scholarly journals The Prediction of Surge Margins During Gas Turbine Transients

1985 ◽  
Author(s):  
N. R. L. Maccallum ◽  
P. Pilidis
Keyword(s):  
Boundary Layer ◽  
Gas Turbine ◽  
Thermal Effects ◽  
Adiabatic Flow ◽  
Surge Margin ◽  
Boundary Layer Development ◽  
Surge Line ◽  
Layer Development

This paper describes how allowance for the thermal effects of non-adiabatic flow, altered boundary layer development, changes in tip clearances and changes in seal clearances have been incorporated into a general gas turbine transient program. This program has been applied to a two-spool bypass engine. Revised predictions of surge margins in three common transients have been obtained. When the engine undergoes a “cold” acceleration, the thermal effects on the trajectory and on the surge line give a much increased proportion of unused surge margin in the H.P. Compressor, as compared to adiabatic predictions. In a “hot” acceleration this improvement is considerably reduced.

scholarly journals The Effect of Heat Transfer on Gas Turbine Transients

1986 ◽  
Author(s):  
P. Pilidis ◽  
N. R. L. MacCallum
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Gas Turbine ◽  
Thermal Effects ◽  
Transient Performance ◽  
Adiabatic Flow ◽  
Boundary Layer Development ◽  
Layer Development

This paper describes how allowance for the thermal effects of non-adiabatic flow, altered boundary layer development, changes in tip clearances and changes in seal clearances have been incorporated into a general gas turbine transient program. These non-adiabatic effects have been investigated, modelling a two-spool bypass engine. The model has predicted events that occur in practice and also indicates which of the parameters are the most influential in the alteration of transient performance.

Assessing the Influence of Aerosol on Radiation and Its Roles in Planetary Boundary Layer Development

2021 ◽  
Vol 35 (2) ◽  
pp. 384-392
Author(s):  
Zhigang Cheng ◽  
Yubing Pan ◽  
Ju Li ◽  
Xingcan Jia ◽  
Xinyu Zhang ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Planetary Boundary Layer ◽  
Boundary Layer Development ◽  
Layer Development

Numerical Simulation of Turbine Blade Boundary Layer and Heat Transfer and Assessment of Turbulence Models

1997 ◽  
Vol 119 (4) ◽  
pp. 794-801 ◽  
Author(s):  
J. Luo ◽  
B. Lakshminarayana
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Reynolds Number ◽  
Low Reynolds Number ◽  
Turbulence Models ◽  
Navier Stokes ◽  
Bypass Transition ◽  
Boundary Layer Development ◽  
Low Reynolds ◽  
Layer Development

The boundary layer development and convective heat transfer on transonic turbine nozzle vanes are investigated using a compressible Navier–Stokes code with three low-Reynolds-number k–ε models. The mean-flow and turbulence transport equations are integrated by a four-stage Runge–Kutta scheme. Numerical predictions are compared with the experimental data acquired at Allison Engine Company. An assessment of the performance of various turbulence models is carried out. The two modes of transition, bypass transition and separation-induced transition, are studied comparatively. Effects of blade surface pressure gradients, free-stream turbulence level, and Reynolds number on the blade boundary layer development, particularly transition onset, are examined. Predictions from a parabolic boundary layer code are included for comparison with those from the elliptic Navier–Stokes code. The present study indicates that the turbine external heat transfer, under real engine conditions, can be predicted well by the Navier–Stokes procedure with the low-Reynolds-number k–ε models employed.

Some Boundary Layer-Porous Wall Coupling Effects in Laminar Flows With Surface Injection

1970 ◽  
Vol 92 (3) ◽  
pp. 257-266
Author(s):  
D. A. Nealy ◽  
P. W. McFadden
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Heat Balance ◽  
Transfer Problem ◽  
Porous Wall ◽  
Laminar Flows ◽  
Stream Velocity ◽  
Axial Conduction ◽  
Boundary Layer Development ◽  
Layer Development

Using the integral form of the laminar boundary layer thermal energy equation, a method is developed which permits calculation of thermal boundary layer development under more general conditions than heretofore treated in the literature. The local Stanton number is expressed in terms of the thermal convection thickness which reflects the cumulative effects of variable free stream velocity, surface temperature, and injection rate on boundary layer development. The boundary layer calculation is combined with the wall heat transfer problem through a coolant heat balance which includes the effect of axial conduction in the wall. The highly coupled boundary layer and wall heat balance equations are solved simultaneously using relatively straightforward numerical integration techniques. Calculated results exhibit good agreement with existing analytical and experimental results. The present results indicate that nonisothermal wall and axial conduction effects significantly affect local heat transfer rates.

Boundary Layer Development and Spillway Energy Losses

1965 ◽  
Vol 91 (3) ◽  
pp. 149-163
Author(s):  
Frank B. Campbell ◽  
Robert C. Cox ◽  
Marden B. Boyd
Keyword(s):  
Boundary Layer ◽  
Energy Losses ◽  
Boundary Layer Development ◽  
Layer Development

Endwall Boundary Layer Development in a Multistage Low-Speed Compressor With Tandem Stator Vanes

2021 ◽  
Author(s):  
Michael Hopfinger ◽  
Volker Gümmer
Keyword(s):  
Boundary Layer ◽  
Boundary Layers ◽  
Shear Stresses ◽  
Flow Area ◽  
Stage Design ◽  
Low Speed ◽  
Boundary Layer Development ◽  
Viscous Shear ◽  
Layer Development ◽  
Highly Loaded

Abstract The development of viscous endwall flow is of major importance when considering highly-loaded compressor stages. Essentially, all losses occurring in a subsonic compressor are caused by viscous shear stresses building up boundary layers on individual aerofoils and endwall surfaces. These boundary layers cause significant aerodynamic blockage and cause a reduction in effective flow area, depending on the specifics of the stage design. The presented work describes the numerical investigation of blockage development in a 3.5-stage low-speed compressor with tandem stator vanes. The research is aimed at understanding the mechanism of blockage generation and growth in tandem vane rows and across the entire compressor. Therefore, the blockage generation is investigated as a function of the operating point, the rotational speed and the inlet boundary layer thickness.

scholarly journals Surge and Stall Detection Using Acoustic Analysis for Gas Turbine Hybrid Cycles

2019 ◽  
Author(s):  
Keishaly Cabrera Cruz ◽  
Paolo Pezzini ◽  
Lawrence Shadle ◽  
Kenneth M. Bryden
Keyword(s):  
Gas Turbine ◽  
Natural Frequencies ◽  
Acoustic Analysis ◽  
General Nature ◽  
Acoustic Sensors ◽  
Frequency Range ◽  
Surge Margin ◽  
Compressor Surge ◽  
Surge Line ◽  
Transient Operations

Abstract Compressor dynamics were studied in a gas turbine – fuel cell hybrid power system having a larger compressor volume than traditionally found in gas turbine systems. This larger compressor volume adversely affects the surge margin of the gas turbine. Industrial acoustic sensors were placed near the compressor to identify when the equipment was getting close to the surge line. Fast Fourier transform (FFT) mathematical analysis was used to obtain spectra representing the probability density across the frequency range (0–5000 Hz). Comparison between FFT spectra for nominal and transient operations revealed that higher amplitude spikes were observed during incipient stall at three different frequencies, 900, 1020, and 1800 Hz. These frequencies were compared to the natural frequencies of the equipment and the frequency for the rotating turbomachinery to identify more general nature of the acoustic signal typical of the onset of compressor surge. The primary goal of this acoustic analysis was to establish an online methodology to monitor compressor stability that can be anticipated and avoided.

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