Guillermo Paniagua

Guillermo Paniagua
Purdue University | Purdue · School of Mechanical Engineering

PhD

About

309
Publications
49,249
Reads
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2,462
Citations
Additional affiliations
August 2017 - present
Purdue University
Position
  • Professor
Description
  • Professor in the School of Mechanical Engineering. Courtesy Professor of Aeronautics and Astronautics.
October 2014 - December 2018
von Karman Institute for Fluid Dynamics
Position
  • Professor (Associate)
October 2014 - July 2017
Purdue University
Position
  • Professor
Education
January 1998 - September 2002
Université Libre de Bruxelles, Belgium
Field of study
  • Sciences Appliquées, Turbomachinery
October 1996 - July 1997
von Karman Institute for Fluid Dynamics
Field of study
  • Turbomachinery
September 1990 - September 1996
Escuela Politécnica Superior de Ingeniería, Gijón, Spain
Field of study
  • Electro-Mechanical Engineering

Publications

Publications (309)
Article
This paper details an energy conversion unit for the combined power extraction and thrust increase from high subsonic to hypersonic flows. The energy transfer is achieved through a wavy hub surface that promotes shocks and expansion fans. First, a design procedure and the non-dimensional steady-state performance characteristics (the reduced torque,...
Article
The present manuscript studies the robustness of leading edge blowing for active control of the upstream bow shock and overall aerothermal characteristics of a supersonic airfoil subject to variability in the injection conditions. The injection boundary conditions were considered stochastic and their randomness was propagated to the flow topology a...
Preprint
Full-text available
The physics of shock-boundary layer interactions in a supersonic turbine cascade is investigated through a wall-resolved large eddy simulation. Special attention is given to the characterization of the low-frequency dynamics of the separation bubbles using flow visualization, spectral analysis, space-time cross correlations, and flow modal decompos...
Article
Full-text available
Detonation-based engines offer a potential surge in efficiency for compact thermal power systems. However, these cycles require ad-hoc components adapted to the high outlet velocity from the detonation combustors. This paper presents the design methodology of turbine stages suitable for supersonic inlet conditions and provides a detailed analysis o...
Article
Converging–diverging nozzles are common in rocket engine systems to increase the exhaust velocity and improve thrust performance. In this study, we focused on the acceleration of subsonic burned gas without a structural throat via detonation to realize a simple and compact engine. We developed and tested a rotating detonation engine (RDE) without a...
Article
This paper analyzes the nozzle start-up of the von Kármán Institute Longshot, an impulse hypersonic gun tunnel, using a combination of the Lagrangian L1D code (used to model the initial compression process of the test gas into a reservoir by an inertial piston) and unsteady Reynolds-averaged Navier–Stokes simulations to model the flow expansion thr...
Article
The optimization of non-premixed rotating detonation combustors (RDCs) requires improved understanding of the coupled effects of reactant stratification, fluid property gradients, and complex shock-wave interactions on the detonation wave structure within annular geometries. In the current work, simultaneous orthogonal views of chemiluminescence an...
Conference Paper
Full-text available
View Video Presentation: https://doi.org/10.2514/6.2022-1264.vid Rotating detonation engines (RDEs) have periodic interactions between the incoming fuel/oxidizer stream(s) and the propagating detonation waves in the annulus. Understanding this interaction plays a critical role in the ability to optimize the performance and stability of practical RD...
Chapter
A key enabler to integrate turbines downstream of rotating detonation combustors is the design of an optimal combustor-turbine passage. Precise estimates of fluctuations, losses, and heat loads are required for the turbine design as rotating detonation combustors feature transonic flow with rotating shocks moving at few kilohertz. This paper analyz...
Article
Full-text available
Optical measurements based on fast response Pressure Sensitive Paint (PSP) provide enhanced spatial resolution of the pressure field. This paper presents lifetime PSP at 20 kHz, with precise calibrations, and results from a demonstration in an annular vane cascade. The laser lifetime PSP methodology is first evaluated in a linear wind tunnel with a...
Article
Increased scrutiny on aviation’s environmental footprint has precipitated a dramatic increase in gas turbine technology development, with a focus on engine performance improvements and the reduction of noise and emissions. In a somewhat limited approach, these studies are often performed at the component level and at a single engine operating condi...
Article
The betterment of the turbine performance plays a prime role in all future transportation and energy production systems. Precise uncertainty quantification of experimental measurement of any performance differential is therefore essential for turbine development programs. In this paper, the uncertainty analysis of loss measurements in a high-pressu...
Conference Paper
View Video Presentation: https://doi.org/10.2514/6.2021-2870.vid This paper details the Wall-Resolved Large Eddy Simulations (LES) of a supersonic vane cascade at Mach 2 inflow conditions. The main objective of this work is to investigate the unsteady characteristics of this flow configuration, including the shock-boundary layer interactions, via h...
Conference Paper
Optical measurements based on fast response Pressure Sensitive Paint (PSP) provide enhanced spatial resolution of the pressure field. This paper presents laser lifetime PSP at 20 kHz, with precise calibrations, and results from a demonstration in an annular vane cascade. The laser lifetime PSP methodology is first evaluated in a linear wind tunnel...
Conference Paper
Cycle benefits of rotating detonation engines show up to five percentage points of efficiency gain for low-pressure ratio engines. An optimal integration between the combustor and the turbine needs to be guaranteed to realize this potential gain. The rotating detonation combustor (RDC) exhausts transonic flow with shocks rotating at frequencies ran...
Conference Paper
The betterment of the turbine performance plays a prime role in all future transportation and energy production systems. Precise uncertainty quantification of experimental measurement of any performance differential is therefore essential for turbine development programs. In this paper, the uncertainty analysis of loss measurements in a high-pressu...
Article
Spatio-temporally resolved measurements of temperature using hybrid femtosecond/picosecond rotational coherent anti-Stokes Raman scattering (fs/ps RCARS) are evaluated for characterizing the highly dynamic exhaust flow of a non-premixed hydrogen-air rotating detonation combustor (RDC). The RCARS system utilizes a recently developed kHz-rate probe-p...
Article
The optimization of the turbine tip geometry remains vital to create more efficient and durable engines. Balancing the aerodynamic and thermal aspects, while maintaining mechanical integrity is key to reshape one of the most vulnerable parts of the entire engine. The increasing turbine gas temperatures, combined with the aerodynamically penalizing...
Article
Trailing edge injection enables control of the detached and unsteady flow within the base region. The interaction of the jet with the base region alters the flow topology causing pressure bifurcations at the trailing edge that affect the aerodynamic performance of the system and modify the vortex patterns downstream the body. The purpose of this wo...
Article
The impact of periodic pulsation normal to the flow passage on the heat and momentum transport is studied using direct numerical simulations. The selected test case is the fully developed supersonic turbulent flow at Reynolds numbers R e b = ρ ¯ b U ¯ b δ / μ ¯ wall = 3000 and 6000 and Mach number M c l = U ¯ c l / c ¯ c l ≈ 1.5, bounded by isother...
Article
Blowdown testing offers a cost-effective experimental tool to replicate the aerothermal conditions in numerous high speed systems. The wind tunnel must replicate the inlet operating conditions, while the spatial and time dependent inlet flow conditions should be assessed carefully. This paper provides a design methodology and rules that ensure adeq...
Article
The boundary layer detachment limits compact power plants' operation at moderate Reynolds number in adverse pressure conditions. Flow detachment is promoted by the lack of momentum in the near-wall region when exposed to adverse pressure gradients. Transient flows or periodic flow perturbations may delay or prevent the flow detachment. The present...
Article
Estimating the distribution and magnitude of heat generation within electronics packages is pivotal for thermal packaging design and active thermal management systems. Inverse heat conduction methods can provide estimates using measured temperature profiles acquired using infrared imaging or discrete temperature sensors. However, if the heater loca...
Article
The aerothermal characterization of film cooled geometries is traditionally performed at reduced temperature conditions, which then requires a debatable procedure to scale the convective heat transfer performance to engine conditions. This paper describes an alternative engine-scalable approach, based on Discrete Green's Functions (DGF) to evaluate...
Article
We present a stability-analysis-based optimization approach that minimizes the growth rate of the least stable mode associated with the flow structure governing flow separation. We compare this approach with a classic optimization approach that minimizes an integral function related to pressure loss. We analyze both approaches on a two-dimensional...
Article
Particle Image Velocimetry (PIV) is a well-established technique for determining the flow direction and velocity magnitude of complex flows. This paper presents a methodology for executing this non-intrusive measurement technique to study a scaled-up turbine vane geometry within an annular cascade at engine-relevant conditions. Custom optical tools...
Article
The harnessing of mechanical power from supersonic flows is constrained by physical limitations and substantial aerodynamic losses. Bladeless axial turbines are a viable alternative to extract power in such harsh conditions without restricting the operating conditions. In this paper, we present a shape optimization of the wavy surface of bladeless...
Article
Full-text available
This manuscript presents a detailed characterization of active control of bow shock waves via leading edge injection, including subsonic coolant ejection and the appearance of Coanda effects. The flow phenomena occurring at steady and pulsating flow injection regimes were analyzed using steady and unsteady two-dimensional Reynolds-Averaged Navier S...
Conference Paper
Small Brayton/Joule engines, operating at low pressure ratios, with relatively large gap clearances exhibit poor efficiency. Instead, the development of a small rotating detonation engine holds great promise to offer mankind a sustainable solution for off-grid power generation as well as distributed systems.
Conference Paper
The harnessing of mechanical power from supersonic flows is constrained by physical limitations and substantial aerodynamic losses. Bladeless axial turbines are a viable alternative to extract power in such harsh conditions without restricting the operating conditions. In this paper, we present a shape optimization of the wavy surface of bladeless...
Conference Paper
Incident tolerant turbine design is a major challenge for any turbomachinery designer. High Pressure Turbines experience large aerodynamic losses when operating at reduced massflow and lower RPM. Turbine performance is adversely impacted at positive incidence angles due to shifting of the stagnation point towards the pressure side. This can cause a...
Conference Paper
Particle Image Velocimetry (PIV) is a well-established technique for determining the flow direction and velocity magnitude of complex flows. This paper presents a methodology for executing this non-intrusive measurement technique to study a scaled-up turbine vane geometry within an annular cascade at engine-relevant conditions. Custom optical tools...
Conference Paper
The aerothermal characterization of film cooled geometries is traditionally performed at reduced temperature conditions, which then requires a debatable procedure to scale the convective heat transfer performance to engine conditions. This paper describes an alternative engine-scalable approach, based on Discrete Green’s Functions (DGF) to evaluate...
Article
The flow field in the rotor-stator rim cavity is controlled by both the instantaneous distortion caused by rotor and stator airfoils. Naturally one would then assume that the design of optimal rim seal geometries would require full unsteady turbine stage simulations, that would then require an experimental assessment. This manuscript presents a red...
Article
The internal flow structures of detonation wave were experimentally analyzed in an optically accessible hollow rotating detonation combustor with multiple chamber lengths. The cylindrical RDC has a glass chamber wall, 20 mm in diameter, which allowed us to capture the combustion self-luminescence. A chamber 70 mm in length was first tested using C2...
Article
In this paper, a diffuser is used to integrate a transonic high-pressure turbine with a rotating detonation combustor (RDC). The paper focuses on the required design modifications to the turbine endwalls (EW) to enable high efficiency, while preserving the airfoil blade-to-blade geometry. The main challenge is the stator passage unstarting, due to...
Article
In the past decade, pressure gain combustion research has promised over 10 percentage-points of increase in power plant thermal efficiency. Alas, to realize such potential gain, one must effectively couple the turbine with the detonation combustor, whose exhaust conditions differ substantially from current state of the art gas turbines. This paper...
Article
Solving for temperature profiles given boundary conditions, geometry, and material properties is relatively straightforward given the wealth of analytical and computational techniques available. However, experimentally we often measure temperatures and seek to understand unknown boundary conditions or material properties. This problem is generally...
Article
Acoustic streaming in high-speed compressible channel flow and its impact on heat and momentum transfer is analysed numerically at two different Mach numbers, M_b=0.75 and 1.5, and moderate Reynolds numbers, Re_b=3000 and 6000. An external time-periodic forcing function is implemented to model the effect of acoustic drivers placed on the sidewalls....
Article
In a wide range of fluid machinery, a turbulent boundary layer can be exposed to rapid transients of the freestream conditions. A simplified model of the boundary layer response would provide valuable guidance in understanding these situations in multiple engineering applications. To this end, a turbulent boundary flow, subject to freestream accele...
Article
Gas turbines operate at extreme temperatures and pressures, constraining the use of both optical measurement techniques as well as probes. A strategy to overcome this challenge consists of instrumenting the external part of the engine, with sensors located in a gentler environment, and use numerical inverse methodologies to retrieve the relevant qu...
Article
This research effort is related to the detailed analysis of the temporal evolution of thermal boundary layer(s) under periodic excitations. In the presence of oscillations, the nonlinear interaction leads to the formation of secondary flows, commonly known as acoustic streaming. However, the small spatial scales and the inherent unsteady nature of...
Conference Paper
Full-text available
Investigations of the structure of non-premixed rotating detonation waves and the influence of the fuel-air injection system are presented in this work. A hydrogen-air rotating detonation combustor (RDC) with optical access extending from the oxidizer injection plenum to the exit plane is used. Via intensified high-speed cameras, the structure of p...
Article
An experimental campaign was carried out to investigate the characteristics of the transitional supersonic wake downstream of a single roughness element. Two Mach numbers were tested, 1.6 and 2.3, and two roughness heights, 0.1 mm and 1 mm. Unsteady and steady wall temperature measurements were taken along and across the roughness wake. The spatial...
Conference Paper
Full-text available
In the present study, we use Direct Numerical Simulation to investigate the effect of acoustic streaming on the heat and momentum transfer within a compressible turbulent flow. A fully-developed channel flow at Reynolds number $Re_b=\overline{\rho} U_b \delta/\mu_{w}=3000$ and $M_b=U_b/c_{w}=0.75$ has been chosen as the test case wherein the acoust...
Article
Supersonic inlet flow is usually considered to be detrimental to the performance of turbine systems. This paper demonstrates an effective manner to harness power from supersonic axial inflow without swirl. The bladeless axial turbine allows for power extraction from harsh environments with minimal maintenance costs. In a first step, a baseline blad...
Article
New compact engine architectures such as pressure gain combustion require ad-hoc turbomachinery to ensure an adequate range of operation with high performance. A critical factor for supersonic turbines is to ensure the starting of the flow passages, which limits the flow turning and airfoil thickness. Radial outflow turbines inherently increase the...
Conference Paper
Full-text available
In the base region of airfoils, an unsteady vortex shedding occurs, which is embroiled with the compression and expansion fronts around the trailing edge. This unsteady phenomenon may be tuned using trailing edge ejection, which in turn can yield different modes of operation. These include a Coanda effect under certain flow ejection conditions. The...
Conference Paper
Full-text available
Turbine blade cooling can be exploited to modulate the flow between turbine stages. The current manuscript explores the potential use of base-bleed control, with the aim of reducing the pressure losses in transonic and supersonic turbines, while enhancing the thermal protection along the trailing edge surface. Older research constrained to low Mach...
Conference Paper
The behavioral characteristics of thermal boundary layer dictate the relative efficiency of forced convection heat transfer. This research effort is related to the detailed analysis of the temporal evolution of thermal boundary layer under periodic excitations. In presence of oscillations, a distinct thin Stokes layer is formed inside the attached...
Article
Full-text available
Rapid aerodynamic design and optimization is essential for the development of future turbomachinery. The objective of this work is to demonstrate a methodology from 1D mean-line-design to a full 3D aerodynamic optimization of the turbine stage using a parameterization strategy that requires few parameters. The methodology is tested by designing a h...
Conference Paper
The operation of compact power units at low Reynolds number environments is constrained by the boundary layer detachment in the low pressure turbines stages. Flow separation is prompt by the lack of momentum on the near wall region when exposed to adverse pressure gradients. Transient flow conditions or periodic flow perturbations induced to the ne...
Conference Paper
The supersonic outlet conditions from a rotating detonation combustor exhibit fluctuations in temperature and pressure that exceed 200% of their mean level. Such unsteady conditions will induce a large convective heat loading onto a downstream supersonic turbine. Hence, the precise evaluation of the thermal load to the vane and rotor is essential t...
Conference Paper
Supersonic inlet flow is usually considered to be detrimental to the performance of turbine systems. This paper demonstrates an effective manner to harness power from supersonic axial inflow without swirl. The bladeless axial turbine allows for power extraction from harsh environments with minimal maintenance costs. In a first step, a baseline blad...
Conference Paper
This work aims to provide a technique with which high frequency heat flux measurement data can be acquired in systems with high operational temperatures and high-speed flows with quantifiable and accurate uncertainty estimates. This manuscript presents the detailed calibration and application of an atomic layer thermopile, for heat fluxes with a fr...
Conference Paper
Gas turbines operate at extreme temperatures and pressures, constraining the use of both optical measurement techniques as well as probes. A strategy to overcome this challenge consists of instrumenting the external part of the engine, with sensors located in a gentler environment, and use numerical inverse methodologies to retrieve the relevant qu...
Conference Paper
The optimization of the turbine rotor tip geometry remains a vital opportunity to create more efficient and durable engines. Balancing the aerodynamic and thermal aspects, while maintaining the mechanical integrity is key to reshape one of the most vulnerable and life determining parts of the entire turbine. The ever-increasing turbine gas temperat...
Conference Paper
New compact engine architectures such as pressure gain combustion require ad-hoc turbomachinery to ensure an adequate range of operation with high performance. A critical factor for supersonic turbines is to ensure the starting of the flow passages, which limits the flow turning and airfoil thickness. Radial outflow turbines inherently increase the...
Article
Following three decades of research in short duration facilities, Purdue University has developed an alternative turbine facility in view of the modern technology in computational fluid mechanics, structural analysis, manufacturing, heating, control, and electronics. The proposed turbine facility can operate continuously and also perform transients...
Preprint
Full-text available
Base pressure control is often employed on drag reduction design, but the interaction of the jet with the base region flow topology can generate undesired or uncontrolled flow configurations. The ejected flow can drive pressure bifurcations at the trailing edge, that without a correct optimization can affect the aerodynamic performance of the syste...
Article
Optimal turbine blade tip designs have the potential to enhance aerodynamic performance while reducing the thermal loads on one of the most vulnerable parts of the gas turbine. This paper describes a novel strategy to perform a multi-objective optimization of the tip geometry of a cooled turbine blade. The parameterization strategy generates arbitr...
Article
The behavioural characteristics of thermal boundary layer inception dictate the efficiency of heat exchangers and the operational limits of fluid machinery. The specific time required by the thermal boundary layer to be established is vital to optimize flow control strategies, as well as the thermal management of systems exposed to ephemeral phenom...
Article
The paper presents a detailed numerical investigation of a pulsed detonation combustor (PDC) coupled with a transonic axial turbine stage. The time-resolved numerical analysis includes detailed chemistry to replicate detonation combustion in a stoichiometric hydrogen–air mixture, and it is fully coupled with the turbine stage flow simulation. The P...
Article
The detailed characterization of the thermal boundary layer under periodic fluctuations is vital to improve the performance of cooled turbine airfoils, as well as to assess noise thermal and structural fatigue. In the present contribution, we performed detailed unsteady Reynolds averaged Navier–Stokes (URANS) simulations to investigate wall heat fl...
Article
In this paper, we propose a two-step methodology to evaluate the convective heat flux along the rotor casing using an engine-scalable approach based on discrete Green’s functions . The first step consists in the use of an inverse heat transfer technique to retrieve the heat flux distribution on the shroud inner wall by measuring the temperature of...