Patent ID: 6106229
Filing Date: 2000-08-22
Classification: F02C,F28D,F28F,Y02T

Abstract:
A heat exchanger system for a gas turbine engine that is disposed about an axis of rotation A.sub.r, the engine having a primary annular flow path for working medium gases disposed about the axis Ar and a secondary annular flow path for working medium gases disposed about the primary flow path, the secondary flow path having a fan duct which is bounded by walls including an inner wall, an outer wall, a radial bifurcator wall extending between the inner wall and the outer wall, the secondary flow path further having lines of flow extending along such walls which include flow lines Fd disturbed by the heat exchanger system and flow lines Fu undisturbed by the heat exchanger system, the heat exchanger system having a heat exchanger which has a heat exchanger inlet, a heat exchanger outlet, a flow path for the heat exchanger system which extends through the heat exchanger inlet and exit and which is in flow communication with the secondary working medium flow path in the fan duct, the heat exchanger system which comprises:an inlet having a first covered section havingan inner wall extending for a width W which is inwardly of the undisturbed flow line of the inner wall of the fan duct, the undisturbed flow line being spaced radially from the outer wall of the fan duct by a distance Hfd,an outer wall which extends circumferentially a width W, which is spaced rearwardly from and radially outward from the inner wall of the inlet by an inlet radial height Hi, and radially outward from the undisturbed flow line an exposed radial height Hf, the inlet having an exposure ratio which is the ratio of the exposed radial height Hf to the inlet radial height Hi and which is not greater than seventy percent of (Hf/Hi.ltoreq.0.7), and the inlet having an aspect ratio which is the ratio of an exposed radial height Hf to the width W of the inlet which is not greater than one half (Hf/W.ltoreq.0.50);a cavity for the heat exchanger which is flow communication with the inlet;an outlet having an exhaust passage which is in flow communication with the cavity which extends axially in the downstream direction, and which terminates at an outlet section, the outlet section being at a location at the inner wall having a static pressure such that an adverse static pressure gradient exists between the inlet and the outlet along a line of undisturbed flow, the outlet further having an outermost wall which is radially outwardly of the undisturbed flow line a maximum radial height Ho and having a width Wo and having an aspect ratio which is not greater than one-half (Ho/Wo.ltoreq.0.50);wherein the flow path for the heat exchanger system extends through the inlet, through the cavity for the heat exchanger and through the outlet and is uninterrupted under all operative conditions of the engine to flow cooling air continuously through the heat exchanger;wherein the inlet faces the oncoming flow and has a mass flow characteristic at the inlet that causes a rise in local static pressure under operative conditions that drives the captured gases along the flow path for the heat exchanger system even though an adverse static pressure gradient exists in the fan bypass duct along the undisturbed flow line at the inner wall between the inlet and outlet;wherein the heat exchanger system has levels of drag and foreign object damage tolerance which results from the exposure ratio of the inlet of less than seventy percent and the aspect ratio of the inlet of less than fifty percent.