Replacing Leading-Edge Slats with Active Flow Control
This project is an experimental study to investigate the feasibility of replacing leading-edge slats in aircraft wings with an innovative active flow control (AFC) system. The research focuses on a specific AFC concept called Suction and Oscillatory Blowing (SaOB), which is integrated into the main wing element. The study involves designing and optimizing a wing model using computational fluid dynamics (CFD) simulations, followed by wind tunnel testing to assess the aerodynamic performance and energy efficiency of the SaOB system compared to traditional slats. The findings of this research could pave the way for the development of lighter and more efficient high-lift devices in future aircraft designs.
The study was funded by the Israeli Innovation Authority and was performed in collaboration with Elbit Systems
Road tests of Aerodynamic Drag Reduction System for Heavy Vehicles
This research focused on developing a system to reduce aerodynamic drag on heavy vehicles, which could significantly decrease fuel consumption and environmental impact. Road tests conducted by the lab’s team have demonstrated a combined 17% reduction in fuel consumption for heavy vehicles equipped with a new drag reduction system. The system consists of a passive and active flow control device attached to the rear of the vehicle, designed to mitigate the drag caused by the flat rear surfaces. The device incorporates an Active Flow Control (AFC) system with blowers and suction holes, controlled from inside the vehicle. These findings highlight the potential of this technology to improve the efficiency and sustainability of heavy vehicles.
Distributed Electric Propulsion for Enhanced Aerodynamic Performance
This project investigates the integration of electric motors into airplane wings, a concept known as distributed propulsion. This approach has the potential to reduce drag and increase lift, thereby improving fuel efficiency and decreasing emissions. We employed computational fluid dynamics (CFD) simulations and wind tunnel experiments with a 3D-printed model to assess the impact of motor integration on airflow and overall aircraft performance. Our research aims to contribute to the advancement of greener aviation technologies.
Soft Pneumatic Actuator (SPA)
This Soft Pneumatic Actuator (SPA) device is a flexible, air-filled device that can change its shape to reduce aerodynamic drag on trucks and improve fuel efficiency. It is attached to the back of a truck and can change its shape to improve airflow and reduce drag, which is the force that opposes the truck's movement. Wind tunnel experiments, which simulate real-world driving conditions, have shown that this device can reduce drag by up to 14%. This translates to significant fuel savings for trucking companies and a decrease in harmful emissions.
Space-station free-flying robot
Research was conducted to develop a free-flying drone designed to operate inside the International Space Station (ISS) or other spacecraft. It uses innovative piezoelectric thrusters, which are small, lightweight, and energy-efficient, to move and stabilize itself in microgravity. The drone is equipped with a camera and human-recognition software to track and follow astronauts, assisting them in their tasks. This technology could potentially save valuable astronaut time and improve efficiency in space operations.
ESSS - External Store Support System
The current study is a risk reduction effort in preparation for flight testing AFC for drag reduction using the UH-60 External Stores Support System (ESSS). The ESSS is a set of stub wings that can be installed on to carry external fuel tanks, munitions, mission support equipment or a combination thereof. When installed, the total vehicle drag can increase by as much as 30-50% depending on load configuration. Beyond being a large drag source, the ESSS was chosen as a test bed for this work because its geometry is made up of relatively simple bluff body shapes, its size allows direct wind tunnel testing of the flight hardware, and it is easily removable, which allows much of the systems development and integration to be done without holding up an aircraft. The motivation for this research is not to develop a specific product solution for the UH-60, but rather to expand understanding of complex AFC problems for real full-scale aircraft.
This work is a joint effort between the US Army Aviation Development Directorate (ADD) and the Meadow laboratory of Tel Aviv University (TAU) and the Israel Aerospace Industries (IAI).
INAFLOWT
In the INAFLOWT project, innovative active flow control (AFC) devices were implemented in a swept-wing high-lift configuration at the slat cut-out region. This is done to reduce flow separation in that region, caused by the installation of the highly fuel-efficient Ultra High Bypass Ratio (UHBR) engine nacelle. The project is part of the CleanSky2 initiative which is a joint European-Union effort to enable low-emission technologies to be implemented in commercial aircrafts.
Experimental studies have been carried out in small-scale in the Tel-Aviv Knapp-Meadow wind tunnel and was then followed by large-scale tests in the T-101 wind tunnel in TsAGI, Russia. Results of this study have proven that the implementation of active flow control actuators, in the form of steady suction and pulsed blowing, are indeed a fitting solution to reduce the flow separation problem created by the installation of the Ultra High Bypass Ratio nacelle.
Axisymmetric Body Optimization Using Suction and Blowing
Drag reduction means higher energetic efficiency. An axisymmetric aerodynamic body will be optimized so the target is to achieve a large volume body (allowing to carry more equipment, passengers, armor, etc.) with minimum drag. In addition, the ability of creating form-thrust using zero net mass flux will be examined. Besides the described main goals of the research, a comparison between CFD results and wind tunnel test (WTT) will be made and a target function will be defined and examine. In the end, if results will satisfy, a transform from the axisymmetric body to “conventional” wing design will be made and the possibility of reducing drag and creating form-thrust using AFC system in a wing with the selected design will be checked.
In this research, an aerodynamic body is designed, and an AFC system is incorporated for reducing the drag forces acting upon the body.
The research is composed of both computational fluid dynamic (CFD) simulations and experimental studies to be conducted.
During the study, numerical optimization of an aerodynamic body will be conducted with and without an AFC system, and a comparison between CFD results and wind tunnel test (WTT) will be made.
Water Application of Suction and Oscillatory Blowing (SaOB) actuator
The Suction and Oscillatory Blowing (SaOB) actuator has been widely studied in the air. For the first time, the actuator was adapted and characterized in water with Time-Resolved Particle Image Velocimetry (TRPIV) and pressure transducers. For the past 2 years, it has been studied the implementation of the SaOB actuator for water applications. The fluidic oscillator part of the SaOB actuator was successfully adapted to this fluid, on different scales, for future implementation in hydrodynamic vehicles with the objective to conduct Active Flow Control (AFC) in this fluid. Also, this opens the opportunity of studying the inner flow of the actuator due to the excellent optical clarity to study the flow physics and favorable time scales.
Heavy Vehicles Drag Reduction
The need to reduce the fuel consumption of road vehicles, in particular heavy ones, is an important scientific and technological challenge, due to its economic and environmental impact.
The main goal of this research is to reduce the drag originating at the rear flat edge of the vehicle by mounting a device with an active system in the rear-end of a model.
Our research deals with advanced methods to reduce the fuel consumption of heavy vehicles driving at highway speeds. The research went beyond the currently available methods, that are passive: only modify the shape of the vehicle end.
Our methods are termed “active” in the sense that they use a system of devices that consume energy, but in the overall we have a positive balance of energy due to the large drag reduction.
The model to be used is a light trailer to simulate a trailer truck. We plan to mount on the rear of the trailer a device which uses an active flow control: Steady flow suction, and test its fuel consumption in the open air.
SaOB (Suction and Oscillatory Blowing) Parametric Study
A parametric study is been conducted to find the correlation between the geometric parameters of a Suction and Oscillatory Blowing (SaOB) fluidic oscillator and its performance.
The geometry of the oscillator is composed of 15 dimensions, each one with a different range of values.
The flow in the oscillator was simulated with 2D steady CFD analysis software (ANSYS Fluent). About 100 simulations were done and the main flow features were extracted.
By manipulation of the input parameters and the output parameters, several correlations were discovered. A good correlation was found between the entrainment and the ratio of the primary nozzle throat and the second throat.
The ratio between the length of the diffuser and the height of the second throat was found to correlate to the feedback tube (FBT) pressure difference divided by the minimal pressure difference needed to switch the flow from side to side.
To validate the findings, several configurations were selected for unsteady simulation and for experimental testing. Excellent agreement was found to the oscillator pressure drop and entrainment. Good agreement was found between the oscillation frequency in the unsteady simulation and the experiment. A fair agreement was found in the switching quality parameter which is the ratio of the standard deviation of the flow at the ports to the mean velocity.
Oscillatory Suction Actuator for Boundary Layer Control
An experimental study of a new innovative fluidic device aimed at creating oscillatory suction and oscillatory blowing (OSOB) with no moving parts was conducted, to be used as an actuator for active flow control applications.
Following the previous generation highly successful SaOB (Steady Suction and Oscillatory Blowing) actuator, a new device was developed, with the aim to create both oscillatory suction (compared to steady suction in the SaOB) and oscillatory blowing. The use of unsteady suction has been shown both experimentally (by Morgulis) and theoretically (by Seifert) to be more efficient than its steady counterpart. The new actuator concept is based on the principle of pulsing a pair of ejectors by a single fluidic oscillator.
