The limited number of experimental investigations on similarity operation in the literature is not sufficient to state the validity of similarity laws for cross-flow fans. This is also due to the operating conditions occurring in practical applications, where the values of impeller size and rotational speed generally result in low Reynolds numbers and, then, in a non-negligible influence of viscous forces on performance. The analysis is further complicated by the high influence of the casing shape on performance, which can lead to induced effects on similarity operation. An experimental test program is presented in this paper, aimed at understanding the influence of Reynolds number on performance for different casing shapes. Five impellers having similar shape and different dimensions were tested, each one matched with five casings at different rotational speed. The results show that similarity laws can be applied with good approximation above critical blade Reynolds numbers of around 4000 to 15,000, depending on the geometrical characteristics of the casing. The strong scale effect, shown by some authors in the literature, is not observed in these tests.

1.
Ilberg, H., and Sadeh, W. Z., 1965–66, “Flow Theory and Performance of Tangential Fans,” Proc. Instn. Mech. Engrs., Vol. 180, Part 1, No 19.
2.
Eck, B. 1973, Fans, Pergamon Press, New York.
3.
Lajos, T., and Preszler, L., 1973, “On the Cross Flow Fan Theory. Part 1: Types of Fans, Operating Principles, Stream Configuration, Velocity Field (In German),” Heizung-Lu¨ftung-Haustechnik, 24 Nr. 5.
4.
Lajos, T., and Preszler, L., 1973, “On the Cross Flow Fan Theory. Part 2: Calculation of the Blade Circulation and the Flow Field, and Comparison of the Experimental Results With the Theory,” (in German). Heizung-Lu¨ftung-Haustechnik, 24 Nr. 6.
5.
Lajos, T., 1975, “Investigation of the Flow Characteristics in the Impeller of the Tangential Fan,” Proceedings of Sixth Conference on Fluid Machinery, Budapest.
6.
Tanaka, S., and Murata, S., 1994, “Scale Effect in Cross-Flow Fans (Effects of Fan Dimension on Performance Curves),” Bull. JSME, Series B, 37, No. 4.
7.
Tanaka, S., and Murata, S., 1995, “Scale Effect in Cross-Flow Fans (Effects of Fan Dimension on Flow Details and the Universal Representation on Performances),” Bull. JSME, Series B, 38, No. 3.
8.
Porter, A. M., and Markland, E., 1970, “A Study of the Cross Flow Fan,” J. Mech. Eng. Sci., 12, No. 6.
9.
Murata, S. I., and Nishihara, K., 1976, “An Experimental Study of Cross Flow-1st Report, Effects of Housing Geometry on the Fan Performance,” Bull. JSME, 19, No. 129.
10.
Murata, S. I., and Nishihara, K., 1976, “An Experimental Study of Cross Flow-2st Report, Movements of Eccentric Vortex inside Impeller,” Bull. JSME, 19, No. 129.
11.
Martegani, A. D, Macor, A., and Lazzaretto, A., 1995, “Theory and Experimental Investigation on Cross Flow Fans. Part II: Testing of a Model (In Italian),” Proceedings of 50° Congresso Nazionale ATI, Vol. 2, pp. 1696–1706, Saint Vincent, 11–15 September. SGEditoriali-Padova.
12.
Lazzaretto, A., Macor, A., Martegani, A. D., and Martina, V., 1997, “Experimental Optimization of the Casing of a Cross Flow Fan. (In Italian),” Proceedings of 52° Convegno Nazionale ATI, Cernobbio (CO), 22–26 September. SGEditoriali-Padova.
13.
UNI 10531, 1995, “Industrial Fans-Performance Testing and Acceptance Terms,” (in Italian), UNI (Italian National Center for Standardization), Milano.
14.
ISO 5801, 1993, “Industrial Fans-Performance Testing using Standardized Airways,” International Organization for Standardization.
15.
Martegani, A. D., Navarro, G., Macor, A., Lazzaretto, A., Masi, M., Antonello, M., and De Lorenzi, S., 1999, “Experimental and numerical analyses of a cross flow fan (In Italian),” Proceedings of 54° Congresso Nazionale ATI, Vol. 2, pp. 1409–1423, L’Aquila, 14–17 September. SGEditoriali-Padova.
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