Showing papers on "Performance prediction published in 1972"

Generalized simulation technique for turbojet engine system analysis

Abstract: A nonlinear analog simulation of a turbojet engine was developed The purpose of the study was to establish simulation techniques applicable to propulsion system dynamics and controls research A schematic model was derived from a physical description of a J85-13 turbojet engine Basic conservation equations were applied to each component along with their individual performance characteristics to derive a mathematical representation The simulation was mechanized on an analog computer The simulation was verified in both steady-state and dynamic modes by comparing analytical results with experimental data obtained from tests performed at the Lewis Research Center with a J85-13 engine In addition, comparison was also made with performance data obtained from the engine manufacturer The comparisons established the validity of the simulation technique

New technology in turbine aerodynamics.

Abstract: A cursory review is presented of some of the recent work that has been done in turbine aerodynamic research at NASA-Lewis Research Center. Topics discussed include the aerodynamic effect of turbine coolant, high work-factor (ratio of stage work to square of blade speed) turbines, and computer methods for turbine design and performance prediction. An extensive bibliography is included. Experimental cooled-turbine aerodynamics programs using two-dimensional cascades, full annular cascades, and cold rotating turbine stage tests are discussed with some typical results presented. Analytically predicted results for cooled blade performance are compared to experimental results. The problems and some of the current programs associated with the use of very high work factors for fan-drive turbines of high-bypass-ratio engines are discussed. Turbines currently being investigated make use of advanced blading concepts designed to maintain high efficiency under conditions of high aerodynamic loading. Computer programs have been developed for turbine design-point performance, off-design performance, supersonic blade profile design, and the calculation of channel velocities for subsonic and transonic flow fields. The use of these programs for the design and analysis of axial and radial turbines is discussed.

An application of statistical methodology in the study of computer system performance

Abstract: In planning for future data processing system performance requirements, as well as in the process of evaluating current system performance, there is a need to identify the proper variables of the environment, which will be the prime determinants of the system's performance, and to quantify the relationship This paper describes a method by which such identification and quantification may be achieved A real-life example in an installation environment using actual data is given and the resultant empirical model thus derived is described for the particular environment The results have enhanced our understanding of system performance in terms of CPU utilization with promising potential for applications in system design, performance optimization, performance prediction, and characterization of installations Some background leading to the particular problem as well as the future directions of the experiment are discussed in the paper

Multi-Mission Turbine Engine Propulsion Simulator Applications Study.

Abstract: : The turbine engine propulsion simulator being developed by the Air Force Aero Propulsion Laboratory is a promising wind tunnel testing tool which may be used to improve the procedure for aircraft performance prediction This study identifies the type of applications which will afford the most successful utilization of the simulator and the model designs which will yield the best results Three aircraft configurations have been used for this study (advanced tactical fighter, advanced bomber, and single-engine-lightweight fighter) These aircraft are representative of a wide range of engine installation types, and hence serve to identify most of the problem to be encountered in using the simulator The first part of this report addresses how the propulsion simulator should be used with wind tunnel test models and when in the development cycle of an aircraft it should be utilized In the second part, the feasibility of model designs incorporating the propulsion simulator is investigated Different balance arrangements and support systems have been developed for the three aircraft configurations The data accuracy, cost, and testing complexity for these designs have been evaluated The last section defines a program plan for developing and evaluating wind tunnel test techniques using the propulsion simulator (Author)

Simplified Modeling of Integrated Circuits for Radiation Performance Prediction

Abstract: : The report describes a simple method for developing computer models for digital and analog integrated circuits The models are capable of allowing computer prediction of both normal performance and performance when the devices are exposed to gamma and neutron radiation environments Device models have been developed for two NAND gates, two flip-flops, one four-bit Shift Register, a Monostable Multivibrator, an AND-OR-INVERTER, and two operational amplifiers All models are demonstrated to agree with observed laboratory performance for conditions of pulsed gamma radiation of 3 x 10 to the 10th power rads (Si)/ Second Neutron fluence levels of 12 x 10 to the 14th power neutrons per square centimeter, as well as non-radiation conditions The 'black box' technique is employed for model development The model descriptions were developed for use with the SCEPTRE circuit analysis program

Digital simulation of continuous error models with application to an instrument landing system error

Abstract: A digital simulation of the continuous error of the localized beam of a conventional instrument landing system is discussed. The digital simulation was developed during the analysis of space shuttle navigation capabilities. A discrete mathematical model for use on a digital computer is described. The model generates an output random sequence which is equivalent, for simulation purposes, to the desired random process. The model is a system of difference equations driven by a zero-mean Gaussian random sequence.