Wing Ng

Virginia Tech (Virginia Polytechnic Institute and State University) | VT · Department of Mechanical Engineering

Vortex tube separator (VTS) arrays are used to filter foreign particles from turboshaft engine intakes. Arrays may consist of hundreds of separators that share a common surrounding plenum, potentially allowing for significant interactions between the devices. However, most VTS studies have been limited to individual separators acting alone. The cur...

An acoustic time of flight sensor is operated across a turbofan exhaust plume and is calibrated to provide nozzle thrust in a ground-test cell. Such a sensor could potentially be used to monitor any degradation of engine performance in an on-wing application. Validation of the technique was performed on an AE3007-A1E turbofan engine. Using a pneuma...

Although the thermal-barrier coating (TBC) can protect the gas turbine components from the hot mainstream gas, it's not uncommon that the TBC partially blocks the film cooling holes during the spraying process. The film cooling hole blockage will alter the coolant flow behaviors and lead to a significant variation in film cooling performance. In th...

This paper presents a detailed experimental and numerical study on endwall film cooling and vane pressure side surface phantom cooling at simulated realistic gas turbine operating conditions (high inlet freestream turbulence level of 16%, exit Mach number of 0.85 and exit Reynolds number of 1.7×106). The experiment measurements were conducted at Vi...

In this paper, the endwall film cooling and vane pressure side surface phantom cooling performances of a first nozzle guide vane (NGV) with endwall contouring, similar to an industry gas turbine, were experimentally and numerically evaluated at simulated realistic gas turbine operating conditions (high inlet freestream turbulence level of 16 %, exi...

In the current work, the "Venturi seeder" method for nozzle plumes is improved and studied to determine suitability for particle image velocimetry. This seeding method involves independently pressurizing the primary flow path and a separate seed liquid reservoir, connecting them at the throat of a Venturi contraction upstream of the nozzle. The pre...

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 ups...

A misalignment between the combustor exit and the nozzle guide vane (NGV) platform commonly exists due to manufacturing tolerances and thermal transience. This study investigated, experimentally and computationally, the effect of the combustor-turbine misalignment on the heat transfer for an axisymmetric converging endwall with a jet purge cooling...

In this paper, a detailed numerical investigation on the endwall film cooling and vane pressure side surface phantom cooling was performed, at the simulated realistic gas turbine operating conditions (high inlet freestream turbulence level of 16 %, exit Mach number of 0.85 and exit Reynolds number of 1.7×106). Based on a double coolant temperature...

Detailed experimental and numerical studies on endwall heat transfer and cooling performance with coolant injection flow through upstream discrete holes is presented in this paper. High resolution heat transfer coefficient (HTC) and adiabatic film cooling effectiveness values were measured using a transient infrared thermography technique on an axi...

Large-scale turbulent structures can be correlated over many jet diameters, and thus, a large field of view measurement resolved in time and space is desired to link their evolution to aeroacoustic noise production. This work describes the development and demonstration of a novel time-resolved Doppler global velocimetry system capable of spatially...

View Video Presentation: https://doi.org/10.2514/6.2021-3476.vid An acoustic time-of-flight sensor is operated across a turbofan exhaust plume, and is calibrated to provide nozzle thrust in a ground test cell. Validation of the technique was performed on an AE3007-A1E turbofan engine at a Rolls-Royce facility in Indianapolis. Using a pneumatic horn...

It is shown that aerosolized fluorescent particles generated using a Venturi-type atomizer, from a solution of fluorescent Kiton Red 620 dye in a water/glycol fluid, provide effective flow seeding for fluorescent PIV. The atomized liquid particles were found to be of acceptable size for PIV purposes, with 92% of detected particles by number concent...

Wake-ingesting propellers are attractive for low-speed propulsion due to their potential fuel savings and aircraft configuration benefits. Aeroacoustic concerns must be addressed for such installed pusher-propeller configurations, though limited validation of reduced-order models has constrained designers who require rapid and accurate predictions...

The present paper focuses on the resilience of 3-hole pressure probes to hot sand fouling in turbomachinery environments. These probes are utilized inside jet engine hot sections for diagnostics and flow characterization. Ingestion of sand and other particulates pose a significant risk to hot section components and measurement devices in gas turbin...

The ability to scale the field of view for velocimetry methods is particularly attractive for aeroacoustics studies, where turbulence contributions in long-lived, low wavenumber structures account for the most important sources of radiated noise. Thanks to its core operating principles, Doppler global velocimetry (DGV) offers interesting opportunit...

Doppler global velocimetry has shown promising ability to resolve flow fields in time and space, although achieving both simultaneously has proven to be a challenge for researchers. Large-scale turbulent structures, which dominate noise production in heated and supersonic jets, can be correlated over long axial distances; thus, a large field-of-vie...

NASA tests new launch and reentry vehicle configurations in wind tunnels, where flow visualizations and quantitative flowfield measurements are often desired. Some of these vehicles have rocket motors for propulsion, retro-propulsion, or reaction control. High-pressure air is used to supply these rocket motor plumes. However, it is difficult to mak...

This paper presents a miniature all-sapphire-fiber Fabry-Perot temperature sensor and its evaluation in the exhaust flow of a Honeywell turbofan engine. The sensor demonstrates reliable and fast response as compared to a commercial thermocouple.

In real gas turbine engines, a gap/step interface commonly exits between upstream of the inlet guide vane endwall and combustor, called upstream endwall misalignment, due to the errors of assembly and the thermal expansion. This endwall misalignment, commonly being presented as the gap/step geometry with different heights, has a significant effect...

In gas turbine engines, the first-stage vanes usually suffer harsh incoming flow conditions from the combustor with high pressure, high temperature and high turbulence. The combustor-generated high freestream turbulence and strong secondary flows in a gas turbine vane passage have been reported to augment the endwall thermal load significantly. Thi...

Nozzle guide vane platforms often employ complex cooling schemes to mitigate ever-increasing thermal loads on endwall. Understanding the impact of advanced cooling schemes amid the highly complex three-dimensional secondary flow is vital to engine efficiency and durability. This study analyzes and describes the effect of coolant to mainstream blowi...

Flow fields near the turbine vane endwall region are very complicated due to the presence of highly three-dimensional passage vortices and endwall secondary flows. This makes it challenging for the endwall to be effectively cooled by employing traditional endwall cooling methods, such as impingement cooling combined with local film cooling inside t...

A misalignment between the combustor exit and the nozzle guide vane (NGV) platform commonly exists due to manufacturing tolerances and thermal transience. This study experimentally investigated the effect of the combustor-turbine misalignment on the heat transfer for an axisymmetric converging endwall with a jet purge cooling scheme at transonic co...

This study describes a detailed investigation on the effects that upstream step misalignment and upstream purge film cooling have on the endwall heat transfer for 1st stage nozzle guide vanes in a gas turbine at transonic conditions. Endwall Nusselt number and adiabatic film cooling effectiveness distributions were experimentally measured and compa...

This paper reports a miniature all-sapphire high temperature fiber sensor based on fiber Fabry-Perot interferometer fabricated by femtosecond laser micromachining and CO2 laser welding. The sensor was tested to 1455°C with up to 5.38 nm/°C sensitivity.

High temperature sensor with robust performance, minimum footprint, and fast response is desirable for many applications in extreme environments. This article introduces a miniature high temperature sensor based on fiber Fabry-Perot interferometer. The interferometric cavity is directly fabricated on the tip of a 125 μm single-crystal sapphire fibe...

Recently, there has been increased concern in reducing supersonic jet noise, due in part to stricter community noise standards, renewed interest in supersonic transport over land, and the hearing damaged sustained by Navy personnel operating on the decks of aircraft carriers. In support of this, we propose an examination of the flow and acoustic fi...

It is shown experimentally that thermal nonuniformity can reduce peak supersonic jet noise while keeping static thrust levels equivalent. A thermal nonuniformity is generated by introducing an unheated stream on the centerline of a plenum containing heated air. This axisymmetric arrangement was studied with the hypothesis that the convection and st...

Purpose The purpose of this paper is to present an acoustics-based method for measuring turbofan nozzle exhaust thrust, while assessing the potential of scaling the methods for in-flight measurements. Design/methodology/approach Although many methods proposed for achieving in-flight thrust measurements involve complicated, sensitive and expense in...

Heat transfer experiments were done on a flat plate to study the effect of internal counter-flow backside cooling on adiabatic film cooling effectiveness and heat transfer coefficient. In addition, the effects of density ratio (DR), blowing ratio (BR), diagonal length over diameter (L/D) ratio, and Reynolds number were studied using this new config...

This study describes a detailed investigation on the effects that step misalignment and upstream purge film cooling have on the endwall heat transfer for 1st stage nozzle guide vanes in a land-based power generating gas turbine at transonic conditions. Endwall Nusselt number and adiabatic film cooling effectiveness distributions were experimentally...

The present paper focuses on the resilience of 3-hole pressure probes to hot sand fouling in turbomachinery environments. These probes are utilized inside jet engine hot sections for diagnostics and flow characterization. Ingestion of sand and other particulates pose a significant risk to hot section components and measurement devices in gas turbin...

An experimental investigation of the mean flow and turbulence characteristics of two Mach 1.5 heated jets (one with a uniform temperature profile and another with an offset nonuniform temperature profile) is presented. The thermal nonuniformity is generated by introducing a matched static pressure stream of low-temperature air into the subsonic, co...

Key flow regions linked to jet noise sources are investigated through comparison of convection velocity and turbulence measurements in high speed three-stream nozzles. A time-resolved Doppler global velocimetry (DGV) instrument was applied in the Nozzle Acoustic Test Rig (NATR) at NASA's Aero-Acoustic Propulsion Lab to measure 250 kHz repetition la...

Key flow regions linked to jet noise sources are investigated through comparison of convection velocity and turbulence measurements in high speed three-stream nozzles. A time-resolved Doppler global velocime-try (DGV) instrument was applied in the Nozzle Acoustic Test Rig (NATR) at NASAs Aero-Acoustic Propulsion Lab to measure 250 kHz repetition la...

This paper presents a detailed experimental and numerical study on the effects of upstream step geometry on the endwall secondary flow and heat transfer in a transonic linear turbine vane passage with axisymmetric converging endwalls. The upstream step geometry represents the misalignment between the combustor exit and the nozzle guide vane endwall...

This paper presents a detailed experimental and numerical study on the effects of upstream step geometry on the endwall secondary flow and heat transfer in a transonic linear turbine vane passage with axisymmetric converging endwalls. The upstream step geometry represents the misalignment between the combustor exit and the nozzle guide vane endwall...

Sand & dust ingestion is a critical issue for aero engines as the particles can deposit on surfaces in the hot sections of the engine. These deposits can block cooling holes, damage to components and alter the gas path geometry leading to performance loss and potentially power failure. A number of sand particle deposition models have been developed...

This paper reports exhaust measurements performed using a nonintrusive acoustic technique on a JT15D-1A turbofan research engine. Using multiple streamwise displaced microphones, the integrated exhaust velocity and static temperature were measured simultaneously in engine flows with bypass Mach numbers up to 0.48. A Kiel pressure and K-type thermoc...

Comparison of heat transfer performance of a nonaxisymmetric contoured endwall to a planar baseline endwall in the presence of leakage flow through stator-rotor rim seal interface and mateface gap is reported in this paper. Heat transfer experiments were performed on a high turning turbine airfoil passage at Virginia Tech's transonic blow down casc...

A hot sand model has been developed to predict the rebounding and sticking behavior of environmental particulates in the hot section of a gas turbine. This paper will focus on the sticking part of the model with rebounding effects to be discussed in a future paper. The key element of the model is determining the probability of the particle sticking...

This paper describes studies completed using a quarter-scaled rig to assess the impact of turbine exit swirl angle and strut stagger on a turbine exhaust system consisting of an integral diffuser-collector. Advanced testing methods were applied to ascertain exhaust performance for a range of inlet conditions aerodynamically matched to flow exiting...

Deposition experiments are performed on a Hastelloy-X coupon using Arizona Road Test Dust (ARD). A statistical empirical model of the initial onset of ARD deposits is developed from the experimental data. The initial onset of deposits are a quadratic function of local surface temperature and impact velocity components (normal and tangential). A pro...

This paper presents a detailed study on the effect of misalignment between the combustor exit and the nozzle guide vane endwall. The Nusselt number distribution and augmentation on an axisymmetric converging endwall as well as stage pressure losses were studied using experimental techniques and computational analysis. The analyzed endwall configura...

Deposit formation on turbine hardware in propulsion turbine engines can occur in many arid regions globally. Characterising crystalline deposits on metallic substrates can aid in component resilience and health monitor algorithms during particle ingestion. This study has developed two statistical empirical models for prediction from acquired experi...

Key flow regions linked to noise sources are investigated through comparison of eddy convection velocity and turbulence measurements in three-stream nozzles. A Time-Resolved Doppler Global Velocimetry (TR-DGV) instrument was applied in the Nozzle Acoustic Test Rig (NATR) at NASA's Aero-Acoustic Propulsion Lab (AAPL) to measure convection velocity....

Initial results for the effect of non-uniform temperature exit conditions on supersonic jet plume evolution and near field pressure are presented. The inlet boundary condition for a perfectly expanded Md = 1.5 nozzle was modified by introducing a region on the centerline with total temperature reduced by 10% compared with the TTR = 2.0 flow surroun...

Time-resolved Doppler global velocimetry measurements with a 250 kHz sampling resolution are presented in the plume exhausting from a biconic nozzle operating at its design Mach number of 1.65 in heated and cold flow. New results for cold conditions [total temperature ratio (TTR) of 1] are compared to prior results in the literature. Further, these...

The noise generated by supersonic plumes is of growing concern given the enormous peak noise intensity radiated by tactical aircraft engines. A key component of this noise is the enhanced radiation of mixing noise caused by large scale eddies convecting supersonically relative to the surrounding quiescent medium. As very little data exist for eddy...

In the literature, the application of sonic anemometry has been limited to low subsonic Mach number, near-incompressible flow conditions. To the best of the authors' knowledge, this paper represents the first time a sonic anemometry approach has been used to characterize flow velocity beyond Mach 0.3. Using a high speed jet, flow velocity was measu...

Increased operations of aircraft, both commercial and military in hostile desert environments have increased the risk of micro-sized particle ingestion into engines. The probability of increased sand and dust ingestion results in increased life cycle costs in addition to increased potential for performance loss. Thus, the ability to accurately asse...

A comprehensive experimental investigation was initiated to evaluate the aerodynamic performance of a gas turbine exhaust diffuser/collector for various strut geometries over a range of inlet angle. The test was conducted on a 1/12th scale rig developed for rapid and accurate evaluation of multiple test configurations. The facility was designed to...

Effect of turbine endwall contouring on its aerodynamic performance has been widely studied, but only a few studies are available in the open literature investigating its effect on heat transfer performance; especially at transonic exit Mach number conditions. In this paper, we report a study of effect of contouring on endwall heat transfer perform...

A new Doppler global velocimeter (DGV) for high-speed flow applications was developed for the measurement of eddy convective velocities in supersonic jet flows for aeroacoustic studies. The key technologies for this instrument are spatially resolving, high sensitivity photomultipliers, field programmable gate array (FPGA)-based signal processors an...

A detailed experimental and numerical study has been conducted to investigate the endwall heat transfer characteristics on a nozzle platform that has been misaligned with the combustor exit, resulting in a backward facing step at the nozzle inlet. The study was carried out under transonic engine representative conditions with an exit Mach number of...

Particle ingestion into modern gas turbine engines is known to reduce performance and may damage many primary gas path components through erosion or deposition mechanisms. Many studies have been conducted that evaluate the effects of particulate ingestion in primary and secondary gas path components. However, modern gas turbines have gas path tempe...

Velocimetry measurements were obtained in three-stream jets at the NASA Glenn Research Center Nozzle Acoustics Test Rig (NATR) using the time-resolved Doppler global velocimetry (TR-DGV) technique. These measurements have the potential to afford exceptional frequency response, to 125 kHz bandwidth, in order to study the detailed dynamics of turbule...

Velocimetry measurements were obtained in three-stream jets at the NASA Glenn Research Center Nozzle Acoustics Test Rig using the time-resolved Doppler global velocimetry technique. These measurements afford exceptional frequency response, to 125 kHz bandwidth, in order to study the detailed dynamics of turbulence in developing shear flows. Mean st...

In this article, we describe the use of proper orthogonal decomposition (POD) to investigate how the dominant wake structures of a bluff-body-stabilized turbulent premixed flame are affected by the heat released by the flame itself. The investigation uses a validated large eddy simulation (LES) to simulate the dynamics of the bluff-body's wake (Bla...

An experimental study of the spatial distribution of integral eddy speeds in heated, supersonic free jets is presented. The physics of such jets are of immediate interest to noise-reduction approaches for tactical aircraft jet noise. In these flows, the noise produced has a strong influence from eddy speeds, particularly for radiation in peak noise...

This paper presents the findings of an experimental and numerical investigation on the shock effect on heat transfer coefficient and film-cooling effectiveness. In this study, coolant was injected on the blade surface through a fan-shaped hole in a transonic cascade. The experimental results indicate that on the film-cooled suction surface of the b...