In this paper, we advocate a strategy for controlling class of turbomachine instabilities, whose primitive phases can be modeled by linear theory, but that eventually grow into performance-limiting modification the basic flow. The phenomena rotating stall and surge are two very different practical examples in which small disturbances to magnitudes such they limit machine performance. We develop theory shows how an additional disturbance, driven from real-time data measured within...

A double-sided, high-frequency response heat-flux gauge has been developed which allows measurement of heat flux from dc to 100 kHz. The instrument is designed for magnitudes ranging one several hundred kW/m2 at temperatures up 400 °C and independent the test article material. gauges consist a metal film (1500 Å) resistance thermometers sputtered on both sides thin (25 μm) polyimide sheet. sheet, can contain many gauges, then adhesively bonded article. temperature difference across direct...

The influence of inlet hot streak temperature distortion on turbine blade heat load was explored a transonic axial flow stage test article using three-dimensional, multiblade row unsteady Euler code. geometry the same as that used for recently reported testing influence. Emphasis placed elucidating physical mechanisms by which streaks affect durability. It found significantly increases both surface nonuniformity and total much 10–30 percent (mainly pressure surface), severity this is strong...

▪ Abstract The compression system instabilities known as surge and rotating stall are natural limits to the performance of all compressors especially troubling in gas turbine engines. In last 15 years, rapid progress has been made understanding this complex problem through application control technology; particular, identification techniques have proven be useful. New findings include roles compressibility nonlinearity stall-inception process. These used implement feedback schemes that...

Time-resolved turbine rotor blade heat transfer data are compared with ab initio numerical calculations. The was taken on a transonic, 4-to-1 pressure ratio, uncooled, single-stage in short duration test facility. consists of the time history distribution about chord at midspan. calculation is accurate, 2-D, thin shear layer, multiblade row code known as UNSFLO. UNSFLO uses Ni’s Lax-Wendroff algorithm, conservative boundary conditions, and tilting algorithm to facilitate flow multiple rows...

Time-resolved turbine rotor blade heat transfer data are compared with ab initio numerical calculations. The were taken on a transonic, 4-to-1 pressure ratio, uncooled, single-stage in short-duration test facility. consist of the time history distribution about chord at midspan. calculation is accurate, two-dimensional, thin shear layer, multiblade row code known as UNSFLO. UNSFLO uses Ni’s Lax-Wendroff algorithm, conservative boundary conditions, and tilting algorithm to facilitate flow...

Experiments were carried out to assess the influence of combustor-exit flow nonuniformities on turbine rotor blade heat transfer. Steady radial and circumferential temperature distortions as well velocity turbulence introduced at inlet a transonic stage their effects surface flux investigated. Heat was measured along chord three spanwise locations representing nominal tip, midspan hub radii. Inlet intensity changes from 0.5% 8% did not change flux. Both increased pressure significantly, much...

Ahstrart A computational and theoretical procedure is described for the analysis of flow instability in high speed, muhistage COInpreSWTS. Specifically, lhe paper presenu first rigorous type twedirnensianal, long wavelength, small amplitude, compressible perturbations which have been experimentally observed to develop into rotating stall. The shows that compressibility has a stabilizing influence both singlestage multistage machines. much more impwtant conclusion, however, axial structure...

Active stabilization of surge was implemented on an Allied Signal LTS-101 axicentrifugal gas producer, reducing the surging mass flow by 1 percent, for operating range increase 11 percent. Control achieved using high-response sensors in inlet and diffuser throat, coupled to actuators that injected air near throat. System identification modeling indicate a classical surge-type eigenmode associated with engine duct acoustics dominate engine’s input–output properties. The eigenmode’s stability...

Cavitation has long been a concern in the engineering of fluid machinery. The state art MEMS is now such that micro-machines are being designed and built which, by conventional macro-world criteria, can operate cavitating regimes. Specifically, cavitation 900-micron-chord cascades characteristic micro-centrifugal pumps was investigated through analysis experiment for working fluids water ethanol. primary finding these micro-devices exhibited static dynamic behavior very similar to expected...

This paper presents an experimental and analytical investigation of compressor stability assessment during engine transient operation. A 2-dimensional, linear, compressible, state-space analysis stall-inception (Feulner et al. (1996)) was modified to account for transients deterioration, with the latter modeled as increased tip-clearance flow blockage. Experiments were performed on large commercial aircraft engines in both undeteriorated deteriorated states. Unsteady measurements pressure...

Recent work has shown that compression systems can be actively stabilized against the instability known as surge, thereby realizing a significant gain in system mass flow range. Ideally, this surge stabilization requires only single sensor and actuator connected by suitable control law. Almost all research to date been aimed at proof of concept studies technique, using various actuators combinations. In contrast, reported herein regarded step towards developing active into practical...

Several years ago an effort was undertaken at MIT to develop high-speed rotating MEMS (Micro Electro-Mechanical Systems) using computer chip fabrication technology. To enable high-power density the micro-turbomachinery must be run tip speeds of order 500 m/s, comparable conventional scale turbomachinery. The high (of 2 million rpm), relatively low bearing aspect ratios (L/D < 0.1) due constraints, and laminar flow regime in gap place micro-bearing designs exotic spot design space for...

Time-resolved radial transport has been measured in a transonic compressor rotor by injecting thin sheet of tracer gas upstream the and then surveying concentration at exit. The simultaneous, co-located, high frequency response measurements local concentration, total temperature, pressure made downstream showed that most fluid transported radially appears blade wakes this considerably higher entropy than circumferential mean. Both inward outward along span was observed (3.5% throughflow...

A low-speed axial research compressor has been fitted with movable inlet guide vanes to allow for feedback stabilization of rotating stall. model exists whose structure captures the input-output behavior, and stall is possible using this model. Quantitative identification parameters in requires ability identify MIMO dynamics, which may be unstable, during closed loop operation. The 'instrumental variable' technique presented as basic approach problem. necessary extensions are discussed,...