This is an experimental rocket injector of ca. 1927 of U.S. rocket pioneer Robert H. Goddard. The larger projecting angled open pipe was most likely the oxidizer (liquid oxygen) inlet while the smaller diameter projecting pipe on the opposite side was probably the fuel (gasoline) inlet. The injector was to spray the oxidizer and fuel into fine streams into the combustion chamber of the rocket motor where they were ignited and burned.
The object shown here was found in the Smithsonian collections, but likely was originally part of a major gift of Goddard artifacts to the Smithsonian by the Daniel and Florence Guggenheim Foundation in 1950.
This object is on display in Rockets & Missiles at the Steven F. Udvar-Hazy Center in Chantilly, VA.