scholarly journals КОНСТРУКТИВНО-ТЕХНОЛОГІЧНІ ОСОБЛИВОСТІ МЕТАЛЕВИХ ЛОПАТЕЙ НЕСУЧОГО І РУЛЬОВОГО ГВИНТІВ ВЕРТОЛЬОТА

2020 ◽  
pp. 5-51
Author(s):  
А. Г. Гребеников ◽  
И. А. Воронько ◽  
Ю. В. Дьяченко ◽  
В. В. Коллеров ◽  
И. В. Малков ◽  
...  
Keyword(s):  
Work Experience ◽  
Construction Materials ◽  
Leading Edge ◽  
Aluminum Foil ◽  
Electric Heating ◽  
Parametric Modeling ◽  
Honeycomb Core ◽  
Surface Strengthening ◽  
Aluminum Honeycomb ◽  
Blade Tip

Analysis of the foreign and domestic work experience, manufacturing and operation of the helicopters with metal blades of the main (MR) and tail (TR) rotors is performed. General requirements for the helicopter MR and TR blades design are formulated. Structural arrangement of the helicopter MR metal blade is reviewed, features of the construction materials for the metal blades are noted. Features of the MR and TR metal blades design with the pressed spar and aluminum honeycomb core are given. Parametric modeling technique of the helicopter MR metal blade is presented. The manufacturing rout technology and the method of the surface strengthening of the metal blade tip are presented. The scheme and the manufacturing rout technology of the pressed aluminum spar are given; the geometrical twist features, the surface strengthening and the assembling of the spar with the blade tip are re- viewed. The features of the electric-heating patch bonding on the spar leading edge are shown. Following technological steps of the blade metal rear area manufacturing are reviewed: the rolled aluminum foil degreasing; the aluminum honeycomb structures manufacturing; the aluminum honeycomb core butt milling. The features of the blade rear area assembling and metal blade assembling by bonding in the jig are presented; the content of works outside of the jig for metal blade of the helicopter main rotor is given.

A study of sound sources and unsteady surface pressure in an axial fan

2021 ◽  
pp. 2150267
Author(s):  
Bo Luo ◽  
Wuli Chu ◽  
Song Yan ◽  
Zhengjing Shen ◽  
Haoguang Zhang
Keyword(s):  
Leading Edge ◽  
Noise Spectrum ◽  
Industrial Applications ◽  
Acoustic Analogy ◽  
Dynamics Modeling ◽  
Axial Fan ◽  
Sound Sources ◽  
Recirculating Flow ◽  
Aerodynamic Interaction ◽  
Blade Tip

The noise emitted from an axial fan has become one of the primary concerns for many industrial applications. This paper presents the work to predict the noise generation and investigate sound sources in a low speed axial fan. Computational fluid dynamics modeling is conducted using Scale Adaptive Simulation for the unsteady flow field. The sound predictions by the acoustic analogy are in good agreement with the experimental data. The results from this study show that the aerodynamic interaction between the blades and outlet vanes has a major contribution to the radiated noise spectrum. Two types of sources of narrowband humps are identified in the axial fan. The first is found at the leading edge of the blade tip, which is related to the interaction of coherent flow structures in the blade tip region. The second is found in the vicinity of the blade hub, which can be attributed to the recirculating flow and hub vortex. The noise below the frequency of 1500 Hz is mainly due to the blade-outlet vane aerodynamic interaction, manifested as the tonal sound at BPF and its harmonics, whereas above 1500 Hz the broadband component of sound is mainly related to the turbulent boundary layers.

scholarly journals Ballistic Resistance of Honeycomb Sandwich Panels under In-Plane High-Velocity Impact

2013 ◽  
Vol 2013 ◽  
pp. 1-20 ◽  
Author(s):  
Chang Qi ◽  
Shu Yang ◽  
Dong Wang ◽  
Li-Jun Yang
Keyword(s):  
Structural Parameters ◽  
Sandwich Panels ◽  
Unit Cell ◽  
Dynamic Responses ◽  
Honeycomb Core ◽  
Ballistic Resistance ◽  
Honeycomb Sandwich ◽  
Aluminum Honeycomb ◽  
Parametric Studies ◽  
Nonmonotonic Effects

The dynamic responses of honeycomb sandwich panels (HSPs) subjected to in-plane projectile impact were studied by means of explicit nonlinear finite element simulations using LS-DYNA. The HSPs consisted of two identical aluminum alloy face-sheets and an aluminum honeycomb core featuring three types of unit cell configurations (regular, rectangular-shaped, and reentrant hexagons). The ballistic resistances of HSPs with the three core configurations were first analyzed. It was found that the HSP with the reentrant auxetic honeycomb core has the best ballistic resistance, due to the negative Poisson’s ratio effect of the core. Parametric studies were then carried out to clarify the influences of both macroscopic (face-sheet and core thicknesses, core relative density) and mesoscopic (unit cell angle and size) parameters on the ballistic responses of the auxetic HSPs. Numerical results show that the perforation resistant capabilities of the auxetic HSPs increase as the values of the macroscopic parameters increase. However, the mesoscopic parameters show nonmonotonic effects on the panels' ballistic capacities. The empirical equations for projectile residual velocities were formulated in terms of impact velocity and the structural parameters. It was also found that the blunter projectiles result in higher ballistic limits of the auxetic HSPs.

scholarly journals Effects of Tip Clearance Gap and Exit Mach Number on Turbine Blade Tip and Near-Tip Heat Transfer

2013 ◽  
Author(s):  
K. Anto ◽  
S. Xue ◽  
W. F. Ng ◽  
L. J. Zhang ◽  
H. K. Moon
Keyword(s):  
Heat Transfer ◽  
Mach Number ◽  
Turbine Blade ◽  
Leading Edge ◽  
Suction Side ◽  
Tip Clearance ◽  
Pressure Side ◽  
Engine Blade ◽  
Blade Tip ◽  
Exit Mach Number

This study focuses on local heat transfer characteristics on the tip and near-tip regions of a turbine blade with a flat tip, tested under transonic conditions in a stationary, 2-D linear cascade with high freestream turbulence. The experiments were conducted at the Virginia Tech transonic blow-down wind tunnel facility. The effects of tip clearance and exit Mach number on heat transfer distribution were investigated on the tip surface using a transient infrared thermography technique. In addition, thin film gages were used to study similar effects in heat transfer on the near-tip regions at 94% height based on engine blade span of the pressure and suction sides. Surface oil flow visualizations on the blade tip region were carried-out to shed some light on the leakage flow structure. Experiments were performed at three exit Mach numbers of 0.7, 0.85, and 1.05 for two different tip clearances of 0.9% and 1.8% based on turbine blade span. The exit Mach numbers tested correspond to exit Reynolds numbers of 7.6 × 105, 9.0 × 105, and 1.1 × 106 based on blade true chord. The tests were performed with a high freestream turbulence intensity of 12% at the cascade inlet. Results at 0.85 exit Mach showed that an increase in the tip gap clearance from 0.9% to 1.8% translates into a 3% increase in the average heat transfer coefficients on the blade tip surface. At 0.9% tip clearance, an increase in exit Mach number from 0.85 to 1.05 led to a 39% increase in average heat transfer on the tip. High heat transfer was observed on the blade tip surface near the leading edge, and an increase in the tip clearance gap and exit Mach number augmented this near-leading edge tip heat transfer. At 94% of engine blade height on the suction side near the tip, a peak in heat transfer was observed in all test cases at s/C = 0.66, due to the onset of a downstream leakage vortex, originating from the pressure side. An increase in both the tip gap and exit Mach number resulted in an increase, followed by a decrease in the near-tip suction side heat transfer. On the near-tip pressure side, a slight increase in heat transfer was observed with increased tip gap and exit Mach number. In general, the suction side heat transfer is greater than the pressure side heat transfer, as a result of the suction side leakage vortices.

scholarly journals Influence of Large Relative Tip Clearances for a Micro Radial Fan and Design Guidelines for Increased Efficiency

2020 ◽  
Author(s):  
Patrick H. Wagner ◽  
Jan Van herle ◽  
Lili Gu ◽  
Jürg Schiffmann
Keyword(s):  
Pressure Rise ◽  
Leading Edge ◽  
High Sensitivity ◽  
Design Guidelines ◽  
Tip Clearance ◽  
Small Scale ◽  
Blade Tip ◽  
Dynamics Simulations ◽  
Experimental Findings ◽  
Blade Tip Clearance

Abstract The blade tip clearance loss was studied experimentally and numerically for a micro radial fan with a tip diameter of 19.2mm. Its relative blade tip clearance, i.e., the clearance divided by the blade height of 1.82 mm, was adjusted with different shims. The fan characteristics were experimentally determined for an operation at the nominal rotational speed of 168 krpm with hot air (200 °C). The total-to-total pressure rise and efficiency increased from 49 mbar to 68 mbar and from 53% to 64%, respectively, by reducing the relative tip clearance from 7.7% to the design value of 2.2%. Single and full passage computational fluid dynamics simulations correlate well with these experimental findings. The widely-used Pfleiderer loss correlation with an empirical coefficient of 2.8 fits the numerical simulation and the experiments within +2 efficiency points. The high sensitivity to the tip clearance loss is a result of the design specific speed of 0.80, the highly-backward curved blades (17°), and possibly the low Reynolds number (1 × 105). The authors suggest three main measures to mitigate the blade tip clearance losses for small-scale fans: (1) utilization of high-precision surfaced-grooved gas-bearings to lower the blade tip clearance, (2) a mid-loaded blade design, and (3) an unloaded fan leading edge to reduce the blade tip clearance vortex in the fan passage.

Increasing Inducer Stability and Suction Performance With a Stability Control Device

2018 ◽  
Vol 141 (1) ◽  
Author(s):  
R. Lundgreen ◽  
D. Maynes ◽  
S. Gorrell ◽  
K. Oliphant
Keyword(s):  
Fluid Dynamic ◽  
Leading Edge ◽  
High Energy ◽  
Stability Control ◽  
Control Device ◽  
Design Flow ◽  
Flow Coefficient ◽  
Blade Tip ◽  
Rotordynamic Forces ◽  
Suction Performance

An inducer is used as the first stage of high suction performance pump. It pressurizes the fluid to delay the onset of cavitation, which can adversely affect performance in a centrifugal pump. In this paper, the performance of a water pump inducer has been explored with and without the implementation of a stability control device (SCD). This device is an inlet cover bleed system that removes high-energy fluid near the blade leading edge and reinjects it back upstream. The research was conducted by running multiphase, time-accurate computational fluid dynamic (CFD) simulations at the design flow coefficient and at low, off-design flow coefficients. The suction performance and stability for the same inducer with and without the implementation of the SCD has been explored. An improvement in stability and suction performance was observed when the SCD was implemented. Without the SCD, the inducer developed backflow at the blade tip, which led to rotating cavitation and larger rotordynamic forces. With the SCD, no significant cavitation instabilities developed, and the rotordynamic forces remained small. The lack of cavitation instabilities also allowed the inducer to operate at lower inlet pressures, increasing the suction performance of the inducer.

Study of Sand Particle Trajectories and Erosion Into the First Compression Stage of a Turbofan

2012 ◽  
Vol 134 (5) ◽  
Author(s):  
Adel Ghenaiet
Keyword(s):  
Equations Of Motion ◽  
Leading Edge ◽  
Sand Particle ◽  
The Finite Element Method ◽  
Particle Trajectories ◽  
Compression Stage ◽  
Trailing Edges ◽  
Blade Tip ◽  
Lagrangian Tracking ◽  
Aero Engines

Aero-engines operating in dusty environments are subject to ingestion of erodent particles leading to erosion damage of blades and a permanent drop in performance. This work concerns the study of particle dynamics and erosion of the front compression stage of a commercial turbofan. Particle trajectories simulations used a stochastic Lagrangian tracking code that solves the equations of motion separately from the airflow in a stepwise manner, while the tracking of particles in different cells is based on the finite element method. As the locations of impacts and rates of erosion were predicted, the subsequent geometry deteriorations were assessed. The number of particles, sizes, and initial positions were specified conformed to sand particle distribution (MIL-E5007E, 0-1000 micrometers) and concentrations 50–700 mg/m3. The results show that the IGV blade is mainly eroded over the leading edge and near hub and shroud; also the rotor blade has a noticeable erosion of the leading and trailing edges and a rounding of the blade tip corners, whereas in the diffuser, erosion is shown to spread over the blade surfaces in addition to the leading edge and trailing edge.

Experimental Results From Controlled Blade Tip/Shroud Rubs at Engine Speed

2006 ◽  
Author(s):  
Corso Padova ◽  
Jeffery Barton ◽  
Michael G. Dunn ◽  
Steve Manwaring
Keyword(s):  
Computational Models ◽  
Engine Speed ◽  
Leading Edge ◽  
Experimental Results ◽  
Trailing Edge ◽  
Metal On Metal ◽  
Non Linear ◽  
Blade Tip ◽  
Force Components ◽  
Tip Shroud

Experimental results obtained for an Inconel compressor blade rubbing a steel casing at engine speed are described. Load cell, strain gauge and accelerometer measurements are discussed and then applied to analyze the metal-on-metal interaction resulting from sudden incursions of varying severity, defined by incursion depths ranging from 13 μm to 762 μm (0.0005-in to 0.030-in). The results presented describe the transient dynamics of rotor and casing vibro-impact response at engine operational speed similar to those experienced in flight. Force components at the blade tip in axial and circumferential directions for a rub of moderate incursion depth (140 μm) are compared to those for a severe rub (406 μm). Similar general trends of variation during the metal-to-metal contact are observed. However, in the nearly three-fold higher incursion the maximum incurred circumferential load increases significantly, while the maximum incurred axial load increases much less, demonstrating the non-linear nature of the rub phenomena. Concurrently, the stress magnification on the rubbing blade at root mid-chord, at tip leading edge, and at tip trailing edge is discussed. The results point to the possibility of failure occurring first at the airfoil trailing edge. Such a failure was in fact observed in the most severe rub obtained to date in the laboratory, consistent with field observations. Computational models to analyze the non-linear dynamic response of a rotating beam with periodic pulse loading at the free-end are currently under development and are noted.

Numerical Simulation of Effects of Tip Geometry on the Performance of an Axial Compressor

2012 ◽  
Author(s):  
Hongwei Ma ◽  
Jun Zhang
Keyword(s):  
Mass Flow ◽  
Tangential Force ◽  
Axial Compressor ◽  
Pressure Rise ◽  
Leading Edge ◽  
Suction Side ◽  
Leakage Flow ◽  
Base Line ◽  
Compressor Rotor ◽  
Blade Tip

The purpose of this paper is to investigate numerically the effects of the tip geometry on the performance of an axial compressor rotor. There are three case studies which are compared with the base line tip geometry. 1) baseline (flat tip); 2) Cavity (tip with a cavity); 3) SSQA (suction side squealer tip) and 4) SSQB (modified suction side squealer tip). The case of SSQB is a combination of suction side squealer tip and the cavity tip. From leading edge to 10% chord, the tip has a cavity. From 10% chord to trailing edge, the tip has a suction side squealer. The numerical results of 2) show that the cavity tip leads to lower leakage mass flow and greater loss in tip gap and the rotor passage. The loading near the blade tip is lower than the baseline, thus the tangential force of the blade is lower. It leads to lower pressure rise than the baseline. The performance of the compressor for the tip with cavity is worse than the baseline. The results of 3) show that the higher curvature of the suction side squealer increases the loading of the blade and the tangential blade force. With the suction side squealer tip, the leakage flow experiences two vena contractor thus the mass of the leakage flow is reduced which is benefit for the performance of the compressor. The loss in the tip gap is lower than baseline. The performance is better than the baseline with greater pressure rise of the rotor, smaller leakage mass flow and lower averaged loss. For the case the SSQB, the leakage mass flow is lower than the SSQA and the loss in the tip gap and the rotor passage is greater than SSQA. The performance of the case of the SSQB is worse than the case of SSQA.

Experimental and Numerical Studies on Defect Characteristics During Milling of Aluminum Honeycomb Core

2019 ◽  
Vol 141 (3) ◽  
Author(s):  
Qinglong An ◽  
Jiaqiang Dang ◽  
Weiwei Ming ◽  
Kunxian Qiu ◽  
Ming Chen
Keyword(s):  
Cell Walls ◽  
Surface Defects ◽  
Tensile Deformation ◽  
Optimization Method ◽  
Cutting Process ◽  
Machining Process ◽  
Honeycomb Core ◽  
Machined Surface ◽  
Entrance Angle ◽  
Aluminum Honeycomb

The honeycomb sandwich structure has been widely used in the aerospace industry due to its high specific strength and stiffness. However, the machining defects of the aluminum honeycomb core (AHC) have become the key factor that restricts its application. In this paper, the defects' characteristics including the formation mechanism, distribution characteristic, and cutting process of honeycomb cell walls during AHC milling process were experimentally investigated. Furthermore, using normalized Cockcroft and Latham ductile fracture criterion and Johnson–Cook (JC) constitutive model, the numerical simulation of the AHC machining process was conducted concerning the entrance angle. It is indicated that six categories of milling defects are obtained and the quantity as well as distribution regularity of AHC milling defects are determined by the double effects of both the entrance angle and cutting force. Most of the surface defects of honeycomb materials were found concentrated in three regions, named by zones I–III, in which extruding, shear, and tensile deformation was mainly generated, respectively. Besides, the finite element simulation results also agree well with the experimental findings. Finally, a novel optimization method to avoid defects in the aforementioned regions by controlling the entrance angle of all the honeycomb walls during the cutting process was proposed in this paper. Meanwhile, the optimal control equations of the entrance angle for all cell walls were derived. This method was verified by milling experiments at last and the results showed that the optimization effect was obvious since the quality of the machined surface was greatly improved.

Alstom’s Reconditioning Technologies for Film Cooled Single Crystal (SX) Turbine Blading

2012 ◽  
Author(s):  
Harald Peter Kissel ◽  
Hosam Shahin ◽  
Alexander Stankowski ◽  
Guenter Ambrosy ◽  
Hans Bissig
Keyword(s):  
High Capacity ◽  
Leading Edge ◽  
Repair Process ◽  
Market Demand ◽  
Damage Scenarios ◽  
Automated Production ◽  
Validation Criteria ◽  
Blade Tip ◽  
And Performance ◽  
Production Solutions

Increased availability, reliability and performance combined with reduced maintenance costs are key factors for the success of gas turbine users. Alstom reconditioning answers to this market demand by providing advanced and competitive repair techniques and an increasing broad reconditioning portfolio to its customers. This paper focuses on the reconditioning of film cooled SX components used in the GT24 and GT26 fleet and the latest enabling technologies. The general reconditioning strategy is based on a thorough analysis of the accumulated field experience with SX parts and a controlled, step-wise introduction of new techniques. Taking advantage of the broad interdisciplinary OEM product and design know-how, as well as Alstom’s rich engineering experience in advanced reconditioning, state of the art reconditioning processes have been developed for different damage scenarios for components. This would include the most technically challenging SX “heavy” scope reconditioning. This paper gives an overview about the reconditioning sequence for SX components and some of its key process steps. As an example, the crack braze repair process is described in detail and several novel SX welding techniques for crack repairs, blade tip and temperature controlled leading edge wall thickness restoration are shown. This covers different processes such as TIG welding or laser metal forming (LMF) of SX components. During the last few years, highly automated production solutions and innovative production tools have been implemented, which enable high capacity and consistently high quality of reconditioning. After their successful validation and a limited phase of monitored production, these techniques are applied on rotating and stationary SX turbine parts. Validation criteria and the experience gained during the first years of commercial production and operation in the field will be presented.

Sign in / Sign up

Export Citation Format

Share Document