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Recent developments of numerical and experimental methods for flow analysis have introduced new concept into design process of fluid machinery. In the basic design of multiblade fan, in which the flow is quite complicated by three-dimensionality and unsteadiness caused by rotating impeller with forward-curved blades and asymmetric housing, numerical and experimental methods are also replacing empirical techniques. Especially PIV method, which has been developed remarkably as a velocity field measurement technique, is powerful tool for the analysis of complicated flows induced in the multiblade fan, and the instantaneous velocity field measured by it can be also used to verify the reliability of numerical results. Recent requirements in the design of the multiblade fan being used in automobile air conditioning units are high pressure at high flow rate, noise reduction and downsizing to realize amenity in the cabin of automobile.

Two kinds of visual tests to recognize the interior air flow of a small pick-up truck are made. One way is the tuft stick grid, and another is numerical simulational analysis. The former is done with arranged tuft. The latter is done by using the super computer. The results of both are very simillar. The tuft stick grid is recognized as a simple, easy, and actual way to see the outline of the vehicle interior flow. Numerical analysis is done as an effective way to see more detail, and to more easily evaluate changes. Another case is calculated in which a doll model is assumed for the passengers. The results are used to predict the air conditioning (A/C) feeling by using the A/C feeling prediction system. The predicted results and the actual A/C feeling test results are similar to each other. As a result, it is said that the numerical simulational analysis is effective in predicting A/C feeling.