Tom Verstraete

Tom Verstraete
von Karman Institute for Fluid Dynamics · Turbomachinery and Propulsion Departement

About

120
Publications
25,607
Reads
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1,231
Citations
Citations since 2016
55 Research Items
889 Citations
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2016201720182019202020212022050100150
2016201720182019202020212022050100150
Introduction
Tom Verstraete currently works at the von Karman Institute for Fluid Dynamics and is a professor at the university of Ghent. Tom does research in Aeronautical Engineering, Aerospace Engineering and Mechanical Engineering and is mainly interested in the multidisciplinary design optimization of engineering components.

Publications

Publications (120)
Conference Paper
The design of radial compressors is typically a trade-off between peak performance at the design conditions and maintaining a good efficiency over a wide operating range. In the present paper, a gradient-based optimization of the well-known SRV2 radial compressor is presented. The optimization problem is formulated to increase the total-to-total ef...
Conference Paper
The present paper addresses the multi-objective aerodynamic shape optimization of the two-dimensional LS-89 turbine cascade. The objective is to minimize the entropy generation at subsonic and transonic flow conditions while maintaining the same flow turning. Nineteen design variables are used to parametrize the geometry. The optimization problem i...
Conference Paper
Non-axisymmetric endwall profiling offers features to simultaneously mitigate aerodynamic losses and hot gas ingestion in axial turbines. The current paper presents an optimization methodology to generate a contoured surface integrated with real geometrical effects such as blade fillets and a rim seal channel with the aim of achieving higher effici...
Conference Paper
The paper addresses the problem of the design optimization of turbomachinery components while considering the impact of manufacturing uncertainties. Standard optimization procedures evaluate only the component nominal shape, which is altered till the achievement of the project targets. The verification of the influence of the geometrical tolerances...
Conference Paper
The present paper aims to optimize one of the highly loaded, compact, axial compressors investigated by NASA, using modern RANS-based optimization techniques. The NASA rotor 37 blade is used as a starting point and has been approximated by a CAD-based parametrization. Predictions by the RANS solver are compared with experimental and numerical data...
Article
The present paper addresses the multi-objective aerodynamic shape optimization of the two-dimensional LS-89 turbine cascade. The objective is to minimize the entropy generation at subsonic and transonic flow conditions while maintaining the same flow turning. Nineteen design variables are used to parametrize the geometry. The optimization problem i...
Article
A sensitivity calculation using adjoint method has a feature of low calculation cost because sensitivity information of all computational grid points can be calculated by only one numerical simulation. From this feature, it has been utilized as a calculation method of sensitivity information for a gradient-based optimization and this optimization p...
Conference Paper
Design methodologies for axial compressor airfoils have undergone significant changes over the past decades. While inverse design methods have played a significant historical role, today they are mostly replaced by direct methods. Inverse methods do impose either the desired pressure or velocity distribution and search for the corresponding blade p...
Article
Nowadays, as industrial designs are close to their optimal configurations, the challenge lies in the extraction of the last percentages of improvement. This necessitates accurate evaluations of the performance and represents a significant higher computational cost. The present work aims at integrating Large Eddy Simulations in the optimization fram...
Chapter
As design tasks are significantly complexifying over time, engineers seek more often assistance by optimization tools in their daily design task. Those cost-effective tools propose innovative solutions which could not be found intuitively by human designers. However, as more and more freedom is given to the design problem, classical optimization al...
Article
Full-text available
This paper addresses the problem of the design optimization of turbomachinery components under thermo-mechanical constraints, with focus on a radial turbine impeller for turbocharger applications. Typically, turbine components operate at high temperatures and are exposed to important thermal gradients, leading to thermal stresses. Dealing with such...
Chapter
Full-text available
The classic approach in turbomachinery design optimization considers only nominal geometries while manufacturing tolerances are evaluated in post-processing. Without any knowledge about such deviations, the optimizer chooses the solution corresponding to the highest attainable performance. However, such a shape may require tight and expensive toler...
Article
This paper presents a multipoint optimization of the LS89 cascade. The objective of the optimization consists in minimizing the entropy losses generated inside the cascade over a predefined operating range. Two aerodynamic constraints are imposed in order to conserve the same performance as the original cascade. The first constraint is established...
Article
Design processes nowadays rely more and more on automated optimisation methods to shorten the development cycle. Within those optimisation methods, gradient-free ones converge slower but rather to a global optimum, while gradient-based methods converge faster to a local optimum. Quite recently gradient-free methods have been assisted by metamodels...
Article
Full-text available
Kriging is increasingly used in metamodel-assisted design optimization. For expensive simulations; however, one can afford only a few samples to build the Kriging model, which consequently lacks prediction accuracy. We propose a bounded Kriging able to handle optimization problems with a small initial database. During the optimization, the proposed...
Article
Full-text available
This paper presents methods used to perform discrete adjoint gradient evaluations for linear stress and vibration analysis. The methods are implemented within the framework of a discrete adjoint structural solver being developed for multidisciplinary adjoint optimizations of turbomachinery components. The code is differentiated using the algorithmi...
Conference Paper
The design optimization of turbomachinery components has witnessed an increased attention in the last decade and is currently adopted in many companies in the daily design cycle. The adjoint method proves to have the highest potential in this field due to its efficient computation of sensi-tivity derivatives with respect to a large number of design...
Chapter
A computer-aided design (CAD) and adjoint based multipoint optimization of the LS89 high pressure axial turbine vane is presented. The aim is to reduce the entropy generation at both subsonic and transonic flow conditions by means of employing CAD and adjoint based methods during the optimization process. The performance metrics at design and off-d...
Chapter
This work introduces and compares two different CAD-based mesh deformation methods. The methods are used within an adjoint structural shape optimization, which is part of an evolving CAD-based adjoint multidisciplinary optimization framework for turbomachinery components. During an optimization, the CAD geometry is updated at each design iteration,...
Chapter
The pressure loss reduction inside the U-bends of internal cooling channels is of crucial importance to increase the performance of cooling systems of gas turbines. The optimization technique proposed in the present work is based on the continuous adjoint shape method and is implemented in the OpenFOAM open-source framework. The calculated gradient...
Conference Paper
This work presents a 2D optimization of a multi-body turbine vane frame (TVF), a particular configuration that can lead to considerable shortening of the aero-engine shaft as well as weight reduction. Traditionally, the turbine vane frame is used to guide the flow from the high pressure (HP) turbine to the low pressure (LP) turbine. Current designs...
Conference Paper
This paper presents a multidisciplinary adjoint-based design optimization of a turbocharger radial turbine for automotive applications. The aim is to improve the total-to-static efficiency of the turbine while keeping mechanical stresses below a predefined limit. The search for the optimal design is accomplished using an efficient Sequential Quadra...
Conference Paper
This paper presents a constrained multipoint optimization of the LS89 turbine cascade. The objective of the optimization consists in minimizing the entropy losses generated inside the cascade over a predefined operating range. The operating range is bounded by two operating points respectively characterized by a downstream isentropic Mach number of...
Article
The correct prediction of the flow field is of crucial importance to drive numerical optimization to a real improvement of a design. For this purpose, different numerical approaches can be used to study the fluid dynamics characteristics and the performance of the design. In particular, in the present work the Reynolds-averaged Navier–Stokes and la...
Article
Full-text available
This paper presents a gradient-based design optimization of a turbocharger radial turbine for automotive applications. The aim is to improve both the total-to-static efficiency and the moment of inertia of the turbine wheel. The search for the optimal designs is accomplished by a high-fidelity adjoint-based optimization framework using a fast seque...
Article
Full-text available
The design of a full gas turbine is a painstaking process, with many interactions between different physics, components, and engineers. Not surprisingly, this is an effort spanning over many years before a compromise can be found that satisfies all involved engineering disciplines. But can the design cycle not be shortened in this modern age, domin...
Article
Flutter is a long standing issue for fan blades of civil aero-engines and becomes of further concern for modern light-weight designs with increasing fan diameters to reach ultra-high bypass ratios. Accurate flutter prediction is therefore of prime consideration in the design process in order to avoid catastrophic blade failure in operation or expen...
Chapter
Full-text available
Evolutionary Algorithms (EAs) have certain advantages above gradient-based methods when applied to design optimization problems. They do not require the objective function to be continuous, are noise tolerant and capable of finding global optima. EAs methods have however a slow convergence rate to the global optimum resulting in a large number of f...
Book
Innovative optimization and design techniques for modern aircraft (manned or UAV/UCAV) and engine systems aiming at maximum performance in a multidisciplinary context (aerodynamic efficiency, safety, drag, losses, weight, strength, heat fluxes, emission, noise, …), are now rapidly moving from research labs to industrial real and virtual platforms....
Article
Full-text available
The LS89 high pressure axial turbine vane was originally designed and optimized for a downstream isentropic Mach number of 0.9. This profile has been widely used for computational fluid dynamics (CFD) validation in the open literature but very few attempts have been made to improve the already optimized design. This paper presents a sound methodolo...
Conference Paper
This paper presents a single point optimization of the LS89 turbine vane cascade for a downstream isentropic Mach number of 0.9. The objective of the optimization is to minimize the entropy generation through the cascade while maintaining the flow turning of the baseline geometry. The optimization is performed using a hybrid optimization algorithm...
Article
The combined solution of fluid convective and solid conductive heat transfer, known as conjugate heat transfer, is becoming increasingly important for engineering design applications, because it allows for more accurate and reliable predictions compared to single-domain simulations. However, predicting conjugate heat transfer requires a coupled sim...
Preprint
Full-text available
The adjoint method is considered as the most efficient approach to compute gradients with respect to an arbitrary number of design parameters. However, one major challenge of adjoint-based shape optimization methods is the integration into a computer-aided design (CAD) workflow for practical industrial cases. This paper presents an adjoint-based fr...
Conference Paper
The design optimization of turbomachinery components has witnessed an increased attention in last decade, and is currently used in many companies in the daily design cycle. The adjoint method proves to have the highest potential in this field, however, has still two major shortcomings before its full potential can be used: 1) the shape is mainly pa...
Conference Paper
The scope of this work is to perform a single-objective optimization of the high-lift and aft-loaded T2 low pressure turbine blade profile previously designed at the von Karman Institute for Fluid Dynamics (VKI). At correct engine Mach and Reynolds numbers and for a uniform inflow at low turbulence level, a laminar separation bubble occurs in the d...
Article
Full-text available
This paper presents the methodology and results of a design optimization of a single stage, axial compressor. At the design point, the compressor achieves a total pressure ratio of 2.33 at a mass-flow rate of 1.11 kg/s. The compressor is part of an electrically powered active high lift system (AHLS) for future civil aircraft. An automated process u...
Conference Paper
Full-text available
Steady state simulations in Computational Fluid Dynamics (CFD), which rely on implicit time integration, are not experiencing great accelerations on GPUs. Moreover, most of the reported acceleration effort concerns solving the linear system of equations while neglecting the acceleration potential of running the entire simulation on the GPU. In this...
Poster
Full-text available
Multi-disciplinary design optimization (MDO) relies heavily on time-consuming simulations with a need for high-performance computing (HPC). Graphics Processing Unit (GPU) are reported to have accelerated applications in many areas. The reported speedups are, however, field-specific, case-dependent, and sometimes contradicting. In this work we aims,...
Article
Full-text available
A computational Fluid Dynamics (CFD) code for steady simulations solves a set of non-linear partial differential equations using an iterative time stepping process, which could follow an explicit or an implicit scheme. On the CPU, the difference between both time stepping methods with respect to stability and performance has been well covered in th...
Article
The prediction of the heat transfer between a fluid and a solid object, known as conjugate heat transfer, is a very common problem in engineering sciences. This work investigates coupling methods which allow to solve such problems numerically by using separate solvers for both domains. The methods converge to the conjugate solution by exchanging bo...
Conference Paper
Full-text available
This paper reviews the key research activities and results produced during the AMEDEO (Aerospace Multidisciplinarity-Enabling Design Optimisation) Marie Curie Initial Training Network (ITN). AMEDEO brought together optimisation researchers and practitioners from European universities, research organisations, multinationals and SMEs to develop innov...
Article
This contribution focuses on the conjugate heat transfer computation of a rib-roughened internal turbine blade cooling channel with a blockage ratio of 0.3 and a Reynolds number of 40,000. The work considers the coupling between two numerical tools: a Large Eddy Simulation flow solver and a solid conduction solver. While interested in the thermal s...
Article
Superior rotor tip geometries possess the potential to simultaneously mitigate aerodynamic losses and severe thermal loads onto the rotor overtip region. However, classical design strategies are usually constrained to a specific type of geometry, narrowing the spread of shape topologies considered during the design phase. The current paper presents...
Conference Paper
Modern Lean Burn combustors generate a complex field at the High Pressure turbine (HPT) inlet, characterized by non-uniform velocity and temperature distributions, together with very high turbulence levels (up to 25%). For these extreme conditions, classical numerical methods employed for the HPT design, such as Reynolds Averaged Navier Stokes (RAN...
Conference Paper
The scope of this work is to obtain a deep insight of the occurrence, development and evolution of the laminar separation bubble which occurs on the suction side of the T106-C high-lift low pressure turbine blade operated at correct engine Mach and Reynolds numbers. A set of three different Reynolds numbers was numerically investigated by means of...
Conference Paper
The aim of the present paper is to analyze and discuss in detail the effects of the upstream incoming wakes on both the aerodynamic loading and the evolution of the laminar separation bubble developing along the suction side of the high lift T106-C low pressure turbine blade at engine similar Reynolds and Mach numbers, but at a low free stream turb...
Book
Innovative optimization and design techniques for modern aircraft (manned or UAV/UCAV) and engine systems aiming at maximum performance in a multidisciplinary context (aerodynamic efficiency, safety, drag, losses, weight, strength, heat fluxes, emission, noise, …), are now rapidly moving from research labs to industrial real and virtual platforms....
Conference Paper
Full-text available
Differential Evolution (DE) is a powerful stochastic optimization method. Compared to gradient-based algorithms, DE is able to avoid local minima but requires at the same time more function evaluations. In turbomachinery applications, function evaluations are performed with time-consuming CFD simulation, which results in a long, non affordable, des...
Conference Paper
Composite fan blades are today increasingly used in high bypass ratio aero-engines due to their inherent weight advantage over metallic blades. However, decreased out-of-plane stiffness and reduced mass density increase their susceptibility to flutter. An accurate prediction of this aeroelastic instability therefore becomes a prime consideration in...
Article
In this paper unsteady RANS computations are used to study the inception of rotating stall in a transonic centrifugal compressor taking into account realistic installation effects on performance, as commonly found nowadays due to space limitations. To this end, the effect of an ideal uniform inlet conditions (normally found for long straight inlet)...
Conference Paper
This study considers the optimization of a complex micro-scale cooling geometry that represents a unit-cell of a full heat sink microstructure. The configuration consists of a channel with a rectangular cross section and a hydraulic diameter of 100 μm, where the fluid flows between two cooling fins connected by rectangular crossbars (50 × 50 μm). A...
Article
Internal cooling channels of turbine blades are rib-roughened to increase the heat transfer between the wall and the coolant. A large effort has been made in simulating these flows with Large Eddy Simulations (LES) to have a better understanding of the flow physics. This contribution focuses on the thermal prediction capabilities of LES for such co...
Article
The trailing edge base pressure is known to play a significant role in the profile losses of turbine blades in particular at transonic outlet Mach numbers. Recent tests have shown that the assumption of an isobaric near wake region is wrong because of the highly unsteady character of the near wake flow which affects directly the trailing edge base...
Conference Paper
Superior rotor tip geometries possess the potential to simultaneously mitigate aerodynamic losses and severe thermal loads onto the rotor overtip region. However, classical design strategies are usually constrained to a specific type of geometry, narrowing the spread of shape topologies considered during the design phase. The current paper presents...
Conference Paper
This paper addresses the optimization of a two-dimensional U-bend passage of an internal serpentine cooling channel for reduced total pressure loss by means of a steepest-descent method. A steady-state incompressible flow is considered at a Reynolds number of 40,000 based on the bulk velocity at the domain inlet. The two-equation k-ε model is used...
Conference Paper
A multidisciplinary and multiobjective optimization of a transonic fan blade for a high bypass ratio turbofan engine is presented including aerodynamic as well as structural static and dynamic performance criteria. The optimization strategy applied is based on a two-level approach consisting of a Differential Evolution algorithm coupled to a Krigin...
Conference Paper
Full-text available
Practical cases of design optimization require nowadays a large amount of design evaluations to reach a tiny improvement.These evaluations are computationally expensive. Reducing the computational cost will result in an increased number of evaluations , thus a higher design improvement. In this work a GeForce GTX 780 Nvidia GPU of Kepler generation...
Article
Full-text available
A multi-objective optimisation procedure was applied to the 3D design of a transonic turbine vane row, considering efficiency and stator outlet pressure distortion, which is directly related to the forcing induced in the rotor. The characteristic features that define different individuals along the Pareto Front were described, analysing the differe...
Chapter
Engineers are often challenged by designing new equipment without any prior knowledge or guidance from an existing similar product. The large degree of freedom that this generates can become a bottleneck as it could lead to a loss of global oversight and may even lead to wrong, uninformed choices. It is essential to have a large exploration of the...
Article
Throughflow axial compressor design relies on empirical correlations to estimate the total pressure losses and deviation generated by a blade row. Those correlation data have been obtained with given measurement uncertainties that are usually not taken into account by meridional design tools or throughflow solvers. Uncertainty quantification techni...
Chapter
In this study a centrifugal compressor impeller for an automotive turbocharger was designed by means of an aerodynamic design optimization system composed of an artificial neural network (ANN) and a genetic algorithm (GA). This resulted in two newly designed centrifugal compressor impellers which were further studied both numerically and experiment...
Presentation
In the design and analysis of gas turbines, Computational Fluid Dynamics (CFD) is nowadays widely used to analyze separately components of the engine, employing specialized flow solvers for every component. When the flow in turbine is studied, RANS and URANS approaches are usually employed. On the other hand, when the flow in a combustion chamber i...
Conference Paper
This paper presents the multidisciplinary and multiobjective optimization of a transonic fan blade for a high bypass ratio turbofan engine. Aerodynamic as well as static and dynamic structural performance criteria are considered in the optimization process. A two level optimization strategy is applied consisting of a Differential Evolution algorith...
Conference Paper
Full-text available
Graphics Processing Units (GPUs) are a promising alternative hardware to Central Processing Units (CPU) for accelerating application s with a high computational power demand. In many fields researchers are taking advantage of the high computational power present in GPUs to speed up their application s. These applications span from data mining to ma...