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Krause, L. N.

Publications and source records attributed to Krause, L. N..

At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1981

Miniature drag-force anemometer

A miniature drag force anemometer is described which is capable of measuring unsteady as well as steady state velocity head and flow direction. It consists of a cantilevered beam with strain gages located at the base of the beam as the force measuring element. The dynamics of the beam are like those of lightly damped second order system with a natural frequency as high as 40 kilohertz depending on beam geometry and material. The anemometer is used in both forward and reversed flow. Anemometer characteristics and several designs are presented along with discussions of several applications.

Krause, L. N.↗
NASA NTRS1981

Miniature drag-force anemometer

A miniature drag-force anemometer is described which is capable of measuring unsteady as well as steady-state velocity head and flow direction. It consists of a cantilevered beam with strain gages located at the base of the beam as the force measuring element. The dynamics of the beam are like those of a lightly damped second-order system with a natural frequency as high as 40 kilohertz depending on beam geometry and material. The anemometer can be used in both forward and reversed flow. Anemometer characteristics and several designs are presented along with discussions of several applications.

Krause, L. N.↗
NASA NTRS1980

Some dynamic and time-averaged flow measurements in a turbine rig

Four types of sensors were used to make both dynamic and time-averaged flow measurements in a cold turbine rig to determine the magnitude of errors in time-averaged total-pressure measurement at a station 5 1/2 blade cords downstream from the rotor. The errors turned out to be negligible. The sensors and their intended use are discussed.

Krause, L. N.↗
NASA NTRS1979

Standardized gas-temperature probes

Standardization by two general probe designs and determination of various correction factors for range of sizes in each design reduces requirements for individual calibration and associated costs.

Glawe, G. E.↗
NASA NTRS1978

Thermocouples measure very-hot gas temperatures

Thermocouple probe incorporates small jet of inert gas to cool thermocouple. To measure gas temperatures, cooling jet is turned off momentarily, allowing thermocouple to heat up to near its melting point, then cooling is reapplied. Heating curve is recorded by high speed digital system. Computing system extrapolates final temperature thermocouple would have attained.

Glawe, G. E.↗
NASA NTRS1978

Multipurpose miniature drag-force anemometer

Simple, rugged, accurate probe measures steady-state and dynamic flow angle, and turbulence intensity in flowing fluids at subsonic velocity. Probe is simpler in design and calibration, and more durable, than hot-wire and hot-film anemometers and is not affected by flow contamination. It is less expensive and complex than laser anemometers. Associated electronics are as simple as those of strain-gage pressure transducers.

Fralick, G. C.↗
NASA NTRS1978

Recovery and radiation corrections and time constants of several sizes of shielded and unshielded thermocouple probes for measuring gas temperature

Performance characteristics were experimentally determined for several sizes of a shielded and unshielded thermocouple probe design. The probes are of swaged construction and were made of type K wire with a stainless steel sheath and shield and MgO insulation. The wire sizes ranged from 0.03- to 1.02-mm diameter for the unshielded design and from 0.16- to 0.81-mm diameter for the shielded design. The probes were tested through a Mach number range of 0.2 to 0.9, through a temperature range of room ambient to 1420 K, and through a total-pressure range of 0.03 to 0.2.2 MPa (0.3 to 22 atm). Tables and graphs are presented to aid in selecting a particular type and size. Recovery corrections, radiation corrections, and time constants were determined.

Glawe, G. E.↗
NASA NTRS1977

Use of miniature, single-wire, sheathed thermocouples

Temperature measurement with small thermocouples is improved by device. Each wire is sheathed separately which increases the interelement insulation by factor of 2 1/2. Each wire in its separate sheath can be brought to junction by independent paths.

Glawe, G. E.↗
NASA NTRS1977

Miniature drag-force anemometer

A miniature drag-force anemometer is described which is capable of measuring dynamic velocity head and flow direction. The anemometer consists of a silicon cantilever beam 2.5 mm long, 1.5 mm wide, and 0.25 mm thick with an integrated diffused strain-gage bridge, located at the base of the beam, as the force measuring element. The dynamics of the beam are like those of a second-order system with a natural frequency of about 42 kHz and a damping coefficient of 0.007. The anemometer can be used in both forward and reversed flow. Measured flow characteristics up to Mach 0.6 are presented along with application examples including turbulence measurements.

Krause, L. N.↗
NASA NTRS1977

Miniature drag force anemometer

A miniature drag force anemometer is described which is capable of measuring dynamic velocity head and flow direction. The anemometer consists of a silicon cantilevered beam 2.5 mm long, 1.5 mm wide, and 0.25 mm thick with an integrated diffused strain gage bridge, located at the base of the beam, as the force measuring element. The dynamics of the beam are like that of a second order system with a natural frequency of about 42 kHz and a damping coefficient of 0.007. The anemometer can be used in both forward and reversed flow. Measured flow characteristics up to Mach 0.6 are presented along with application examples including turbulence measurements.

Krause, L. N.↗
NASA NTRS1976

A new approach to the pulsed thermocouple for high gas temperature measurements

Pulsed thermocouple systems can be used to measure gas temperatures above the melting point of the thermocouple by various techniques of short term of intermittent exposure of the thermocouple operating at lower temperatures. An approach is described which uses a thermocouple cooled by a small jet of inert gas. When a measurement is to be made, the cooling jet is turned off and the thermocouple allowed to heat up to near its melting point, at which time the cooling is reapplied. The final temperature which the thermocouple should have attained is then calculated by extrapolating an exponential curve fit to the data. Temperature measurements can be recorded and displayed in near real time by using modern high-speed computing systems to perform these calculations. Examples of the technique applied to high temperature jet engine combustor development are presented.

Glawe, G. E.↗
NASA NTRS1976

A new approach to the pulsed thermocouple for high gas temperature measurements

Pulsed thermocouple systems can be used to measure gas temperatures above the melting point of the thermocouple by various techniques of short term or intermittent exposure of the thermocouple operating at lower temperatures. This paper describes an approach which uses a thermocouple cooled by a small jet of inert gas. When a measurement is to be made, the cooling jet is turned off and the thermocouple allowed to heat up to near its melting point, at which time the cooling is reapplied. The final temperature which the thermocouple should have attained is then calculated by extrapolating an exponential curve fit to the data. Temperature measurements can be recorded and displayed in near real time by using modern high-speed computing systems to perform these calculations. Examples of the technique applied to high temperature jet engine combustor development are presented.

Glawe, G. E.↗
NASA NTRS1975

Miniature probes for use in gas turbine testing

Because of space limitations and system complexity in many applications associated with gas turbine testing, extremely small flow measuring probes have sometimes been required. This paper presents several examples of these miniature probes - null type as well as fixed position - which have proved useful in aircraft and space power systems component testing and are applicable to automotive gas turbine testing. These probes are used to determine component or system performance from the measurement of gas temperature as well as total and static pressure, and flow direction. Detailed drawings of the sensors are presented along with experimental data covering the flow characteristics over the range of intended use.

Glawe, G. E.↗
NASA NTRS1974

Miniature sheathed thermocouples for turbine blade temperature measurement

An investigation was made of sheathed thermocouples for turbine blade temperature measurements. Tests were performed on the Chromel-Alumel sheathed thermocouples with both two-wire and single-wire configurations. Sheath diameters ranged from 0.25 to 0.76 mm, and temperatures ranged from 1080 to 1250 K. Both steady-state and thermal cycling tests were performed for times up to 450 hr. Special-order and commercial-grade thermocouples were tested. The tests showed that special-order single-wire sheathed thermocouples can be obtained that are reliable and accurate with diameters as small as 0.25 mm. However, all samples of 0.25-mm-diameter sheathed commercial-grade two-wire and single-wire thermocouples that were tested showed unacceptable drift rates for long-duration engine testing programs. The drift rates were about 1 percent in 10 hr. A thermocouple drift test is recommended in addition to the normal acceptance tests in order to select reliable miniature sheathed thermocouples for turbine blade applications.

Holanda, R.↗
NASA NTRS1974

Miniature probes for use in gas turbine testing

Several examples of miniature probes (null type as well as fixed position) are presented which have proved useful in aircraft and space power systems component testing and are applicable to automotive gas turbine testing. These probes are used to determine component or system performance from the measurement of gas temperature as well as total and static pressure, and flow direction. Detailed drawings of the sensors are presented along with experimental data covering the flow characteristics over the range of intended use.

Glawe, G. E.↗
NASA NTRS1973

Total-pressure measurement in pulsating flows

Pneumatic-type probe was used as comparison instrument with total pressure tubes to determine true average pressure and, thus, to determine if nonlinear averaging effects were significant. Since pneumatic probe is more complicated to use than a total-pressure tube, it is used only as a comparison instrument to determine extent of averaging effects.

Krause, L. N.↗
NASA NTRS1973

Total-pressure-tube averaging in pulsating flows.

A number of total-pressure tubes were tested in a nonsteady flow generator in which the fraction of period that pressure is a maximum is approximately 0.8, thereby simulating turbomachine-type flow conditions. The tests were performed at a pressure level of 1 bar, for Mach numbers up to near 1, and frequencies up to 3 kHz. Most of the tubes indicated a pressure which was higher than the true average. Organ-pipe resonances which further increased the indicated pressure were encountered within the tubes at discrete frequencies. There was no obvious combination of tube diameter, length, and/or geometry variation used in the tests which resulted in negligible averaging error. A pneumatic-type probe was found to measure true average pressure, and is suggested as a comparison instrument to determine whether nonlinear averaging effects are serious in unknown pulsation profiles.

Krause, L. N.↗