Laser absorption measurements of OH concentration and temperature in pulsed facilities

A laser absorption technique for measuring the thermomechanical state of OH in pulsed facilities is discussed. Experiments are carried out wherein a high-sensitivity ultraviolet laser absorption instrument is applied to expanding flows present in a shock tunnel facility nozzle at a frequency of 3.3 kiloHertz. The facility test time is found to exceed the test times normally associated with pulsed facilities.