FE Approach: Electro-Mechanical-Fluid Interaction of Jet Pipe Electrohydraulic Flow Control Servovalve

2003 ◽  
Author(s):  
Somashekhar S. Hiremath ◽  
M. Singaperumal ◽  
R. Krishna Kumar
Keyword(s):  
Steady State ◽  
Force Balance ◽  
Fe Model ◽  
Volume Changes ◽  
New Approach ◽  
Turbine Engine ◽  
Steady State Operation ◽  
Actual Flow ◽  
The Relationship ◽  
Fluid Interaction

Jet pipe electrohydraulic servovalve finds main application in feedback control system working on jet engine and fighter aircrafts. The analyzed jet pipe electrohydraulic servovalve is used in precise fuel control applications in gas turbine engine. This paper gives a new approach for servovalve modeling with the hydrostatic fluid elements in achieve steady state operation. The actual flow required to achieve the force balance is presented analytically. FE model gives the relationship between the spool and jet pipe position in achieving the steady state operation. The spool end cavity volume changes are presented.

Development and Test of a Catalytic Combustor for an Automotive Gas Turbine

1998 ◽  
Author(s):  
John J. Lipinski ◽  
Philip R. Brine ◽  
Rajesh D. Buch ◽  
George R. Lester
Keyword(s):  
Steady State ◽  
Gas Turbine ◽  
Hybrid Electric Vehicle ◽  
Nox Emissions ◽  
Turbine Engine ◽  
Fuel Consumption Rate ◽  
Steady State Operation ◽  
Full Speed ◽  
Unburned Hydrocarbons ◽  
Catalytic Combustor

A catalytic combustor was designed and tested for a small recuperated gas turbine engine for use in a hybrid electric vehicle (HEV). Combustor rig and engine tests were performed with DF-2 diesel fuel, kerosene, and automotive gasoline. Rig test steady-state emissions were measured over the full engine operating range. Nitrogen oxides (NOx) emissions were insensitive to operating condition, and were almost strictly a function of fuel nitrogen content. For low-nitrogen kerosene, NOx emissions less than 1 ppm(vol) (at 15 percent O2) were demonstrated. Startup emissions were measured for conditions modeling engine spoolup from ignition to full speed. Laboratory engine tests on DF-2 over a range of speeds and loads demonstrated tailpipe emissions less than 10 ppm(vol) NOx and less than 1 ppm(vol) unburned hydrocarbons (HC). NOx, HC, and carbon monoxide (CO) emissions were less than the California State Ultra-Low Emissions Vehicle (ULEV) standards for steady-state operation, corrected for assumed vehicle load and fuel consumption rate.

Vibration analysis of a test rig for a radial compressor

2001 ◽  
Vol 215 (1) ◽  
pp. 21-29
Author(s):  
S U Lee ◽  
D Robb ◽  
C Besant
Keyword(s):  
High Speed ◽  
Performance Testing ◽  
Operating Conditions ◽  
Fe Model ◽  
Aerodynamic Efficiency ◽  
Radial Compressor ◽  
Turbine Engine ◽  
Compressor Performance ◽  
The Relationship ◽  
Rotor Dynamic

A radial compressor has been designed at Imperial College for cooling a high-speed generator (HSG) coupled directly to a small gas turbine engine to produce 100kW electric power. The compressor has a significant influence on the overall dynamics of the generator. Therefore, it is designed to be lightweight for rotor-dynamic reasons together with reasonable aerodynamic efficiency. An experimental rig for the compressor performance testing was also designed. In order to operate this rig safely, it is very important to be able to predict and analyse its dynamic behaviour. For this purpose, a systematic procedure was used to develop a finite element (FE) model to predict natural frequencies under operating conditions. In the procedure, the relationship between FE analyses, modal analyses and results of a running test are established. Vibration analyses of the compressor rig using the proposed procedure are carried out. Finally, the results of computations and experiments for the rig are presented and compared.

The mechanics of flight in the hawkmoth Manduca sexta. II. Aerodynamic consequences of kinematic and morphological variation.

1997 ◽  
Vol 200 (21) ◽  
pp. 2723-2745 ◽  
Author(s):  
A P Willmott ◽  
C P Ellington
Keyword(s):  
Steady State ◽  
Force Balance ◽  
Angle Of Incidence ◽  
Force Measurements ◽  
Forward Flight ◽  
Incidence Data ◽  
Flight Mode ◽  
Thrust Generation ◽  
State Force ◽  
The Relationship

Mean lift coefficients have been calculated for hawkmoth flight at a range of speeds in order to investigate the aerodynamic significance of the kinematic variation which accompanies changes in forward velocity. The coefficients exceed the maximum steady-state value of 0.71 at all except the very fastest speeds, peaking at 2.0 or greater between 1 and 2 ms-1. Unsteady high-lift mechanisms are therefore most important during hovering and slow forward flight. In combination with the wingtip paths relative to the surrounding air, the calculated mean lift coefficients illustrate how the relative contributions of the two halfstrokes to the force balance change with increasing forward speed. Angle of incidence data for fast forward flight suggest that the sense of the circulation is not reversed between the down- and upstrokes, indicating a flight mode qualitatively different from that proposed for lower-speed flight in the hawkmoth and other insects. The mid-downstroke angle of incidence is constant at 30-40 degrees across the speed range. The relationship between power requirements and flight speed is explored; above 5 ms-1, further increases in forward velocity are likely to be constrained by available mechanical power, although problems with thrust generation and flight stability may also be involved. Hawkmoth wing and body morphology, and the differences between males and females, are evaluated in aerodynamic terms. Steady-state force measurements show that the hawkmoth body is amongst the most streamlined for any insect.

Colonialism and the Highland Clearances

2017 ◽  
Vol 8 (1) ◽  
pp. 22-48 ◽  
Author(s):  
Iain Mackinnon
Keyword(s):  
Industrial Development ◽  
Comparative Approach ◽  
Indigenous Research ◽  
Internal Colonialism ◽  
New Approach ◽  
A Site ◽  
Relationship Of ◽  
The Relationship ◽  
Imperial State ◽  
Late Modern

This article employs a new approach to studying internal colonialism in northern Scotland during the 18th and 19th centuries. A common approach to examining internal colonial situations within modern state territories is to compare characteristics of the internal colonial situation with attested attributes of external colonial relations. Although this article does not reject the comparative approach, it seeks to avoid criticisms that this approach can be misleading by demonstrating that promoters and managers of projects involving land use change, territorial dispossession and industrial development in the late modern Gàidhealtachd consistently conceived of their work as projects of colonization. It further argues that the new social, cultural and political structures these projects imposed on the area's indigenous population correspond to those found in other colonial situations, and that racist and racialist attitudes towards Gaels of the time are typical of those in colonial situations during the period. The article concludes that the late modern Gàidhealtachd has been a site of internal colonization where the relationship of domination between colonizer and colonized is complex, longstanding and occurring within the imperial state. In doing so it demonstrates that the history and present of the Gaels of Scotland belongs within the ambit of an emerging indigenous research paradigm.

Mast Cells as a Double-Edged Sword in Immunity: Their Function in Health and Disease. First of Two Parts

2020 ◽  
Vol 20 (5) ◽  
pp. 654-669
Author(s):  
Thea Magrone ◽  
Manrico Magrone ◽  
Emilio Jirillo
Keyword(s):  
Steady State ◽  
Mast Cells ◽  
Immune Cells ◽  
Food Antigens ◽  
Health And Disease ◽  
The Relationship

Mast cells (MCs) have recently been re-interpreted in the context of the immune scenario in the sense that their pro-allergic role is no longer exclusive. In fact, MCs even in steady state conditions maintain homeostatic functions, producing mediators and intensively cross-talking with other immune cells. Here, emphasis will be placed on the array of receptors expressed by MCs and the variety of cytokines they produce. Then, the bulk of data discussed will provide readers with a wealth of information on the dual ability of MCs not only to defend but also to offend the host. This double attitude of MCs relies on many variables, such as their subsets, tissues of residency and type of stimuli ranging from microbes to allergens and food antigens. Finally, the relationship between MCs with basophils and eosinophils will be discussed.

scholarly journals Estimation of resistance force at steady-state sinkage for cylindrical wheel-typed lunar/planetary exploration rovers with function of push–pull locomotion

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Daisuke Fujiwara ◽  
Naoki Tsujikawa ◽  
Tetsuya Oshima ◽  
Kojiro Iizuka
Keyword(s):  
Steady State ◽  
Estimation Method ◽  
Planetary Exploration ◽  
Experimental Result ◽  
Resistance Force ◽  
Estimation Model ◽  
Loose Soil ◽  
Key Factor ◽  
The Relationship ◽  
Resistance Forces

Abstract Planetary exploration rovers have required a high traveling performance to overcome obstacles such as loose soil and rocks. Push-pull locomotion rovers is a unique scheme, like an inchworm, and it has high traveling performance on loose soil. Push-pull locomotion uses the resistance force by keeping a locked-wheel related to the ground, whereas the conventional rotational traveling uses the shear force from loose soil. The locked-wheel is a key factor for traveling in the push-pull scheme. Understanding the sinking behavior and its resistance force is useful information for estimating the rover’s performance. Previous studies have reported the soil motion under the locked-wheel, the traction, and the traveling behavior of the rover. These studies were, however, limited to the investigation of the resistance force and amount of sinkage for the particular condition depending on the rover. Additionally, the locked-wheel sinks into the soil until it obtains the required force for supporting the other wheels’ motion. How the amount of sinkage and resistance forces are generated at different wheel sizes and mass of an individual wheel has remained unclear, and its estimation method hasn’t existed. This study, therefore, addresses the relationship between the sinkage and its resistance force, and we analyze and consider this relationship via the towing experiment and theoretical consideration. The results revealed that the sinkage reached a steady-state value and depended on the contact area and mass of each wheel, and the maximum resistance force also depends on this sinkage. Additionally, the estimation model did not capture the same trend as the experimental results when the wheel width changed, whereas, the model captured a relatively the same trend as the experimental result when the wheel mass and diameter changed.

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