Download or read book Enhanced Design of Turbo jet Lpt by Separation Control Using Phase Plasma Actuators Nasa cr 2003 212294 National Aeronautics and Spac written by United States. National Aeronautics and Space Administration and published by . This book was released on 2003* with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Enhanced Design of Turbo Jet LPT by Separation Control Using Phased Plasma Actuators written by and published by DIANE Publishing. This book was released on 2003 with total page 25 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Enhanced Design of Turbo Jet LPT by Separation Control Using Phased Plasma Actuators written by and published by . This book was released on 2003 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Demonstration of Separation Delay with Glow Discharge Plasma Actuators written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-27 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt: Active flow control of boundary-layer separation using glow-discharge plasma actuators is studied experimentally. Separation is induced on a flat plate installed in a closed-circuit wind tunnel by a shaped insert on the opposite wall. The flow conditions represent flow over the suction surface of a modern low-pressure-turbine airfoil. The Reynolds number, based on wetted plate length and nominal exit velocity, is varied from 50,000 to 300,000, covering cruise to takeoff conditions. Low (0.2 percent) and high (2.5 percent) free-stream turbulence intensities are set using passive grids. A spanwise-oriented phased-plasma-array actuator, fabricated on a printed circuit board, is surface-flush-mounted upstream of the separation point and can provide forcing in a wide frequency range. Static surface pressure measurements and hot-wire anemometry of the base and controlled flows are performed and indicate that the glow-discharge plasma actuator is an effective device for separation control. Hultgren, Lennart S. and Ashpis, David E. Glenn Research Center NASA/TM-2003-212204/REV1, AIAA Paper 2003-1025, E-13807-1/REV1
Download or read book DEMONSTRATION OF SEPARATION DELAY WITH GLOW DISCHARGE PLASMA ACTUATORS NASA TM 2003 212204 NATIONAL AERONAUTICS AND SPACE ADMINISTRAT written by United States. National Aeronautics and Space Administration and published by . This book was released on 2003* with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Low Pressure Turbine Separation Control written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-19 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt: The present work details a computational study, using the Glenn HT code, that analyzes the use of vortex generator jets (VGJs) to control separation on a low-pressure turbine (LPT) blade at low Reynolds numbers. The computational results are also compared with the experimental data for steady VGJs. It is found that the code determines the proper location of the separation point on the suction surface of the baseline blade (without any VGJ) for Reynolds numbers of 50,000 or less. Also, the code finds that the separated region on the suction surface of the blade vanishes with the use of VGJs. However, the separated region and the wake characteristics are not well predicted. The wake width is generally over-predicted while the wake depth is under-predicted. Garg, Vijay K. Glenn Research Center NASA/CR-2002-211689, NAS 1.26:211689, E-13419, GT-2002-30229
Download or read book Control of Flow Separation from the Deflected Flap of a High lift Airfoil Using Multiple Dielectric Barrier Discharge DBD Plasma Actuators written by Kristine L. McElligott and published by . This book was released on 2010 with total page 46 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: In current wing design, multiple flaps are incorporated into the trailing edge to allow mixing of high and low pressure sides to reduce flow separation. These flaps reduce the efficiency by adding weight and complexity to the aircraft. A single hinged flap would reduce these inefficiencies but is more susceptible to flow separation. Active flow control is a means by which the fluid flow over a body is deliberately altered and can be altered such that it becomes less likely to separate from the object. By energizing the flow, the degree of separation of the flow can be controlled, and this inherently controls lift. Dielectric barrier discharge (DBD) plasma actuators are a form of active flow control. These actuators are created by asymmetrically aligning two electrodes and adding a dielectric layer between the electrodes. When the electrodes are electrically connected, ionized air (plasma) travels from the exposed electrode towards the covered electrode. Collisions occur between the plasma and neutral air over the body, and momentum is transferred to the neutral air, effectively energizing it. The purpose of this study is to examine the lift enhancement and flow control authority that multiple DBD plasma actuators have on a high-lift airfoil when compared to the flow exhibited by non-controlled and single DBD plasma actuator controlled cases. Electrodes were mounted onto a simplified NASA Energy Efficient Transport airfoil near the flap. The airfoil was tested in a closed, recirculating wind tunnel operating at a Reynolds number of 240,000, 20° flap deflection angle and 0° degree angle of incidence. The actuators were independently powered in order to determine the most effective input parameters. Using multiple actuators operated in-phase has increased the lift and has delayed flow separation on the trailing edge flap when compared to baseline and single actuation cases.
Download or read book Separation Control Using Plasma Actuators Experimental Studies of Plasma Actuator Performance written by DartKen Poon and published by . This book was released on 2011 with total page 86 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book High lift Airfoil Separation Control with Dielectric Barrier Discharge Plasma Actuators written by Jesse Little and published by . This book was released on 2010 with total page 217 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: This work examines the performance of dielectric barrier discharge (DBD) plasma actuators for controlling separation from the leading edge and trailing edge flap shoulder of a supercritical high-lift airfoil. DBD plasma actuators driven by both typical AC voltages (AC-DBD) and more developmental nanosecond duration pulses (NS-DBD) are investigated. Characterization of the two actuators shows that very different behavior is created when exciting the plasma discharge using these two waveforms. The AC-DBD plasma actuator functions through electrohydrodynamic effects that introduce zero net mass, but nonzero net momentum into the flow. Conversely, the electrohydrodynamic effects of the NS-DBD are quite weak suggesting thermal effects from rapid localized heating by the plasma are responsible for control authority. The performance of both devices as separation control actuators is tested on a high-lift airfoil system. The AC-DBD is effective for controlling turbulent boundary layer separation from a deflected trailing edge flap between Reynolds numbers of 240,000 and 750,000. Momentum coefficients for the AC-DBD plasma actuator are generally an order of magnitude lower than those usually employed for such studies yet control authority is still realized through amplification of natural vortex shedding from the flap shoulder. The corresponding lift enhancement is primarily due to upstream effects from increased circulation around the entire model rather than full separated flow reattachment to the deflected flap surface. Lift enhancement via instability amplification is found to be relatively insensitive to changes in angle of attack provided that the separation location and underlying dynamics do not change. Control authority decreases with increasing Reynolds number and flap deflection highlighting the necessity for further optimization of AC-DBD plasma actuators for use in realistic takeoff and landing transport aircraft applications. As a whole, these findings compare favorably to studies on a similar high-lift platform using piezoelectric driven zero net mass flux actuation. The NS-DBD plasma actuator is ineffective for controlling separation from the deflected trailing edge flap. However, the device is found to be superior to the tested AC-DBD plasma actuators for controlling leading edge separation and rivals the performance of a passive droop by extending the stall angle by six degrees in the Reynolds number range 750,000-1,000,000. Detailed flow diagnostics show the NS-DBD plasma actuator functions as an active trip for pre-stall incidence angles and generates coherent spanwise vortices that entrain freestream momentum into the separated region at post-stall angles. These structures are generated across all surveyed frequencies, but optimal dimensionless frequencies for controlling separation are in the range four to six depending on the incidence angle. The contrasting performance of the NS-DBD plasma actuator at the leading and trailing edge in comparison to the AC-DBD is discussed and recommendations for future work are provided.
Download or read book On the Physics of Flow Separation Along a Low Pressure Turbine Blade Under Unsteady Flow Conditions written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-20 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt: The present study, which is the first of a series of investigations dealing with specific issues of low pressure turbine (LPT) boundary layer aerodynamics, is aimed at providing detailed unsteady boundary flow information to understand the underlying physics of the inception, onset, and extent of the separation zone. A detailed experimental study on the behavior of the separation zone on the suction surface of a highly loaded LPT-blade under periodic unsteady wake flow is presented. Experimental investigations were performed at Texas A&M Turbomachinery Performance and Flow Research Laboratory using a large-scale unsteady turbine cascade research facility with an integrated wake generator and test section unit. To account for a high flow deflection of LPT-cascades at design and off-design operating points, the entire wake generator and test section unit including the traversing system is designed to allow a precise angle adjustment of the cascade relative to the incoming flow. This is done by a hydraulic platform, which simultaneously lifts and rotates the wake generator and test section unit. The unit is then attached to the tunnel exit nozzle with an angular accuracy of better than 0.05 , which is measured electronically. Utilizing a Reynolds number of 110,000 based on the blade suction surface length and the exit velocity, one steady and two different unsteady inlet flowconditions with the corresponding passing frequencies, wake velocities and turbulence intensities are investigated using hot-wire anemometry. In addition to the unsteady boundary layer measurements, blade surface pressure measurements were performed at Re=50,000, 75,000, 100,000, and 125,000 at one steady and two periodic unsteady inlet flow conditions. Detailed unsteady boundary layer measurement identifies the onset and extent of the separation zone as well as its behavior under unsteady wake flow. The results presented in ensemble-averaged and contour plot forms contribute to understanding t
Download or read book Separation Control in Low Pressure Turbines Using Plasma Actuators with Passing Wakes written by Debashish Burman and published by . This book was released on 2013 with total page 170 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Separation Control Using Plasma Actuators in a High Pressure Bend written by Michael J. Arthur and published by . This book was released on 2014 with total page 197 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Robust Nonlinear Feedback Control of Aircraft Propulsion Systems written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-13 with total page 122 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is the final report on the research performed under NASA Glen grant NASA/NAG-3-1975 concerning feedback control of the Pratt & Whitney (PW) STF 952, a twin spool, mixed flow, after burning turbofan engine. The research focussed on the design of linear and gain-scheduled, multivariable inner-loop controllers for the PW turbofan engine using H-infinity and linear, parameter-varying (LPV) control techniques. The nonlinear turbofan engine simulation was provided by PW within the NASA Rocket Engine Transient Simulator (ROCETS) simulation software environment. ROCETS was used to generate linearized models of the turbofan engine for control design and analysis as well as the simulation environment to evaluate the performance and robustness of the controllers. Comparison between the H-infinity, and LPV controllers are made with the baseline multivariable controller and developed by Pratt & Whitney engineers included in the ROCETS simulation. Simulation results indicate that H-infinity and LPV techniques effectively achieve desired response characteristics with minimal cross coupling between commanded values and are very robust to unmodeled dynamics and sensor noise. Garrard, William L. and Balas, Gary J. and Litt, Jonathan (Technical Monitor) Glenn Research Center NAG3-1975
Download or read book Dbd Plasma Actuators for Flow Control in Air Vehicles and Jet Engines written by Nasa Technical Reports Server (Ntrs) and published by BiblioGov. This book was released on 2013-06 with total page 42 pages. Available in PDF, EPUB and Kindle. Book excerpt: The NASA Technical Reports Servcr (NTRS) houses half a million publications that are a valuable means of information to researchers, teachers, students, and the general public. These documents are all aerospace related with much scientific and technical information created or funded by NASA. Some types of documents include conference papers, research reports, meeting papers, journal articles and more. This is one of those documents.
Download or read book A Study on the Requirements for Fast Active Turbine Tip Clearance Control Systems written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-21 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper addresses the requirements of a control system for active turbine tip clearance control in a generic commercial turbofan engine through design and analysis. The control objective is to articulate the shroud in the high pressure turbine section in order to maintain a certain clearance set point given several possible engine transient events. The system must also exhibit reasonable robustness to modeling uncertainties and reasonable noise rejection properties. Two actuators were chosen to fulfill such a requirement, both of which possess different levels of technological readiness: electrohydraulic servovalves and piezoelectric stacks. Identification of design constraints, desired actuator parameters, and actuator limitations are addressed in depth; all of which are intimately tied with the hardware and controller design process. Analytical demonstrations of the performance and robustness characteristics of the two axisymmetric LQG clearance control systems are presented. Takeoff simulation results show that both actuators are capable of maintaining the clearance within acceptable bounds and demonstrate robustness to parameter uncertainty. The present model-based control strategy was employed to demonstrate the tradeoff between performance, control effort, and robustness and to implement optimal state estimation in a noisy engine environment with intent to eliminate ad hoc methods for designing reliable control systems. DeCastro, Jonathan A. and Melcher, Kevin J. Glenn Research Center NASA/TM-2004-213121, E-14615, AIAA Paper 2004-4176
Download or read book DBD Plasma Actuators for Flow Control in Air Vehicles and Jet Engines written by David E. Ashpis and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Plasma Actuators for Turbomachinery Flow Control Final Report written by Richard Bryant Miles and published by . This book was released on 2012 with total page 55 pages. Available in PDF, EPUB and Kindle. Book excerpt:
