Experimental investigation of an 0.8 hub-tip radius-ratio,nontwisted-rotor-blade turbine

An experimental investigation of a 0.8 hub-tip radius ratio, nontwisted-rotor-blade turbine designed for a stagnation-pressure ratio of 2.5 and an equivalent mean blade speed of 643 feet per second was made in a cold-air turbine with (a) nontwisted stator blades, and (b) twisted stator blades designed to maintain zero rotor-inlet incidence angles. Turbine efficiencies of the order of 0.85 at the design point were obtained with a nontwisted-rotor-blade turbine with a hub-tip radius ratio of 0.80. The turbine with the twisted stator blades gave higher efficiencies at the design point (of the order of 1.5 percentage points) than the turbine with the nontwisted stator blades

NACA Technical Notes

From Introduction: "The purpose the present report is to investigate the aerodynamic characteristics of nontwisted-rotor-blade turbines and to evaluate the characteristics of this type of design by comparison with the characteristics of free-vortex designs.

NACA Research Memorandums

From Introduction: "A comparison is also made of the actual performance of two contemporary jet engines with estimated performance, assuming the engines were equipped with adjustable-angle stators and adjustable exhaust nozzles. Charts are presented that aid in estimating the performance of adjustable-stator turbines.

NACA Research Memorandums

In order to insure satisfactory turbine performance under five turbojet-engine operating conditions, turbine design requirements were determined for the following operating conditions: take-off, maximum thrust at altitude, altitude cruising at rated rotative speed, altitude cruising with maximum-thrust exhaust nozzle area, and engine acceleration at 80 percent equivalent design rotative speed. If cruising is to be at rated engine speed, both cruising and take-off should be considered in turbine design. Design requirements for the other conditions are nearly identical. Without compressor-exit bleed, a turbine cannot accelerate this compressor at 80 percent of rated speed; with 28.6-percent bleed, the design requirements are within those for take-off