5 percent blockage, to the overall roughened heat transfer coefficient was found to be considerable. The vortex-dominated flow field was interpreted from the detailed form of the measured local heat transfer contours. Computational Fluid Dynamics calculations support this model of the flow and yield friction factors that agree with measured values. Advances in the heat transfer measuring technique and data analysis procedure that confirm the accuracy of the transient method are described in full.

scholarly journals Self-Oscillating-Impinging-Jet as a Gas Turbine Cooling Enhancement System

1997 ◽  
Author(s):  
Frank Herr ◽  
Cengiz Camci
Keyword(s):  
Heat Transfer ◽  
Gas Turbine ◽  
Turbine Blades ◽  
Impinging Jet ◽  
Stagnation Line ◽  
Number Range ◽  
Gas Turbine Blades ◽  
Turbine Cooling ◽  
Oscillating Jet ◽  
Gas Turbine Cooling

Impinging jets are widely used in local enhancement of heat removed from internal passages of gas turbine blades. Arrays of stationary jets are usually impinged on inner surfaces of gas turbine blades exposed to severe thermal/hydrodynamic environment of hot mainstream gases. The current practice is to benefit from the high heat transfer coefficients existing in the immediate vicinity of the jet impingement region on a target wall. The present study shows that a self-oscillating impinging-jet configuration can be extremely beneficial in enhancing the heat removal performance of a conventional stationary impinging jet. In addition to a highly elevated stagnation line Nusselt number, the area coverage of the impingement zone is significantly enlarged because of the sweeping motion of the oscillating coolant jet. When an oscillating jet (Re = 14,000) is impinged on a plate normal to the jet axis (x/d = 24 hole to plate distance), a typical enhancement of Nu number on the stagnation line is shown to be 70 %. The present paper explains detailed fluid dynamics structure of the oscillating jet by using a triple decomposition technique on a crossed hot wire signal. High resolution heat transfer measurements are also presented in a Re number range between 7,500 and 14,000 (24<x/d<60). The current heat transfer enhancement levels achieved suggest that it is possible to implement the present self-oscillating-impinging-jet concept in future gas turbine cooling systems, on rotating disks, in electronic equipment cooling, aircraft de-icing systems and heat exchanger systems.

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