Cooling-Air Injection Into Secondary Flow and Loss Fields Within a Linear Turbine Cascade

1991 ◽  
Vol 113 (3) ◽  
pp. 375-383 ◽  
Author(s):  
A. Yamamoto ◽  
Y. Kondo ◽  
R. Murao
Keyword(s):  
Leading Edge ◽  
Secondary Flows ◽  
Air Injection ◽  
Internal Flows ◽  
Flow Angle ◽  
Secondary Air Injection ◽  
Outlet Flow ◽  
Overall Performance ◽  
Secondary Air ◽  
Cooling Air

In order to understand overall performance and internal flows of air-cooled turbine blade rows, flows in a model linear cascade were surveyed with secondary air injection from various locations of the blade surfaces. The secondary air interacted with the cascade passage vortices and changed the loss distribution significantly. The cascade overall loss decreased when the air was injected along the mainstream and increased when the air was injected against the mainstream from some locations of the blade leading edge. Effects on overall kinetic energy of the secondary flows and on the cascade outlet flow angle were also discussed in this paper.

scholarly journals Cooling-Air Injection Into Secondary Flow and Loss Fields Within a Linear Turbine Cascade

1990 ◽  
Author(s):  
A. Yamamoto ◽  
Y. Kondo ◽  
R. Murao
Keyword(s):  
Leading Edge ◽  
Secondary Flows ◽  
Air Injection ◽  
Internal Flows ◽  
Flow Angle ◽  
Secondary Air Injection ◽  
Outlet Flow ◽  
Overall Performance ◽  
Secondary Air ◽  
Cooling Air

In order to understand overall performance and internal flows of air-cooled turbine blade rows, flows in a model linear cascade were surveyed with secondary air injection from various locations of the blade surfaces. The secondary air interacted with the cascade passage vortices and changed the loss distribution significantly. The cascade overall loss decreased when the air was injected along the mainstream and increased when the air was injected against the mainstream from some locations of the blade leading edge. Effects on overall kinetic energy of the secondary flows and on the cascade outlet flow angle were also discussed in this paper.

Investigation of Cooling-Air Injection on the Flow Field Within a Linear Turbine Cascade

1997 ◽  
Author(s):  
Yang Hong ◽  
Chen Fu ◽  
Gong Cunzhong ◽  
Wang Zhongqi
Keyword(s):  
Leading Edge ◽  
Secondary Flows ◽  
Air Injection ◽  
Internal Flows ◽  
Suction Surface ◽  
Flow Angle ◽  
Pressure Surface ◽  
Secondary Air Injection ◽  
Secondary Air ◽  
Cooling Air

In order to make clear how air injection influence the internal flows of turbine guide vanes, flows in a lagre-scale linear cascade were surveyed with secondary air injection from the locations of the blade leading-edge, and the rear of the suction and the pressure surfaces. The experimental results show that the secondary air interacts with the vortices in the cascade, alters the pressure distribution over blade profile and increases the energy loss obviously. It has been found that the air injection from the rear of the suction surface leads to the largest effect on the loss increase while the air injection from the rear of the pressure surface exerts the least influence. All the injections pertaining to the experiment have been found to have little effect on the exit flow angle. Effects on secondary flows, vortex intensity, and some averaged parameters are also discussed in this paper.

Assessment of Reynolds-Averaged Turbulence Models for Prediction of the Flow and Heat Transfer in an Inlet Vane-Endwall Passage

2004 ◽  
Vol 126 (3) ◽  
pp. 305-315 ◽  
Author(s):  
Hugo D. Pasinato ◽  
Kyle D. Squires ◽  
Ramendra P. Roy
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Leading Edge ◽  
Air Injection ◽  
Stanton Number ◽  
Computational Domain ◽  
Cooling Effectiveness ◽  
Vortical Structures ◽  
Secondary Air Injection ◽  
Secondary Air

Predictions of the flow and thermal fields in an inlet vane passage are obtained via solution of the incompressible Reynolds-averaged Navier-Stokes (RANS) equations. RANS predictions of the steady-state solutions are obtained using two scalar eddy viscosity models and full Reynolds stress transport to close the turbulent stress in the momentum equations. The turbulent heat flux is modeled using a constant turbulent Prandtl number. In the geometric configuration of the inlet vane passage, the hub endwall is flat. Calculations are performed for a baseline configuration and an additional configuration in which secondary air is injected through three small, angled slots positioned upstream of the vane leading edge. Solutions are obtained on unstructured grids with the densest mesh comprised of 1.9×106 elements. The simulations are assessed via an inter-comparison of predictions obtained using the different models, as well as through evaluation against experimental measurements of the Stanton number and cooling effectiveness on the hub endwall. The flow develops from a turbulent boundary layer at momentum thickness Reynolds number 955 prescribed at the inlet to the computational domain, 1.3 axial chord lengths upstream of the vane leading edge. The mean velocity at the inlet is prescribed to match an experimentally-measured profile with low freestream turbulence. For the case with secondary air injection, the blowing ratio was 1.3. Solid surfaces are isothermal at temperatures below that of the mainstream gas. Simulation results show that the vortical structures resolved by the models in the vicinity of the vane leading edge for the baseline case are relatively insensitive to the particular turbulence closure. The elevation in heat flux levels due to entrainment of higher temperature mainstream gas towards the endwall by the horseshoe vortex is captured, Stanton number distributions exhibit adequate agreement with measured values. While there are similarities in the coherent structures resolved by the models, details of their evolution through the passage lead to differences in heat transfer distribution along the endwall. Secondary air injection strongly distorts the flow structure in the vicinity of the leading edge, the vortical structures that develop in the calculations with air injection evolve primarily from the interaction of the fluid issuing from the slots and the mainstream flow. Elevated levels of cooling effectiveness predicted by the models correspond to larger areas of the endwall than measured, peak Stanton numbers are higher than the experimental values.

Flow and Heat Transfer at the Hub Endwall of Inlet Vane Passages — Experiments and Simulations

2000 ◽  
Author(s):  
R. P. Roy ◽  
K. D. Squires ◽  
M. Gerendas ◽  
S. Song ◽  
W. J. Howe ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Leading Edge ◽  
Turbulent Heat Flux ◽  
Air Injection ◽  
Turbulent Heat ◽  
Flow And Heat Transfer ◽  
Secondary Air Injection ◽  
Secondary Air ◽  
Transient Liquid Crystal Technique ◽  
Low Speed Wind Tunnel

The heat transfer distribution on the hub endwall of a model turbine vane passage was studied experimentally and by numerical simulation. The experiments were carried out in a low speed wind tunnel featuring a linear cascade of scaled-up inlet vanes. Measurements were made both without and with secondary air injection through slots located upstream of the vane leading edge using the transient liquid crystal technique. Results are presented for ReCax, in = 6.76 × 104 and blowing ratios of zero (no secondary air injection) and 1.3. Simulations were performed on unstructured grids using Fluent. A near-wall description of the flow field was employed. Turbulent stresses in the momentum equations were closed using the Spalart-Almaras model, and the turbulent heat flux in the thermal energy equation was closed using a constant turbulent Prandtl number. The agreement between the measurements and the simulations is generally good.

Gas mixing in a multi-stage conversion fluidized bed (MFB) with secondary air injection. Part I: an experimental study

RSC Advances ◽  
2016 ◽  
Vol 6 (43) ◽  
pp. 36642-36655 ◽  
Author(s):  
Rong Zhang ◽  
Zhenhua Hao ◽  
Zhiyu Wang ◽  
Xiaodong Huo ◽  
Junguo Li ◽  
...  
Keyword(s):  
Experimental Study ◽  
Fluidized Bed ◽  
Air Injection ◽  
Gas Mixing ◽  
Cold Model ◽  
Stage Conversion ◽  
Multi Stage ◽  
Secondary Air Injection ◽  
Secondary Air

This paper investigated the distribution of secondary air after injection into a multi-stage conversion fluidized bed (MFB) cold model.

Experimental Studies of Leading Edge Contouring Influence on Secondary Losses in Transonic Turbines

2012 ◽  
Author(s):  
Ranjan Saha ◽  
Jens Fridh ◽  
Torsten Fransson ◽  
Boris I. Mamaev ◽  
Mats Annerfeldt
Keyword(s):  
Gas Turbine ◽  
Guide Vane ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Leading Edge ◽  
Secondary Flows ◽  
Noticeable Effect ◽  
Flow Angle ◽  
Wide Range ◽  
Contour Plots

An experimental study of the hub leading edge contouring using fillets is performed in an annular sector cascade to observe the influence of secondary flows and aerodynamic losses. The investigated vane is a three dimensional gas turbine guide vane (geometrically similar) with a mid-span aspect ratio of 0.46. The measurements are carried out on the leading edge fillet and baseline cases using pneumatic probes. Significant precautions have been taken to increase the accuracy of the measurements. The investigations are performed for a wide range of operating exit Mach numbers from 0.5 to 0.9 at a design inlet flow angle of 90°. Data presented include the loading, fields of total pressures, exit flow angles, radial flow angles, as well as profile and secondary losses. The vane has a small profile loss of approximately 2.5% and secondary loss of about 1.1%. Contour plots of vorticity distributions and velocity vectors indicate there is a small influence of the vortex-structure in endwall regions when the leading edge fillet is used. Compared to the baseline case the loss for the filleted case is lower up to 13% of span and higher from 13% to 20% of the span for a reference condition with Mach no. of 0.9. For the filleted case, there is a small increase of turning up to 15% of the span and then a small decrease up to 35% of the span. Hence, there are no significant influences on the losses and turning for the filleted case. Results lead to the conclusion that one cannot expect a noticeable effect of leading edge contouring on the aerodynamic efficiency for the investigated 1st stage vane of a modern gas turbine.

EFFECT OF AXIAL CASING GROOVE GEOMETRY ON ROTOR-GROOVE INTERACTIONS IN THE TIP REGION OF A COMPRESSOR

2021 ◽  
pp. 1-54
Author(s):  
Subhra Shankha Koley ◽  
Huang Chen ◽  
Ayush Saraswat ◽  
Joseph Katz
Keyword(s):  
Rotor Blade ◽  
Leading Edge ◽  
Secondary Flows ◽  
Low Flow ◽  
Flow Angle ◽  
Flow Rates ◽  
Piv Measurements ◽  
Tip Leakage ◽  
Large Vortex ◽  
Blade Leading Edge

Abstract This experimental study characterizes the interactions of axial casing grooves with the flow in the tip region of an axial turbomachine. The tests involve grooves with the same inlet overlapping with the rotor blade leading edge, but with different exit directions located upstream. Among them, U grooves, whose circumferential outflow opposes the blade motion, achieve a 60% reduction in stall flowrate, but degrade the efficiency around the best efficiency point (BEP) by 2%. The S grooves, whose outlets are parallel to the blade rotation, improve the stall flowrate by only 36%, but do not degrade the BEP performance. To elucidate the mechanisms involved, stereo-PIV measurements covering the tip region and interior of grooves are performed in a refractive index matched facility. At low flow rates, the inflow into both grooves, which peaks when they are aligned with the blade pressure side, rolls up into a large vortex that lingers within the groove. By design, the outflow from S grooves is circumferentially positive. For the U grooves, fast circumferentially negative outflow peaks at the base of each groove, causing substantial periodic variations in the flow angle near the blade leading edge. At BEP, interactions with both grooves become milder, and most of the tip leakage vortex remains in the passage. Interactions with the S grooves are limited hence they do not degrade the efficiency. In contrast, the inflow into and outflow from the U grooves reverses direction, causing entrainment of secondary flows, which likely contribute to the reduced BEP efficiency.

Scavenging of Two Stroke Petrol Engine by Using Secondary Air Injection System

2019 ◽  
pp. 913-922
Author(s):  
Sagar Namdev Khurd ◽  
U. B. Andh ◽  
S. V. Kulkarni ◽  
Sandeep S. Wangikar ◽  
P. P. Kulkarni
Keyword(s):  
Air Injection ◽  
Petrol Engine ◽  
Injection System ◽  
Secondary Air Injection ◽  
Secondary Air

scholarly journals STUDY ON EFFECTS OF SECONDARY AIR INJECTION FOR COMPRESSED AIR TRANSPORT IN HORIZONTAL PIPE

2000 ◽  
Vol 16 ◽  
pp. 427-432
Author(s):  
Yoshihito SUZUKI ◽  
Yasumasa KUROSAWA ◽  
Minoru OCHIAI ◽  
Shigekatsu ENDO
Keyword(s):  
Air Injection ◽  
Compressed Air ◽  
Air Transport ◽  
Horizontal Pipe ◽  
Secondary Air Injection ◽  
Secondary Air
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