scholarly journals Performance Enhancement by Wing Sweep for High-Speed Dynamic Soaring

Aerospace ◽  
2021 ◽  
Vol 8 (8) ◽  
pp. 229
Author(s):  
Gottfried Sachs ◽  
Benedikt Grüter ◽  
Haichao Hong
Keyword(s):  
High Speed ◽  
Degrees Of Freedom ◽  
Performance Enhancement ◽  
Aerodynamic Characteristics ◽  
Progressive Increase ◽  
Maximum Speed ◽  
Horizontal Shear ◽  
Dynamic Soaring ◽  
Speed Performance ◽  
Wing Sweep

Dynamic soaring is a flight mode that uniquely enables high speeds without an engine. This is possible in a horizontal shear wind that comprises a thin layer and a large wind speed. It is shown that the speeds reachable by modern gliders approach the upper subsonic Mach number region where compressibility effects become significant, with the result that the compressibility-related drag rise yields a limitation for the achievable maximum speed. To overcome this limitation, wing sweep is considered an appropriate means. The effect of wing sweep on the relevant aerodynamic characteristics for glider type wings is addressed. A 3-degrees-of-freedom dynamics model and an energy-based model of the vehicle are developed in order to solve the maximum-speed problem with regard to the effect of the compressibility-related drag rise. Analytic solutions are derived so that generally valid results are achieved concerning the effects of wing sweep on the speed performance. Thus, it is shown that the maximum speed achievable with swept wing configurations can be increased. The improvement is small for sweep angles up to around 15 deg and shows a progressive increase thereafter. As a result, wing sweep has potential for enhancing the maximum-speed performance in high-speed dynamic soaring.

scholarly journals ОСОБЛИВОСТІ ЗАБЕЗПЕЧЕННЯ АЕРОДИНАМІЧНИХ ХАРАКТЕРИСТИК РЕГІОНАЛЬНОГО ПАСАЖИРСЬКОГО ЛІТАКА

2019 ◽  
pp. 106-133
Author(s):  
Олександр Дмитрович Донець ◽  
Володимир Олександрович Кудрявцев
Keyword(s):  
High Speed ◽  
Research Work ◽  
Flight Dynamics ◽  
Aerodynamic Characteristics ◽  
Static Stability ◽  
Control Mode ◽  
Aviation Industry ◽  
Maximum Speed ◽  
Flight Tests ◽  
Aerodynamic Configuration

Principal results of the computational and research work performed during development of a regional passenger aircraft to ensure its aerodynamic characteristics are given. When creating the An-148-100/An-158 family of aircraft, such level of the aircraft aerodynamic perfection was achieved, which ensured fulfillment of the specified requirements for their flight performance – maximum speed, cruising flight altitude and flight range with different payloads. The developed aerodynamic configuration made it possible to create a family of regional passenger high-wing planes with a flight speed of up to 870 km/h (true speed) (M = 0.8), which have no analogues in the world aviation industry. Developed for the An-148-100 / An- 158 aircraft, supercritical profiles of the new generation with a large maximum relative thickness formed the basis of the aerodynamic configuration of a high-speed  wing with moderate sweep. The aircraft lift-to-drag ratio in cruise flight is Kcruise = 15.8, which corresponds to the worldwide values. Developed aerodynamic configuration of the wing high-lift devices provides high bearing properties of the wing during take-off and landing stages, which allows to fully meet the requirements for the runway required length of the base airfields Lrun = 1485...1950 m. Developed algorithms are implemented in the electric remote control system and provide necessary standard characteristics of stability, controllability and flight dynamics in the main control mode. Selected margins of the aircraft’s own static stability and effectiveness of its controls ensure safe completion of the flight in standby control mode. The certification flight tests of the An-148-100/An-158 airplanes confirmed full compliance of their take-off and landing performance, as well as the stability, controllability and flight dynamics characteristics with the requirements of the Certification basis in both standard and in failure situations tested in flight tests. Necessary and sufficient amount of experimental work was conducted in the lowspeed  and high-speed wind tunnels of the ANTONOV SC and TsAGI to verify the aerodynamic and spin characteristics of the An-148-100/An-158 airplane models, which improved the aerodynamic configuration of the aircraft and its individual units and allowed to apply the work results in calculation of aircraft strength, as well as for development of their systems.

scholarly journals Trajectory Optimization and Analytic Solutions for High-Speed Dynamic Soaring

Aerospace ◽  
2020 ◽  
Vol 7 (4) ◽  
pp. 47
Author(s):  
Gottfried Sachs ◽  
Benedikt Grüter
Keyword(s):  
Mach Number ◽  
Vehicle Dynamics ◽  
Trajectory Optimization ◽  
High Speed ◽  
Analytic Solutions ◽  
Flight Mechanics ◽  
Maximum Speed ◽  
Dynamic Soaring ◽  
Mechanics Model ◽  
Flight Mode

Dynamic soaring is a non-powered flight mode that enables extremely high speeds by extracting energy from thin shear wind layers. Trajectory optimization is applied to construct solutions of the maximum speed achievable with dynamic soaring and to determine characteristic properties of that flight mode, using appropriate models of the vehicle dynamics and the shear wind layer. Furthermore, an energy-based flight mechanics model of high-speed dynamic soaring is developed, with reference made to trajectory optimization. With this model, analytic solutions for high-speed dynamic soaring are derived. The key factors for the maximum speed performance are identified and their effects are determined. Furthermore, analytic solutions for other, non-performance quantities of significance for high-speed dynamic soaring are derived. The analytic solutions virtually agree with the results achieved with the trajectory optimization using the vehicle dynamics model. This is considered a validation of the energy-based model yielding analytic solutions. The analytical solutions are also valid for the high subsonic Mach number region involving significant compressibility effects. This is of importance for future developments in high-speed dynamic soaring, as modern gliders are now capable of reaching that Mach number region.

scholarly journals Problems of ensuring the acceleration dynamics of aircraft during track tests at a speed of 1600 m/s

2020 ◽  
Vol 12 (S) ◽  
pp. 33-42
Author(s):  
Sergey A. ASTAKHOV ◽  
Vasilii I. BIRIUKOV
Keyword(s):  
Test Object ◽  
High Speed ◽  
Variable Mass ◽  
Aerodynamic Characteristics ◽  
Maximum Speed ◽  
Rocket Engines ◽  
Rail Track ◽  
Hypersonic Aircraft ◽  
Engine Thrust ◽  
Upper Stage

The article discusses the problems that arise when creating new models of supersonic and hypersonic aircraft, which can be solved by model high-speed ground track tests. Mathematical modelling of the aerodynamic characteristics of an aircraft (test object) placed on a rail carriage and accelerated by the solid fuel rocket engines is performed. The numerical method solves the problem of the motion of a body of variable mass along a rail track. To determine the required length of the rail track, a mathematical model of the ballistic characteristics of the upper stage of the rocket carriage was compiled, calculations were made, and the influence of various factors on achieving the maximum speed of the test object was analysed. An analysis is made of the influence of the total mass of the carriage with the load and engine thrust on the possibility of accelerating the test object to the Mach speed (4-5).

Laser Silicon Interaction Study on Ring Oscillators to Establish Temperature Voltage Dependency Trends on 14 nm and Future FinFET Technologies

2017 ◽  
Author(s):  
Gaurav Mattey ◽  
Lava Ranganathan
Keyword(s):  
High Speed ◽  
Laser Frequency ◽  
Ring Oscillator ◽  
Switching Speed ◽  
Dual Nature ◽  
Voltage Imaging ◽  
Multiple Cores ◽  
Speed Performance ◽  
Self Test ◽  
Frequency Changes

Abstract Critical speed path analysis using Dynamic Laser Stimulation (DLS) technique has been an indispensable technology used in the Semiconductor IC industry for identifying process defects, design and layout issues that limit product speed performance. Primarily by injecting heat or injecting photocurrent in the active diffusion of the transistors, the laser either slows down or speeds up the switching speed of transistors, thereby affecting the overall speed performance of the chip and revealing the speed limiting/enhancing circuits. However, recently on Qualcomm Technologies’ 14nm FinFET technology SOC product, the 1340nm laser’s heating characteristic revealed a Vt (threshold voltage) improvement behavior at low operating voltages which helped identify process issues on multiple memory array blocks across multiple cores failing for MBIST (Memory Built-in Self-test). In this paper, we explore the innovative approach of using the laser to study Vt shifts in transistors due to process issues. We also study the laser silicon interactions through scanning the 1340nm thermal laser on silicon and observing frequency shifts in a high-speed Ring Oscillator (RO) on 16nm FinFET technology. This revealed the normal and reverse Temperature Dependency Gate voltages for 16nm FinFET, thereby illustrating the dual nature of stimulation (reducing mobility and improving Vt) from a thermal laser. Frequency mapping through Laser Voltage Imaging (LVI) was performed on the Ring Oscillator (RO) using the 1340nm thermal laser, while concurrently stimulating the transistors of the RO. Spatial distribution of stimulation was studied by observing the frequency changes on LVI.

Efficient Computing in Image Processing and DSPs with ASIP Based Multiplier

2019 ◽  
Vol 13 (2) ◽  
pp. 174-180
Author(s):  
Poonam Sharma ◽  
Ashwani Kumar Dubey ◽  
Ayush Goyal
Keyword(s):  
Image Processing ◽  
High Speed ◽  
Computation Time ◽  
Digital Signal ◽  
Instruction Set ◽  
Computationally Efficient ◽  
Specific Instruction ◽  
Processor Core ◽  
Speed Performance ◽  
Application Specific

Background: With the growing demand of image processing and the use of Digital Signal Processors (DSP), the efficiency of the Multipliers and Accumulators has become a bottleneck to get through. We revised a few patents on an Application Specific Instruction Set Processor (ASIP), where the design considerations are proposed for application-specific computing in an efficient way to enhance the throughput. Objective: The study aims to develop and analyze a computationally efficient method to optimize the speed performance of MAC. Methods: The work presented here proposes the design of an Application Specific Instruction Set Processor, exploiting a Multiplier Accumulator integrated as the dedicated hardware. This MAC is optimized for high-speed performance and is the application-specific part of the processor; here it can be the DSP block of an image processor while a 16-bit Reduced Instruction Set Computer (RISC) processor core gives the flexibility to the design for any computing. The design was emulated on a Xilinx Field Programmable Gate Array (FPGA) and tested for various real-time computing. Results: The synthesis of the hardware logic on FPGA tools gave the operating frequencies of the legacy methods and the proposed method, the simulation of the logic verified the functionality. Conclusion: With the proposed method, a significant improvement of 16% increase in throughput has been observed for 256 steps iterations of multiplier and accumulators on an 8-bit sample data. Such an improvement can help in reducing the computation time in many digital signal processing applications where multiplication and addition are done iteratively.

scholarly journals Aerodynamics of inclined cylindrical bodies free-flying in a hypersonic flowfield

2021 ◽  
Vol 62 (9) ◽  
Author(s):  
Patrick M. Seltner ◽  
Sebastian Willems ◽  
Ali Gülhan ◽  
Eric C. Stern ◽  
Joseph M. Brock ◽  
...  
Keyword(s):  
High Speed ◽  
Degrees Of Freedom ◽  
Numerical Data ◽  
Static Stability ◽  
Free Flight ◽  
Aerodynamic Coefficients ◽  
Flow Topology ◽  
Motion Data ◽  
Continuous Rotation ◽  
German Aerospace

Abstract The influence of the flight attitude on aerodynamic coefficients and static stability of cylindrical bodies in hypersonic flows is of interest in understanding the re/entry of space debris, meteoroid fragments, launch-vehicle stages and other rotating objects. Experiments were therefore carried out in the hypersonic wind tunnel H2K at the German Aerospace Center (DLR) in Cologne. A free-flight technique was employed in H2K, which enables a continuous rotation of the cylinder without any sting interferences in a broad angular range from 0$$^{\circ }$$ ∘ to 90$$^{\circ }$$ ∘ . A high-speed stereo-tracking technique measured the model motion during free-flight and high-speed schlieren provided documentation of the flow topology. Aerodynamic coefficients were determined in careful post-processing, based on the measured 6-degrees-of-freedom (6DoF) motion data. Numerical simulations by NASA’s flow solvers Cart3D and US3D were performed for comparison purposes. As a result, the experimental and numerical data show a good agreement. The inclination of the cylinder strongly effects both the flowfield and aerodynamic loads. Experiments and simulations with concave cylinders showed marked difference in aerodynamic behavior due to the presence of a shock–shock interaction (SSI) near the middle of the model. Graphic abstract

scholarly journals Research on aerodynamic characteristics of two-stage axial micro air turbine spindle for small parts machining

2020 ◽  
Vol 12 (12) ◽  
pp. 168781402098437
Author(s):  
Liu Jiang ◽  
Guo Zhiping ◽  
Miao Shujing ◽  
He Xiangxin ◽  
Zhu Xinyu
Keyword(s):  
High Speed ◽  
Aerodynamic Characteristics ◽  
Maximum Efficiency ◽  
Two Stage ◽  
Output Torque ◽  
Air Turbine ◽  
Solid Foundation ◽  
Computational Fluid Dynamics Cfd ◽  
Micro Machine ◽  
Small Parts

In order to meet the requirements of output torque, efficiency and compact shape of micro-spindles for small parts machining, a two-stage axial micro air turbine spindle with an axial inlet and outlet is proposed. Based on the k-ω turbulence model of SST, the flow field and operation characteristics of the two-stage axial micro air turbine spindle were studied using computational fluid dynamics (CFD) combined with an experimental study. We obtained the air turbine spindle under different working conditions of the loss and torque characteristics. When the inlet pressure was 300 KPa, the output speed of the two-stage turbine was 100,000 rpm, 9% higher than that of a single-stage turbine output torque. The total torque reached 6.39 N·mm, and the maximum efficiency of the turbine and the spindle were 42.2% and 32.3%, respectively. Through the research on the innovative structure of the two-stage axial micro air turbine spindle, the overall performance of the principle prototype has been significantly improved and the problems of insufficient output torque and low working efficiency in high-speed micro-machining can be solved practically, which laid a solid foundation for improving the machining efficiency of small parts and reducing the size of micro machine tool.

Sign in / Sign up

Export Citation Format

Share Document