# Holger BabinskyUniversity of Cambridge | Cam · Department of Engineering

Holger Babinsky

## About

259

Publications

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4,680

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Citations since 2016

## Publications

Publications (259)

This paper describes the flow about a smooth isolated wheel rolling steadily along a plane surface. The shape chosen is typical of those used for Formula 1 racing cars, and it is fitted with an inflatable tyre to ensure that an appropriate contact patch geometry is realised. Single-pass PIV is used to obtain instantaneous records of the velocity fi...

Wings can experience a large increase in lift when subjected to a high-amplitude transverse gust, which may adversely affect their controllability. This study analyzes the capability of airfoil pitch motions to mitigate such lift spikes. The mitigation pitch kinematics are calculated preemptively from gust velocity measurements using two approaches...

View Video Presentation: https://doi.org/10.2514/6.2022-0699.vid A full-span, 20° compression corner is used to generate a separated, shock-wave/turbulent boundary layer interaction (SBLI) in a rectangular cross-sectioned wind tunnel with a free stream Mach number of 2.5. The experiments are intended to isolate the influence of corner separation-in...

Interactions between vortices and shock waves, which are often encountered in transonic and supersonic flows, can cause the vortices to break down or burst. Experiments aimed at better understanding these interactions are performed in the range Mach 1.3 to Mach 1.5, with a particular focus on obtaining validation-quality reference data. The resulti...

View Video Presentation: https://doi.org/10.2514/6.2022-1181.vid A 20 deg compression corner is used to generate a separated oblique shock wave/turbulent boundary layer interaction in a rectangular cross-sectioned wind tunnel with an incoming Mach number of 2.5. An experimental investigation is conducted to establish the influence of separation in...

View Video Presentation: https://doi.org/10.2514/6.2022-0332.vid A wing travelling at a constant angle of attack, alpha, experiences a large lift spike when subjected to a high-amplitude transverse gust. This study analyses the capability of a low-order model to calculate a pitch profile that mitigates such a lift increase. The simple model makes u...

View Video Presentation: https://doi.org/10.2514/6.2022-1961.vid The effect of serrations applied to the top edge of a winglet on the wingtip vortex is explored experimentally using dye-flow visualisation and stereoscopic particle image velocimetry. The wing is towed in a water tank at a chord-based Reynolds number of 100000 and four different serr...

View Video Presentation: https://doi.org/10.2514/6.2022-1806.vid Experiments investigate the influence of surface geometry and massflow on the fan-plane boundary-layer in a generic transonic engine intake at high-incidence climb. A 2^4 full-factorial Design of Experiments approach explores a wide parameter space of massflow, highlight curvature, cu...

The quadratic constitutive relation was proposed as an extension of minimal complexity to linear eddy-viscosity models in order to improve mean flow predictions by better estimating turbulent stress distributions. However, the successes of this modification have been relatively modest and are limited to improved calculations of flow along streamwis...

The capabilities and limitations of the quadratic constitutive relation in computing streamwise corner flows are investigated using publicly-available data from direct numerical simulations of a square duct flow. The increased accuracy of RANS computations which use the quadratic constitutive relation in corner flows is not due to significantly imp...

Model validation studies are becoming increasingly relevant when investigating complex flow problems in high-speed aerodynamics. This paper presents the lessons learned from the practical aspects of a joint experimental–computational investigation, aimed at validating the quadratic constitutive relation in Mach 2.5 corner flows. Several instructive...

The quadratic constitutive relation is a simple extension to the linear eddy-viscosity hypothesis and has shown some promise in improving the computation of flow along streamwise corner geometries. In order to further investigate these improvements, the quadratic model is validated by comparing RANS simulations of a Mach 2.5 wind tunnel flow with h...

A 20 deg compression corner is used to establish a separated oblique shock wave/turbulent boundary layer interaction in a rectangular cross-sectioned wind tunnel with an incoming Mach number of 2.5. An experimental investigation is conducted to establish the influence of separation in the streamwise corners, formed by the intersection of the workin...

Extreme atmospheric conditions can affect the stability of aerial vehicles that, consequently, require control mechanisms. The study presented in this paper introduces a simple analytical model for the forces on a wing experiencing high-amplitude transverse gusts, which is then applied to determine mitigation strategies. The model is based on the c...

The impulse theory used to calculate the force from a vorticity distribution in two-dimensional, incompressible flow, is re-cast with the aim of estimating the forces generated by a specific flow feature, such as a region of external vorticity passing an object. Specifically, the effect of gust shear layer distortion on the force during a flat plat...

Study of transition location effect (from natural transition to fully turbulent) on separation size, shock structure and unsteadiness was the focus of this WP. Boundary layer tripping (by wire or roughness) and flow control devices (VG) were used for boundary layer transition induction. Although this type of flow field had been studied widely in th...

In order to be able to judge the effectiveness of transition induction in WP-2, reference flow cases were planned in WP-1. There are two obvious reference cases—a fully laminar interaction and a fully turbulent interaction. Here it should be explained that the terms “laminar” and “turbulent” interaction refer to the boundary layer state at the begi...

An important goal of the TFAST project was to study the effect of the location of transition in relation to the shock wave on the separation size, shock structure and unsteadiness of the interaction area. Boundary layer tripping (by wire or roughness) and flow control devices (Vortex Generators and cold plasma) were used for boundary layer transiti...

This book presents experimental and numerical findings on reducing shock-induced separation by applying transition upstream the shock wave. The purpose is to find out how close to the shock wave the transition should be located in order to obtain favorable turbulent boundary layer interaction.
The book shares findings obtained using advanced flow m...

A large variety of gusts that develop in the atmospheric boundary layer affect aerial vehicles. This study, performed in water tow tanks, compares the response of a flat plate wing to transverse vertical gusts with a top-hat and a sine-squared velocity profile at Reynolds numbers of 20,000–30,000. Experiments are performed for a wide range of gust...

The origin of the noncirculatory force arising during a cylinder sharp-edged gust encounter is investigated experimentally at a Reynolds number of 6000. Planar particle image velocimetry and force balance measurements are employed simultaneously to assess the response of a translating cylinder encountering nominal gust ratios of 0.5, 1, and 1.5. Al...

Streamwise-coherent structures were observed in schlieren images of a Mach 2.5 flow in an empty supersonic wind tunnel with a rectangular cross section. These features are studied using Reynolds-averaged Navier–Stokes computations in combination with wind-tunnel experiments. The structures are identified as regions of streamwise vorticity embedded...

The generation of lift is a fundamental problem in aerodynamics and in general in fluid mechanics. The explanations on how lift is generated are often very incomplete or even not correct. Perhaps the most popular explanation of lift is the one with the Bernoulli equation and with the longer path over an airfoil as compared to the path below the air...

Wind tunnel experiments are conducted to investigate the effect of the corner regions of a Mach 2.5 channel flow on the response of the floor boundary layer to an oblique shock. To study this, two different nozzle setups are used, which produce distinct corner boundary layers for the same core flow and floor boundary layer. The setup with a higher-...

The interaction between a normal shock wave and a boundary layer is investigated over a curved surface for a Reynolds number range, based on boundary-layer growing length x, of \(0.44\times 10^6\le \text {Re}_x\le 1.09\times 10^6\). The upstream boundary layer develops around the leading edge of the model before encountering a \(M\) \(\sim \)1.4 no...

The flowfield around five transonic inlet lips at high incidence is investigated for a variety of flow conditions around a design point representative of high-incidence maneuvering. Changes to the operating point are simulated by varying the angle of incidence and the mass flow rate over the lip, which is intended to mimic the effect of an increase...

Added mass characterises the additional force required to accelerate a body when immersed in an ideal fluid. It originates from an asymmetric change to the surrounding pressure field so the fluid velocity satisfies the no-through-flow condition. This is intrinsically linked with the production of boundary vorticity. A body in potential flow may be...

Validation studies are becoming increasingly relevant when investigating complex flow problems in high-speed aerodynamics. These investigations require calibration of numerical models with accurate data from the physical wind tunnel being studied. This paper presents the characterisation process for a joint experimental-computational study to inves...

Experiments on supersonic flows are typically conducted in wind tunnels with either a "full" or the "half" two-dimensional nozzle geometry. The onset and shape of shock-induced separation on the floor are dependent on the size of corner separation and, in turn, the momentum within the corner boundary-layer. This study examines the influence of nozz...

During high-incidence maneuvers, shock-wave/boundary-layer interactions can develop over transonic inlet lower lips, significantly impacting aerodynamic performance. Here, a novel experimental rig is used to investigate the nature and severity of these interactions for a typical high-incidence scenario. Furthermore, the sensitivity to changes in an...

In a rectangular cross-section wind tunnel, a separated oblique shock reflection is set to interact with the turbulent boundary layer (oblique shock wave/turbulent boundary layer interaction (SBLI)) both on the bottom wall and in the corners formed by the intersection of the floor with the sidewalls. To examine how corner separations can affect the...

In supersonic flows, the separation in streamwise corners is a significant and widely encountered problem which can not be reliably predicted with the numerical methods commonly used in industry. The few previous studies on this topic have suggested conflicting corner flow topologies. Experiments of supersonic flow are typically conducted in wind t...

Wind tunnel experiments were conducted to investigate the effect of vortex generators on a transonic corner flow separation, resulting from the interaction of a normal shock wave with a turbulent boundary layer in a duct at M 1.4. The shape of the vortex generators was rectangular. The vortex generators were mounted on the bottom wall of the test s...

Small unmanned aerial vehicles and biological fliers can experience wind gusts of similar magnitude to the flight speed, which is detrimental to flight stability. For one encounter type, the low Reynolds number transverse gust, little is known about the fundamental fluid mechanics due in part to the difficulties in replicating the scenario experime...

This paper address problems that arise when investigating vortices within an unsteady flow when a true picture of the velocity field can only be obtained from single-shot PIV surveys (SS-PIV). The implications of noise within data are considered when it is not legitimate to minimise this by averaging the results from repeated tests. An improvement...

Flat plate experiments investigating flow development downstream of normal shock wave–laminar boundary-layer interactions are reported. Laminarity is desirable for low drag, but problems are expected at shock interactions due to separation, leading to unsteadiness and large boundary-layer growth. A flat plate with elliptical leading edge profile is...

Flat plate experiments investigating flow development downstream of normal shock wave–laminar boundary layer interactions are reported. Laminarity is desirable for low drag, but problems are expected at shock interactions due to separation, leading to un- steadiness and large boundary layer growth. A flat plate with elliptical leading edge profile...

An investigation into the capability of passive porosity to reduce the drag of a bluff-body is presented. This initial work involves integrating varying degrees of porosity into the side and back faces of a small-scale model to determine optimum conditions for maximum drag reduction. Both force and pressure measurements at differing degrees of mode...

This paper discusses the force history and flow topology of accelerating flat-plate wings. The work is a collaborative effort to study fundamental, unsteady low-Reynolds-number flows. The motion kinematics is designed to be relevant to the micro air vehicle flight regime. A combination of experimental and computational techniques is used to obtain...

This paper discusses the force history and flow topology of accelerating flat-plate wings. The work is a collaborative effort to study fundamental, unsteady low-Reynolds-number flows. The motion kinematics is designed to be relevant to the micro air vehicle flight regime. A combination of experimental and computational techniques is used to obtain...

The ready availability of full-field velocity measurements in present-day experiments has kindled interest in using such data for force estimation, especially in situations where direct measurements are difficult. Among the methods proposed, a formulation based on impulse is attractive, for both practical and physical reasons. However, evaluation o...

The ready availability of full-field velocity measurements in present-day experiments has kindled interest in using such data for force estimation, especially in situations where direct measurements are difficult. Among the methods proposed, a formulation based on impulse is attractive, for both practical and physical reasons. However, evaluation o...

© 2017 by the American Institute of Aeronautics and Astronautics, Inc.Many test sections used to study shock wave boundary layer interaction (SBLI) phenomena employ rectangular geometries which exhibit various levels of three-dimensionality in the generated shock structure. Previous studies have suggested the three-dimensional nature to be heavily...

© 2017, American Institute of Aeronautics and Astronautics Inc. All rights reserved.This article presents an experimental investigation into the unsteady force response of a at plate wing when accelerated from rest at 90° incidence to the free stream direction. The work was performed to test a low order model developed by the NATO AVT-202 task grou...

2016, The Author(s).Pitching flat plates are a useful simplification of flapping wings, and their study can provide useful insights into unsteady force generation. Non-circulatory and circulatory lift producing mechanisms for low Reynolds number pitching flat plates are investigated. A series of experiments are designed to measure forces and study...

Pitching flat plates are a useful simplification of flapping wings, and their study can provide useful insights into unsteady force generation. Non-circulatory and circulatory lift producing mechanisms for low Reynolds number pitching flat plates are investigated. A series of experiments are designed to measure forces and study the unsteady flowfie...

The underbody of a truck is responsible for an appreciable portion of the vehicle’s aerodynamic drag, and thus its fuel consumption. A better understanding of the underbody aerodynamics could lead to designs that are more environmentally friendly. Unfortunately there are difficulties with correctly replicating the ground condition and rotating whee...

Transonic aircraft engine intakes can experience incoming flow at high incidence angles, α, where the strong streamline curvature in the lip region can rapidly accelerate flow to supersonic speeds. This creates localised supersonic regions at the tip of the inner intake lip terminated by a normal shock, impacting onto a transitioning boundary layer...

The work here presents an experimental and computational study of a simplified intake bottom lip at incidence. The experiments are carried out in a small-scale blow-downwind tunnel.Computations are carried out in parallel to experiments using an in-house unstructured compressible flow solver. Evaluation of current Reynolds Averaged Navier-Stokes (R...

© 2016, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.This paper describes the investigation into the flow over the lip of subsonic engine intakes at incidence, focusing on the shock wave-boundary layer interaction occurring over the inner lip. A baseline geometry is considered along with two variations, characte...

Three-dimensional shock control bumps have long been investigated for their promising wave drag reduction capability. However, a recently emerging application has been their deployment as "smart" vortex generators, which offset the parasitic drag of their vortices against their wave drag reduction. It is known that three-dimensional shock control b...

The original paper
'How Wings Work' was published in 2003 (Babinsky 2003 Phys. Educ.
38
497). At the time of writing it has been downloaded over 140 000 times and cited 18 times. The abstract states 'The popular explanation of lift is common, quick, sounds logical and gives the correct answer, yet also introduces misconceptions, uses a nonsensica...

The underbody of a truck is responsible for an appreciable portion of the vehicle’s aerodynamic drag, and thus its fuel consumption. This paper investigates experimentally the flow around side-skirts, a common underbody aerodynamic device which is known to be effective at reducing vehicle drag. A full, 1/10 scale European truck model is used. The c...