Analysis of Propulsion and Lift Power Requirements for the Artic Surface Effect Vehicle

1972 ◽  
Author(s):  
J. H. Garrett ◽  
R. K. Muench
Keyword(s):  
Free Stream ◽  
Surface Effect ◽  
Dynamic Pressure ◽  
Pressure Ratio ◽  
Total Power ◽  
Specific Power ◽  
Vehicle Speed ◽  
System Parameters ◽  
Fuel Fraction

The power requirements of large surface effect vehicles are parametrically examined. The results are first derived in terms of total specific power as a function of the cushion to free stream dynamic pressure ratio and other propulsion and lift system parameters. The propulsion, lift and total power requirements are then examined as a function of vehicle speed, vehicle gross weight and daylight clearance. The fuel fraction-range and payload-range relationship for a given cushion pressure is also examined.

A New Method of Modeling Underexpanded Exhaust Plumes for Wind Tunnel Aerodynamic Testing

1989 ◽  
Vol 111 (4) ◽  
pp. 748-754
Author(s):  
V. Salemann ◽  
J. M. Williams
Keyword(s):  
Wind Tunnel ◽  
Free Stream ◽  
Dynamic Pressure ◽  
Pressure Ratio ◽  
Area Ratio ◽  
Full Scale ◽  
New Method ◽  
Thrust Coefficient ◽  
Model Scale ◽  
Exhaust Plumes

A new method for modeling hot underexpanded exhaust plumes with cold model scale plumes in aerodynamic wind tunnel testing has been developed. The method is applicable to aeropropulsion testing where significant interaction between the exhaust and the free stream and aftbody may be present. The technique scales the model and nozzle external geometry, including the nozzle exit area, matches the model jet to free-stream dynamic pressure ratio to full-scale jet to free-stream dynamic pressure ratio, and matches the model thrust coefficient to full-scale thrust coefficient. The technique does not require scaling of the internal nozzle geometry. A generalized method of characteristic computer code was used to predict the plume shapes of a hot (γ = 1.2) half-scale nozzle of area ratio 3.2 and of a cold (γ = 1.4) model scale nozzle of area ratio 1.3, whose pressure ratio and area ratio were selected to satisfy the above criteria and other testing requirements. The plume shapes showed good agreement. Code validity was checked by comparing code results for cold air exhausting into a quiescent atmosphere to pilot surveys and shadowgraphs of model nozzle plumes taken in a static facility.

Turbulent jet in crossflow analysis with LES approach

2016 ◽  
Vol 88 (6) ◽  
pp. 717-728 ◽  
Author(s):  
Mojtaba Tahani ◽  
Mohammad Hojaji ◽  
Seyed Vahid Mahmoodi Jezeh
Keyword(s):  
Mach Number ◽  
Free Stream ◽  
Dynamic Pressure ◽  
Pressure Ratio ◽  
Content Type ◽  
Order Polynomial ◽  
Pressure Area ◽  
Barrel Shock ◽  
Free Stream Mach Number ◽  
Shock Zone

Purpose This study aims to investigate effects of sonic jet injection into supersonic cross-flow (JISC) numerically in different dynamic pressure ratio values and free stream Mach numbers. Design/methodology/approach Large Eddy simulation (LES) with dynamic Smagorinsky model is used as the turbulence approach. The numerical results are compared with the experimental data, and the comparison shows acceptable validation. Findings According to the results, the dynamic pressure ratio has critical effects on the zone related to barrel shock. Despite free stream Mach number, increasing dynamic pressure ratio leads to expansion of barrel shock zone. Consequently, expanded barrel shock zone would bring about more obstruction effect. In addition, the height of counter-rotating vortex pair increases, and the high-pressure area before jet and low-pressure area after jet will rise. The results show that the position of barrel shock is deviated by increasing free stream Mach number, and the Bow shock zone becomes stronger and close to barrel shock. Moreover, high pressure zone, which is located before the jet, decreases by high free stream Mach number. Practical implications In this study, LES with a dynamic Smagorinsky model is used as the turbulence approach. Effects of sonic JISC are investigated numerically in different dynamic pressure ratio values and free stream Mach numbers. Originality/value As summary, the following are the contribution of this paper in the field of JISC subjects: several case studies of jet condition have been performed. In all the cases, the flow at the nozzle exit is sonic, and the free stream static pressure is constant. To generate proper grid, a cut cell method is used for domain modelling. Boundary condition effect on the wall pressure distribution around the jet and velocity profiles, especially S shape profiles, is investigated. The results show that the relation between representing the location of Mach disk centre and at transonic regime is a function of second-order polynomial, whereas at supersonic regime, the relationship is modelled as a first-order polynomial. In addition, the numerical results are compared with the experimental data demonstrating acceptable validation.

The Effect of Size on Optimization of Solid Oxide Fuel Cell/Gas Turbine Hybrid Cycles

2010 ◽  
Vol 132 (9) ◽  
Author(s):  
Michael J. Brear ◽  
Michael J. Dunkley
Keyword(s):  
Fuel Cell ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Pressure Ratio ◽  
Solid Oxide ◽  
Total Power ◽  
Specific Power ◽  
Oxide Fuel ◽  
Secondary Importance ◽  
Power Outputs

The coupling of solid oxide fuel cells (SOFCs) and recuperated gas turbines (GTs) in a hybrid system has the potential to lead to efficiencies exceeding 60%. SOFC/GT hybrids have been proposed at power outputs from 20 MW down to power outputs as low as 25 kW. The optimum configuration for high and low power outputs is therefore likely to be significantly different. This paper proposes a simple model of the SOFC/GT hybrid to investigate the desired flow rate and pressure ratio for optimum hybrid efficiency with varying component performance and, hence, varying inferred size. The overall hybrid specific power will be dominated by the fuel cell and is therefore of secondary importance when matching with a gas turbine. The results presented suggest that hybrid cycles with total power output of the order MW or greater are preferable.

Roles of vanes in diffuser on stability of centrifugal compressor

2019 ◽  
Vol 233 (14) ◽  
pp. 5380-5392
Author(s):  
Wangzhi Zou ◽  
Xiao He ◽  
Wenchao Zhang ◽  
Zitian Niu ◽  
Xinqian Zheng
Keyword(s):  
High Pressure ◽  
Centrifugal Compressor ◽  
Dynamic Pressure ◽  
Pressure Ratio ◽  
Pressure Rise ◽  
Rotating Stall ◽  
Centrifugal Compressors ◽  
Compression System ◽  
The Stability ◽  
Rotating Instability

The stability considerations of centrifugal compressors become increasingly severe with the high pressure ratios, especially in aero-engines. Diffuser is the major subcomponent of centrifugal compressor, and its performance greatly influences the stability of compressor. This paper experimentally investigates the roles of vanes in diffuser on component instability and compression system instability. High pressure ratio centrifugal compressors with and without vanes in diffuser are tested and analyzed. Rig tests are carried out to obtain the compressor performance map. Dynamic pressure measurements and relevant Fourier analysis are performed to identify complex instability phenomena in the time domain and frequency domain, including rotating instability, stall, and surge. For component instability, vanes in diffuser are capable of suppressing the emergence of rotating stall in the diffuser at full speeds, but barely affect the characteristics of rotating instability in the impeller at low and middle speeds. For compression system instability, it is shown that the use of vanes in diffuser can effectively postpone the occurrence of compression system surge at full speeds. According to the experimental results and the one-dimensional flow theory, vanes in diffuser turn the diffuser pressure rise slope more negative and thus improve the stability of compressor stage, which means lower surge mass flow rate.

scholarly journals Modeling of Piezoelectric Energy Harvesting from Freely Oscillating Cylinders in Water Flow

2014 ◽  
Vol 2014 ◽  
pp. 1-13 ◽  
Author(s):  
Min Zhang ◽  
YingZheng Liu ◽  
ZhaoMin Cao
Keyword(s):  
Energy Harvesting ◽  
Free Stream ◽  
Piezoelectric Materials ◽  
Load Resistance ◽  
Stream Velocity ◽  
Piezoelectric Energy Harvesting ◽  
Vibratory System ◽  
System Parameters ◽  
Piezoelectric Energy ◽  
Vortex Induced Vibrations

A concept of energy harvesting from vortex-induced vibrations of a rigid circular cylinder with two piezoelectric beams attached is investigated. The variations of the power levels with the free stream velocity are determined. A mathematical approach including the coupled cylinder motion and harvested voltage is presented. The effects of the load resistance, piezoelectric materials, and circuit combined on the natural frequency and damping of the vibratory system are determined by performing a linear analysis. The dynamic response of the cylinder and harvested energy are investigated. The results show that the harvested level in SS and SP&PS modes is the same with different values of load resistance. For four different system parameters, the results show that the bigger size of cylinder with PZT beams can obtain the higher harvested power.

Measurements of Multiple Pure Tone Propagation From a High Bypass Turbofan Rotor in an Internal Flow Facility

2020 ◽  
Author(s):  
Richard F. Bozak
Keyword(s):  
Pure Tone ◽  
Dynamic Pressure ◽  
Pressure Ratio ◽  
Internal Flow ◽  
Principal Component ◽  
Pressure Transducers ◽  
Acoustic Liners ◽  
Pure Tones ◽  
Dynamic Pressure Measurements ◽  
Stagger Angle

Abstract An important noise source in modern high bypass ratio turbofans is from multiple pure tones produced by the fan during takeoff. An experiment conducted on a 1.5 pressure ratio fan in an internal flow facility provided dynamic pressure measurements to investigate multiple pure tone generation and propagation. Since multiple pure tones are generated by blade shock variation primarily due to the fan’s blade stagger angle differences, the blade stagger angles were measured with an array of over-the-rotor dynamic pressure transducers. Multiple pure tone measurements were made with 30 wall-mounted dynamic pressure transducers from 0.4 to 1.1 diameters upstream of the rotor. Measured blade stagger angle differences correspond to the the shock amplitude variation measured upstream. The acoustic field was extracted from the dynamic pressure signals using principal component analysis as well as duct mode beamforming. Shocks traveling out the inlet were found to couple to duct modes propagating at similar angles. Over-the-rotor acoustic liners appear to reduce rotor shock variation resulting in a reduction of sub-harmonic multiple pure tone sound pressure levels by 3–4 dB.

Performance Analysis of Piezoelectric Energy Harvesting in Pavement: Laboratory Testing and Field Simulation

2019 ◽  
Vol 2673 (3) ◽  
pp. 115-124 ◽  
Author(s):  
Abbas F. Jasim ◽  
Hao Wang ◽  
Greg Yesner ◽  
Ahmad Safari ◽  
Pat Szary
Keyword(s):  
Energy Harvesting ◽  
Power Output ◽  
Laboratory Testing ◽  
Energy Harvester ◽  
Total Power ◽  
Piezoelectric Energy Harvesting ◽  
Loading Frequency ◽  
Vehicle Speed ◽  
Piezoelectric Energy ◽  
Energy Harvesting System

This study investigated the energy harvesting performance of a piezoelectric module in asphalt pavements through laboratory testing and multi-physics based simulation. The energy harvester module was assembled with layers of Bridge transducers and tested in the laboratory. A decoupled approach was used to study the interaction between the energy harvester and the surrounding pavement. The effects of embedment location, vehicle speed, and temperature on energy harvesting performance were investigated. The analysis findings indicate that the embedment location and vehicle speed affects the resulted power output of the piezoelectric energy harvesting system. The embedment depth of the energy module affects both the magnitude and frequency of stress pulse on top of the energy module induced by tire loading. On the other hand, higher vehicle speed causes greater loading frequency and thus greater power output; the effect of pavement temperature is negligible. The analysis of total power output before reaching fatigue failure of the energy module can be used to determine the optimum embedment location in the asphalt layer. The proposed energy harvesting system provides great potential to generate green energy from waste kinetic energy in roadway pavements. Field study is recommended to verify these findings with long-term performance monitoring of pavement with embedded energy harvesters.

Pressure Distribution in a Simplified Human Ear Model for High Intensity Sound Transmission

2014 ◽  
Vol 136 (11) ◽  
Author(s):  
Takumi Hawa ◽  
Rong Z. Gan
Keyword(s):  
Growth Rate ◽  
Middle Ear ◽  
High Intensity ◽  
Dynamic Pressure ◽  
Pressure Ratio ◽  
Linear Growth Rate ◽  
Ear Canal ◽  
Fluid Structure ◽  
Pressure Impulse ◽  
Bench Model

High intensity noise/impulse transmission through a bench model consisting of the simplified ear canal, eardrum, and middle ear cavity was investigated using the CFX/ANSYS software package with fluid-structure interactions. The nondimensional fluid-structure interaction parameter q and the dimensionless impulse were used to describe the interactions between the high intensity pressure impulse and eardrum or tympanic membrane (TM). We found that the pressure impulse was transmitted through the straight ear canal to the TM, and the reflected overpressure at the TM became slightly higher than double the incident pressure due to the dynamic pressure (shocks) effect. Deformation of the TM transmits the incident pressure impulse to the middle ear cavity. The pressure peak in the middle ear cavity is lower than the incident pressure. This pressure reduction through the TM was also observed in our experiments that have dimensions similar to the simulation bench model. We also found that the increase of the pressure ratio as a function of the incident pressure is slightly larger than the linear growth rate. The growth rate of the pressure ratio in this preliminary study suggests that the pressure increase in the middle ear cavity may become sufficiently high to induce auditory damage and injury depending on the intensity of the incident sound noise.

Impact of Inlet Fogging on the Performance of Steam Injected Cooled Gas Turbine Based Combined Cycle Power Plant

2017 ◽  
Author(s):  
Anoop Kumar Shukla ◽  
Onkar Singh
Keyword(s):  
Power Plant ◽  
Gas Turbine ◽  
Film Cooling ◽  
Pressure Ratio ◽  
Steam Injection ◽  
Combined Cycle ◽  
Specific Power ◽  
Temperature Cycle ◽  
Inlet Temperature ◽  
Combined Cycle Power Plant

Gas/steam combined cycle power plants are extensively used for power generation across the world. Today’s power plant operators are persistently requesting enhancement in performance. As a result, the rigour of thermodynamic design and optimization has grown tremendously. To enhance the gas turbine thermal efficiency and specific power output, the research and development work has centered on improving firing temperature, cycle pressure ratio, adopting improved component design, cooling and combustion technologies, and advanced materials and employing integrated system (e.g. combined cycles, intercooling, recuperation, reheat, chemical recuperation). In this paper a study is conducted for combining three systems namely inlet fogging, steam injection in combustor, and film cooling of gas turbine blade for performance enhancement of gas/steam combined cycle power plant. The evaluation of the integrated effect of inlet fogging, steam injection and film cooling on the gas turbine cycle performance is undertaken here. Study involves thermodynamic modeling of gas/steam combined cycle system based on the first law of thermodynamics. The results obtained based on modeling have been presented and analyzed through graphical depiction of variations in efficiency, specific work output, cycle pressure ratio, inlet air temperature & density variation, turbine inlet temperature, specific fuel consumption etc.

Thermodynamic Assessment of Hybrid PSOFC/GT Systems for Mechanical/Electric Power Generation

2000 ◽  
Author(s):  
K. K. Botros ◽  
G. R. Price ◽  
R. Parker
Keyword(s):  
Power Generation ◽  
Electric Power ◽  
Gas Turbine ◽  
Life Cycle Cost ◽  
Pressure Ratio ◽  
Pollutant Emissions ◽  
Mechanical Power ◽  
Total Power ◽  
Specific Work ◽  
System Pressure

Hybrid PSOFC/GT cycles consisting of pressurized solid oxide fuel cells integrated into gas turbine cycles are emerging as a major new power generation concept. These hybrid cycles can potentially offer thermal efficiencies exceeding 70% along with significant reductions in greenhouse gas and NOX emissions. This paper considers the PSOFC/GT cycle in terms of electrical and mechanical power generation with particular focus on gas pipeline companies interested in diversifying their assets into distributed electric generation or lowering pollutant emissions while more efficiently transporting natural gas. By replacing the conventional GT combustion chamber with an internally reformed PSOFC, electrical power is generated as a by-product while hot gases exiting the fuel cell are diverted into the gas turbine for mechanical power. A simple one-dimensional thermodynamic model of a generic PSOFC/GT cycle has shown that overall thermal efficiencies of 65% are attainable, whilst almost tripling the specific work (i.e. energy per unit mass of air). The main finding of this paper is that the amount of electric power generated ranges from 60–80% of the total power available depending on factors such as the system pressure ratio and degree of supplementary firing before the gas turbine. Ultimately, the best cycle should be based on the “balance of plant”, which considers factors such as life cycle cost analysis, business and market focus, and environmental emission issues.

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