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  • Other Sources  (663)
  • Aircraft Propulsion and Power
  • Cell & Developmental Biology
  • Seismology
  • 2005-2009  (596)
  • 1940-1944  (35)
  • 1935-1939  (32)
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  • 1
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    Low-noise fan exit guide vanes (2008)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: Low-noise fan exit guide vanes are disclosed. According to the present invention a fan exit guide vane has an outer shell substantially shaped as an airfoil and defining an interior cavity. A porous portion of the outer shell allows communication between the fluctuations in the air passing over the guide vane and the interior cavity. At least one acoustically resonant chamber is located within the interior cavity. The resonant chamber is in communication with the porous portion of the outer perimeter. The resonant chamber is configured to reduce the noise generated at a predetermined frequency. In various preferred embodiments, there is a plurality of acoustically resonant chambers located within the interior cavity. The resonant chambers can be separated by one or more partitions within the interior cavity. In these embodiments, the resonant chambers can be configured to reduce the noise generated over a range of predetermined frequencies.
    Keywords: Aircraft Propulsion and Power
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 2
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    Shape memory alloy actuated adaptive exhaust nozzle for jet engine (2009)
    In:  CASI
    Details
    Publication Date: 2019-08-26
    Description: The proposed adaptive exhaust nozzle features an innovative use of the shape memory alloy (SMA) actuators for actively control of the opening area of the exhaust nozzle for jet engines. The SMA actuators remotely control the opening area of the exhaust nozzle through a set of mechanism. An important advantage of using SMA actuators is the reduction of weight of the actuator system for variable area exhaust nozzle. Another advantage is that the SMA actuator can be activated using the heat from the exhaust and eliminate the need of other energy source. A prototype has been designed and fabricated. The functionality of the proposed SMA actuated adaptive exhaust nozzle is verified in the open-loop tests.
    Keywords: Aircraft Propulsion and Power
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 3
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    Tandem Air Propellers (1937)
    In:  CASI
    Details
    Publication Date: 2019-08-26
    Description: Tests of 2-blade, adjustable-pitch, counterrotating tandem model propellers, adjusted to absorb equal power at maximum efficiency, were made at Stanford University. The characteristics, for 15 degrees, 25 degrees, 35 degrees, and 45 degrees pitch settings at 0.75 R of the forward propeller and for 8 1/2%, 15% and 30% diameter spacings, were compared with those of 2-blade and 4-blade propellers of the same blade form. The tests showed that the efficiency of the tandem propellers was from 0.5% to 4% greater than that of a 4-blade propeller and, at the high pitch settings, not appreciable inferior to that of a 2-blade propeller. It was found that the rear tandem propeller should be set at a pitch angle slightly less than that of the forward propeller to realize the condition of equal power at maximum efficiency. Under this condition the total power absorbed by the tandem propellers was from 3% to 9% more than that absorbed by the 4-blade propeller and about twice that absorbed by a 2-blade propeller.
    Keywords: Aircraft Propulsion and Power
    Type: NACA-SR-66
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 4
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    Advanced Thermal HPT Clearance Control (2006)
    In:  CASI
    Details
    Publication Date: 2019-08-17
    Description: OBJECTIVE: Develop a fast acting HPT Active Clearance Control System to improve engine efficiency and reduce emissions CHALLENGE: Reduction of HPT blade clearance throughout engine operation System complexity, reliability and cost must remain comparable or surpass today s engines Reduced clearance may increase possibility of rubs
    Keywords: Aircraft Propulsion and Power
    Type: 2005 NASA Seal/Secondary Air System Workshop, Volume 1; 167-178; NASA/CP-2006-214383/VOL1
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 5
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    Compressibility and Heating Effects on Pressure Loss and Cooling of a Baffled Cylinder Barrel (1944)
    In:  CASI
    Details
    Publication Date: 2019-08-17
    Description: Theoretical investigations have shown that, because air is compressible, the pressure-drop requirements for cooling an air-cooled engine will be much greater at high altitudes and high speeds than at sea level and low speeds. Tests were conducted by the NACA to obtain some experimental confirmation of the effect of air compressibility on cooling and pressure loss of a baffled cylinder barrel and to evaluate various methods of analysis. The results reported in the present paper are regarded as preliminary to tests on single-cylinder and multi-cylinder engines. Tests were conducted over a wide range of air flows and density altitudes.
    Keywords: Aircraft Propulsion and Power
    Type: NACA-TR-783
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 6
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    A Demonstration of a Retrofit Architecture for Intelligent Control and Diagnostics of a Turbofan Engine (2005)
    In:  CASI
    Details
    Publication Date: 2019-08-15
    Description: A retrofit architecture for intelligent turbofan engine control and diagnostics that changes the fan speed command to maintain thrust is proposed and its demonstration in a piloted flight simulator is described. The objective of the implementation is to increase the level of autonomy of the propulsion system, thereby reducing pilot workload in the presence of anomalies and engine degradation due to wear. The main functions of the architecture are to diagnose the cause of changes in the engine s operation, warning the pilot if necessary, and to adjust the outer loop control reference signal in response to the changes. This requires that the retrofit control architecture contain the capability to determine the changed relationship between fan speed and thrust, and the intelligence to recognize the cause of the change in order to correct it or warn the pilot. The proposed retrofit architecture is able to determine the fan speed setting through recognition of the degradation level of the engine, and it is able to identify specific faults and warn the pilot. In the flight simulator it was demonstrated that when degradation is introduced into an engine with standard fan speed control, the pilot needs to take corrective action to maintain heading. Utilizing the intelligent retrofit control architecture, the engine thrust is automatically adjusted to its expected value, eliminating yaw without pilot intervention.
    Keywords: Aircraft Propulsion and Power
    Type: NASA/TM-2005-214019 , ARL-TR-3667 , AIAA Paper 2005-6905 , E-15334 , Infotech; Sep 26, 2005 - Sep 29, 2005; Arlington, VA; United States
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    NASA TECHNICAL REPORTS
  • 7
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    Unitized Regenerative Fuel Cell System Gas Storage-Radiator Development (2005)
    In:  CASI
    Details
    Publication Date: 2019-08-15
    Description: High-energy-density regenerative fuel cell systems that are used for energy storage require novel approaches to integrating components in order to preserve mass and volume. A lightweight unitized regenerative fuel cell (URFC) energy storage system concept is being developed at the NASA Glenn Research Center. This URFC system minimizes mass by using the surface area of the hydrogen and oxygen storage tanks as radiating heat surfaces for overall thermal control of the system. The waste heat generated by the URFC stack during charging and discharging is transferred from the cell stack to the surface of each tank by loop heat pipes, which are coiled around each tank and covered with a thin layer of thermally conductive carbon composite. The thin layer of carbon composite acts as a fin structure that spreads the heat away from the heat pipe and across the entire tank surface. Two different-sized commercial-grade composite tanks were constructed with integral heat pipes and tested in a thermal vacuum chamber to examine the feasibility of using the storage tanks as system radiators. The storage tank-radiators were subjected to different steady-state heat loads and varying heat load profiles. The surface emissivity and specific heat capacity of each tank were calculated. In the future, the results will be incorporated into a model that simulates the performance of similar radiators using lightweight, spacerated carbon composite tanks.
    Keywords: Aircraft Propulsion and Power
    Type: NASA/TM-2005-213442 , E-14978 , SAE Power Systems Conference; Nov 02, 2005 - Nov 04, 2005; Reno, Nevada; United States
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 8
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    Development and Characterization Testing of an Air Pulsation Valve for a Pulse Detonation Engine Supersonic Parametric Inlet Test Section (2005)
    In:  CASI
    Details
    Publication Date: 2019-08-15
    Description: In pulse detonation engines, the potential exists for gas pulses from the combustor to travel upstream and adversely affect the inlet performance of the engine. In order to determine the effect of these high frequency pulses on the inlet performance, an air pulsation valve was developed to provide air pulses downstream of a supersonic parametric inlet test section. The purpose of this report is to document the design and characterization tests that were performed on a pulsation valve that was tested at the NASA Glenn Research Center 1x1 Supersonic Wind Tunnel (SWT) test facility. The high air flow pulsation valve design philosophy and analyses performed are discussed and characterization test results are presented. The pulsation valve model was devised based on the concept of using a free spinning ball valve driven from a variable speed electric motor to generate air flow pulses at preset frequencies. In order to deliver the proper flow rate, the flow port was contoured to maximize flow rate and minimize pressure drop. To obtain sharp pressure spikes the valve flow port was designed to be as narrow as possible to minimize port dwell time.
    Keywords: Aircraft Propulsion and Power
    Type: NASA/TM-2005-213893 , E-15264
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 9
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    Endwall Treatment and Method for Gas Turbine (2006)
    In:  CASI
    Details
    Publication Date: 2019-08-13
    Description: An endwall treatment for a gas turbine engine having at least one rotor blade extending from a rotatable hub and a casing circumferentially surrounding the rotor and the hub, the endwall treatment including, an inlet formed in an endwall of the gas turbine engine adapted to ingest fluid from a region of a higher-pressure fluid, an outlet formed in the endwall and located in a region of lower pressure than the inlet, wherein the inlet and the outlet are in a fluid communication with each other, the outlet being adapted to inject the fluid from the inlet in the region of lower pressure, and wherein the outlet is at least partially circumferentially offset relative to the inlet.
    Keywords: Aircraft Propulsion and Power
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 10
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    NACA Investigation of a Jet-Propulsion System Applicable to Flight (1943)
    In:  CASI
    Details
    Publication Date: 2019-08-13
    Description: Following a brief history of the NACA investigation of jet propulsion, a discussion is given of the general investigation and analysis leading to the construction of the jet-propulsion ground-test mock-up. The results of burning experiments and of test measurements designed to allow quantitative flight performance predictions of the system are presented and correlated with calculations. These calculations are then used to determine the performance of the system on the ground and in the air at various speeds and altitudes under various burning conditions. The application of the system to an experimental airplane is described and some performance predictions for this airplane are made.
    Keywords: Aircraft Propulsion and Power
    Type: NACA/TR-802
    Format: application/pdf
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    NASA TECHNICAL REPORTS
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