Flow Measurements in a Nozzle Guide Vane Passage With a Low Aspect Ratio and Endwall Contouring

2000 ◽  
Vol 122 (4) ◽  
pp. 659-666 ◽  
Author(s):  
Steven W. Burd ◽  
Terrence W. Simon
Keyword(s):  
Aspect Ratio ◽  
Flow Field ◽  
Large Scale ◽  
Guide Vane ◽  
Flow Measurements ◽  
Aspect Ratios ◽  
Nozzle Guide Vane ◽  
Endwall Contouring ◽  
Nozzle Guide

Most turbine cascade studies in the literature have been performed in straight-endwall, high-aspect-ratio, linear cascades. As a result, there has been little appreciation for the role of, and added complexity imposed by, reduced aspect ratios. There also has been little documentation of endwall profiling with these reduced spans. To examine the role of these factors on cascade hydrodynamics, a large-scale nozzle guide vane simulator was constructed at the Heat Transfer Laboratory of the University of Minnesota. This cascade is comprised of three airfoils between one contoured and one flat endwall. The geometries of the airfoils and endwalls, as well as the experimental conditions in the simulator, are representative of those in commercial operation. Measurements with hot-wire anemometry were taken to characterize the flow approaching the cascade. These measurements show that the flow field in this cascade is highly elliptic and influenced by pressure gradients that are established within the cascade. Exit flow field measurements with triple-sensor anemometry and pressure measurements within the cascade indicate that the acceleration imposed by endwall contouring and airfoil turning is able to suppress the size and strength of key secondary flow features. In addition, the flow field near the contoured endwall differs significantly from that adjacent to the straight endwall. [S0889-504X(00)01104-1]

Flow Measurements in a Nozzle Guide Vane Passage With a Low Aspect Ratio and Endwall Contouring

2000 ◽  
Author(s):  
Steven W. Burd ◽  
Terrence W. Simon
Keyword(s):  
Aspect Ratio ◽  
Flow Field ◽  
Guide Vane ◽  
Flow Measurements ◽  
Vast Number ◽  
Aspect Ratios ◽  
Nozzle Guide Vane ◽  
Endwall Contouring ◽  
Nozzle Guide

The vast number of turbine cascade studies in the literature has been performed in straight-endwall, high-aspect-ratio, linear cascades. As a result, there has been little appreciation for the role of, and added complexity imposed by, reduced aspect ratios. There also has been little documentation of endwall profiling at these reduced spans. To examine the role of these factors on cascade hydrodynamics, a large-scale nozzle guide vane simulator was constructed at the Heat Transfer Laboratory of the University of Minnesota. This cascade is comprised of three airfoils between one contoured and one flat endwall. The geometries of the airfoils and endwalls, as well as the experimental conditions in the simulator, are representative of those in commercial operation. Measurements with hot-wire anemometry were taken to characterize the flow approaching the cascade. These measurements show that the flow field in this cascade is highly elliptic and influenced by pressure gradients that are established within the cascade. Exit flow field measurements with triple-sensor anemometry and pressure measurements within the cascade indicate that the acceleration imposed by endwall contouring and airfoil turning is able to suppress the size and strength of key secondary flow features. In addition, the flow field near the contoured endwall differs significantly from that adjacent to the straight endwall.

scholarly journals Effects of Tip Endwall Contouring on the Three Dimensional Flow Field in an Annular Turbine Nozzle Guide Vane: Part 2 — Numerical Investigation

1985 ◽  
Author(s):  
Tony Arts
Keyword(s):  
Flow Field ◽  
Numerical Investigation ◽  
Guide Vane ◽  
Three Dimensional ◽  
Three Dimensional Flow ◽  
Dimensional Flow ◽  
Nozzle Guide Vane ◽  
Contour Plots ◽  
Endwall Contouring ◽  
Nozzle Guide

This paper describes the numerical investigation of the three dimensional flow through a low speed, low aspect ratio, high turning annular turbine nozzle guide vane with meridional tip endwall contouring. This rotational flow field has been simulated using a finite volume discretization and a time marching technique to solve the three dimensional, time dependent Euler equations expressed in a cylindrical coordinates system. The results are presented under the form of contour plots, spanwise pitch-averaged distributions and blade static pressure distributions. Detailed comparisons with the measurements described in part I of the paper are also provided.

Effects of Tip Endwall Contouring on the Three-Dimensional Flow Field in an Annular Turbine Nozzle Guide Vane: Part 1—Experimental Investigation

1985 ◽  
Vol 107 (4) ◽  
pp. 983-990 ◽  
Author(s):  
E. Boletis
Keyword(s):  
Experimental Investigation ◽  
Aspect Ratio ◽  
Guide Vane ◽  
Three Dimensional ◽  
Three Dimensional Flow ◽  
Low Aspect Ratio ◽  
Dimensional Flow ◽  
Nozzle Guide Vane ◽  
Endwall Contouring ◽  
Nozzle Guide

Tip endwall contouring is one of the most effective methods to improve the performance of low aspect ratio turbine vanes [1]. In view of the wide variety of geometric parameters, it appears that only the physical understanding of the three-dimensional flow field will allow us to evaluate the probable benefits of a particular endwall contouring. The paper describes the experimental investigation of the three-dimensional flow through a low-speed, low aspect ratio, high-turning annular turbine nozzle guide vane with meridional tip endwall contouring. The full impact of the effects of tip contouring is evaluated by comparison with the results of a previous study in an annular turbine nozzle guide vane of the same blade and cascade geometry with cylindrical endwalls [12]. In parallel, the present experimental study provides a fully three-dimensional test case for comparison with advanced theoretical calculation methods [15]. The flow is explored by means of double-head, four-hole pressure probes in five axial planes from far upstream to downstream of the blade row. The results are presented in the form of contour plots and spanwise pitch-averaged distributions.

Flow Field Simulations of a Gas Turbine Combustor

2002 ◽  
Vol 124 (3) ◽  
pp. 508-516 ◽  
Author(s):  
M. D. Barringer ◽  
O. T. Richard ◽  
J. P. Walter ◽  
S. M. Stitzel ◽  
K. A. Thole
Keyword(s):  
Flow Field ◽  
Gas Turbine ◽  
Large Scale ◽  
Guide Vane ◽  
Wall Region ◽  
Turbine Engine ◽  
Tunnel Section ◽  
Nozzle Guide ◽  
Nozzle Guide Vanes ◽  
Combustor Liner

The flow field exiting the combustor in a gas turbine engine is quite complex considering the presence of large dilution jets and complicated cooling schemes for the combustor liner. For the most part, however, there has been a disconnect between the combustor and turbine when simulating the flow field that enters the nozzle guide vanes. To determine the effects of a representative combustor flow field on the nozzle guide vane, a large-scale wind tunnel section has been developed to simulate the flow conditions of a prototypical combustor. This paper presents experimental results of a combustor simulation with no downstream turbine section as a baseline for comparison to the case with a turbine vane. Results indicate that the dilution jets generate turbulence levels of 15–18% at the exit of the combustor with a length scale that closely matches that of the dilution hole diameter. The total pressure exiting the combustor in the near-wall region neither resembles a turbulent boundary layer nor is it completely uniform putting both of these commonly made assumptions into question.

scholarly journals Wake Region Measurements of a Highly Three-Dimensional Nozzle Guide Vane Tested at DRA Pyestock Using Particle Image Velocimetry

1994 ◽  
Author(s):  
M. Funes-Gallanzi ◽  
P. J. Bryanston-Cross ◽  
K. S. Chana
Keyword(s):  
Flow Field ◽  
High Speed ◽  
Guide Vane ◽  
Three Dimensional ◽  
Light Sheet ◽  
Test Facility ◽  
Velocity Mapping ◽  
Nozzle Guide Vane ◽  
Nozzle Guide ◽  
Annular Cascade

The quantitative whole field flow visualization technique of PIV has over the last few years been successfully demonstrated for transonic flow applications. A series of such measurements has been made at DRA Pyestock. Several of the development stages critical to a full engine application of the work have now been achieved using the Isentropic Light Piston Cascade (ILPC) test facility operating with high inlet turbulence levels: • A method of seeding the flow with 0.5μm diameter styrene particles has provided an even coverage of the flow field. • A method of projecting a 1 mm thick high power Nd/YAG laser light sheet within the turbine stator cascade. This has enabled a complete instantaneous intra-blade velocity mapping of the flow field to be visualized, by a specially developed diffraction-limited optics arrangement. • Software has been developed to automatically analyze the data. Due to the sparse nature of the data obtained, a spatial approach to the extraction of the velocity vector data was employed. • Finally, a comparison of the experimental results with those obtained from a three-dimensional viscous flow program of Dawes; using the Baldwin-Lomax model for eddy viscosity and assuming fully turbulent flow. The measurements provide an instantaneous quantitative whole field visualization of a high-speed unsteady region of flow in a highly three-dimensional nozzle guide vane; which has been successfully compared with a full viscous calculation. This work represents the first such measurements to be made in a full-size transonic annular cascade at engine representative conditions.

EXPERIMENTAL STUDY OF THE ENDWALL HEAT TRANSFER OF A TRANSONIC NOZZLE GUIDE VANE WITH UPSTREAM JET PURGE COOLING PART 1 - EFFECT OF DENSITY RATIO

2021 ◽  
pp. 1-36
Author(s):  
Shuo Mao ◽  
Ridge A. Sibold ◽  
Wing Ng ◽  
Zhigang LI ◽  
Bo Bai ◽  
...  
Keyword(s):  
Large Scale ◽  
Guide Vane ◽  
Flow Direction ◽  
Density Ratio ◽  
Leading Edge ◽  
Horseshoe Vortex ◽  
Vital Role ◽  
Blowing Ratio ◽  
Nozzle Guide Vane ◽  
Nozzle Guide

Abstract Nozzle guide vane platforms often employ complex cooling schemes to mitigate the ever-increasing thermal loads on endwall. This study analyzes, experimentally and numerically, and describes the effect of coolant to mainstream blowing ratio, momentum ratio and density ratio for a typical axisymmetric converging nozzle guide vane platform with an upstream doublet staggered, steep-injection, cylindrical hole purge cooling scheme. Nominal flow conditions were engine-representative and as follows: Maexit = 0.85, Reexit,Cax = 1.5×106 and an inlet large-scale freestream turbulence intensity of 16%. Two blowing ratios were investigated, each corresponding to the design condition and its upper extrema at M = 2.5 and 3.5, respectively. For each blowing ratio, the coolant to mainstream density ratio was varied between DR=1.2, representing typical experimental neglect of coolant density, and DR=1.95, representative of typical engine conditions. The results show that with a fixed coolant-to-mainstream blowing ratio, the density ratio plays a vital role in the coolant-mainstream mixing and the interaction between coolant and horseshoe vortex near the vane leading edge. A higher density ratio leads to a better coolant coverage immediately downstream of the cooling holes but exposes the in-passage endwall near the pressure side. It also causes the in-passage coolant coverage to decay at a higher rate in the flow direction. From the results gathered, both density ratio and blowing ratio should be considered for accurate testing, analysis, and prediction of purge jet cooling scheme performance.

On the Unsteady Formation of Secondary Flow Inside a Rotating Turbine Blade Passage

2013 ◽  
Vol 136 (6) ◽  
Author(s):  
C. M. Schneider ◽  
D. Schrack ◽  
M. Kuerner ◽  
M. G. Rose ◽  
S. Staudacher ◽  
...  
Keyword(s):  
Flow Field ◽  
Secondary Flow ◽  
Guide Vane ◽  
Low Pressure ◽  
Flow Structures ◽  
Low Pressure Turbine ◽  
Interaction Processes ◽  
Nozzle Guide Vane ◽  
Nozzle Guide ◽  
Secondary Flow Field

This paper addresses the unsteady formation of secondary flow structures inside a turbine rotor passage. The first stage of a two-stage, low-pressure turbine is investigated at a Reynolds Number of 75,000. The design represents the third and the fourth stages of an engine-representative, low-pressure turbine. The flow field inside the rotor passage is discussed in the relative frame of reference using the streamwise vorticity. A multistage unsteady Reynolds-averaged Navier–Stokes (URANS) prediction provides the time-resolved data set required. It is supported by steady and unsteady area traverse data acquired with five-hole probes and dual-film probes at rotor inlet and exit. The unsteady analysis reveals a nonclassical secondary flow field inside the rotor passage of this turbine. The secondary flow field is dominated by flow structures related to the upstream nozzle guide vane. The interaction processes at hub and casing appear to be mirror images and have characteristic forms in time and space. Distinct loss zones are identified, which are associated with vane-rotor interaction processes. The distribution of the measured isentropic stage efficiency at rotor exit is shown, which is reduced significantly by the secondary flow structures discussed. Their impacts on the steady as well as on the unsteady angle characteristics at rotor exit are presented to address the influences on the inlet conditions of the downstream nozzle guide vane. It is concluded that URANS should improve the optimization of rotor geometry and rotor loss can be controlled, to a degree, by nozzle guide vane (NGV) design.

Effects of Slot Bleed Injection Over a Contoured End Wall on Nozzle Guide Vane Cooling Performance: Part II — Thermal Measurements

2000 ◽  
Author(s):  
Steven W. Burd ◽  
Cynthia J. Satterness ◽  
Terrence W. Simon
Keyword(s):  
Heat Transfer ◽  
Large Scale ◽  
Thermal Protection ◽  
Guide Vane ◽  
Secondary Flows ◽  
Transfer Coefficients ◽  
Core Mass ◽  
Core Flow ◽  
Nozzle Guide Vane ◽  
Nozzle Guide

Endwall heat transfer has become a major issue in the design of the inlet nozzle guide vane region of modern gas turbine engines. To compensate for high rates of convective heat transfer and the uncertain flow pattern along endwall surfaces, coolant flows are often excessive and distributed in a less than optimum fashion. In many instances, coolant is carried away or mixed into the core flow by the secondary flows without being effective. There is a need for more effective cooling concepts. In this paper, the results of an experimental study examining the thermal performance of bleed injection through an inclined slot positioned upstream of the nozzle airfoil leading edge plane are presented. This paper demonstrates that this type of combustor bleed cooling is a promising cooling concept. Testing is performed in a large-scale, guide vane cascade comprised of three airfoils between one contoured and one flat endwall. The Reynolds number, based upon approach velocity and true chord length, is 350,000 and the approach flow is with large-scale, high-intensity (9.5%) turbulence. Combustor bleed cooling flow is injected ahead of a contoured endwall with bleed-to-core mass flow ratios as high as 6%. Measurements are taken to document core flow temperature distributions at several axial positions within the cascade to evaluate surface adiabatic effectiveness values and local heat transfer coefficients. This film cooling arrangement offers significant thermal protection. The coolant is shown to provide thermal protection over most of the endwall as well as portions of the pressure and suction surfaces of the airfoils. To achieve this coverage, combustor bleed flow must be strong enough to overcome the influence of endwall region secondary flows.

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