Showing papers on "Gas compressor published in 1994"

High pressure gas generator rotor tie rod system for gas turbine engine

Abstract: An improved high pressure gas generator rotor for a gas turbine engine is disclosed in which a tie rod of unitary construction provides an axial compressive load across a plurality of non-bolted compressor and turbine components arranged in rotational driving arrangement, for example, by face splines and rabbets. An interim compressive load path solely through the compressor rotor portion is automatically provided upon relaxation of the operational compressive load in the rotor to maintain mechanical integrity of the compressor and facilitate assembly and maintenance activity. An anti-rotated midspan locknut on the tie rod obviates the need for additional, special tooling configured to clamp the compressor components during disassembly of the turbine.

Gas turbine engine cooling supply circuit

Abstract: A turbine cooling supply circuit for a gas turbine engine is disclosed in which the flow of coolant through the engine is directed to minimize temperature rise prior to discharge into the turbine. Bleed air from an impeller stage of a compressor is channeled along a backwall thereof into a cavity disposed radially inwardly of a combustor casing. The cavity is divided by a lightweight tubular member having a circumferentially uniform contour into a non-flow zone proximate the casing and a flow zone proximate a rotor. Maintenance of a high tangential flow component in the bleed flow in the flow zone facilitates discharge of the flow through apertures in a rotor into a bore portion thereof, minimizing work input and temperature rise of the coolant. Further, the coolant is isolated from the hot casing wall and nonuniform structures disposed thereon, thereby reducing heat flux and temperature rise associated with aerodynamic drag caused by increased surface area, nonuniform interruptions in the stationary surface or any combination thereof. Features are incorporated in the tubular member to provide margin against buckling.

Development of an Aeroderivative Gas Turbine Dry Low Emissions Combustion System

Abstract: This paper gives the development status of GE’s new aeroderivative premixed combustion system. This system consists of a new fuel staged annular combustor, compressor rear frame, first-stage turbine nozzle, electronic staging controller, and fuel delivery system. Component test results along with a description of the combustion system are presented. This new system will reduce NOx emissions by 90 percent relative to the original aircraft engine combustion system while maintaining low emissions of CO and UHCs. Tests of a LM6000 gas turbine equipped with the new system are planned for early 1994.

Active Stabilization of Rotating Stall in a Three-Stage Axial Compressor

Abstract: A three-stage, low-speed axial research compressor has been actively stabilized by damping low-amplitude circumferentially traveling waves, which can grow into rotating stall. Using a circumferential array of hot-wire sensors, and an array of high-speed individually positioned control vanes as the actuator, the first and second spatial harmonics of the compressor were stabilized down to a characteristic slope of 0.9, yielding an 8 percent increase in operating flow range. Stabilization of the third spatial harmonic did not alter the stalling flow coefficient. The actuators were also used open loop to determine the forced response behavior of the compressor

Experimental Investigation of a Hermetic Scroll Expander–Generator.

Abstract: This paper describes a 1 to 3.5 kWe hermetic scroll expander generator modified from a standard hermetic compressor, an organic Rankine cycle test facility built to test expanders up to 10 kWe and a set of experimental results using HFC 134a in the dry vapor domain. Peak overall isentropic efficiencies in the range of 63 to 65% for speeds of rotation varying between 2400 and 3600 rpm are reported. Performance is fairly constant in the range of pressure ratios considered (2.4

Control method and apparatus for a centrifugal chiller using a variable speed impeller motor drive

Abstract: A method of controlling the operation of a centrifugal compressor in a water chiller system. The compressor's capacity is variable by modulating its speed of rotation or by modulating its inlet guide vane's position. The water chiller includes an evaporator having a leaving water temperature. The method comprises the steps of: monitoring the leaving water temperature; determining if the leaving water temperature is in a steady state; modulating the compressor capacity by modulating speed of rotation if the leaving water temperature is in a steady state; and modulating the compressor capacity by modulating inlet guide vane position if the leaving water temperature is not in a steady state.

Electronically controlled beverage dispenser

Abstract: An electronic control for the operation of a beverage dispenser of the refrigerated ice bank type is shown The control provides for reliable determinations of when ice production is needed and when it is not needed A microprocessor receives information from an ice bank probe and from a temperature probe located within the ice bank Data collected by the microprocessor from both the ice bank probe and the temperature probe is used to determine if the ice bank is either insufficient in size and should be increased or is of sufficient size such that the compressor can be turned off A carbonator level probe is also shown and connected to the microprocessor The microprocessor is programmed whereby the carbonator probes are sampled in a manner to accurately determine the level of water in the carbonator and therefore the need for turning on or turning off any water pump connected thereto Both the operation of the compressor and the water pump are controlled by the microprocessor wherein the programming thereof provides for adequate hysteresis protection so that short cycling of the compressor and water pump is avoided

Turbine disk cooling system

Abstract: A turbine disk cooling system for a gas turbine engine of a type having a compressor section including first and second disks connected by a seal and defining a compressor interstage volume, a turbine section including first and second stage disks connected by a seal and defining a turbine inner stage volume, and a compressor shaft interconnecting the compressor disks with the turbine disks including orifices located in the compressor seal for allowing air in the compressor section to enter the compressor interstage volume, and a radial inflow impeller for guiding the compressor air towards the compressor shaft. The impeller including a plurality of radially-extending conduits suspended in the compressor interstage volume, the conduits having a plurality of interior, radially-extending passages for conveying the compressor air from the orifice to the compressor shaft. The cooling system further including ducts concentric with the engine centerline for conveying air from the compressor interstage volume to the turbine section, wherein the first stage turbine disk includes an aft shaft having a plurality of openings therethrough allowing the flow of air from the ducts into the turbine interstage volume. The tubular conduit elements having a radially outer portion divided into a plurality of spaced longitudinal segments and a radially inner portion protruding from the conduit element and including a peripheral flange shaped to engage the peripheral flange of the conduit elements.

GETRAN: A Generic, Modularly Structured Computer Code for Simulation of Dynamic Behavior of Aero- and Power Generation Gas Turbine Engines

Abstract: The design concept, the theoretical background essential for the development of the modularly structured simulation code GETRAN, and several critical simulation cases are presented in this paper. The code being developed under contract with NASA Lewis Research Center is capable of simulating the nonlinear dynamic behavior of single- and multispool core engines, turbofan engines, and power generation gas turbine engines under adverse dynamic operating conditions. The modules implemented into GETRAN correspond to components of existing and new-generation aero- and stationary gas turbine engines with arbitrary configuration and arrangement. For precise simulation of turbine and compressor components, row-by-row diabatic and adiabatic calculation procedures are implemented that account for the specific turbine and compressor cascade, blade geometry, and characteristics. The nonlinear, dynamic behavior of the subject engine is calculated solving a number of systems of partial differential equations, which describe the unsteady behavior of each component individually. To identify each differential equation system unambiguously, special attention is paid to the addressing of each component. The code is capable of executing the simulation procedure at four levels, which increase with the degree of complexity of the system and dynamic event. As representative simulations, four different transient cases with single- and multispool thrust and power generation engines were simulated. These transient cases vary from throttling the exit nozzle area, operation with fuel schedule, rotor speed control, to rotating stall and surge.

Piston type variable displacement compressor

Abstract: A compressor has a swash plate (15) tiltable between maximum and minimum inclining angles with respect to a plane perpendicular to an axis of a drive shaft (9) according to a difference between pressures in a crank chamber (2a) and a suction chamber (3a). An internal gas passage (2a, 3a, 3b, 30, 31) includes the crank chamber (2a), the suction chamber (3a) and a discharge chamber (3b). The internal gas passage is connected to an external circuit (35) separately provided from the compressor. The rotation of the drive shaft (9) is converted to a reciprocating movement of a piston (22) to vary a capacity of a cylinder bore (1a). The piston (22) compresses a gas supplied from the external circuit (35) to the internal gas passage (2a, 3a, 3b, 30, 31) and discharges the gas to the external circuit (35). A inhibiting apparatus (21, 28, 42; 21, 28, 57; 28, 58, 59, 60; 28, 61, 62, 63; 28, 64, 65, 66) inhibits the circulation of the gas through the internal gas passage (2a, 3a, 3b, 30, 31) and the external circuit (35) when the swash plate (15) is located between the minimum inclining angle and a first inclining angle. The first inclining angle is greater than the minimum inclining angle of the swash plate (15).

Integrated gas turbine solid oxide fuel cell system

Abstract: An improved integrated gas turbine solid oxide fuel cell system. The system has a compressor for producing compressed air that is pre-heated and then supplied to a solid oxide fuel cell generator. The solid oxide fuel cell generator, which is also supplied with a first stream of fuel, produces electrical power and a hot gas. In the solid oxide fuel cell generator, the unreacted portion of the fuel is combusted with the oxygen remaining in the hot gas to further heat the hot gas. The further heated hot gas is then directed to a topping combustor that is supplied with a second stream of fuel so as to produce a still further heated hot gas that is then expanded in a turbine.

Modeling and Analysis of Gas Turbine Performance Deterioration

Abstract: The effects of performance deterioration in both land and aircraft gas turbines are presented in this paper. Models for two of the most common causes of deterioration, viz., fouling and erosion, are presented. A stage-stacking procedure, which uses new installed engine field data for compressor map development, is described. The results of the effect of fouling in a powerplant gas turbine and that of erosion in a aircraft gas turbine are presented. Also described are methods of fault threshold quantification and fault matrix simulation. Results of the analyses were found to be consistent with field observations.

Method of operating a gas-turbine group

Abstract: In a method of operating a gas-turbine group having sequential combustion, action is taken first of all on the inlet temperatures (A, B) at the two turbines (6, 10) in order to provide a partial-load operation. The subsequent lowering of the load takes place by adjustment of the compressor guide blades (C), that is, by reducing the mass flow (E) to below 50% of the rated load (X). During this lowering, the inlet temperature (A) at the first turbine (6) is kept constant, while the other inlet temperature (B) at the second turbine (10) is continuously lowered; the outlet temperature (D) of the second turbine (10) is in contrast kept constant. After the lowering of the load is complete by adjusting the compressor guide blades, the inlet temperatures (A, B) are reduced directly or in a phase-displaced manner (Y).

Very high speed radial inflow hydraulic turbine

Abstract: A very high speed radial inflow hydraulic turbine drive. Inflow nozzles drilled in a nozzle body intersect a circular nozzle body exit surface, the centerline of each nozzle forming an angle of between 8 and 25 degrees with the tangent of the exit circle at the point of intersection. The turbine wheel of the drive is small. Its diameter measured at the tips of the blades is less than 2 inches. In a preferred embodiment, built and tested by Applicant, the wheel is only 0.80 inch diameter. This embodiment was tested with a turbine hydraulic fluid pressure drop of 700 psi and flow of 19.5 GPM. The 0.8 inch turbine produced 5.9 HP at 62,000 RPM driving the compressor portion of a TO4B-V turbocharger. The compressed air flow was measured at 11.3 pounds per minute (161.4 inlet CFM) at a pressure ratio of 1.41. During the test the acceleration of the supercharger was measured from idle to 62,000 RPM in about 1/2 second. This preferred embodiment utilizes a plastic-metal turbine wheel in which the plastic portion of the wheel other than the blades is solidly anchored within a metal containing wheel. In other preferred embodiments the turbine drive drives superchargers for supercharging internal combustion engines such as bus and truck turbodiesel engines. The superchargers provided by the present invention produce immediate response to engine demand for increased combustion air and will dramatically reduce smoke emission during low speed acceleration of these bus and truck engines as well as greatly improve engine efficiency.

Capacity control system for pressure swing adsorption apparatus and associated method

Abstract: A pressure swing adsorption apparatus including a compressor for pumping a flow of a gaseous mixture through an adsorption medium utilizes a capacity control system by which the operating capacity of the compressor can be preselected. The capacity control system is disposed upstream, i.e. on the suction side of, the compressor for limiting, when desired, the feed stream drawn into the compressor. A reduction in the operating capacity of the apparatus by way of the control system results in a corresponding reduction in the power consumption and noise levels of the compressor. The system is particularly advantageous when incorporated in an oxygen-generating unit intended for use by a patient requiring oxygen therapy in his home in that the capacity of a high capacity unit can be reduced, when appropriate, by a distributor or technician prior to use of the unit by the patient so that the patient receives the oxygen-rich product stream that he has been prescribed to receive and to reduce operating costs of the unit. The method of the invention includes the steps performed by the control system.

Axial compressor performance during surge

Abstract: There is limited information available in the literature about flow conditions in axial compressors during surge. This article presents detailed measurements from a low-speed test rig instrumented to pick up details of axial and circumferential flow disturbances. The results show that surge is initiated by rotating stall, and that the ensuing surge cycle is a sequence of well ordered cause-and-effect events. The differences in cycle behavior between "classic surge" and "deep surge" are investigated, and it is shown that the shape of the compressor characteristic determines which of these will occur. From the results it is also concluded that some important factors, such as overall pressure rise and size of hysteresis loop, have not received sufficient attention in existing techniques for predicting the rotating stall/surge boundary. In line with these findings an Appendix by E. M. Greitzer presents a more general version of the "B Parameter," which takes into account the influence of compressor design variables on the stalling behavior of the compressor.

Boundary conditions for unsteady supersonic inlet analyses

Abstract: New bleed and compressor face boundary conditions have been developed to improve the accuracy of unsteady supersonic inlet calculations. The new bleed boundary condition relates changes in the bleed hole discharge coefficient to changes in the local flow conditions; the local bleed flow rate can more than double as a shock moves forward over a bleed band in response to inlet flow disturbances. The stability margin of the inlet is strongly dependent on the throat bleed configuration since the locally rapid increase in bleed flow has a strong effect on the motion of the normal shock. The new compressor face boundary condition accounts for changes in the unsteady flow conditions at the compressor face by specifying the compressor face corrected mass flow or Mach number either as a constant or as a linear function of the stagnation conditions. The effects of inlet flow disturbances on the flow at the compressor face are represented more realistically with this new boundary condition than with traditional fixed static pressure or mass flow conditions. Euler calculations of the dynamic response of an inlet flow to a flow disturbance at the compressor face with 20- and 90-deg throat bleed hole angles are reported. These results indicate that an extra margin of stability for the inlet is obtained with 90-deg bleed holes because the increase in bleed flow rate as the shock moves forward over a bleed band is much larger for 90-deg holes than for 20-deg holes.

A toolkit for primary HVAC system energy calculation. Part 2: Reciprocating chiller models

Abstract: This is the second in a series of papers presenting the fundamentals of a new simulation tool kit developed by ASHRAE TC 4.7 The modeling used in this tool kit is oriented toward simple solutions with a minimum number of parameters that are accurate enough for annual energy calculations of whole building systems. Quasi-static models, which are generally sufficient for such applications, allow the user to deal with the part-load regime. The chiller model is developed and documented on the basis of the following elements: an information flow diagram in which a selection of input and output variables and parameters is proposed, three conceptual schemes in which the main physical hypotheses are expressed, and a set of equations derived from the conceptual schemas. The actual refrigerant cycle is taken into account. Heat exchangers and reciprocating compressors are modeled with some realism. This approach is easy to understand for most engineers and can be easily updated at any time. Practical possibilities of parameter identification (on the basis of catalog data, for example) are provided, and some information about auxiliary consumption is also given. Two alternatives are available for the compressor model: with and without the addition of a fictitious exhaust nozzlemore » intended to produce an effect equivalent to valve pressure drops. Two alternatives are also proposed for parameter identification: looking to the compressor alone or to the whole chiller (i.e., including condenser and evaporator characteristics). Part-load is presumed to be realized by cylinder unloading and cycling between two unloading levels or between the ON and OFF regimes.« less

Low refrigerant charge detection using a combined pressure/temperature sensor

Abstract: Low refrigerant charge in a refrigeration system is detected by monitoring the compressor discharge pressure and temperature. This monitoring is accomplished with a combined pressure/temperature sensor located at or near the compressor outlet. The sensor output signals are fed to a controller which produces a low charge signal whenever a combination of high discharge temperature and a low discharge pressure is detected. The controller can optionally receive input of additional operating characteristics of the refrigeration system to provide a more accurate low charge signal. The controller is connected to an indicator and/or the compressor so that the low charge signal activates the indicator and/or deactivates the compressor.

Pulse tube refrigerator

Abstract: The present invention provides a pulse tube refrigerator, comprising a regenerator having an inlet port and an outlet port, a pulse tube having one end portion connected in series to the outlet port of the regenerator, a gas compressor connected to the inlet port of the regenerator, a first valve disposed between the discharge port of the gas compressor and the inlet port of the regenerator, a second valve disposed between the suction port of the gas compressor and the inlet port of the regenerator, a first valve controller for selectively opening/closing alternately the first and second valves to permit a high pressure coolant gas discharged from the discharge port of the gas compressor to be guided into the pulse tube through the regenerator and, then, to permit said coolant gas to be sucked into the gas compressor through the suction port thereof via the reverse passageway so as to generate coldness, a third valve disposed between the other end portion of the pulse tube and the discharge port of the gas compressor, a fourth valve disposed between the other end portion of the pulse tube and the suction port of the gas compressor, and a second valve controller serving to open/close the third and fourth valves in relation to the opening/closing of the first and second valves

Method and apparatus for regulating a compressor lubrication system

Abstract: An apparatus for regulating a compressor lubrication system includes an oil-flooded rotary gas compressor, a reservoir flow connected to the compressor, a heat exchanger for cooling a lubricant, and a controller. A thermal mixing valve regulates the temperature of the lubricant flowing to the compressor. A first temperature sensor measures a discharge temperature at a compressor outlet, and provides a signal corresponding to the discharge temperature to the controller. A second temperature sensor measures a lubricant temperature at a lubricant inlet to the compressor, and provides a signal corresponding to the lubricant temperature to the controller. A pressure sensor measures the pressure at the outlet of the compressor, and provides a corresponding pressure signal to the controller. A valve means continuously regulates the supply of lubricant to the compressor, the valve means being controlled by the controller in response to the temperature signal of the first temperature sensor and the pressure signal. Operation of the thermal mixing valve is controlled by the controller, in response to the temperature signal of the second temperature sensor, to continuously regulate the temperature of the lubricant supplied to the compressor to minimize preheating of the low pressure gas.

Steam-augmented gas turbine

Abstract: A steam-augmented gas turbine engine system generally includes a compressor (3), first and second combustors (4a, 4b), a compressor turbine (6) and a power turbine (7). A heat exchanging system (8b) removes heat from an exhaust product from the power turbine (7) and preheats water which has been desalinated by a water purification system (12). The desalinated water is provided to the first combustor (4a), as a predetermined quantity of water-stream mass, along with fuel and compressed air, and is used to efficiently power the turbine system. In one embodiment, a two-boiler system (8b) is employed in which first and second steam outputs are provided to first and second combustors (4a, 4b) such that a mass flow of the compressor turbine (6) is substantially constant from a Cheng point to a stoichiometric point of a predetermined power profile. This constancy of mass flow ensures that the gas generator operates on design from the Cheng point to the stoichiometric combustion point. Additionally, the free-power turbine (7) always operates on design.

Cryogenic refrigerator with single stage compressor

Abstract: A closed cycle refrigerating system for cryogenic temperatures using a single stage compressor (12) with a refrigerant comprising a gas mixture. The refrigerating system includes a heat exchanger (28) having a throttling orifice (34) which is arranged to provide refrigeration, and a single stage oil lubricated compressor (12) for compressing the refrigerant. The compressor is typically of the rolling piston type. The refrigerant is a mixture of at least one cryogenic gas having a normal boiling point below 120 degrees K and at least two other gases having normal boiling point temperatures below 300 degrees K different from each other and from said one gas. There is also included means (18) for cooling the compressed refrigerant and for circulating the cooled refrigerant to the heat exchanger and its throttling orifice and then back to the compressor. The system does not require any cascaded heat exchangers or intermediate phase separators.

Controlling/driving apparatus for an electrically-driven compressor in a car

Abstract: A controlling/driving apparatus for an electrically-driven compressor of an air conditioner mounted in an automobile. The apparatus comprises a DC-AC converting invertor 4 for converting a DC voltage into a pseudo AC voltage (e.g. a pulse train of positive and negative pulses), a DC voltage detector 7, and a pulse width changing unit 8 for changing the width of each pulse of the pulse train in accordance with the DC voltage detected by the DC voltage detector. Thus, the apparatus enables safe and efficient operation of the compressor with improved electric insulation and durability when large fluctuations in the power source voltage of the compressor occur.

Blown boundary layer control system for a jet aircraft

Abstract: A blown boundary layer control system for an aircraft having a jet engine with an engine compressor, an inlet including a compression surface with an external part and internal part, a cowl lip including an internal lip surface and an external lip surface and an external afterbody. The system includes several ducts from the engine compressor. A series of nozzles and valves control and direct air flow to various surfaces. A computer is electrically connected to the valves to control the operation of the valves thereby controlling the blowing of air from a commanded number of nozzles. The computer controls the valves in position as functions of RPM of the engine, free stream flight conditions and aircraft attitude.

Scroll compressor having high temperature control

Abstract: A thermal protection system for a scroll compressor has a temperature sensor which is positioned directly within the discharge passage of the scroll compressor by being directed through an access passageway between the discharge zone and the suction zone of the compressor. The lead wires from the temperature sensor are wired in series with the normal motor temperature sensor circuit to provide the scroll discharge temperature control function as an integral part of the motor temperature control system located within the hermetic shell of the compressor. An additional embodiment of the present invention not only detects discharge gas temperatures but it also has the ability to detect the actual temperature of other selected compressor components.

Control apparatus for and control method of gas turbine

Abstract: A control apparatus for a gas turbine having an air flow control valve for controlling the flow rate of combustion air in an air flow passage from a compressor to the gas turbine, includes an air velocity or flow sensor arranged in the vicinity of the air flow control valve. A control unit operates to control the opening of a fuel flow regulation valve and/or an air flow control valve on the basis of a signal from the air velocity or flow sensor, thereby to control the air fuel ratio in a combustion section of the gas turbine.

Exhaust gas turbocharger for a supercharged internal combustion engine

Abstract: An exhaust gas turbocharger for a supercharged internal combustion engine, in which the exhaust gas turbocharger includes at least one turbine and at least one compressor and the turbine has a turbine casing with a spiral-shaped flow guide duct, a turbine wheel, an inlet end and an outlet end and the compressor includes a compressor casing with a diffuser duct, an impeller, a pressure side and a suction side and the turbine wheel and the compressor impeller are mounted on a common shaft and the turbine casing and the compressor casing, together with a bearing housing, an exhaust gas turbocharger casing and define a gas conduit connection between the inlet end of the turbine and the pressure side of the compressor with at least one control valve and a gas delivery device arranged in the gas conduit connection for controlling the flow of gas between the inlet end of the turbine and the pressure side of the compressor.

Pre-Stall Behavior of Several High-Speed Compressors

Abstract: High speed compressor data immediately prior to rotating stall inception are analyzed and compared to stability theory. New techniques for the detection of small amplitude rotating waves in the presence of noise are detailed and experimental and signal processing pitfalls discussed. In all nine compressors examined, rotating stall precedes surge. Prior to rotating stall inception, all the machines support small-amplitude (<1% of fully developed stall) waves travelling about the circumference. Travelling wave strength and structure are shown to be a strong function of corrected speed. At low speeds, a −0.5 times shaft speed wave is present for hundreds of rotor revolutions prior to stall initiation. At 100% speed, a shaft speed rotating wave dominates, growing as stall initiation is approached (fully developed rotating stall occurs at about 1/2 of shaft speed). A new, 2-D, compressible hydrodynamic stability analysis is applied to the geometry of two of the compressors and gives results in agreement with data. The calculations show that, at low corrected speeds, these compressors behave predominantly as incompressible machines. The wave which first goes unstable is the 1/2 shaft frequency mode predicted by the incompressible Moore-Greitzer analysis and previously observed in low speed compressors. Compressibility becomes important at high corrected speeds and adds axial structure to the rotating waves. At 100% corrected speed, it is one of these hitherto unrecognized compressible modes which goes unstable first. The rotating frequency of this mode is constant and predicted to be approximately coincident with shaft speed at design. Thus, it is susceptible to excitation by geometric nonuniformities in the compressor. This new understanding of compressor dynamics is used to introduce the concept of travelling wave energy as a measure of compressor stability. Such a wave energy-based scheme is shown to consistently give an indication of low stability for significant periods (100–200 rotor revolutions) before stall initiation, even at 100% corrected speed.Copyright © 1994 by ASME