Abstract
The paper is introduced with a discussion on how a knowledge of total pressures in exhaust systems would help in the development of internal combustion engines. The concept of a total pressure in a steady flow is straightforward and well known but it is shown that under unsteady flow conditions the concept needs further qualification. A full discussion on the matter is given in the paper.
A brief review of previous work on similar types of probes is presented before the ‘Fecheimer’ type of probe is described. In order to test the probes a special ‘simple wave’ technique was used. A discussion of the technique together with the theory on which it is based is included. The tests on the Fecheimer type of probe are described and results presented. The second type of probe, which was an impact-tube type, is also described. The tests on the second type of probe revealed interesting results which were explained by a theoretical calculation. Details of the test results and the theoretical analysis which explain the results are discussed. It is shown that the theory could explain some of the results obtained with the Fecheimer type of probe.
Finally, conclusions are given on the concept of a total pressure and the results of the tests carried out on the probes are discussed.
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