Jet Impingement Test Research Articles

Dual-luminophore pressure-sensitive paint measurement using three-gate lifetime method with photodegradation correction.

In this paper, we propose a photodegradation correction method for the dual-luminophore pressure-sensitive paint (PSP) measurement using lifetime-based imaging, which was proposed for correction of the temperature-induced error but has suffered from photodegradation in the previous studies. We introduced a parameter that characterizes the photodegradation of a dual-luminophore PSP as the intensity ratio between the two luminophores. The changes in the calibration coefficients for the pressure and the temperature due to photodegradation were corrected based on this parameter. In this study, a coupon-based calibration test was performed, and the luminescence characteristics of the dual-luminophore PSP including photodegradation were investigated. Then, the proposed method was applied to a coupon-based validation test and a jet impingement test, and the effectiveness of the method was evaluated by comparing results with and without correction. The pressure measurement accuracy was significantly improved by photodegradation correction.

Investigation of the Mechanical Behaviors and Damage Mechanism of C/C Composites Impacted by High-Velocity Jets.

Carbon/Carbon (C/C) composites exhibit excellent mechanical properties at high temperatures, making them widely used in aerospace, such as the leading edges of spaceplane wings and the nose cones of hypersonic aircraft. However, damage caused by rain erosion to C/C composites affects their mechanical properties and poses significant challenges during operational service periods. A jet impingement test platform was employed to conduct single and multiple water-jet erosion tests on three-dimensional orthogonal C/C composite materials and to investigate the residual mechanical properties of the specimens after jet impact. The damage was characterized using optical microscopy, scanning electron microscopy, and X-ray computed tomography. The results showed that the damage types of the C/C composite materials under water-jet impingement included fiber bundle fracturing, delamination, and debonding. The extent of erosion damage was positively correlated with the jet velocity and diameter. The changes in the multi-jet damage indicated a cumulative expansion process, and z-directional fiber bundles exhibited superior resistance to jet impact damage propagation. The results of the three-point bending tests showed that the greater the initial impact damage, the lower the residual mechanical properties of the materials, and the residual strength of the specimen suddenly decreased when damage occurred at the back of the specimen.

Novel Strategy for Thermal Evaluation of Film-Cooled Blades Using Thermographic Phosphors at Simulated Engine Conditions

Abstract Practical strategy for the thermal evaluation of film-cooled blade is of great importance to the gas turbine community. Due to the physical or methodology limitations, it is difficult to evaluate the blade’s thermal performance at simulated engine conditions. The present study proposed novel focal-sweep-based phosphor thermometry for blade cooling inspection. While Mg4FGeO6:Mn (MFG) served as the temperature sensor to quantify the blade temperatures as well as simulated the thermal barrier coating (TBC) effect, the focal sweep method was adopted to overcome the optical constraints in cascade testing. The obtained MFG results of microstructures, jet impingement, and anti-erosion test demonstrated that the MFG phosphor is robust enough to simulate the thermal insulation effect of TBC and can withstand high-speed flow erosion. Furthermore, the proposed strategy clearly captured the blade temperature distributions (mainstream at T0,∞=∼850K) with high spatial resolution, which was then successfully remapped onto the three-dimensional twisted blade. Additional comparisons with the thermocouples demonstrated that the simulated TBC has a thermal insulation effect of about 68 K. This study addressed the common problems of phosphor thermometry in blade cooling evaluation, offering a practical strategy for future thermal diagnostics of the gas turbine.

An improved CFD/experimental combined methodology for the calibration of empirical erosion models

A significant source of uncertainty in CFD-based erosion prediction is represented by the erosion model, used to turn the particle-wall impingement characteristics into an estimate of the removal of material. In engineering computations, frequent use is made of empirical erosion models obtained by fitting the experimental results of air-solid jet impingement tests. However, since the applicability conditions of these models are often unknown or unavailable to the users of CFD codes, they are frequently misapplied, producing not only uncertain, but at times also highly inaccurate wear estimates. As part of his PhD thesis defended at the University of Tulsa in 2016, Amir Mansouri proposed a methodology to calibrate the coefficients of an empirical erosion correlation by combining experimental data and CFD results of a slurry jet impingement test. This methodology provided an effective way to overcome the criticisms of using empirical erosion models taken from the literature without facing the complexity and the high computational burden of a multiscale, physically-based approach, in which the micro-scale mechanical interactions between the particles and the target surface are resolved according to the fundamental laws of damage mechanics. This paper presents an improved formulation of Mansouri's methodology, which not only increases the calibration accuracy of the empirical erosion equation, but also enhances the reliability of the CFD-based erosion prediction model as a whole. To this purpose, numerical simulations were supported by in-house slurry jet impingement experiments on an aluminum sample and curved Glass Reinforced Epoxy samples.

On the Microstructure and Erosion Corrosion Behavior of Laser Processed Nickel Aluminium Bronze

Slurry jet impingement test was carried out on a laser processed nickel aluminium bronze (NAB) and the results are compared with the as-cast NAB. It is observed that the invariably, erosion corrosion rate is increasing with the jet velocity. Also, as the slurry impact angle is increased, the erosion corrosion rate of laser processed and as-cast NAB decreased. The erosion corrosion rate of laser processed sample exhibited 28 % higher erosion resistance as compared to the as-cast NAB. Enhanced surface hardness and fine grain formation due to laser processed are the main reasons for the improvement in the erosion corrosion resistance.

Effects of the precipitation of secondary phases on the erosion-corrosion of 25% Cr duplex stainless steel

This study examined the effect of aging at 850 °C on the precipitation of secondary phases and the resultant erosion-corrosion behavior of 25% Cr duplex stainless steels (DSS). An aging time of 30 min, which led to a ratio of reactivation current to activation current (ir/ia × 100) of ˜1% in a DL-EPR test and a current density of ˜0.8 mA cm−2 at 9 m s−1 in a jet impingement test, is regarded as a boundary aging condition for erosion-corrosion. Further, the current density response of ˜0.8 mA cm−2 can be considered a criterion for the surface depassivation resulting from erosion-corrosion.

CFD study of fluid flow changes with erosion

For the first time, a three dimensional mesh deformation algorithm is used to assess fluid flow changes with erosion. The validation case chosen is the Jet Impingement Test, which was thoroughly analysed in previous works by Hattori et al. (Kenichi Sugiyama and Harada, 2008), Gnanavelu et al. in (Gnanavelu et al., 2009, 2011), Lopez et al. in (Lopez et al., 2015) and Mackenzie et al. in (Mackenzie et al., 2015). Nguyen et al. (2014) showed the formation of a new stagnation area when the wear scar is deep enough by performing a three-dimensional scan of the wear scar after 30 min of jet impingement test. However, in the work developed here, this stagnation area was obtained solely by computational means. The procedure consisted of applying an erosion model in order to obtain a deformed geometry, which, due to the changes in the flow pattern lead to the formation of a new stagnation area. The results as well as the wear scar were compared to the results by Nguyen et al. (2014) showing the same trend. OpenFOAM® was the software chosen for the implementation of the deforming mesh algorithm as well as remeshing of the computational domain after deformation. Different techniques for mesh deformation and approaches to erosion modelling are discussed and a new methodology for erosion calculation including mesh deformation is developed. This new approach is independent of the erosion modelling approach, being applicable to both Eulerian and Lagrangian based equations for erosion calculation. Its different applications such as performance decay in machinery subjected to erosion as well as modelling of natural erosion processes are discussed here.

The effect of sub-models and parameterizations in the simulation of abrasive jet impingement tests

Since experimental erosion testing is rarely feasible in the engineering practice, the estimate of erosion is often performed by numerical simulations. Computational Fluid Dynamics (CFD) codes are often equipped with utilities for wear estimation which rely on a well-established methodology. However, besides requiring stringent assumptions, this methodology involves a number of sub-models and parameterizations which, being difficult to define a priori, are potential sources of uncertainty. The objective of this work is to investigate how the erosion estimates are affected by the different sub-models and parameters of a CFD-based wear prediction model, so that its actual predictive capacity may be established. We referred to the benchmark case of the abrasive jet impingement test which, despite being widely studied both experimentally and numerically, highlights all the issues of impact erosion modelling. A systematic activity of simulation of previous experiments revealed the key role played by some fluid-dynamics related quantities, such as the formulation of the particle equation of motion, besides the erosion model. Moreover, it allowed providing guidelines for increasing the reliability of the estimates.

Development of a Finite Volume Particle Method for 3-D fluid flow simulations

The Finite Volume Particle Method (FVPM) is a meshless method for simulating fluid flows which includes many of the desirable features of mesh-based finite volume methods. FVPM benefits from particle interaction vectors to weight conservative fluxes exchanged between particles. These vectors are equivalent to the intercell area vectors in mesh-based finite volume methods. To compute the interaction vectors, either numerical or exact integration has been used. Numerical integration, based on quadrature rules, is approximate and costly, whereas the exact method, employing a top-hat kernel, is precise and fast. To date, quadrature integration has not been used in 3-D due to its excessive cost and the exact method has been developed only for 2-D computations. In this study, we develop a new 3-D FVPM formulation which features a rectangular top-hat kernel to compute interaction vectors exactly and efficiently. We also introduce a new boundary condition enforcement technique based on a single layer of boundary particles. In this technique, no-slip wall boundary conditions with complex geometries are precisely enforced by overlaying a layer of particles on wall surfaces. Employing AUSM+ for inviscid fluxes, weakly-compressible fluid flow is studied with the proposed method. To achieve more accurate results, the solution can be refined near the wall boundary by splitting the fluid particles. This formulation is validated for lid-driven cavity flow, a moving square and jet impingement test cases.

A mixed Euler–Euler/Euler–Lagrange approach to erosion prediction

Providing quantitative assessment of erosion in the various parts of a piping system is of considerable importance in the oil&gas industry. Field and lab erosion testing are extremely onerous and, for this reason, this task is typically achieved by means of algebraic erosion correlations in conjunction with CFD two-phase models based on the Euler–Lagrange approach for flow computation. However, the high computational burden makes this approach onerous even for relatively simple benchmark cases, and it cannot be actually applied in many practical applications. In this paper, we present an innovative approach to erosion prediction, which relies on the combined use of Euler–Euler and Euler–Lagrange CFD two-phase models. The strength of the proposed approach, compared to the standard practice, resides in its numerical efficiency, arising from the fact that the Lagrangian description of the solid phase is restricted to certain subdomains bounded by the surfaces most vulnerable to erosion. The outcomes of two application cases, namely an abrasive jet impingement test and a simplified model of a needle and seat choke valve, demonstrate that the new approach allows considerable reduction of the computational burden for particle tracking and wear estimation. This will open the way for addressing more complex flows of considerable interest in practical applications, which are actually precluded at present.

Investigation of slurry concentration effects on solid particle erosion rate for an impinging jet

The slurry particle concentration effect on the erosion rate of tool components is a critical factor in the design and maintenance of industrial equipment. The relationship between slurry particle concentration and erosion rate was tested and evaluated at a jet impingement test facility using glass spheres impacting acrylonitrile butadiene styrene (ABS) coupons. Particle concentration ranged from 4.6% to 22.4% by weight, and three different nozzle standoff heights were used (H/D=3.0, 5.2, and 7.4). The results show the erosion rate is dependent on the slurry concentration and the test duration. Two distinct erosion profiles correlated with changes in erosion rate over the test duration. The transition between the erosion profiles and the change in erosion rate were dependent on the initial test geometry and slurry concentration.

CFD study of Jet Impingement Test erosion using Ansys Fluent® and OpenFOAM®

The initial aim of this study was to compare OpenFoam and Ansys Fluent in order to verify OpenFoam’s Lagrangian Library and erosion capabilities. However, it was found that previous versions of Fluent have been providing wrong results for the discrete phase and the differences with the latest version (Ansys Fluent 15) are shown. A Submerged Jet Impingement Test is an effective method for studying erosion created by solid particles entrained in a liquid. When considering low particle concentrations a Lagrangian modeling of the particulate phase is a reasonable approach. Proper linkage between OpenFOAM’s Lagrangian library and the solver pimpleFoam for incompressible transient flows allows two-phase simulations to be undertaken for comparison with Ansys Fluent with the aim of verifying OpenFoam’s accuracy. Steady state convergence for the fluid flow is first accomplished and the results are compared, confirming a good agreement between the two packages. A transient simulation was then set up and spherical particles incorporated into the fluid flow. An assessment of the two codes’ discrete phase models was carried out, focusing on the differences between impact angles and velocities yielded at the impingement plate’s surface employing a similar strategy to that outlined first by Hattori et al. (2008) and later by Gnanavelu et al. (2009, 2011). In the comparison of OpenFoam with the latest version of Fluent, the main differences between the injection models are highlighted and the coupling possibilities between phases are taken into consideration. Agreement between trends for both impact angles and velocities is satisfactory when the last version of the commercial package is considered and the average discrepancy between numerical values is very low, verifying OpenFoam’s Lagrangian library. Two different Jet Impingement Test configurations are also compared and the differences highlighted.

Thermal-mechanical response of microscale functional film for infrared window

Infrared window in hypersonic missile usually suffers complex aerodynamic force/heat during high-speed flight. A finite element method was adopted to simulate the thermal and stress response of microscale functional film for infrared window under different aerodynamic heats/forces conditions. Temperature and stress distribution were obtained with different heat fluxes. There is almost constant stress distribution along the film thickness except a sudden decrease near the substrate. The maximum stresses are located at the points which are 0.5 mm away from the edges. Different film materials result in different stress values. The temperature and stress in ZrN are larger than those in Y2O3. Besides the numerical simulation, an oxygen propane flame jet impingement test was performed to investigate thermal shock failure of the infrared window. Some place of the window surface has spots damage and some place has line crack damage after thermal shock.

A numerical investigation of a geometry independent integrated method to predict erosion rates in slurry erosion

An erosion prediction method with the objective of determining wear profiles on various geometries due to slurry erosion, based on material wear data acquired from a minimum set of carefully selected laboratory tests and CFD (computational fluid dynamic) simulations has been developed. Data from a single standard laboratory test [Jet Impingement Test on a flat specimen oriented at 90° to an impinging solid suspension (water and sand)] is characterised using CFD to acquire wear data for a range of erosion parameters as a function of position. This data is used to build a wear map for that specific material–abrasive (316L steel-AFS50/70 sand) combination. The accuracy of this method is assessed by predicting wear from further jet impingement tests at 90° but under different flow velocities to that used to build the map and subsequently assessing against experiments. A good correlation between predicted and measured wear was observed. An assessment of two phenomenological wear models (which profess to capture wear characteristics as a function of material properties) and one wear model that captures the above wear map statistically through the use of appropriate fitting functions is made.

An integrated methodology for predicting material wear rates due to erosion

Erosion–corrosion damage within pipelines and associated fluid handling equipment is prevalent in the oil and gas sector and other process industries where solid-laden flows, such as those involved in the processing of oil sands are found. As a first step towards trying to understand the interactions between erosion and corrosion it is important to understand the erosion damage that occurs as a result of solid particle impact on a surface (usually metal). This paper addresses this in relation to transport of fluids in the oil-sands industry. A method for predicting erosion damage has been developed, using a combination of standard laboratory based experiments and Computational Fluid Dynamic (CFD) simulations. This paper provides validation of such an approach: (i) a universal wear map is generated for the material in question using a jet impingement test (JIT) to generate a wear scar. The local wear rate from this is interpreted using a CFD simulation of the test to generate a map giving local wear as a function of particle impact velocity and angle; (ii) a CFD solution is calculated for a series of different erosion configurations giving the particle impact data at each point on the surface. The wear map from the first stage is then used to give the local wear rate. The power of this method is that once a material-specific map has been generated then wear on any geometry can be calculated through the simulation of flow using CFD.

Performance evaluation of some fusion-bonded epoxy coatings under water transmission line conditions

The work presented in this paper deals with the performance evaluation of some fusion-bonded epoxy (FBE) coatings under water transmission line conditions. The work is aimed to evaluate corrosion–erosion behavior of selected FBE coatings in different product waters under simulated water transmission line conditions to find applications in sections of water transmission lines which are subjected to high flow, water hammer or turbulence. Three different FBE coatings, namely, Scotchkote 206 N, NAP-GARD 7–2500, and RESICOAT R4 Blue were considered for the studies. The studies were carried out in treated SWRO (seawater reverse osmosis) permeate and treated and untreated MSF (multistage flash) product water. To generate data about the erosion–corrosion resistance of the coatings under pipelines operating conditions, coated steel panels of fixed dimension were subjected to jet impingement test (JIT). ac impedance tests were carried out on the coated steel samples obtained after subjecting to JIT. The tests were carried out to evaluate qualitatively water uptake by the coatings. Adhesion test was carried out to assess the adhesive strength of the coatings. The monitoring of total organic carbon (TOC) in the test media, before and after subjecting of JIT, was also carried out. The extent of formation of TOC in the test media is indicative of the possible degradation/leaching of coatings under severe JIT conditions. All the three coatings subjected to JIT did not show any impingement damage, loss of adhesion, blistering damage or color changes, thus reflecting their excellent corrosion–erosion property. The effect of residual chlorine concentration on the corrosion–erosion property of the coatings appears to be insignificant. The results of ac impedance showed very high initial impedance for all the three coatings giving them excellent ratings. However, the performances of Scotchkote 206 N and NAP-GARD 7–2500 in treated SWRO permeate was found to be affected after 10 months immersion. The results of TOC monitoring indicated the presence of some organic compounds in the test media possibly due to the degradation/leaching of coatings under severe JIT conditions. The residual chlorine concentration in the test media appears to influence the formation of TOC. Therefore, further studies are needed to establish the safety of the coating from health point of view.

Erosion and corrosion of PSZ-zirconia and the t–m phase transformation

Partially stabilised zirconia (PSZ) has received special attention due to its high strength, high corrosion and erosion resistance, and high resistance to fracture. The phase transformations of ZrO 2 in its application process have long been known to be important. Various physical, hydrothermal, and chemical effects can cause the phase transformations. Although many advances have been made in recent years in the understanding of the effects, foundations and mechanisms of the ZrO 2 phase transformation, however, no study has yet reported on the phase transformation from t-ZrO 2 to m-ZrO 2 in corrosion solution at room temperature. In the present study, both the corrosion resistance of ZrO 2 and the ZrO 2 phase transformation in a corrosive solution (1.5% HF+5% HCl) used in the oil industry to clean downhole pipes were investigated. The erosion behaviours of PSZ-ZrO 2 before and after corrosion have been studied using a SiC/water slurry jet impingement test rig with the aim of providing some information on the material's response to erosion attack. SEM and X-ray were used to characterise the microstructure of the corroded layer, and phase change after corrosion. After corrosion, the peaks of monoclinic structures increase dramatically; ZrCl 4 or ZrF 4 were not detected. By increasing the length of corrosion time, the monoclinic structure is markedly increased. Thus, the corroded layer is the main source contributing to the increase in the monoclinic phase. The possible reaction steps in HF+HCl solution are discussed. The mechanism of t–m phase transformation is discussed in this work. From the thermodynamic viewpoint, a phase structure would tend to transform from the metastable phase to the more stable under the attack of a corrodent, or under impact stress or tensile stress. However, the difference between the two cases is that during the transformation induced by impacting stress, part of the t-ZrO 2 transforms into m-ZrO 2 and microcracks develop, which consume crack propagation energy and release stress concentration, while t–m transformation due to the corrosion process forms a porous m-zirconia layer. Microstructural evaluation as well as chemical analysis shows that the surface structure of PSZ-ZrO 2 changes and becomes more porous during corrosion process, not only due to the t–m phase transformation, in which cracks and voids are anticipated owing to 3%–5% volume change; but also due to the effect of higher corrosion rates of additives in PSZ-ZrO 2 as well. The erosion behaviours of PSZ-ZrO 2 before and after corrosion, using a SiC/water slurry jet, are also compared with other ceramic materials.

Effects of composition and microstructure on the slurry erosion of WC-Co cermets

Cemented carbides of optimum composition and microstructure are the preferred materials for resisting the severe erosion encountered in components handling erosive slurries. They possess an attractive combination of erosion resistance and fracture toughness required for structural reliability. In this paper the results are presented of an investigation of the effects of composition and microstructure of well-characterized WC-Co cermets on their erosion wear as assessed in a slurry jet impingement test. The effects of binder volume fraction and microstructural parameters such as WC grain contiguity and mean carbide grain size are rationalized in terms of a phenomenological analysis of erosion in the two-phase microstructure. Quantitative predictions of the semiempirical analysis are shown to be consistent with the experimental observations.

Jet Impingement Tests

This paper describes the operation of jet impingement test apparatus in the laboratories of The British Non‐Ferrous Metals Research Association in London and at International Nickel Company's Marine Corrosion Test Station at Harbor Island, N. C. Certain differences in results obtained on the same materials in the two laboratories are discussed with relation to differences in testing conditions. Particular attention is given a comparison between results secured with water that is recirculated and used over and over again, as is the practice in the B.N.F.M.R.A. laboratories, with results obtained with water that is passed through the apparatus only once, as has been the regular practice at Harbor Island. Effects of air bubbles, jet velocity, and other incidental factors are also discussed. The relationship between test results and service experience is considered. It is concluded that test conditions established for use in the B.N.F.M.R.A. laboratory, using recirculated water, are too drastic when applied at Harbor Island, using water that is not recirculated, to permit proper comparisons of materials. The testing conditions at Harbor Island can be modified to yield results in harmony with the B.N.F.M.R.A. results either by reducing the jet velocity or by recirculating the water.