Accession Number:

ADA231048

Title:

Constant-Current Stagnation-Point Film-Anemometer Probe

Descriptive Note:

Final rept. Jun-Dec 1989

Corporate Author:

CALSPAN CORP SAN DIEGO CA

Personal Author(s):

Report Date:

1991-01-01

Pagination or Media Count:

49.0

Abstract:

Hypersonic turbulence measurements of boundary layer stability and pressure, temperature, and velocity fluctuation levels in continuous-flow wind tunnels can require survey probes capable of withstanding uncommonly hostile test conditions, especially of temperature and dynamic pressure. Stagnation- point hot-film anemometer probes have demonstrated good durability in AEDC tunnels at Mach numbers 4,6,and 8. The present report addresses questions associated with the use of such probes for the quantitative measurement of flow fluctuations in wind tunnel test applications. The steady-state and time- dependent response characteristics of the hot-film probe are analyzed. The film is assumed infinitesimally thin, subjected to a constant electric current during operation, and deposited on a substrate in which the heat flow is one- dimensional. The conduction equation in the substrate is solved simultaneously with the film power flow, conductive transfer to the substrate, and ohmic heating. It is found that the film response is describable by two parameters 1 the intrinsic no-substrate film time constant, and 2 a substrate loss factor which is a mix of the film, flow, and substrate properties. The flow- fluctuation sensitivities of the heated film sensor are found to be similar to those of hot wires.

Subject Categories:

  • Test Facilities, Equipment and Methods
  • Fluid Mechanics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE