scholarly journals Effects of Nonuniform Blade Pitch on the Flow Through an Annular Turbine Nozzle

1995 ◽  
Vol 2 (1) ◽  
pp. 59-65 ◽  
Author(s):  
Rainer Kurz
Keyword(s):  
Gas Turbine ◽  
Flow Measurement ◽  
Static Pressure ◽  
Leading Edge ◽  
Inviscid Flow ◽  
Viscous Effect ◽  
Measurement Results ◽  
Flow Through ◽  
The Mean ◽  
Gas Turbine Nozzle

This paper discusses flow measurement results both upstream and downstream of a transonic annular gas turbine nozzle with a nonuniform pitch. The downstream measurements are performed in the plane where the leading edge of the rotor blade is located in the gas turbine. The experiments were performed using total pressure probes and wall static pressure taps. The pitch variation modifies the flow field both upstream and downstream of the nozzle, although the experiments show that the effect is localized to the immediate neighborhood of the involved blades. The effects on the wakes and on the inviscid flow are discussed separately. The mean velocities show a strong sensitivity to the changes of the pitch, which is due to a potential flow effect rather than a viscous effect.

scholarly journals The Flow Through an Annular Turbine Nozzle With Nonuniform Pitch

1994 ◽  
Author(s):  
Rainer Kurz
Keyword(s):  
Flow Field ◽  
Gas Turbine ◽  
Total Pressure ◽  
Flow Measurement ◽  
Leading Edge ◽  
Inviscid Flow ◽  
Vortex Model ◽  
Measurement Results ◽  
Flow Through ◽  
The Mean

This paper discusses flow measurement results both upstream and downstream of a transonic annular turbine nozzle with a nonuniform pitch. The downstream measurements are performed in the plane, where the leading edge of the rotor is located in the gas turbine. The experiments were performed using total pressure probes and static wall pressure taps. This type of nonuniformity creates a different behavior of the flow field both upstream and downstream of the blades. The effects on the wakes and on the inviscid flow are discussed separately. The mean velocities show a strong sensitivity to the changes of the pitch, which is identified as a potential flow effect by using a simple vortex model.

Effect of Prediffuser Angle on the Static Pressure Recovery in Flow Through Casing-Liner Annulus of a Gas Turbine Combustor at Various Swirl Levels

2015 ◽  
Vol 8 (1) ◽  
Author(s):  
Prakash Ghose ◽  
Amitava Datta ◽  
Achintya Mukhopadhyay
Keyword(s):  
Gas Turbine ◽  
Static Pressure ◽  
Numerical Study ◽  
Pressure Recovery ◽  
Gas Turbine Combustor ◽  
Pressure Losses ◽  
Pressure Distributions ◽  
Inlet Swirl ◽  
Flow Through ◽  
The Ideal

A numerical study has been performed in an axisymmetric diffuser followed by a casing-liner annulus of a typical gas turbine combustor to analyze the flow structure and pressure recovery in the geometry. Static pressure recovery in a gas turbine combustor is important to ensure high pressure of air around the liner. However, the irreversible pressure losses reduce the static pressure recovery from the ideal value. The presence of swirl in the flow from compressor and prediffuser geometry before the dump diffuser influences the flow pattern significantly. In this study, flow structures are numerically predicted with different prediffuser angles and inlet swirl levels for different dump gaps. Streamline distributions and pressure plots on the casing and liner walls are analyzed. Static pressure recovery coefficients are obtained from the pressure distributions across the combustor. The effect of dump gap on the static pressure recovery has also been evaluated. It is observed that the best static pressure recovery can be obtained at optimum values of inlet swirl level and prediffuser angle. Dump gap is found to have significant influence on the static pressure recovery only at small prediffuser angle.

An Experimental Analysis of Flow Through Annular Diffuser With and Without Struts

2006 ◽  
Author(s):  
R. Prakash ◽  
P. Sudhakar ◽  
N. V. Mahalakshmi
Keyword(s):  
Gas Turbine ◽  
Static Pressure ◽  
Structural Members ◽  
Pressure Development ◽  
Annular Diffuser ◽  
Fundamental Research ◽  
Flow Through ◽  
Gas Turbine Exhaust ◽  
Industrial Gas Turbine ◽  
Turbine Exhaust

This paper presents the static pressure development and the effect of struts on the performance of an annular diffuser. A typical exhaust diffuser of an industrial gas turbine is annular with structural members, called struts, which extend radially from the inner to the outer annulus wall. An annular diffuser model, primarily intended for fundamental research, has been tested on a wind tunnel. Similar conditions that prevail in an industrial gas turbine have been generated in the diffuser. Measurements were made using a five holed Pitot probe. The research had been carried out to make a detailed investigation on the effect of struts and to advance computational and design tools for gas turbine exhaust diffusers.

Numerical Investigation of Flow Through an Ultra-Micro Scale Gas Turbine

2017 ◽  
Author(s):  
Rohann D’souza ◽  
Rajnish Sharma
Keyword(s):  
Gas Turbine ◽  
Leading Edge ◽  
Integrated System ◽  
Tip Clearance ◽  
Cfd Modelling ◽  
3 Dimensional ◽  
Micro Scale ◽  
Viscous Heat ◽  
Flow Through ◽  
Nozzle Guide

The ultra-micro scale gas turbine (UMGT) is an ongoing area of research, as an alternate power source for portable electronic devices. To advance our understanding that will help in its development, this paper focuses on a numerical analysis via computational fluid dynamics (CFD) of flow through a 3 dimensional (3D) blade profiled UMGT turbine. CFD modelling was based off an integrated turbine that consists of a volute, nozzle guide vanes (NGV) and rotor. Firstly, the flow through the integrated system as well as each component was analyzed. Secondly, the turbine was simulated under three different isothermal conditions and compared to the adiabatic situation, in order to understand the loss mechanisms. Lastly, the effect of tip clearance was studied, where it was varied between 0–10% of the blade height. CFD results showed, the flow through the turbine was quite well behaved, however separation of flow at the NGV leading edge, and residual swirl at the rotor trailing edge, were observed. The effects of the isothermal wall boundary condition was very pronounced at the volute and NGV, resulting in a large amount of good heat to be conducted away, at the rotor however conduction was only a percentage of the viscous heat generated. Lastly tip clearance proved to have a linearly detrimental effect on power.

The influence of mean shear on unsteady aperture flow, with application to acoustical diffraction and self-sustained cavity oscillations

1981 ◽  
Vol 109 ◽  
pp. 125-146 ◽  
Author(s):  
M. S. Howe
Keyword(s):  
Leading Edge ◽  
Vortex Sheet ◽  
Mean Flow ◽  
Kutta Condition ◽  
Sustained Oscillations ◽  
Linearized Theory ◽  
Flow Through ◽  
The Mean ◽  
Theoretical Results ◽  
Disturbed Motion

This paper discusses the linearized theory of unsteady flow through a two-dimensional aperture in a thin plate in the presence of a grazing mean flow on one side of the plate. The mean shear layer is modelled by a vortex sheet, and it is predicted that at low mean-flow Mach numbers there is a transfer of energy from the mean flow to the disturbed motion of the vortex sheet provided (i) the Kutta condition is imposed at the leading edge of the aperture, resulting in the unsteady shedding of vorticity from the edge, and (ii) the width of the aperture 2s satisfies ½ < 2s/λ < 1.1, where λ is the hydrodynamic wavelength of the disturbance on the vortex sheet within the aperture. The theory is used to examine the effect of mean shear on the diffraction of sound by a perforated screen, and to predict the spontaneous excitation and suppression of self-sustained oscillations in a wall-cavity beneath a nominally steady mean flow. In the latter case support for the proposed theory is provided by a favourable comparison of theoretical results with experimental data available in the literature.

Effects of Fluid Inertia and Compressibility on the Performance of Valves and Flow Meters Operating under Unsteady Conditions

1966 ◽  
Vol 8 (1) ◽  
pp. 52-61 ◽  
Author(s):  
D. McCloy
Keyword(s):  
Pressure Drop ◽  
Flow Rate ◽  
Flow Measurement ◽  
Fluid Inertia ◽  
Mean Flow ◽  
Flow Meters ◽  
Orifice Area ◽  
Flow Through ◽  
The Mean ◽  
Compressibility Effects

Incompressible flow theory is used in the investigation of the effects of fluid inertia on unsteady flow through valves and flow meters. Two types of oscillatory disturbance are considered, one being due to valve oscillation at constant pressure drop and the other to pressure pulsation at constant orifice area. With the former type of disturbance it is shown that the mean flow rate decreases with frequency of oscillation. When the pressure drop pulsates the mean flow rate increases with frequency. These phenomena are shown to be of importance in hydraulic servomechanisms and in dynamic flow measurement. Compressibility effects are considered and it is shown that cavitation can occur at the valve during oscillation.

Development of Improvements to “Controlled Flow” Technology for Large Steam Turbines

2017 ◽  
Author(s):  
B. R. Haller ◽  
G. Singh ◽  
P. R. Millington ◽  
F. C. Mund ◽  
K. Vernon
Keyword(s):  
Leading Edge ◽  
Back Surface ◽  
Steam Turbines ◽  
3D Design ◽  
Design Philosophy ◽  
Previous Design ◽  
Flow Through ◽  
The Mean ◽  
And Performance ◽  
Controlled Flow

The aim of this paper is to present advances in the blading design for large steam turbines — ‘Controlled Flow’ technology. The purpose of the design is to improve the turbine efficiency in a cost neutral manner, adding value for the customer. Controlled Flow is a 3D design philosophy which passes more flow through the efficient middle sections of the blade, and less flow through the comparatively inefficient regions near the endwalls. It has been used for the Impulse Technology Blading ITB guide blades. The current improvement builds on the previous successful Controlled Flow design but incorporates the following new features: - Ultra High Lift for the mean section (at significantly reduced axial width) - Ultra High Back Surface Deflection for the mean section - forward leading edge sweep. The new guide delivers the same radial distribution of absolute fluid exit angle to the runner as the previous design. Confirmatory model turbine tests demonstrated that the new guide delivered a stage efficiency improvement of 0.35%, above an already very high datum level. The endwall sections of the guide are kept the same which maintains the mechanical strength of the diaphragm (same stress and deflection). Therefore, the new design can easily ‘slot-in’ and replace the previous design. The following will be described in detail: - History of the designs/background and design philosophy - Flow physics - Stage optimization and performance prediction - Probabilistic analysis and robustness of the design - Confirmatory model turbine testing and validation (comparison with design predictions).

The effects of trailing vorticity on the flow through highly loaded cascades

1976 ◽  
Vol 74 (4) ◽  
pp. 721-740 ◽  
Author(s):  
James E. Mccune ◽  
William R. Hawthorne
Keyword(s):  
Incompressible Flow ◽  
Design Problem ◽  
Three Dimensional ◽  
Inviscid Flow ◽  
Dimensional Theory ◽  
Blade Loading ◽  
Large Pressure ◽  
Flow Through ◽  
The Mean ◽  
Highly Loaded

This paper presents a procedure whereby three-dimensional inviscid flow through a highly loaded turbomachinery cascade of lifting lines can be treated by methods corresponding to classical aerodynamic theory. In contrast to earlier linearized (thin airfoil) three-dimensional theory, the present study allows analysis of the flow corresponding to the large turning and/or large pressure ratios induced by practical rotors or stators. For the sake of simplicity, the present paper is limited to incompressible flow through a highly loaded rectilinear cascade and to the design problem, i.e. given blade loading. Formulae are derived for both the mean and the three-dimensional components of the flow; in particular, the velocities at the blades induced by the trailing vorticity associated with nonuniform blade circulation are determined.

Influence of Tip Clearance on the Inter Blade and Exit Flow Field of a Turbine Rotor Cascade

1994 ◽  
Author(s):  
M. Govardhan ◽  
N. Venkatrayulu ◽  
V. S. Vishnubhotla
Keyword(s):  
Static Pressure ◽  
Leading Edge ◽  
Turbine Rotor ◽  
Tip Clearance ◽  
Turbine Cascade ◽  
Suction Surface ◽  
Static Pressure Distribution ◽  
Blade Tip ◽  
Flow Through ◽  
Downstream Flow

A detailed study of flow through the blade passage and downstream of a linear turbine cascade was carried out for four cases of tip clearance including zero clearance. Apart from inlet traverse, a total of eight stations were chosen for inter-blade flow traversing between 5% and 95% of axial chord from leading edge. Downstream flow surveys were made at distances of 106% of axial chord from the blade leading edge. Pitchwise and spanwise traverses were conducted for each tip clearance at these stations using a small five hole probe. Provision was also made for the measurement of static pressure distribution on the suction and pressure surfaces and also on the blade tip surface when clearance is present. At about 40% of axial chord from the leading edge, the presence of clearance vortex is identified inside the passage. The growth of the clearance vortex in size, its movement towards the suction surface and its increase in strength with the gap size were observed beyond 55% of axial chord till the trailing edge region. The rate of growth of the losses in the endwall region increased with clearance. Horse shoe vortex was not observed for the highest clearance. The overall losses increase rapidly with clearance in the rear half of the blade.

Overall Cooling Effectiveness on a Gas Turbine Vane With Swirl-Film Cooling

2019 ◽  
Author(s):  
Haifen Du ◽  
Danmei Xie ◽  
Wei Chen ◽  
Ziyue Mei ◽  
Jing Zhang
Keyword(s):  
Gas Turbine ◽  
Mass Flow ◽  
Film Cooling ◽  
Conjugate Heat Transfer ◽  
Leading Edge ◽  
Cooling Effectiveness ◽  
Turbine Vane ◽  
Cooling Chamber ◽  
Sst Turbulence Model ◽  
Flow Through

Abstract Numerical calculation of conjugate heat transfer is carried out to study the effect of combined film and swirl cooling at the leading edge of a gas turbine vane with a a cooling chamber inside, in which 3-D steady RANS approach with the k-ω SST turbulence model is used. Two different kinds of coolant chamber configuration (C1 and C2) are selected. In C2, the cooling chamber is composed of a front cavity and a back cavity, and the two cavities are connected by a passage which is divided into 16 segments. The comparative investigations between C1 and C2 cases have been carried out to study the effect of different cooling chambers at M = 0.25, 0.5, 1 and 2. For two cases, overall cooling effectiveness increases with M increasing. In C1 case, with increasing M, differences of mass flow through film holes rows will decrease. The variation of mass flow from holes changes by less than 26.7% at M = 2. However, in C2 case, mass flow through S1 and S2 is significantly larger than that through other film holes rows. Area-averaged overall effectiveness in C2 is larger by 2.5% at M = 0.25 compared to C1 case.

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