Development of Turbulence-Measuring Equipment

Hot wire turbulence-measuring equipment has been developed to meet the more stringent requirements involved in the measurement of fluctuations in flow parameters at supersonic velocities. The higher mean speed necessitates the resolution of higher frequency components than at low speed, and the relatively low turbulence level present at supersonic speed makes necessary an improved noise level for the equipment. The equipment covers the frequency range from 2 to about 70,000 cycles per second. Constant-current operation is employed. Compensation for hot-wire lag is adjusted manually using square-wave testing to indicate proper setting. These and other features make the equipment adaptable to all-purpose turbulence work with improved utility and accuracy over that of older types of equipment. Sample measurements are given to demonstrate the performance

NACA Technical Reports

"Hot wire turbulence-measuring equipment has been developed to meet the more stringent requirements involved in the measurement of fluctuations in flow parameters at supersonic velocities. The higher mean speed necessitates the resolution of higher frequency components than at low speed, and the relatively low turbulence level present at supersonic speed makes necessary an improved noise level for the equipment. The equipment covers the frequency range from 2 to about 70,000 cycles per second" (p. 1)

Turbulent‐nonturbulent interface detector

An analog circuit is presented for the detection in real time of the turbulent‐nonturbulent interface at the free stream edge of turbulent shear flows. The output of the circuit is a square wave whose value is unity when the detector probe is in turbulent flow, and is zero when in nonturbulent flow. The effectiveness of several detection schemes is evaluated. A method for calibrating the detector circuit is given by using a ``synthetic,'' intermittently turbulent simulated signal of known intermittency properties. A circuit for generating the simulated signal is also presented.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/69674/2/RSINAK-45-9-1138-1.pd