Inst. Strömungsmechanik und Technische Akustik (ISTA)

195 Items

Recent Submissions
Aeroacoustic noise reduction by application of end plates on wall-mounted finite airfoils

Schneehagen, Erik ; Geyer, Thomas F. ; Sarradj, Ennes ; Moreau, Danielle J. (2021-04-24)

One known method to reduce vortex shedding from the tip of a blade is the use of end plates or winglets. Although the aerodynamic impact of such end plates has been investigated in the past, no studies exist on the effect of such end plates on the far-field noise. The aeroacoustic noise reduction of three different end-plate geometries is experimentally investigated. The end plates are applied ...

Long-term water conservation is fostered by smart meter-based feedback and digital user engagement

Cominola, Andrea ; Giuliani, Matteo ; Andrea Castelletti, Andrea ; Fraternali, Piero ; Gonzalez, Sergio Luis Herrera ; Herrero, Joan Carles Guardiola ; Novak, Jasminko ; Rizzoli, Andrea Emilio (2021-05-07)

Consumption-based feedback has been demonstrated to encourage water conservation behaviors. Smart meters and digital solutions can support customized feedback and reinforce behavioral change. Yet, most of the studies documenting water conservation effects induced by feedback and smart meter data visualization evaluate them in short-term experimental trials only. Here we show that water conserva...

Challenges and procedures for experiments with steady and unsteady model velocities in a water towing tank

Jentzsch, Marvin ; Schmidt, Hanns -Joachim ; Woszidlo, René ; Nayeri, Christian Navid ; Paschereit, Christian Oliver (2021-03-23)

Challenges for steady and unsteady model motion in a large water towing tank and procedures to overcome them are the focus of the presented work. Some challenges are attributed to experiments conducted in water, whereas others are uniquely ascribed to a towing tank facility. Data convergence and outlier detection are studied based on the phase averaged pressure in order to ensure proper data qu...

Switching Action of a Bistable Fluidic Amplifier for Ultrasonic Testing

Schweitzer, Thorge ; Hörmann, Marla ; Bühling, Benjamin ; Bobusch, Bernhard (2021-04-25)

Air-coupled ultrasonic testing is widely used in the industry for the non-destructive testing of compound materials. It provides a fast and efficient way to inspect large concrete civil infrastructures for damage that might lead to catastrophic failure. Due to the large penetration depths required for concrete structures, the use of traditional piezoelectric transducer requires high power elect...

Development of a New Testing Approach for Decentralised Technical Sustainable Drainage Systems

Neupert, Johannes Wolfgang ; Lau, Philipp ; Venghaus, Daniel ; Barjenbruch, Matthias (2021-03-06)

A part of the sustainable drainage systems (SuDS) are used to treat stormwater and must be tested for their hydraulic performance and the removal efficiency to assess serviceability and retention of the pollutants efficacy for in situ use. Current test procedures provide a good basis for laboratory testing SuDS on the test stand. However, the evaluation is not sufficiently representative to com...

Design of a Fluidic Actuator with Independent Frequency and Amplitude Modulation for Control of Swirl Flame Dynamics

Adhikari, Amrit ; Schweitzer, Thorge ; Lückoff, Finn ; Oberleithner, Kilian (2021-03-20)

Fluidic actuators are designed to control the oscillatory helical mode, called a precessing vortex core (PVC), which is often observed in gas turbine combustors. The PVC induces large-scale hydrodynamic coherent structures, which can considerably affect flow and flame dynamics. Therefore, appropriate control of this structure can lead to a more stable and efficient combustion process. Currently...

Adjoint-based optimisation of detonation initiation by a focusing shock wave

Bengoechea, Sergio ; Reiss, Julius ; Lemke, Mathias ; Sesterhenn, Jörn (2021-03-25)

An optimisation study of a shock-wave-focusing geometry is presented in this work. The configuration serves as a reliable and deterministic detonation initiator in a pulsed detonation engine. The combustion chamber consists of a circular pipe with one convergent–divergent axisymmetric nozzle, acting as a focusing device for an incoming shock wave. Geometrical changes are proposed to reduce the ...

Dynamic mode decomposition analysis of rotating detonation waves

Bohon, Myles D. ; Orchini, Alessandro ; Bluemner, Richard ; Paschereit, Christian Oliver ; Gutmark, Ephraim J. (2020-11-03)

A rotating detonation combustor (RDC) is a novel approach to achieving pressure gain combustion. Due to the steady propagation of the detonation wave around the perimeter of the annular combustion chamber, the RDC dynamic behavior is well suited to analysis with reduced-order techniques. For flow fields with such coherent aspects, the dynamic mode decomposition (DMD) has been shown to capture w...

Numerical investigation of detonation initiation by a focusing shock wave

Bengoechea Lozano, Sergio ; Reiss, Julius ; Lemke, Mathias ; Sesterhenn, Jörn (2020-10-06)

This work presents a numerical study of detonation initiation by means of a focusing shock wave. The investigated geometry is a part of a pulsed detonation combustion chamber, consisting of a circular pipe in which the flow is obstructed by a single convergent–divergent axisymmetric nozzle. This obstacle acts as a focusing device for an incoming shock wave, serving as a low-energy detonation in...

Dataset from a microphone arraymeasurement of a rotating fan

Jekosch, Simon ; Sarradj, Ennes (2021-03-31)

The following instruction gives a summary of an microphone array measurement conducted at the TU Berlin in October 2019. The setup consists of a five-bladed fan with a diameter of 800mm and a sunflower array with 63 microphones as well as a laser trigger. The given dataset contains 9 measurement files with different rpm speed and distances between the array and the fan as well as a modified bla...

Akustische Charakterisierung Nanosekunden-gepulster Plasmasequenzen und deren Verwendung zur Regelung thermoakustischer Instabilitäten

Bölke, Olaf (2021)

Um einen effizienten und schadstoffarmen Betrieb moderner Gasturbinen zu ermöglichen, werden diese mit mageren Brennstoff-Luft-Gemischen befeuert. Dabei sind gerade diese mageren Flammen anfällig für thermoakustische Instabilitäten. Bei dieser Kopplung von Druck- und Wärmeschwankungen können im Resonanzfall in der Brennkammer so hohe Schwankungsamplituden erzeugt werden, dass es zur Schädigung ...

Numerical investigation on vortex pump

Song, Yang (2021)

The vortex pump is a kind of impurity pump. Characteristics of vortex pumps are their recessed, semi-open impeller and their enlarged gap between the impeller and the casing. The gap and impeller give the pump a good non-clogging performance. The pump is widely used in transporting sewage water or mixed liquid containing fiber or large particle. However, vortex pumps are relatively inefficient...

Smart Urban Water Networks: Solutions, Trends and Challenges

Di Nardo, Armando ; Boccelli, Dominic L. ; Herrera, Manuel ; Creaco, Enrico ; Cominola, Andrea ; Sitzenfrei, Robert ; Taormina, Riccardo (2021-02-15)

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Implementation and Validation of an Advanced Wind Energy Controller in Aero-Servo-Elastic Simulations Using the Lifting Line Free Vortex Wake Model

Perez-Becker, Sebastian ; Marten, David ; Nayeri, Christian Navid ; Paschereit, Christian Oliver (2021-02-02)

Accurate and reproducible aeroelastic load calculations are indispensable for designing modern multi-MW wind turbines. They are also essential for assessing the load reduction capabilities of advanced wind turbine control strategies. In this paper, we contribute to this topic by introducing the TUB Controller, an advanced open-source wind turbine controller capable of performing full load calcu...

TopCycle: A Novel High Performance and Fuel Flexible Gas Turbine Cycle

Dybe, Simeon ; Bartlett, Michael ; Pålsson, Jens ; Stathopoulos, Panagiotis (2021-01-12)

High pressure humidified cycles can combine high operational flexibility and high thermal efficiency. The current work introduces such a cycle, namely TopCycle, which provides the necessary combustion infrastructure to operate on a wide fuel variety in a steam-rich atmosphere. The cycle configuration is presented in detail, and its operation is exemplified on the basis of simulation results. Op...

Urban Water Consumption at Multiple Spatial and Temporal Scales. A Review of Existing Datasets

Di Mauro, Anna ; Cominola, Andrea ; Castelletti, Andrea ; Di Nardo, Armando (2020-12-28)

Over the last three decades, the increasing development of smart water meter trials and the rise of demand management has fostered the collection of water demand data at increasingly higher spatial and temporal resolutions. Counting these new datasets and more traditional aggregate water demand data, the literature is rich with heterogeneous urban water demand datasets. They are characterized b...

Experimental investigation of the aerodynamic drag of roof-mounted insulators for trains

Tschepe, Jonathan ; Maaß, Jörg-Torsten ; Nayeri, Christian Navid ; Paschereit, Christian Oliver (2020-09-01)

This paper presents the results of experimental investigations on the aerodynamic drag of roof-mounted insulators for use on low- and high-speed trains. Wind tunnel investigations at different Reynolds numbers in the subcritical, critical, and supercritical flow regime were performed, in addition to investigations using wall-mounted cylinders. Furthermore, the impact of insulator sheds made of ...

Determination of the angle of attack on a research wind turbine rotor blade using surface pressure measurements

Soto-Valle, Rodrigo ; Bartholomay, Sirko ; Alber, Jörg ; Manolesos, Marinos ; Nayeri, Christian Navid ; Paschereit, Christian Oliver (2020-12-22)

In this paper, a method to determine the angle of attack on a wind turbine rotor blade using a chordwise pressure distribution measurement was applied. The approach used a reduced number of pressure tap data located close to the blade leading edge. The results were compared with the measurements from three external probes mounted on the blade at different radial positions and with analytical ca...

Aerodynamic effects of Gurney flaps on the rotor blades of a research wind turbine

Alber, Jörg ; Soto-Valle, Rodrigo ; Manolesos, Marinos ; Bartholomay, Sirko ; Nayeri, Christian Navid ; Schönlau, Marvin ; Menzel, Christian ; Paschereit, Christian Oliver ; Twele, Joachim ; Fortmann, Jens (2020-11-26)

This paper investigates the aerodynamic impact of Gurney flaps on a research wind turbine of the Hermann-Föttinger Institute at the Technische Universität Berlin. The rotor radius is 1.5 m, and the blade configurations consist of the clean and the tripped baseline cases, emulating the effects of forced leading-edge transition. The wind tunnel experiments include three operation points based on ...

An extension of the virtual rotating array method using arbitrary microphone configurations for the localization of rotating sound sources

Jekosch, Simon ; Sarradj, Ennes (2020-05-15)

The characterization of rotating aeroacoustic sources using microphone array methods has been proven to be a useful tool. One technique to identify rotating sources is the virtual rotating array method. The method interpolates the pressure time data signals between the microphones in a stationary array to compensate the motion of the rotating sources. One major drawback of the method is the req...