Effect of Wake-Type Nonuniform Inlet Velocity Profiles on First Appreciable Stall in Plane-Wall Diffusers

1980 ◽  
Vol 102 (3) ◽  
pp. 283-289 ◽  
Author(s):  
K. F. Kaiser ◽  
A. T. McDonald
Keyword(s):  
High Speed ◽  
Velocity Profiles ◽  
Plane Wall ◽  
Flow Distortion ◽  
Turbine Engine ◽  
Inlet Velocity ◽  
Outlet Flow ◽  
Engine Compressor ◽  
Design Tradeoffs ◽  
Definition Of

The combustor diffuser in a gas turbine engine must accept a high-speed, unsteady, distorted flow from the engine compressor. It must deliver flow to the combustor with minimum loss in total pressure and minimum velocity profile distortion. Both pressure recovery and outlet flow distortion characteristics of diffusers must be considered in design tradeoffs. The purpose of this investigation was to study the effects of nonuniform inlet velocity profiles on the inception of stall in two-dimensional plane-wall diffusers. Centrally-located “wake-type” inlet velocity profiles were chosen to simulate the flow conditions at the inlet of a combustor diffuser. The inlet distortion was characterized by dimensionless wake strength and wake width parameters. The experiments were performed on an open surface water table to make flow visualization possible. A centerline or pocket-type stall, such as previously reported in swirling flows, was observed for sufficiently severe inlet profile distortion. A new definition of first appreciable stall, based on a fraction of the exit area stalled, was introduced to characterize stalls which did not occur on a solid surface.

scholarly journals Investigation of Flows in Rectangular Diffusers With Inlet Flow Distortion

1982 ◽  
Author(s):  
M. M. Al-Mudhafar ◽  
M. Ilyas ◽  
F. S. Bhinder
Keyword(s):  
Experimental Study ◽  
Velocity Profiles ◽  
Pressure Recovery ◽  
Two Dimensional ◽  
Flow Distortion ◽  
Inlet Flow ◽  
Inlet Velocity ◽  
Inlet Distortion ◽  
Mach Numbers ◽  
Inlet Flow Distortion

The results of an experimental study on the influence of severely distorted velocity profiles on the performance of a straight two-dimensional diffuser are reported. The data cover entry Mach numbers ranging from 0.1 to 0.6 and several inlet distortion levels. The pressure recovery progressively deteriorates as the inlet velocity is distorted.

Effect of Inlet Flow Distortion on Performance of Vortex Controlled Diffusers

1992 ◽  
Vol 114 (2) ◽  
pp. 191-197 ◽  
Author(s):  
R. K. Sullerey ◽  
V. Ashok ◽  
K. V. Shantharam
Keyword(s):  
Reynolds Number ◽  
High Pressure ◽  
Velocity Profiles ◽  
Short Length ◽  
Experimental Investigations ◽  
Two Dimensional ◽  
Flow Distortion ◽  
Exit Velocity ◽  
Inlet Velocity ◽  
Vortex Control

The present experimental investigations are concerned with diffusers employing the concept of vortex control to achieve high pressure recovery in a short length. Two types of two-dimensional diffusers have been studied, namely, vortex controlled and hybrid diffusers. Investigations have been carried out on such short diffusers with symmetrically and asymmetrically distorted inlet velocity profiles for area ratios 2.0 and 2.5 and divergence angle of 30 and 45 deg at a Reynolds number of 105. For each of the above configurations, experiments have been carried out for a range of fence subtended angles and bleed rates. The results indicate improvement in diffuser effectiveness up to a particular bleed off for both types of diffusers. It was observed that the nature of exit velocity profiles could be controlled by differential bleed.

Computational Study of the Effect of Inlet Velocity Profile and Rib Orientation on Heat Transfer in Rotating Ribbed Radial Turbine Cooling Passages

2016 ◽  
Author(s):  
Robert Pearce ◽  
Peter Ireland ◽  
Matthew McGilvray ◽  
Eduardo Romero
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Aspect Ratio ◽  
Velocity Profile ◽  
Computational Study ◽  
Velocity Profiles ◽  
Turbine Engine ◽  
Inlet Velocity ◽  
Turbine Cooling ◽  
Radial Turbine

This study investigates the effect of inlet velocity profiles and rib orientations on the Nusselt number distribution within ribbed radial turbine cooling passages representative of systems used in current engines. A triple-pass serpentine passage is investigated, which includes rib turbulators angled at 45° and 180° bends. The first two passes are radially outward and inward respectively and both have an aspect ratio of 1:4, with the third pass radially outward with an aspect ratio of 1:2. Multiple inlet velocity profiles are studied in RANS CFD simulations under both stationary and rotating conditions. The rotating simulations have Reynolds, Rotation and Buoyancy numbers representative of a passage within a HP turbine blade of a gas turbine engine. The flow structure and Nusselt number distributions are discussed in detail with the inlet velocity profile found to have a very large influence in the first pass under both stationary and rotating conditions, with smaller differences observed in the later passes. The rib orientation in the second pass was also investigated, with simulations of reversed and non-reversed rib orientation compared. Improved heat transfer characteristics were found in simulations where the ribs were orientated in the same direction for all three passages. These simulations are compared to experimental results in order to explain previous discrepancies found between experimental and CFD data from an experimental setup with complex inlet geometry.

scholarly journals Axial Compressor Fouling Evaluation at High Speed Settings Using an Aerothermodynamic Model

1993 ◽  
Author(s):  
Inam Ul Haq ◽  
H. I. H. Saravanamuttoo
Keyword(s):  
High Speed ◽  
Axial Compressor ◽  
Field Tests ◽  
Ambient Conditions ◽  
Turbine Engine ◽  
Discharge Temperature ◽  
Engine Compressor ◽  
Flow Compressor ◽  
Industrial Gas Turbine

An aerothermodynamic model for a widely used industrial gas turbine engine compressor has been developed for studying in-situ compressor deterioration due to atmospheric fouling at high power settings. The model is developed using available geometrical dimensions of the compressor annulus. It is based on a mean line stage stacking method utilizing the basic turbomachinery equations. The model requires minimum inputs (mass flow, compressor speed, ambient conditions) from the instrument sensors and derives all the necessary information (compressor discharge temperature and pressure, isentropic efficiency, and power) that defines overall performance. The validity of the model was confirmed by comparing the results with the field tests and excellent agreement was achieved. The model is very economical in operation and is fully capable of detecting small changes that occur in the compressor due to fouling.

Designing Forging and Die Tooling for the Manufacture of Turbine Engine Compressor Blades in Siemens NX

2016 ◽  
Vol 684 ◽  
pp. 497-506 ◽  
Author(s):  
D.S. Goryainov ◽  
V.V. Anokhin ◽  
Aleksey Shlyapugin
Keyword(s):  
Point Cloud ◽  
Compressor Blade ◽  
Compressor Blades ◽  
Turbine Engine ◽  
Direct Modeling ◽  
Engine Compressor ◽  
Data Source ◽  
Theoretical Contour ◽  
Gas Turbine Compressor ◽  
Complex Parts

For designing forging and die tooling for bulk forging a necessity in using the data of the geometry of the part produced arises. Obviously, the use as a data source for designing drawings of commonly applied in “manual alternate design” (without a computer) especially such complex parts as compressor blades is not perspective because of the complexity of developing theoretical contour specified by a point cloud. In this case the use of special tooling of direct modeling that provides changing the original model of the part developed by the designers is a perspective one. It should be taken into account during the process of forging and die tooling designing that it is necessary to register the special features of the technology, upon that, the technologist should be highly proficient in using the software. The work given describes the designing technique of gas turbine compressor blade with the account of using the potential of NX Siemens program.

Effect of Divergence Angle on Flow Through Inlet Section of Diffuser of a Gas Turbine Combustion Chamber: The CFD Approach

2006 ◽  
Author(s):  
Digvijay B. Kulshreshtha ◽  
S. A. Channiwala ◽  
Jitendra Chaudhary ◽  
Zoeb Lakdawala ◽  
Hitesh Solanki ◽  
...  
Keyword(s):  
Combustion Chamber ◽  
Gas Turbine ◽  
Total Pressure ◽  
Divergence Angle ◽  
Velocity Head ◽  
Turbine Engine ◽  
Inlet Velocity ◽  
Pressure Losses ◽  
Flow Through ◽  
Mach Numbers

In the combustor inlet diffuser section of gas turbine engine, high-velocity air from compressor flows into the diffuser, where a considerable portion of the inlet velocity head PT3 − PS3 is converted to static pressure (PS) before the airflow enters the combustor. Modern high through-flow turbine engine compressors are highly loaded and usually have high inlet Mach numbers. With high compressor exit Mach numbers, the velocity head at the compressor exit station may be as high as 10% of the total pressure. The function of the diffuser is to recover a large proportion of this energy. Otherwise, the resulting higher total pressure loss would result in a significantly higher level of engine specific fuel consumption. The diffuser performance must also be sensitive to inlet velocity profiles and geometrical variations of the combustor relative to the location of the pre-diffuser exit flow path. Low diffuser pressure losses with high Mach numbers are more rapidly achieved with increasing length. However, diffuser length must be short to minimize engine length and weight. A good diffuser design should have a well considered balance between the confliction requirements for low pressure losses and short engine lengths. The present paper describes the effect of divergence angle on diffuser performance for gas turbine combustion chamber using Computational Fluid Dynamic Approach. The flow through the diffuser is numerically solved for divergence angles ranging from 5 to 25°. The flow separation and formation of wake regions are studied.

High Speed Imaging of Forced Ignition Kernels in Non-Uniform Jet Fuel/Air Mixtures

2017 ◽  
Author(s):  
Sheng Wei ◽  
Brandon Sforzo ◽  
Jerry Seitzman
Keyword(s):  
Heat Release ◽  
High Speed ◽  
Air Flow ◽  
Cetane Number ◽  
High Energy ◽  
Liquid Fuels ◽  
High Speed Imaging ◽  
Ignition Probability ◽  
Turbine Engine ◽  
Planar Laser

This paper describes experimental measurements of forced ignition of prevaporized liquid fuels in a well-controlled facility that incorporates non-uniform flow conditions similar to those of gas turbine engine combustors. The goal here is to elucidate the processes by which the initially unfueled kernel evolves into a self-sustained flame. Three fuels are examined: a conventional Jet-A and two synthesized fuels that are used to explore fuel composition effects. A commercial, high-energy recessed cavity discharge igniter located at the test section wall ejects kernels at 15 Hz into a preheated, striated crossflow. Next to the igniter wall is an unfueled air flow; above this is a premixed, prevaporized, fuel-air flow, with a matched velocity and an equivalence ratio near 0.75. The fuels are prevaporized in order to isolate chemical effects. Differences in early ignition kernel development are explored using three, synchronized, high-speed imaging diagnostics: schlieren, emission/chemiluminescence, and OH planar laser-induced fluorescence (PLIF). The schlieren images reveal rapid entrainment of crossflow fluid into the kernel. The PLIF and emission images suggest chemical reactions between the hot kernel and the entrained fuel-air mixture start within tens of microseconds after the kernel begins entraining fuel, with some heat release possibly occurring. Initially, dilution cooling of the kernel appears to outweigh whatever heat release occurs; so whether the kernel leads to successful ignition or not, the reaction rate and the spatial extent of the reacting region decrease significantly with time. During a successful ignition event, small regions of the reacting kernel survive this dilution and are able to transition into a self-sustained flame after ∼1–2 ms. The low aromatic/low cetane number fuel, which also has the lowest ignition probability, takes much longer for the reaction zone to grow after the initial decay. The high aromatic, more easily ignited fuel, shows the largest reaction region at early times.

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